Environ Sci Pollut Res DOI 10.1007/s11356-017-8687-0 REVIEW ARTICLE Agroforestry: a sustainable environmental practice for carbon sequestration under the climate change scenarios—a review Farhat Abbas 1 & Hafiz Mohkum Hammad 2 & Shah Fahad 3 & Artemi Cerdà 4 & Muhammad Rizwan 1 & Wajid Farhad 5 & Sana Ehsan 1 & Hafiz Faiq Bakhat 2 Received: 16 November 2016 / Accepted: 22 February 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract Agroforestry is a sustainable land use system with a promising potential to sequester atmospheric carbon into soil. This system of land use distinguishes itself from the other systems, such as sole crop cultivation and afforestation on croplands only through its potential to sequester higher amounts of carbon (in the above- and belowground tree biomass) than the aforementioned two systems. According to Kyoto protocol, agroforestry is recognized as an afforestation activity that, in addition to sequestering carbon dioxide (CO2) to soil, conserves biodiversity, protects cropland, works as a windbreak, and provides food and feed to human and livestock, pollen for honey bees, wood for fuel, and timber for shelters construction. Agroforestry is more attractive as a land use practice for the farming community worldwide instead of cropland and forestland management systems. This practice is a win–win situation for the farming community and for the environmental sustainability. This review presents agroforestry potential to counter the increasing concentration of Responsible editor: Philippe Garrigues * Farhat Abbas farhat@gcuf.edu.pk * Shah Fahad fahad80@yahoo.com; shah.fahad@mail.hzau.edu.cn 1 Department of Environmental Sciences and Engineering, Government College University, Faisalabad 38000, Pakistan 2 Department of Environmental Sciences, COMSATS Institute of Information Technology, Vehari 61100, Pakistan 3 College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China 4 Departament de Geografia, Universitat de València, Blasco Ibàñez, 28, 46010 Valencia, Spain 5 Department of Agronomy, Lasbela University of Agriculture, Water and Marine Sciences, Uthal 90150, Pakistan atmospheric CO2 by sequestering it in above- and belowground biomass. The role of agroforestry in climate change mitigation worldwide might be recognized to its full potential by overcoming various financial, technical, and institutional barriers. Carbon sequestration in soil by various agricultural systems can be simulated by various models but literature lacks reports on validated models to quantify the agroforestry potential for carbon sequestration. Keywords Climate variability . Environmental sustainability . Forest . Land use management . Model . Soil Background An agroforestry system Growing of trees in combination with other field agricultural activities, such as cultivation of crops and rearing of animals, can typically be termed as an agroforestry system. Agroforestry practices on agricultural land make an important contribution to climate change mitigation, but are not systematically accounted for in either global carbon budgets or national carbon accounting. Agroforestry has traditionally been important elements of temperate regions around the world. This practice results in a number of benefits including ensured food security, enhanced biodiversity, enrichment of an ecosystem with increased resources, and attainment of various environmental targets, e.g., maintaining atmospheric CO2 to certain limits (Ajayi et al. 2011). In addition, the trees just planted on 3–5% of agricultural lands increase farm productivity, reduce vulnerability to climate change, and decrease greenhouse gases emission (Possu et al. 2016); hence, the practice has been regarded as climate-smart agriculture (FAO 2010). Cumulatively, these benefits provide mitigation strategies to Environ Sci Pollut Res global climate change impacts (Schoeneberger et al. 2012; Cubbage et al. 2013). The main goals of agroforestry system are increasing the overall productivity and efficiency of a land use system (Nair 2005). Agroforestry systems have higher capability to store carbon in above- and belowground as compared to treeless systems (Montagnini and Nair 2004). Therefore, this system provides a sink for of atmospheric carbon. The trees, especially those with a deep rooting systems, store a large amount of atmospheric carbon in their biomass on long-term basis. Furthermore, Steinbeiss et al. (2008) reported that specific functional traits of trees with grassland species increase carbon uptake into the underground environment through resource partitioning. Afforestation with crop production can be a strategy to control carbon fluxes in atmosphere and to mitigate climate change impacts on ecosystem (Lal 2004a; Fialho and Zinn 2014; De Moraes Sá et al. 2015; Ono et al. 2015; Muñoz-Rojas et al. 2015). Agroforestry has gained high attention in most of the developing countries for its potential for mitigating the climate variability and atmospheric CO2 sequestration (Anderson and Zerriffi 2012). This is because the climate change adaptation and mitigation objectives are highly dependent on agroforestry (Matocha et al. 2012; Stavi and Lal 2013). Therefore, agroforestry can instantaneously help addressing climate and development goals by Fig. 1 The global carbon cycle with different reservoirs and the exchange of carbon between the reservoirs. The black arrows show the natural processes of carbon transfer, while the red arrows show changes creating Bco-benefits^ such as providing alternate energy source and maintaining the impact land use change on flora and fauna of a region (Watson et al. 2000; May et al. 2005; Pandey 2007; Roshetko et al. 2007; Nair et al. 2009a). The land use and land cover changes Land use is exercising various agricultural and nonagricultural (development) practices, whereas the land cover change increases or decreases of a given type of land use or land cover. Under this context, soil formation due to changes in vegetation land cover induced by global climate variations are at the forefront of environmental discussions (Brevik et al. 2015; Keesstra et al. 2016; Fahad and Bano 2012; Fahad et al., 2013, 2014a, b, 2015a, b, 2016a, b, c, d). The phenomena of geochemical and biological cycles and their impact on the resources, goods, and services the soils and the vegetation offer to the societies is important to understand to figure out the role of a soil system and the carbon cycle (Keesstra et al. 2012; Mol and Keesstra 2012; Decock et al. 2015; Smith et al. 2015; Berendse et al. 2015). The carbon cycle (Fig. 1) is a key part of the environmental systems of the soil and the vegetation and their management that determine the potential use of soil for the land cover change dynamics of earth system (Gümüs and Şeker 2015; driven by anthropogenic activities. The values are in units of gigatons of carbon per year (Bralower and Bice 2016) Environ Sci Pollut Res Garcia-Diaz et al. 2016; Mukhopadhyay et al. 2016). The management of the crop production is a key factor on agriculture and forest lands (Wasak and Drewnik 2015; Musinguzi et al. 2015; Turgut 2015; Novara et al. 2015) that can determine the carbon cycle and consequently changes related to it under the scenarios of climate change (Abbasi et al. 2015; Parras-Alcántara et al. 2015; Peng et al. 2015). The recent literature reported on the impact of management of the soil organic matter and the quantification of atmospheric carbon sequestration (Bruun et al. 2015; De Oliveira et al. 2015; Behera and Shukla 2015 and references therein). Greenhouse gases in atmosphere Gaseous formation of earth’s atmosphere composes major greenhouse gases (GHGs) including water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (NO), and ozone (O3) in addition to traces of other minor GHGs (Hussain et al. 2014). In the earth’s atmosphere, CO2 is among major GHGs. Atmospheric presence of GHGs governs average ambient air temperature, i.e., −18 °C in absence of GHGs and 15 °C in presence of GHGs (Ming et al. 2014). The earth’s climate is changing in direct response to anthropogenic GHGs emission as manifested by increase in the global average temperatures, rise of the sea levels, and melting of snow glaciers (Intergovernmental Panel on Climate Change (IPCC) 2007a; Achard et al. 2014; Liu et al. 2014; Anaya-Romero et al. 2015). The buildup of GHGs including CO2 in the atmosphere is the major cause of global climate change. The global food production is estimated to contribute at the minimum of one third of all global anthropogenic GHGs emissions, more than twice than that of the transport sector (IPCC 2007b; Scialabba and Muller-Lindenlauf 2010). Agriculture alone contributes between 10 and 25% of annual GHGs, both directly and indirectly, through land use changes, land management, and production practices (Scialabba and Muller-Lindenlauf 2010; Smith et al. 2007). The atmospheric concentration of CO2 and other GHGs has also been increased since the industrial revolution (Cerdà et al. 2010). Though not all of released CO2 is stored in the earth’s atmosphere, considerable quantities are sequestered by land-based sinks, i.e., nearly 27.5% of CO2 productions by anthropogenic activities are taken up and recycled (Peters et al. 2012). Recent reports from the IPCC propose that even if substantial reductions in anthropogenic carbon emissions are achieved in the near future, efforts to sequester previously emitted carbon will be necessary to ensure safe levels of atmospheric carbon and to mitigate impact of climate change (Smith et al. 2014). Carbon dioxide production in the air is believed to be enhanced by anthropogenic activities especially due to deforestation and burning of fossil fuels. Increased atmospheric CO2 is considered to be the predominant reason of global climatic variability (IPCC 2007b). Furthermore, atmospheric CO2 have touched to 400 ppm (Le Quéré et al. 2015) and is predicted to reach between 700 to 900 ppm (Watson-Lazowski et al. 2016). Limiting of atmospheric CO2 concentration is possible through forest restoration and agroforestry (Montagnini and Nair 2004). There is a growing interest to identify the role of various land use systems contribution in stabilizing the atmospheric CO2 and decreasing its emissions (Murthy et al. 2013). It is anticipated that agricultural practices could modulate the increasing CO2 levels by carbon sequestration. Similarly, substitute agricultural practices not only sequester carbon but also can substitute fossil fuel consumption with biomass production. Agroforestry systems store carbon in biomass and sequester CO2 by photosynthetic processes (David and Crane 2002; Benites et al. 1999). Additionally, several studies have demonstrated that degraded land quality could be restored by adopting agroforestry system (Shazana et al. 2013; Novara et al. 2013; Tesfaye et al. 2014). Therefore, proper management of agroforestry land use systems can act as a vital option in decreasing atmospheric CO2 (Post and Kwon 2000). This system have substantially changed the land use from lone crop cultivation to adding trees and sequestering carbon in above- and belowground biomass and have fascinated the environmentalists of both developed and developing countries (IPCC 2000a; Makundi and Sathaye 2004; Takimoto et al. 2008; Gutierrez et al. 2009; Nair 2012; Poeplau and Don 2013). Therefore, agroforestry offers great potential for sequestering carbon and producing biomass for biofuels like many other land use systems (Jose and Bardhan 2012). As these have ability to capture a significant amount of atmospheric CO2 and accumulate the carbon in soil and plants. Although agroforestry systems are not primarily designed as a solution to decrease atmospheric CO2 yet it can play a major role in capturing or storing carbon in above and belowground biomass (Sathaye et al. 2001). An agroforestry approach Field- and home-based approaches Agroforestry is defined as a land use system in which trees deliver biomass and environmental services. In these arrangements, various cropping systems are merged with tree plantation in the same locality for a positive change in environment and net economic returns for the farmers (Otegbeye 2002). Alao and Shuaibu (2013) defined agroforestry system as a unique arrangement of trees, crops, and animals in space and time. Agroforestry is recognized as an afforestation activity for GHGs mitigation under the Kyoto Protocol (Nair et al. 2009b). Cultivation of crops along with tree plantation in agricultural fields recovers soil fertility, prevents soil erosion, regulates water infiltration, reduces pressure on forests for fuel, and produces forage for animals (Makundi and Sathaye 2004; Yu and Jia 2014). These land use systems also maintain several other ecosystem services such as increasing, species Environ Sci Pollut Res diversity, carbon sequestration, improving soil and ecosystem health and reducing emissions of CO2 (Nair et al. 2010; Garrity et al. 2010; Hu et al. 2015; Thakur et al. 2015). Agroforestry reduces the water losses by drainage and evaporation from soil surface and improves water use efficiency (Bayala and Wallace 2015). Rockström (1997) estimated that approximately 40% of the rainfall water in water harvesting systems was lost as evaporation while drainage caused 33–40% water losses, with only 6–16% being used by crop. Therefore, planting trees can reduce high percentages of available water lost as evaporation and drainage (Ong et al. 2006). The additional benefit of planting trees with crops is that trees do not compete with crops for the water recourses as the trees mainly absorb water beneath the root zone of crop plants below the surface soil. In arid regions, the field crop roots benefit from the soil moisture present in the rhizosphere due to hydraulic lift of water by trees (Burgess et al. 1998; Jackson et al. 2000; Hultine et al. 2003; Hao et al. 2009). change from forest to cropland caused carbon losses from the soil but conversion of forest to pastures land might increase the net carbon in the soil due to high carbon and nitrogen stocks, higher soil microbial biomass and lower respiratory quotient results in net carbon sequestration in the soil. The establishment of agroforestry as home garden and coffee production on agriculture land caused SOC stocks to rebound to near forest levels. On the other hands, planting mango and coconut trees increased SOC stocks slightly above the agriculture SOC stocks. The authors have found a strong correlation between tree species diversity in home garden and coffee agroforestry and SOC stocks (Cadotte 2013). Therefore, judicious use of agroforestry practices should be made to enhance the system use efficiency for agricultural productivity on sustainable basis in combination with meeting other societal needs from forestry (Fagbemi 2002). This is a win–win situation both in terms of meeting human demand as well as environment sustainability for longer period of time (Alao and Shuaibu 2013). Agroforestry and soil organic carbon stocks Atmospheric carbon sequestration Several farmers in developing countries practice agroforestry and economically benefit from it (Sarkhot et al. 2007). Although several researchers reported that agroforestry land use systems have a higher capability to sequester CO2 than croplands, but it greatly depends on the environment of the area, biological, physical, and socioeconomic features of the land use system (Sanchez 2000; Sharrow and Ismail 2004; Nair and Nair 2014). Hombegowda et al. (2016) studied the effect of four land use systems: a natural forest, agriculture, and two agroforestry types of two ages (30–60 and >60 years) on carbon stocks in soils. The conversion of forest land use to agricultural system resulted in huge losses (50–61%) of original soil organic carbon (SOC) stocks in the top soil (Straaten et al. 2015). In addition to land use system, soil type can also change the SOC losses when forest land use is changed to agriculture land use (McDonagh et al. 2001; Birch-Thomsen et al. 2007). A detailed study conducted by Muñoz-Rojas et al. (2015) they evaluated the transformation of land use and land cover changes between 1956 and 2007 in Andalusia, containing the data of 1357 soil profiles. Land use changes resulted in SOC losses, specifically in Cambisols, Luvisols, and Vertisols, with the total loss of 16.8 Tg (approximately 0.33 Tg year−1). The area where forest plantation was done, increased SOC in the topsoil and it contributed 862 Mg ha−1 of SOC stocks (25%) (Muñoz-Rojas et al. 2015). Cultivation of the Vertisol for 20 years resulted in 40% lower SOC content in comparison to area under forest land use and during this time about 95% of the forest originated SOC was lost in area under cultivation. In contrast, Ultisol cultivation resulted only 20% lower SOC than soil under forest land use and only 30% of the forest originated SOC was lost (Bruun et al. 2015). However, Ferreira et al. (2016) demonstrated that land use Carbon is present in various forms in different parts of the Earth. In the atmosphere carbon present as CO2 converted into various organic compounds through photosynthesis. The photosynthetically metabolized CO2 is converted back in to CO2 through respiration. Some of the carbon from the atmosphere is absorbed by the ocean that subsequently is converted into sedimentary rocks, and much later, this carbon may be released to the atmosphere. So carbon moves around, it flows from place to place and circulates among various components in the cycle as shown in Fig. 1. The continued buildup of atmospheric CO2 over the last century with projected rise in near future (Paustian et al. 2000) has raised serious concern among the environmentalists. The increased CO2 in the atmosphere have some benefits as it serves as a stimulant to improve plants growth and productivity (Schaffer et al. 1997; Keutgen and Chen 2001). However, climate extremes including rising temperatures and uneven distribution of rainfall are also associated with an increased concentration of atmospheric CO2 (USDA NRCS 2000; Abbas 2013; Abbas et al. 2014). A rich literature has been produced on carbon sequestration especially during the last two decades. However, significant differences exist among individuals about the role of increasing concentration of atmospheric CO2 and the related pros and cons to the ecosystem. Persistent increase of carbon storage in soil and plant material and in the sea is termed as carbon sequestration (Hutchinson et al. 2007; Pandey et al. 2016). According to United Nations Framework Convention on Climate Change, carbon sequestration is the secure storage of CO2 in soil and plant. It depends on the metabolic conversion of CO2 into long-lived, carbon containing materials (through photosynthesis), a process that is called Environ Sci Pollut Res bio-sequestration (DOE/SC-108, US Department of Energy 2008). Carbon sequestration is successful when carbon storage resulting from land management and/or conservation practices exceeds carbon losses (IPCC 2007a; Smith et al. 2014). Carbon sequestration is possible through a range of processes, occurring naturally in plants and soils. Recently, carbon sequestration and decreased emissions from circumvented deforestation have received more attention as a method to reduce the buildup of GHGs in the earth atmosphere (Sedjo and Brent 2012). Carbon sequestration happens in two main segments of agroforestry systems: belowground and aboveground. The aboveground segment is described as specific plant components (such as stem and leaves of herbaceous plants and trees), while the belowground segment contains roots and soil microorganisms, and soil organic carbon present in different soil horizons. Due to net positive contribution of agroforestry to climate change system, the system has become habitual for the term carbon sequestration. The belowground biomass carbon is more stabilized in the soil due to its interactions with soil particles (Rasse et al. 2005) and its slow decomposition rate in comparison to above ground biomass (Cusack et al. 2009). As Scheu and Schauermann (1994) reported that relative contribution of belowground biomass by Fagus sylvatica L. to SOC was 1.55 times higher than that above ground biomass (Johnson et al. 2006). Researchers have demonstrated that carbon sequestration to stabilize SOC in urban and agricultural soils is one of numerous options to reduce the atmospheric concentration of CO2 (Bruce et al. 1999; Pouyat et al. 2002; Leified 2006; Pataki et al. 2006; Pickett et al. 2008; Blanco-Canqui and Lal 2008). Additionally, SOC is due to historic buildup of humus in the soil. When soil humus reaches a point of stability, it results in long-term storage of carbon in soil (Whitehead and Tinsley 2006). If soil remains undisturbed, soil humus can retain carbon for an average lifetime of hundreds to thousands of years (Holmén 2000). Carbon sequestration through agroforestry depends on cropping systems that define land cover change (Thevathasan and Gordon 2004; Steinbeiss et al. 2008). Agriculture-based land use changes contribute approximately 20% of the total CO2 sequestration by anthropogenic sources (Dumanski and Lal 2004). The top 30 cm of soil layer has average SOC value reaching approximately 15 Mg ha−1; however, during cultivation, about 50–75% of this carbon is released to the atmosphere within the first 20 years in the tropical regions and 20–30% in temperate regions (De Blécourt et al. 2013; Chiti et al. 2014). Nevertheless, by adopting soil conservation practices on arable soils, considerable amount of this carbon can be prevented from emission through soils. A huge carbon sequestration potential by major croplands has been estimated by Dumanski and Lal (2004) as shown in Table 1. Montagnini and Nair (2004) reported that the agroforestry land use systems with higher net primary carbon assimilation treeless land use system returned a greater portion of plant Table 1 Possibilities of world’s major croplands for carbon sequestration (Dumanski and Lal (2004) Carbon sequester potential Tg carbon year−1 Reduction emission (%) USA 75–208 Canada 24 24 10 European Union China 90–120 105–198 – – India 39–49 47 biomass back to the soil and it had the greater potential to increase soil organic carbon. In addition, agroforestry systems have a higher ability to store carbon than field crops and grasslands (Kirby and Potvin 2007). Moreover, tree, shrub, and pastures residues in agroforestry systems increase SOC (Abbasi et al. 2015). Agroforestry also offers a great scope of economic development of rural people. Mitigation of climate change impacts through agroforestry Carbon sequestration by agroforestry practices has been considered beneficial in climate change impact mitigation. Agroforestry has diverse advantages such as the plants provide a considerable sink for atmospheric carbon due to their high growth rate and quick biomass productivity. The trees in agricultural land use systems can enhance the carbon sequestered in farm soils reserved to agriculture, while simultaneously allowing for the growing of food crops (Kursten 2000). Soils act as a sink to store carbon from the atmosphere for longer period of time. Based on historic global estimates carbon stocks and emissions, soil provides a useful carbon sink for necessary solution to environmental problems (Lal 2004c, 2008). Since agriculture occupies over one third of arable land globally (World Bank 2015); therefore, agroforestry presents a great potential for increased sequestration of carbon in agricultural lands. Planting trees with nitrogen fixing capability may also increase biomass production. Since the sequestered carbon and nitrogen in soils has complex interaction. Study conducted in Malawi and Zambia showed that cultivating maize with Gliricida—a nitrogen fixing trees—has 42% higher yields than non-fertilized fields and similar to fields receiving 92 kg N ha−1 (Sileshi et al. 2012). Moreover, integrating Gliricidia trees during fallow periods between crops resulted in 55% increase in sorghum productivity (Hall et al. 2005). However, strategies must focus on synchronizing legume tress with crop nitrogen demand to regulate gaseous and leaching losses of N from the soil (Rosenstock et al. 2014). A study is needed to further investigate interactions of SOC with various forms of nitrogen produced during its mineralization and immobilization under agroforestry systems (Nair et al. 2009a; Environ Sci Pollut Res Gärdenäs et al. 2011). Among the other reasons, positive effect of trees on SOC sequestration may become obvious due to modifications in belowground C stocks (Laganière et al. 2010). The higher SOC sequestration potential under agroforestry may be reflected by higher amount of SOC in deeper mineral soil layers in comparison to fields with only crop cultivation (Nepstad et al. 1994; Jobbágy and Jackson 2000). Furthermore, the tree species modify the microbial community structure and diversity in soil that may also enhance soil carbon sequestration. However, detailed investigations are needed to further elaborate the mechanisms associated with SOC sequestration in managed agroforestry systems. Because some of the planted tree species may have negative impacts on crops due competition for water (Burgess et al. 1998), more negative effects may arise due to allelochemicals (Jose et al. 2004; Inderjit 2002). Most of the tropical agroforestry have negative allelopathic effects on food and fodder crops and vice versa may also occur. Therefore, species mixtures with no or positive allelopathic effects on the companion crops must be created in agroforestry systems (Rizvi et al. 1999). Estimation of carbon sequestration in agroforestry system Some efforts have been carried out to evaluate the global potential of agroforestry systems as a sink for carbon. Approximately, Table 2 Total biomass carbon on agricultural land (in PgC, and as a percentage of the total biomass carbon from 2000 and 2010) globally, and the contribution by trees to biomass carbon on agricultural land Region a carbon sequestration potential of 391,000 MgC year−1 by 2010 and 586,000 MgC year−1 by 2040 by converting 630 million ha of unproductive croplands into agroforestry land use system have been estimated for 50-year period with its calculated range between 1.13 and 2.24 PgC year−1 globally (Jose 2009; Dixon 1995). A comprehensive study has been conducted by Zomer et al. (2016) in which they have estimated the contribution of agroforestry in carbon sequestration at global, regional and at country level negated by IPCC for estimating carbon biomass in agricultural systems (Table 2). According to IPCC estimates total biomass carbon through tree distribution on agricultural land broadly followed bioclimatic zones (Fig. 2) and the high tree cover (>45%) was found in the humid regions (Zomer et al. 2016). Overall, the amount of area classed as agricultural is the globally the carbon stored in above- and belowground biomass is 11.1 PgC in agricultural lands, when agricultural area is ~22.2 million km2 (Bartholomé and Belward 2005). However, when tree in agro systems are considered in carbon storage the agricultural land has four times higher values (45.30 PgC) than the default values estimated by IPCC (Zomer et al. 2016). In addition, the authors has also found that there was 2% an additional increase tree cover between 2000 and 2010, resulting in an increase of >2 PgC (or 4.6%) biomass carbon (Fig. 3). The carbon sequestration capacity differs across the geography of the area and plant species used in agroforestry system (Newaj and Dhyani 2008). However, evidence shows that Total biomass carbon on agriculture land PgC Total agricultural area (km2) Increase/ Decrease as % of total C 2000 2010 Australia/Pacific Central America Central Asia East Asia Eastern and Southern Africa Europe North Africa North America 2.11 1.42 0.48 2.37 2.31 2.13 0.11 3.31 2.28 1.52 0.47 2.53 2.30 2.15 0.11 3.40 8.06 6.45 −1.04 6.95 −0.17 0.96 −0.01 2.68 790,658 269,235 830,949 1,795,893 1,573,527 2,299,766 155,948 2,073,033 Russia South America South Asia South East Asia West and Central Africa Western Asia Global Agricultural Baseline Contribution by Trees 1.07 11.34 2.30 10.03 5.57 0.75 45.30 11.08 34.22 1.07 12.13 2.48 10.69 5.45 0.79 47.37 11.08 36.29 0.02 6.95 7.85 6.59 −2.18 4.72 4.57 1,669,166 3,888,792 1,827,025 1,648,268 2,390,980 955,689 22,168,929 Source: Zomer et al. 2016 4.57 Environ Sci Pollut Res Fig. 2 Global map of average biomass carbon per hectare on agricultural land in 2000 and 2010 (t C per ha). Source Zomer et al. 2016 agroforestry land use can act as both source and sink of carbon in the environment (Montagnini and Nair 2004; Ajayi et al. 2011). For example, agrisilvicultural systems in which crops and trees are cultivated together act as net sinks of CO2 while agro silvipastoral systems are possible net sources of greenhouse gases (Montagnini and Nair 2004). In contrast, Mangalassery et al. (2014) reported that silvipastoral system sequestered 36–60% higher CO2 compared to the tree system and 27–71% more in comparison to the grasslands. Silvipastoral system involving trees and grasses sequestered more soil organic carbon compared with only trees or pasture containing systems. Carbon sequestering potential of different agroforestry systems varies depending on species composition, soil and climate. Similarly, tropical regions have higher vegetation carbon sequestration potential than temperate agroforestry regions. The sequestered carbon in the above- and belowground biomass is highly variable of an agroforestry system and is usually much higher than treeless land use system (Nair et al. 2009a; Fialho and Zinn 2014). Potential for sequestering carbon in aboveground components of agroforestry systems is estimated to be 2.1 × 109 MgC year−1 in tropical and 1.9 × 109 MgC year−1 in temperate biomes (Oelbermann et al. 2004). The IPCC report suggest that even after achieving global targets of carbon sequestration, efforts to sequester previously emitted carbon will remain necessary to achieve safe levels of atmospheric concentration of carbon for mitigating climate change impacts (Smith et al. 2014). Higher soil organic carbon (SOC) in agroforestry land use systems can be particularly obtained by enhancing the amount of carbon returned to the soil and by strengthening soil organic matter (Lal 2005; Sollins et al. 2007). Agroforestry land use systems can also be managed by increasing SOC reservoir in the soil through avoiding burning and minimizing soil disturbance by minimum or zero tillage practices and by erosion control (Soto-Pinto et al. 2010). As Sá et al. (2015) compared the tillage system in relation to SOC losses and concluded that no-till systems have a large potential to decrease soil degradation and SOC decline in comparison to conventional tillage systems. Environ Sci Pollut Res Fig. 3 Global map in average biomass carbon from 2000 and 2010 per hectare on agricultural land (t C per ha). Source Zomer et al. 2016 Soil organic carbon pools do not only reduce the net CO2 in the atmosphere but also play an important role in maintaining soil productivity by improving nitrogen (N) cycling in soil– plant systems (Yu and Jia 2014; Abbasi et al. 2015). For every Mg increase in profile SOC stock, an increase yield of 0.17 (pearl millet), 0.14 (cluster bean), and 0.15 (castor) Mg ha−1 year−1 were observed (Srinivasarao et al. 2014). Soil organic carbon is reliable and field-based soil quality indicator for assessing yield (Carter et al. 2003; Lal 2006). In addition, researchers reported that trading sequestered carbon was a viable economic opportunity for practitioners of agroforestry for the subsistence farmers in low-income countries (Nair et al. 2010). While agroforestry is documented as having the greatest capability for carbon sequestration, IPCC (2000b) examined land uses as described in Table 3. Table 3 Potential of carbon sequestration by 2040 Sources Mt C year−1 Water land restoration Restoration of degraded land Agroforestry Forest management Grazing management Rice management Crop land management 20 50 600 250 375 20 150 Terrestrial biosphere plays an important role in global carbon cycle; the environmental changes are continuously changing global terrestrial carbon uptake. Carbon is continually being cycled between different pools such as soil, atmosphere, and oceans. In fact, the total amount of carbon remains constant while increased amount of carbon into a pool is balanced by an addition of equal amount of carbon into another pool. Carbon budget is actually a list of all transformations and changes occurring in various pools in which carbon is stored. Presently, a budget of the earth’s carbon cycle shows an imbalance among of various carbon pools that is mainly caused by burning of fossil fuel and change in land use system. Resultantly, CO2 is building up in atmosphere. According to the global carbon budget report of 2015 (Fig. 4), during the year 1870 to 2014, burning of fossil fuel and land use change added 1465 and 549.6 Gt of CO2 in atmosphere, respectively, while 545 ± 55 Gt of this added CO2 is recycled by atmosphere (230 ± 5 Gt), ocean (155 ± 20 Gt), and the land (160 ± 60 Gt) (Le Quéré et al. 2015). Globally, the soils store 2500 billion tons of carbon. It is more than that is stored in atmosphere (780 billion tons) and plants (560 billion tons). Approximately 5000–10,000 billion tons of carbon is stored by fossil fuels originated from fossilized plants and animals store (Le Quéré et al. 2015). Plant functioning in terms of photosynthesis stabilizes atmospheric CO2 and releases the oxygen to the atmosphere. Almost 40% of the photosynthetically stabilized CO2 is released by plant in the form of roots exudates that provide food to soil microbes. The Environ Sci Pollut Res Fig. 4 Global average carbon budget (Gt CO2 per year) for the decade 2005–2014 (Le Quéré et al. 2015) design by GBP soil microbes depend on these root exudates and convert simpler organic compounds into complex, stable forms of soil carbon, such as humus (Ahmad et al. 2009: Le Quéré et al. 2015). Carbon sequestration in above- and belowground biomass The concept of the carbon sequestration contains ambiguity particularly with the concept of Blong-lived^ pools. In agroforestry systems, carbon stocks are represented as synonym to carbon sequestration. The carbon sequestration determinations are simple mathematical calculations, in which aboveground biomass is assessed from general allometric equations while, belowground biomass is usually 30% of aboveground biomass, whereas 50% of the total plant biomass is considered as carbon stock or sequestered carbon. Complex mixtures of agricultural crops and trees are widely used for estimating aboveground carbon sequestration potential. Carbon constitutes almost 45 to 50% of stem/branches biomass and 30% of foliage dry weight (Shepherd and Montagnini 2001; Schroth et al. 2002). The carbon sequestration in soils differs extensively by depending on the agroforestry system. However, in this regard, the literature, for instance, Oelbermann et al. (2006), Amézquita et al. (2005), and Nair et al. (2009b), reported that SOC pools range from 1.3 MgC ha−1 in the top 40 cm to 173 MgC ha−1 in the top 100 cm of soil layer with 13-year-old alley cropping practices in southern Canada and 10- to 16-year-old silvopastoral systems at the Atlantic Coast of Costa Rica, respectively. Soil carbon stocks in croplands and forests under slash-and-burn systems showed that intensive cropping with short-term fallow systems in sub-humid tropics have relatively lesser carbon sequestration potential than slash-and-burn systems of the humid region of Brazil (Mutuo et al. 2005). Additionally, physical and biotic factors, as well as on management practices determine the carbon sequestration capacity. Modeling the carbon sequestration Model is a representation of system that allows investigation of properties of the system and prediction of future outcomes of real systems. Models are used in a variety of scientific Environ Sci Pollut Res disciplines ranging from physics and chemistry to ecology and the Earth sciences. Models are also used in food production systems support the farmers in planning day-to-day crop management practices on farms, guiding the ways to alleviate rural poverty, and predicting the effects of climate variability on food security issues (Thornton et al. 1997; Hochman et al. 2009; Webber et al. 2014). Models are helpful regarding strategic decisions and can simulate the productivity of farms and food system in various environmental conditions (Holzworth et al. 2014). Numerous models can be used to simulate the potential of SOC sequestration (Rickman et al. 2001; Verburg et al. 2002; Smith et al. 1993, 2008; Verburg and Overmars 2009; Debolini et al. 2015). Changes in the SOC pool can be measured on small scale and on large regional scales. For a small (plot) scale (Bruce et al. 1999), the direct measurement is an efficient technique (Qian et al. 2003). For large (regional) scales measurements, mathematical models of SOC have been established and extensively used to study SOC dynamics worldwide (Post et al. 2004; Qian et al. 2003; Smith et al. 2008). Models have been used to evaluate the effect of management practices on the changes in the SOC pool (Blanco-Canqui and Lal 2004; Bruce et al. 1999; Lal 2004b). The RothC (Rothamsted model) and CENTURY models are the most commonly used as tool for simulation of soil carbon (Coleman and Jenkinson 1996). The RothC model application is based on the long-term trials conducted on Rothamsted research station to study the cycling of organic matter in soil. Although the assumptions or variables of the models are simple, the models cannot appropriately and accurately predict the carbon cycling in tropical agroforestry systems. The CENTURY model is used for the cycling of carbon and its interaction with plant species and management practices such as tillage and agricultural system. Several models in agroforestry have been used including; SCUAF, HyPAR, Hi-SAFE/Yield-SAFE and WaNuLCAS; however, their use has remained limited due to inflexibility, restricted capacity to simulate various interactions and lack of model calibration in different scenarios (Luedeling et al. 2016). To expand the applicability of this model for estimating carbon sequestration at global scale, it must also consider the agroforestry during the prediction of carbon cycling in the system. Several scientific models have been developed to forecast the response of soil organic carbon. There are some complications in obtaining information which are necessary for the models (Nair et al. 2010). These complications reduce applicability of these models to integrate agroforestry system. Few attempts have been made to integrate agroforestry systems into existing models or models that have been developed with agroforestry in target. For example, Palma et al. (2007) modeled silvoarble agroforestry in Europe, Negash and Kanninen (2015) used the CO2FIX model to predict soil carbon sequestration, and Francaviglia et al. (2012) used the RothC model to simulate an agro-silvopastoral system. Palma et al. (2007) used nitrogen leaching, soil erosion, landscape biodiversity, and carbon sequestration as indicators that are assessed using Yield-SAFE (from BYield Estimator for Long term Design of Silvoarable AgroForestry in Europe^) while soil erosion was simulated using the revised universal soil loss equation (Renard et al. 1997). In Ethiopia, the CO2FIX model was used to predict the effects of three agroforestry systems on organic carbon pools in soil. Model validated that long-term (10–40 years) carbon sequestration was in the range of measured biomass for two agroforestry system (Enset-tree and Enset-coffee-tree systems), but significantly differed for the tree-coffee system (Negash and Kanninen 2015). The authors concluded that the prediction of the biomass carbon stocks could be improved by having more accurate input parameters for the model. Basic problem in application of existing modeling framework and sub-models in agroforestry system is the complexity of simulating tree growth for different tree species. The existing models have deficiency to simulate developing foliage, wood, branches, and roots. Modifications in the existing models are necessary to make them compatible with crop growth models (Pinkard et al. 2010; Almeida et al. 2010; Ghezehei et al. 2015). For instance, some tree models are not able to simulate at a daily time step basis. Notable exceptions are present in tree sub-models such as in APSIM, CABALA and 3PG. Therefore, a rapid progress in reliable modeling and its calibration for tree and crop agroforestry systems are needed for evaluating and predicting future outcomes of site specific agroforestry systems potential to sequester carbon under changing climate. Conclusions The evidences suggest that conversion of forest to agriculture land use results in land degradation with huge losses of soil organic carbon stocks. Cultivation of land releases about 20– 70% of the stored carbon within two decades depending on the climatic conditions. Resultantly, CO2 is building up in atmosphere. Agroforestry systems retain much higher quantities of carbon in above and belowground biomass in comparison to crop and grazing land use systems. At global scale, 630 million ha of unproductive croplands could be used for agroforestry as part of an ecological engineering practice to potentially sequester 586,000 MgC year−1 by 2040. Moreover, in current global and national carbon monitoring protocols, there is a need to incorporate agroforestry in carbon stocks to precisely estimate the contribution of this neglected pool. To simulate the potential of agroforestry systems in sequestering carbon new models are needed that can precisely predict net uptake of atmospheric CO2 compared to treeless systems especially under the IPCC scenarios of projected global climate change. Environ Sci Pollut Res Reference Abbas F (2013) Analysis of a historical (1981-2010) record of temperature of semi-arid Punjab, Pakistan. Earth Interact 17:1–23 Abbas F, Ahmad A, Safeeq M, Ali A, Saleem F, Hamad HM, Farhad W (2014) Changes in precipitation extremes over arid to semi-arid and sub-humid Punjab, Pakistan. Theor Appli Climatolo 116:671–680 Abbasi MK, Tahir MM, Sabir N, Khurshid M (2015) Impact of the addition of different plant residues on nitrogen mineralization–immobilization turnover and carbon content of a soil incubated under laboratory conditions. Solid Earth 6:197–205 Achard F, Beuchle R, Mayaux P, Stibig HJ, Bodart C, Brink A, Carboni S, Desclée B, Donnay F, Eva HD, Lupi A, Raši R, Seliger R, Simonetti D (2014) Determination of tropical deforestation rates and related carbon losses from 1990 to 2010. Glob Chang Biol 20:2540–2554 Burgess SSO, Adams MA, Turner NC, Ong CK (1998) The redistribution of soil water by tree root systems. Oecologia 115:306–311 Ahmad AA, Fares A, Paramasivam S, Elrashidi MA, Savabi RM (2009) Biomass and nutrient concentration of sweet corn roots and shoots under organic amendments application. J Environ Sci Health, Part B Pesticides, Food Contaminants, and Agricultural Waste 44(7):742–754 Ajayi OC, Place F, Akinnifesi FK, Sileshi GW (2011) Agricultural success from Africa: the case of fertilizer tree systems in southern Africa (Malawi, Tanzania, Mozambique, Zambia and Zimbabwe). Inter J Agri Sustain 9:130–136 Alao JS, Shuaibu RB (2013) Agroforestry practices and concepts in sustainable land use systems in Nigeria. J Horti Forestry 10: 156–159 Almeida AC, Siggins A, Batista TR, Beadle C, Fonseca S, Loos R (2010) Mapping the effect of spatial and temporal variation in climate and soils on Eucalyptus plantation production with 3-PG, a processbased growth model. Forest Ecol Manag 9:1730–1740 Amézquita MC, Ibrahim M, Llanderal T, Buurman P, Amézquita E (2005) Carbon sequestration in pastures, silvopastoral systems and forests in four regions of the Latin American tropics. Inter J Sustain Future Human Security 21:31–49 Anaya-Romero M, Abd-Elmabod SK, Muñoz-Rojas M, Castellano G, Ceacero CJ, Alvarez S, Méndez M, De la Rosa D (2015) Evaluating soil threats under climate change scenarios in the Andalusia region, southern Spain. Land Degrad Develop 26:441– 449. doi:10.1002/ldr.2363 Anderson E, Zerriffi H (2012) Seeing the trees for the carbon: agroforestry for development and carbon mitigation. Clim Chang 115:741–757 Bartholomé E, Belward AS (2005) GLC2000 a new approach to global land cover mapping from earth observation data. Int J Remote Sens 26:1959–1977 Bayala J, Wallace JW (2015) The water balance of mixed tree-crop systems In. In: Black, C, Wilson, J., Ong, C.K (Eds.), Tree–Crop Interactions: Agroforestry in a Changing Climate. CABI, pp. 140–190 Behera SK, Shukla AK (2015) Spatial distribution of surface soil acidity, electrical conductivity, soil organic carbon content and exchangeable potassium, calcium and magnesium in some cropped acid soils of India. Land Degrad Develop 26:71–79. doi:10.1002/ldr. 2306 Benites J, Dudal R, Koohafkan P (1999) Land, the platform oflocal food security and global environmental protection. In: Prevention of Land Degradation, Enhancement of Carbon Sequestration and Conservation of Biodiversity Through Land Use Change and Sustainable Management with a Focus on Latin America and the Caribbean. Proceedings of the IFAD/FAO Expert Consultation, IFAD, Rome, Italy, April 15, pp. 37–42 Berendse F, van Ruijven J, Jongejans E, Keesstra S (2015) Loss of plant species diversity reduces soil erosion resistance. Ecosystems 18: 881–888. doi:10.1007/s10021-015-9869-6 Birch-Thomsen T, Elberling B, Fog B, Magid J (2007) Temporal and spatial trends in soil organic carbon stocks following maize cultivation in semiarid Tanzania, East Africa. Nutr Cycl Agroecosys 79:291–302 Blanco-Canqui H, Lal R (2004) Mechanisms of carbon sequestration in soil aggregates. Critical Reviews Plant Sci 23:481–504 Bralower T, Bice D 2016 Overview of the carbon cycle from a systems perspective. https://www.e-education.psu.edu/earth103/node/1019 (accessed on October 28, 2016) Brevik EC, Cerdà A, Mataix-Solera J, Pereg L, Quinton JN, Six J, Van Oost K (2015) The interdisciplinary nature of soil. Soil 1:117–129. doi:10.5194/soil-1-117-2015 Bruce JP, Frome M, Haites E, Janzen H, Lal R, Paustian K (1999) Carbon sequestration in soils. J Soil Water Conser 54:382–390 Bruun TB, Elberling B, de Neergaard A, Magid J (2015) Organic carbon dynamics in different soil types after conversion of forest to agriculture. Land Degrad Develop 26:272–283 Cadotte MW (2013) Experimental evidence that evolutionarily diverse assemblages result in higher productivity. Proceedings of the National Academy of Sci 110:8996–9000 Carter M, Angers D, Gregorich E, Bolinder M (2003) Characterizing organic matter retention for surface soils in eastern Canada using density and particle size fractions. Canad J Soil Sci 83:11–23 Cerdà A, Lavee H, Romero-Díaz A, Hooke J, Montanarella L (2010) Preface. Land Degrad Develop 21:71–74 Chiti T, Grieco E, Perugini L, Rey A, Valentini R (2014) Effect of the replacement of tropical forests with tree plantations on soil organic carbon levels in the Jomoro district, Ghana. Plant Soil 375:47–59 Coleman K, Jenkinson DS (1996) RothC-26.3 A model for the turnover of carbon in soil. In: Evaluation of Soil Organic Matter Models using Existing, Long-term Datasets (eds Powlson DS, Smith P, Smith JU), pp. 237–246 Cubbage F, Balmelli G, Bussoni A, Noellemeyer E, Pachas AN, Fassola H, Colcombet L, Rossner B, Frey G, Dube F, deSilva ML, Stevenson H, Hamilton J, Hubbard W (2013) Comparing silvopastoral systems and prospects in eight regions of the world. Agroforestry Sys 86:303–314 Cusack DF, Chou WW, Yang WH, Harmon ME, Silver WL (2009) Controls on long-term root and leaf litter decomposition in neotropical forests. Global Change Bio 15:1339–1355 David N, Crane DE (2002) Carbon storage and sequestration by urban trees in the USA. Environ Pollution 116:381–389 De Blécourt M, Brumme R, Xu J, Corre MD, Veldkamp E (2013) Soil carbon stocks decrease following conversion of secondary forests to rubber (Hevea brasiliensis) plantations. PLoS One 8:e69357. doi: 10.1371/journal.pone.0069357 De Moraes Sá JC, Séguy L, Tivet F, Lal R, Bouzinac S, Borszowskei PR, Briedis C, dos Santos JB, da Cruz HD, Bertoloni CG, Rosa J, Friedrich T (2015) Carbon depletion by plowing and its restoration by no-till cropping systems in oxisols of subtropical and tropical agro-ecoregions in Brazil. Land Degrad Develop 26:531–543. doi: 10.1002/ldr.2218 De Oliveira SP, de Lacerda NB, Blum SC, Escobar MEO, de Oliveira TS (2015) Organic carbon and nitrogen stocks in soils of northeastern Brazil converted to irrigated agriculture. Land Degrad Develop 26: 9–21. doi:10.1002/ldr. 2264 Debolini M, Schoorl JM, Temme A, Galli M, Bonari E (2015) Changes in agricultural land use affecting future soil mredistribution patterns: a case study in southern Tuscany (Italy). Land Degrad Develop 26:574–586 Decock CJ, Lee M, Necpalova EIP, Pereira DM, Tendall JS (2015) Mitigating N2O emissions from soil: from patching leaks to transformative action. Soil 1:687–694. doi:10.5194/soil-1-687-2015 Dixon RK (1995) Agroforestry systems: sources or sinks of greenhouse gases? Agroforestry Sys 31:99–116 DOE/SC-108, US Department of Energy (2008) Carbon cycling and bio sequestration: integrating biology and climate through systems science, report from the March 2008 Workshop, U.S. Department of Environ Sci Pollut Res Energy Office of Science. http://genomicsgtl.energy.gov/ carboncycle (validated: February 4, 2016) Dumanski J, Lal R (2004) THEME PAPER: Soil Conservation and the Kyoto Protocol Facts and Figures. Agriculture and the Environment, Environment Bureau, Agriculture and Agri-Food Canada, Ottawa, ONTARIO. Available at: http://www.agr.gc.ca/policy/environment/ soil_cons_e.phtml (validated: March 5, 2016) Fagbemi T (2002) Investment opportunities in renewable resources industry-forestry, 1st edn. Belodan Press, Nigeria Fahad S, Bano A (2012) Effect of salicylic acid on physiological and biochemical characterization of maize grown in saline area. Pak J Bot 44:1433–1438 Fahad S, Chen Y, Saud S, Wang K, Xiong D, Chen C, Wu C, Shah F, Nie L, Huang J (2013) Ultraviolet radiation effect on photosynthetic pigments, biochemical attributes, antioxidant enzyme activity and hormonal contents of wheat. J Food, Agri Environ 11(3&4):1 6 3 5–1 6 4 1 Fahad S, Hussain S, Bano A, Saud S, Hassan S, Shan D, Khan FA, Khan F, Chen Y, Wu C, Tabassum MA, Chun MX, Afzal M, Jan A, Jan MT, Huang J (2014a) Potential role of phytohormones and plant growthpromoting rhizobacteria in abiotic stresses: consequences for changing environment. Environ Sci Pollut Res. doi:10.1007/s11356-014-3754-2 Fahad S, Hussain S, Matloob A, Khan FA, Khaliq A, Saud S, Hassan S, Shan D, Khan F, Ullah N, Faiq M, Khan MR, Tareen AK, Khan A, Ullah A, Ullah N, Huang J (2014b) Phytohormones and plant responses to salinity stress: a review. Plant Growth Regul. doi:10. 1007/s10725-014-0013-y Fahad S, Hussain S, Saud S, Tanveer M, Bajwa AA, Hassan S, Shah AN, Ullah A, Wu C, Khan FA, Shah F, Ullah S, Chen Y, Huang J (2015a) A biochar application protects rice pollen from high-temperature stress. Plant Physiol Biochem 96:281–287 Fahad S, Nie L, Chen Y, Wu C, Xiong D, Saud S, Hongyan L, Cui K, Huang J (2015b) Crop plant hormones and environmental stress. Sustain Agric Rev 15:371–400 Fahad S, Hussain S, Saud S, Hassan S, Chauhan BS, Khan F et al (2016a) Responses of rapid viscoanalyzer profile and other rice grain qualities to exogenously applied plant growth regulators under high day and high night temperatures. PLoS One 11(7):e0159590. doi:10. 1371/journal.pone.0159590 Fahad S, Hussain S, Saud S, Hassan S, Ihsan Z, Shah AN, Wu C, Yousaf M, Nasim W, Alharby H, Alghabari F, Huang J (2016b) Exogenously applied plant growth regulators enhance the morphophysiological growth and yield of rice under high temperature. Front Plant Sci 7:1250. doi:10.3389/fpls.2016.01250 Fahad S, Hussain S, Saud S, Khan F, Hassan S, Jr A, Nasim W, Arif M, Wang F, Huang J (2016c) Exogenously applied plant growth regulators affect heat-stressed Rice pollens. J Agron Crop Sci 202:139–150 Fahad S, Hussain S, Saud S, Hassan S, Tanveer M, Ihsan MZ, Shah AN, Ullah A, Nasrullah KF, Ullah S, AlharbyH NW, Wu C, Huang J (2016d) A combined application of biochar and phosphorus alleviates heat-induced adversities on physiological, agronomical and quality attributes of rice. Plant Physiol Biochem 103:191–198 FAO (Food and Agriculture Organization of the United Nations) (2010) BClimate-Smart^ Agriculture policies, practices and financing for food security, adaptation and mitigation. http://www.fao.org/ docrep/013/i1881e/i1881e00.pdf. Accessed 8 Feburary 2017 Ferreira ACC, Leite LFC, de Araújo ASF, Eisenhauer N (2016) Land-use type effects on soil organic carbon and microbial properties in a semiarid region of northeast Brazil. Land Degrad Develop 27:171–178 Fialho RC, Zinn YL (2014) Changes in soil organic carbon under Eucalyptus plantations in Brazil: a comparative analysis. Land Degrad Develop 25:428–437. doi:10.1002/ldr.2158 Francaviglia R, Coleman K, Whitmore AP, Doro L, Urracci G, Rubino M, Ledda L (2012) Changes in soil organic carbon and climate change—application of the RothC model in agrosilvo-pastoral Mediterranean systems. Agric Syst 112:48–54 Garcia-Diaz A, Bienes-Allas R, Gristina L, Cerdà A, Novara A, Pereira P (2016) Carbon input threshold for soil carbon budget optimization in eroding vineyards. Geoderma 271:144–149. doi:10.1016/j.geoderma Gärdenäs AI, Ågren GI, Bird JA, Clarholm M, Hallin S, Ineson P, Kätterer T, Knicker H, Nilsson SI, Näsholm T, Ogle S, Paustian K, Persson T, Stendahl J (2011) Knowledge gaps in soil carbon and nitrogen interactions—from molecular to global scale. Soil Biol Biochem 43:702–717. doi:10.1016/j.soilbio.2010.04.006 Garrity DP, Akinnifesi FK, Ajayi OC, Weldesemayat SG, Mowo JG, Kalinganire A, Larwanou M, Bayala J (2010) Evergreen agriculture: a robust approach to sustainable food security in Africa. Food Security 2:197–214 Ghezehei SB, Annandale JG, Everson CS (2015) Modelling radiation interception and water balance in agroforestry systems. In: Black, C., Wilson, J., Ong, C.K. (Eds.), Tree –Crop Interactions: Agroforestry in a Changing Climate CABI, pp. 41–56 Gümüs I, Şeker C (2015) Influence of humic acid applications on modulus of rupture, aggregate stability, electrical conductivity, carbon and nitrogen content of a crusting problem soil. Solid Earth 6: 1231–1236. doi:10.5194/se-6-1231-2015 Gutierrez V, Harris VH, Pearson NL, Petrova TRH, Grimland S, Brown SS (2009) USAID Forest Carbon Calculator: Data and Equations for the Agroforestry Tool. Submitted by Winrock International under USAID Cooperative Agreement No. EEM-A-00-06-00024–00 Hall NM, Kaya B, Dick J, Skiba U, Niang A, Tabo R (2005) Effect of improved fallow on crop productivity, soil fertility and climate forcing gas emissions in semi-arid conditions. Biol Fert Soils 42:224–230 Hao XM, Chen YN, Li WH (2009) Indicating appropriate groundwater tables for desert river-bank forest at the Tarim River, Xinjiang, China. Environ Monit Assess 152:167–177 Hochman Z, van Rees H, Carberry PS, Hunt JR, McCown RL, Gartmann A, Holzworth D, van Rees S, Dalgliesh NP, Long W, Peake AS, Poulton PL, McClelland T (2009) Re-inventing model-based decision support with Australian dryland farmers. 4. Yield Prophet (R) helps farmers monitor and manage crops in a variable climate. Crop Pasture Sci 11:1057–1070 Holmén K (2000) The global carbon cycle. In: Jacobson JM, Charlson RJ, Rodhe H, Orians G (eds) Earth systems science: from biogeochemical cycles to global change. Academic Press, New York, pp 282–321 Holzworth DP, Huth NI, deVoil PG, Zurcher EJ, Herrmann NI, McLean G, Chenu K, van Oosterom EJ, Snow V, Murphy C (2014) APSIMevolution towards a new generation of agricultural systems simulation. Environ Modelling Soft 62:327–350 Hombegowda HC, Van-Straaten O, Köhler M, Hölscher D (2016) On the rebound: soil organic carbon stocks can bounce back to near forest levels when agroforests replace agriculture in southern India. Soil 2:13–23 Hu Y, Niu Z, Zeng D, Wang C (2015) Soil amendment improves tree growth and soil carbon and nitrogen pools in mongolian pine plantations on post-mining land in northeast China. Land Degrad Develop 26:807–812 Hultine KR, Williams DG, Burgess SSO, Keefer TO (2003) Contrasting patterns of hydraulic redistribution in three desert phreatophytes. Oecologia 2:167–175 Hussain S, Shaobing P, Fahad S, Abdul K, Huang J, Kehui C, Lixiao N (2014) Rice management interventions to mitigate greenhouse gas emissions: a review. Environ Sci Pollut Res. doi:10.1007/s11356-014-3760-4 Hutchinson JJ, Campbell CA, Desjardins RL (2007) Some perspectives on carbon sequestration in agriculture. Agri Forest Meteorol 142:288–302 Inderjit MAU (2002) Chemical ecology of plants: allelopathy in aquatic and terrestrial ecosystems. Birkhäuser-Verlag, Berlin IPCC (2000a) Land use, land-use change, and forestry. Cambridge University Press, Cambridge, UK, p 375 A special report of the IPCC IPCC, (2000b) Land Use, Land-Use Change, and Forestry. A Special Report of the IPCC. Cambridge University Press, Cambridge, UK IPCC (2007a) Summary for Policymakers. In Solomon SS, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL Environ Sci Pollut Res IPCC (2007b) Climate change 2007: mitigation of climate change. Working group III contribution to the intergovernmental panel on climate change. Fourth Assessment Report, Bangkok http://www. ipcc.ch/ipccreports/index.htm (accessed: Jan. 28, 2015) Jackson NA, Wallace JS, Ong CK (2000) Tree pruning as a means of controlling water use in an agroforestry system in Kenya. Forest Ecol Manag 2:133–148 Jobbágy EG, Jackson RB (2000) The vertical distribution of soil organic carbon and its relation to climate and vegetation. Ecol Appl 10:423–436 Johnson JMF, Allmaras RR, Reicosky DC (2006) Estimating source carbon from crop residues, roots and rhizodeposits using the national grainyield database. Agron J 98:622–636. doi:10.2134/agronj2005.0179 Jose S (2009) Agroforestry for ecosystem services and environmental benefits: an overview. Agrofor Sys 76:1–10 Jose S, Bardhan S (2012) Agroforestry for biomass production and carbon sequestration: an overview. Agroforest Syst 86:105–111. doi: 10.1007/s10457-012-9573-x Jose S, Gillespie AR, Pallardy SG (2004) Interspecific interactions in temperate agroforestry. Agrofor Sys 61:237–255. doi:10.1023/B: AGFO.0000029002.85273.9b Keesstra SD, Geissen V, van Schaik L, Mosse K, Piiranen S (2012) Soil as a filter for groundwater quality. Current Opinions in Environ Sustain 4:507–516. doi:10.1016/j.cosust.2012.10.007 Keesstra SD, Bouma J, Wallinga J, Tittonell P, Smith P, Cerdà A, Montanarella L, Quinton JN, Pachepsky Y, van der Putten WH, Bardgett RD, Moolenaar S, Mol G, Jansen B, Fresco LO (2016) The significance of soils and soil science towards realization of the United Nations sustainable development goals. Soil 2:111–128. doi: 10.5194/soil-2-111-2016 Keutgen N, Chen K (2001) Responses of citrus leaf photosynthesis, chlorophyll fluorescence, macronutrient and carbohydrate contents to elevated CO2. J Plant Physiol 158:1307–1316 Kirby KR, Potvin C (2007) Variation in carbon storage among tree species: implications for the management of a small-scale carbon sink project. Forest Ecol Manag 246:208–221 Kursten E (2000) Fuelwood production in agroforestry systems for sustainable land use and CO2 mitigation. Ecolog Eng 16:S69–S72 Laganière J, Angers D, Paré D (2010) Carbon accumulation in agricultural soils after afforestation: a meta-analysis. Glob Chang Biol 16: 439–453. doi:10.1111/j.1365 2486.2009.01930.x Lal R (2004a) Soil carbon sequestration to mitigate climate change. Geoderma 123:1–22 Lal R (2004b) Carbon emissions from farm operations. Environ Inter 30: 981–990 Lal R (2004c) Soil carbon sequestration impacts on global climate change and food security. Sci 304:1623–1627 Lal R (2005) Soil carbon sequestration in natural and managed tropical forest ecosystems. Inter J Sustain Future Human Security 21:1–30 Lal R (2006) Enhancing crop yields in the developing countries through restoration of the soil organic carbon pool in agricultural lands. Land Degrad Develop 17:197–209 Lal R (2008) Carbon sequestration. Philosophical transactions of the Royal Society B Biological Sci 363:815–830 Le Quéré CL, Moriarty R, Andrew RM, Canadell JG, Sitch S et al (2015) Global Carbon Budget 2015. Earth System Science Data. doi:10. 5194/essd-7-349-2015 Leified J (2006) Soils as sources and sinks of greenhouse gases. Geological Society Special Publications 266:23–44 Liu Z, Yao Z, Huang H, Wu S, Liu G (2014) Land use and climate changes and their impacts on runoff in the Yarlung Zangbo river basin, China. Land Degrad Develop 25:203–215. doi:10. 1002/ldr. 1159 Luedeling E, Smethurstc PJ, Baudrond F, Bayalae J, Huthf NI, van Noordwijkg M, Ongh CK, Muliag R, Lusianag B, Muthuria C, Sinclaira FL (2016) Field-scale modeling of tree–crop interactions: challenges and development needs. Agri Systems 142:51–69 Makundi WR, Sathaye JA (2004) GHG mitigation potential and cost in tropical forestry-relative role for agroforestry. Environ Develop Sustain 6:235–260 Mangalassery S, Dayal D, Meena SL, Ram B (2014) Carbon sequestration in agroforestry and pasture systems in arid northwestern India. Current Sci 107:8–25 Matocha J, Schroth G, Hills T, Hole D (2012) Integrating climate change adaptation and mitigation through agroforestry and ecosystem conservation. In: Nair PKR, Garrity D (eds) Agroforestry-the future of global land use. Springer, Dordrecht, pp 105–126 May P, Boyd E, Chang M, Veiga Neto F (2005) Incorporating sustainable development into carbon forest projects in Brazil and Bolivia. Estudos Sociedade e Agricultura 1:5–50 McDonagh JF, Thomsen TB, Magid J (2001) Soil organic matter decline and compositional change associated with cereal cropping in southern Tanzania. Land Degrad Develop 12:13–26 Ming TR, Liu W, Caillol S (2014) Fighting global warming by climate engineering: is the earth radiation management and the solar radiation management any option for fighting climate change? Renew Susta Energy Rev 12:792–834. doi:10.1016/j.rser.2013.12.032 Mol G, Keesstra S (2012) Soil science in a changing world. Current Opinion in Environ Sustainability 4:473–477. doi:10.1016/j. cosust.2012.10.013 Montagnini F, Nair PKR (2004) Carbon sequestration: an underexploited environmental benefit of agroforestry systems. Agroforestry Sys 61: 281–295 Mukhopadhyay S, Masto SE, Cerdà A, Ram LC (2016) Rhizosphere soil indicators for carbon sequestration in a reclaimed coal mine spoil. Catena 141:100–108 Muñoz-Rojas M, Jordán A, Zavala LM, De la Rosa D, Abd-Elmabod SK, Anaya-Romero M (2015) Impact of land use and land cover changes on organic carbon stocks in mediterranean soils (1956–2007). Land Degrad Develop 26:168–179 Murthy IK, Gupta M, Tomar S, Munsi M, Tiwari R, Hegde GT, Ravindranath NH (2013) Carbon sequestration potential of agroforestry systems in India. J Earth Sci Climatic Change 1:1–7 Musinguzi P, Ebanyat P, Tenywa JS, Basamba TA, Tenywa MM, Mubiru D (2015) Precision of farmer-based fertility ratings and soil organic carbon for crop production on a Ferralsol. Solid Earth 6:1063–1073. doi:10.5194/se-6-1063-2015 Mutuo PK, Cadisch G, Albrecht Palm CA, Verchot L (2005) Potential of agroforestry for carbon sequestration and mitigation of greenhouse gas emissions from soils in the tropics. Nutrient Cycling in Agroecosys 71:43–54 Nair PKR (2005) Agroforestry: trees in support of sustainable agriculture. In: Hillel H, Hatfield JL, Powlson DS, Rosenzweig C, Scow KM, Singer MJ, Sparks DL (eds) Encyclopedia of soils in the environment, Vo1. 1. Elsevier, London, pp 35–44 Nair PKR (2012) Carbon sequestration studies in agroforestry systems: a reality-check. Agroforestry Sys 86:243–253 Nair PKR, Nair VD (2014) ‘Solid–fluid–gas’: the state of knowledge on carbon-sequestration potential of agroforestry systems in Africa. Current Opinion Environ Sustain 6:22–27 Nair PKR, Kumar BM, Nair VD (2009a) Agroforestry as a strategy for carbon sequestration. J Plant Nutri Soil Sci 172:10–23 Nair PKR, Nair VD, Kumar BM, Haile SG (2009b) Soil carbon sequestration in tropical agroforestry systems: a feasibility appraisal. Environ Sci Pol 12:1099–1111 Nair PKR, Nair VD, Kumar BM, Showalter JM (2010) Carbon sequestration in agroforestry systems. Advance Agron 108:237–307 Negash M, Kanninen M (2015) Modeling biomass and soil carbon sequestration of indigenous agroforestry systems using CO2FIX approach. Agri Ecosy Environ 203:147–155 Nepstad DC, De Carvalhot CR, Davidson EA, Jipp PH, Lefebvre PA, Negreiros GH, Da Silva ED, Stone TA, Trumbore SE, Vieira S Environ Sci Pollut Res (1994) The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures. Nature 372:666–669 Newaj R, Dhyani SK (2008) Agroforestry for carbon sequestration: scope and present status. Indian journal of agroforestry 10:1–9 Novara A, Gristina L, Guaitoli F, Santoro A, Cerdà A (2013) Managing soil nitrate with cover crops and buffer strips in Sicilian vineyards. Solid Earth 4:255–262 Novara A, Rühl J, La Mantia T, Gristina L, La Bella S, Tuttolomondo T (2015) Litter contribution to soil organic carbon in the processes of agriculture abandon. Solid Earth 6:425– 432. doi:10.5194/se-6-425-2015 Oelbermann M, Voroney RP, Gordon AM (2004) Carbon sequestration in tropical and temperate agroforestry systems: a review with examples from Costa Rica and southern Canada. Agri Ecosys Environ 104: 359–377. doi:10.1016/j.agee.2004.04.001 Oelbermann M, Voroney RP, Gordon AM, Kass DCL, Schlönvoigt AM, Thevathasan NV (2006) Soil carbon dynamics and residue stabilization in a costa Rican and southern Canadian alley cropping system. Agroforestry Sys 68:27–36 Ong CK, Black CR, Muthuri CW (2006) Modifying forestry and agroforestry to increase water productivity in the semi-arid tropics. CAB reviews. Perspectives in Agriculture, Veterinary Science, Nutrition Natural Resour 65:1–19 Ono K, Mano M, Han GH, Nagai H, Yamada T, Kobayashi Y, Miyata A, Inoue Y, Lal R (2015) Environmental controls on fallow carbon dioxide flux in a single-crop rice paddy, Japan. Land Degrad Develop 26:331–339. doi:10.1002/ldr.2211 Otegbeye GO (2002) Report on Agroforestry and Land Management Practices, Diagnostics Survey of Katsina State of Nigeria. May 2000, Katsina State Agricultural and Rural Development Authority.Katsina. P. 89 Palma J, Herzog F, Reisner Y, Graves A, Burgess P, Keesman K, van Keulen H, Mayus M, De Filippi R, Bunce R (2007) Methodological approach for the assessment ofenvironmental effects of agroforestry at the landscape scale. Ecol Eng 29:450–462 Pandey DN (2007) Multifunctional agroforestry systems in India. Current Sci 4:455–463 Pandey VC, Sahu N, Behera SK, Singh N (2016) Carbon sequestration in fly ash dumps: comparative assessment of three plant association. Ecol Eng 95:198–205 Parras-Alcántara L, Lozano-García B, Galán-Espejo A (2015) Soil organic carbon along an altitudinal gradient in the Despenaperros Natural Park, southern Spain. Solid Earth 1:125–134. doi:10.5194/se-6-125-2015 Pataki DE, Alig RJ, Fung AS, Golubiewski NE, Kennedy CA, McPherson EG, Norwalk DJ, Pouyat RV, Lankao PR (2006) Urban ecosystems and the North American carbon cycle. Glob Chang Biol 12:1–11 Paustian K, Six J, Elliott ET, Hunt HW (2000) Management options for reducing CO2 emissions from agricultural soils. Biogeochemistry 48:147–163 Peng F, Quangang Y, Xue X, Guo J, Wang T (2015) Effects of rodentinduced land degradation on ecosystem carbon fluxes in an alpine meadow in the Qinghai-Tibet plateau, China. Solid Earth 6:303–310 . doi:10.5194/se-6-303-2015Cited 2 times Peters GP, Marland G, Le Quéré C, Boden T, Canadell JG, Raupach MR (2012) Rapid growth in CO2 emissions after the 2008–2009 global financial crisis. Nat Clim Chang 2:2–4 Pickett SA, Cadenasso ML, Grove JM, Groffman PM, Band LE, Boone CG, Burch WR, Jr Grimmond CSB, Hom J, Jenkins JC, Law NL, Nilon CH, Pouyat RV, Szlavecz K, Warren PS, Wilson MA (2008) Beyond urban legends: an emerging framework of urban ecology, as illustrated by the Baltimore ecosystem study. Biological Sci 58:1–12 Pinkard EA, Battaglia M, Bruce J, Leriche A, Kriticos DJ (2010) Processbased modelling of the severity and impact of foliar pest attack on eucalypt plantation productivity under current and future climates. Forest Ecology Manag 4:839–847 Poeplau C, Don A (2013) Sensitivity of soil organic carbon stocks and fractions to different land-use changes across Europe. Geoderma 192:189–201 Possu WB, Brandle JR, Domke GM, Schoeneberger M, Blankenship E (2016) Estimating carbon storage in windbreak trees on U.S. agricultural lands. Agroforest Syst 90:889. doi:10.1007/s10457-016-9896-0 Post WM, Kwon KC (2000) Soil carbon sequestration and land use change: processes and potential. Glob Chang Biol 6:317–327 Post WM, Izaurralde C, Jastrow JD, McCarl BA, Amonette JE, Bailey VL, Jardine PM, West TO, Zhou J (2004) Enhancement of carbon sequestration in US soils. Biological Sci 54:895–908 Pouyat R, Groffman P, Yesilonis I, Hernandez L (2002) Soil carbon pools and fluxes in urban ecosystems. Environ Pollution 116:S107–S118 Qian Y, Bandaranayake W, Parton WJ, Mecham B, Harivandi MA, Mosier AR (2003) Long-term effects of clipping and nitrogen management in turfgrass on soil organic carbon and nitrogen dynamics: the CENTURY model simulation. J Environ Quality 32:1694–1700 Rasse DP, Rumpel C, Dignac MF (2005) Is soil carbon mostly root carbon? Mechanisms for a specific stabilization. Plant Soil 269: 341–356. doi:10.1007/s11104-004-0907-y Renard K, Foster G, Weesies G, McCool D, Yoder D (1997) Predicting Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation(RUSLE), v. Washington, D.C. US Department of Agriculture, USDA Agricultural HandbookNo.703 Rickman RW, Douglas CL, Albrech SL, Bundy LG, Berc JL (2001) CQUESTER: A model to estimate carbon sequestration in agricultural soils. J Soil Water Conser 56:237–243 Rizvi SJH, Tahir M, Rizvi V, Kohli RK, Ansari A (1999) Allelopathic interactions in agroforestry systems. Crit Rev Plant Sci 19:773–796. doi:10.1080/07352689991309487 Rockström J (1997) On-farm agrohydrological analysis of the Sahelian yield crisis: rainfall partitioning, soil nutrients and water use efficiency of pearl millet. Stockholm University, Stockholm 62 pp. Rosenstock TS, Tully KT, Arias-Navarro C, Neufeldt H, Butterbach-Bahl K, Verchot LV (2014) Agroforestry with N2-fixing trees: sustainable development's friend or foe? Current Opinion Environ Sustain 6:15–21 Roshetko J, Lasco R, Angeles M (2007) Smallholder agroforestry systems for carbon storage. Mitigation Adaptation Strategies Global Change 2:219–242 Sá JCD, Séguy L, Tivet F, Lal R, Bouzinac S, Borszowskei PR, Briedis C, dos Santos JB, Hartman DC, Bertoloni CG, Rosa J, Friedrich T (2015) Carbon depletion by plowing and its restoration by no-till cropping systems in oxisols of subtropical and tropical agroecoregions in Brazil. Land Degrad Develop 26:531–543 Sanchez PA (2000) Linking climate change research with food security and poverty reduction in the tropics. Agri Ecosys Environ 82:371–383 Sarkhot DV, Comerford NB, Jokela EJ, Reeves JB III, Harris WG (2007) Aggregation and aggregate carbon in a forested southeastern coastal plain spodosol. Soil Sci Soci America J 71:1779–1787 Sathaye JA, Makundi WR, Andrasko K, Boer R, Ravindranath NH (2001) Carbon mitigation potential and costs of forestry options in Brazil, China, India, Indonesia,Mexico, the Philippines and Tanzania. Mitigation Adapt Strat Global Change 6:185–211 Schaffer B, Whiley AW, Searle C, Nissen RJ (1997) Leaf gas exchange, dry matter partitioning, and mineral element concentrations in mango as influenced by elevated atmospheric carbon dioxide and root restriction. J American Society Horti Sci 122:849–855 Scheu S, Schauermann J (1994) Decomposition of roots and twigs: effects of wood type (beech and ash), diameter, site of exposure and macrofauna exclusion. Plant Soil 241:155–176. doi:10.1007/BF00033936 Schoeneberger M, Bentrup G, de Gooijer H, Soolanayakanahally R, Sauer T, Brandle J, Zhou X, Current D (2012) Branching out: agroforestry as a climate change mitigation and adaptation tool for agriculture. J Soil Water Conser 67:128–136 Environ Sci Pollut Res Schroth G, D’Angelo SA, Teixeira WG, Haag D, Lieberei R (2002) Conversion of secondary forest into agroforestry and monoculture plantations in Amazonia: consequences for biomass, litter and soil carbon stocks after 7 years. Forest Ecology Manag 163:131–150 Scialabba N, Muller-Lindenlauf M (2010) Organic agriculture and climate change. Renewable Agri Food Sys 2:158–169 Sedjo R, Brent S (2012) Carbon sequestration in forests and soils. Ann Review Economics 4:127–153 Sharrow SH, Ismail S (2004) Carbon and nitrogen storage in agroforests, tree plantations, and pastures in western Oregon, USA. Agroforestry Sys 60:123–130 Shazana MAR, Shamshuddin J, Fauziah CI, Syed OSR (2013) Alleviating the infertility of an acid sulphate soil by using ground basalt with or without lime and organic fertilizer under submerged conditions. Land Degrad Develop 24:129–140 Shepherd D, Montagnini F (2001) Carbon sequestration potential in mixed and pure tree plantations in the humid tropics. J Tropical Forest Sci 13:450–459 Sileshi GW, Debusho LK, Akinnifesi FK (2012) Can integration of legume trees increase yield stability in rainfed maize cropping systems in southern Africa? Agron J 104:1392–1398 Smith TM, Cramer WP, Dixon RK, Leemans R, Neilson RP, Solomon AM (1993) The global terrestrial carbon cycle. Water Air Soil Pollution 70:19–37 Smith P, Martino D, Cai Z, Gwary D, Janzen H, Kumar P, McCarl B, Towprayoon S (2007) Policy and technological constraints to implementation of greenhouse gas mitigation options in agriculture. Agri, Ecosys Environ 118:6–28 Smith P, Fang C, Dawson JJC, Moncrieff JB (2008) Impact of global warming on soil organic carbon. Advances Agron 97:1–43 Smith P, Edenhofer O, Pichs-Madruga R, Sokona Y, Farahani E et al. (2014) Agriculture, forestry and other land use (AFOLU). In: (Eds.), Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom, New York, NY, USA Smith P, Cotrufo MF, Rumpel C, Paustian K, Kuikman PJ, Elliott JA, McDowell R, Griffiths RI, Asakawa S, Bustamante M, House JI, Sobocká J, Harper R, Pan G, West PC, Gerber JS, Clark JM, Adhya T, Scholes RJ, Scholes MC (2015) Biogeochemical cycles and biodiversity as key drivers of ecosystem services provided by soils. Soil 1:665–685. doi:10.5194/soil-1-665-2015 Sollins P, Swanston C, Kramer M (2007) Stabilization and destabilization of soil organic matter-a new focus. Biogeochemistry 85:1–7 Soto-Pinto L, Anzueto M, Mendoza J, Ferrer GJ, de Jong B (2010) Carbon sequestration through agroforestry in indigenous communities of Chiapas, Mexico. Agroforestry Sys 78:39–51 Srinivasarao C, Venkateswarlu B, Lal R, Singh AK, Kundu S, KPR V, Patel JJ, Patel MM (2014) Long-term manuring and fertilizer effects on depletion of soil organic carbon stocks under pearl millet-cluster beancastor rotation in western India. Land Degrad Develop 25:173–183 Stavi I, Lal R (2013) Agroforestry and biochar to offset climate change: a review. Agron Sustain Develop 33:81–96 Steinbeiss S, Bessler H, Engels C, Temperton VM, Buchmanns N, Roscher C, Kreutziger Y, Baade J, Habekost M, Gleixner G (2008) Plant diversity positively affects short-term soil carbon storage in experimental grasslands. Glob Chang Biol 14:2937–2949 Straaten V, Corre O, Wolf MD, Tchienkoua K, Cuellar M, Matthews ER, Veldkamp E (2015) Conversion of lowland tropical forests to tree cash-crop plantations loses up to half of stored soil organic carbon. Proceedings National Academy Sci 112:9956–9960 Takimoto A, Nair PKR, Nair VD (2008) Carbon stock and sequestration potential of traditional and improved agroforestry systems in the West African Sahel. Agri Ecosys Environ 125:159–166 Tesfaye MA, Bravo-Oviedo A, Bravo F, Kidane B, Bekele K, Sertse D (2014) Selection of tree species and soil management for simultaneous fuel wood production and soil rehabilitation in the Ethiopian central highlands. Land Degrad Develop 26:665–679 Thakur MP, Milcu A, Manning P, Niklaus PA, Roscher C et al (2015) Plant diversity drives soil microbial biomass carbon in grasslands irrespective of global environmental change factors. Glob Chang Biol 21:4076–4085 Thevathasan NV, Gordon AM (2004) Ecology of tree intercropping systems in the north temperate region: experiences from southern Ontario, Canada. Agroforestry Sys 61:257–268 Thornton PK, Bowen WT, Ravelo AC, Wilkens PW, Farmer G, Brock J, Brink JE (1997) Estimating millet production for famine early warning: an application of crop simulation modelling using satellite and groundbased data in Burkina Faso. Agri Forest Meteorol 83:95–112 Turgut B (2015) Comparison of wheat and safflower cultivation areas in terms of total carbon and some soil properties under semi-arid climate conditions. Solid Earth 6:719–725. doi:10.5194/se-6-719-2015 USDA-NRCS (2000) Growing Carbon: A New Crop that Helps Agricultural Producers and the Climate Too. United States Department of Agriculture Natural Resources Conservation Service Verburg PH, Overmars KP (2009) Combining top-down and bottom-up dynamics in land use modeling: exploring the future of abandoned farmlands in Europe with the Dyna-CLUE model. Landsc Ecol 24: 1167–1181 Verburg PH, Soepboer W, Veldkamp A, Limpiada R, Espaldon V, Mastura SAS (2002) Modeling the spatial dynamics of regional land use: the CLUE-S model. Environ Manag 30:391–405 Wasak K, Drewnik M (2015) Land use effects on soil organic carbon sequestration in calcareous Leptosols in former pastureland-a case study from the Tatra Mountains (Poland). Solid Earth 6:1103–1115. doi:10.5194/se-6-1103-2015 Watson RT, Noble IR, Bolin B, Ravindranath NH, Verardo DJ, Dokken DJ (2000) Land use, land-use change, and forestry. Published for the Intergovernmental Panel on Climate Change by Cambridge University Press, New York Watson-Lazowski A, Lin Y, Miglietta F, Edwards RJ, Chapman MA, Taylor G (2016) Plant adaptation or acclimation to rising CO2? Insight from first multigenerational RNA-Seq transcriptome. Glob Change Biol 22:3760–3773. doi:10.1111/gcb.13322 Webber H, Gaiser T, Ewert F (2014) What role can crop models play in supporting climate change adaptation decisions to enhance food security in sub-Saharan Africa? Agri Sys 127:161–177 Whitehead DC, Tinsley J (2006) The biochemistry of humus formation. J Sci Food Agri 14:849–857 World Bank (2015) Agricultural land (% of land area). Available at http:// data.worldbank.org/indicator/AG.LND.AGRI.ZS/countries? display=graph (verified 16 September 2015) Yu Y, Jia ZQ (2014) Changes in soil organic carbon and nitrogen capacities of Salix cheilophila Schneid. along a revegetation chronosequence in semi-arid degraded sandy land of the Gonghe Basin, Tibetan plateau. Solid Earth 5:1045–1054 Zomer RJ, Neufeldt H, Xu J, Ahrends A, Bossio D, Trabucco A, van Noordwijk M, Wang M (2016) Global tree cover and biomass carbon on agricultural land: the contribution of agroforestry to global and national carbon budgets. Sci Rep 6:29987. doi:10.1038/srep29987