ABSTRACT Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terre... more ABSTRACT Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terrestrial surface, and increased agricultural intensification has resulted in the degradation of biodiversity and various ecosystem services associated with agriculture. However, individual agroecosystems have varying impacts on ecosystem services, and attention is turning to methods of agricultural management that are capable of providing not only food, but also multiple services. In determining how to optimize food production and ecosystem service provision, it is crucial to first understand what ecological factors—both at a local- and landscape-level scale—are most influential in providing these services. I addressed the question of how pest predation by vertebrates and biodiversity conservation are influenced by local- and landscape-level heterogeneity in Puerto Rican coffee farms. Central to this question is whether plant diversity or simply vegetation structure has a stronger influence on service provision. At the farm level, we recorded various plant diversity and vegetation structure metrics, while at the landscape-level we measured the surrounding area in different landuses. To assess biocontrol of insect pests on coffee bushes, we excluded birds and bats in one treatment and birds, bats, and anoles in another treatment. To determine biodiversity conservation, we surveyed parasitoid wasps, ground-foraging ants, birds, and anoles. Results/Conclusions Based on the vertebrate predator exclusions, we observed an additive effect of bird, bat, and anole predation on Petrusa epilepsis (Hemiptera: Flatidae), the largest coffee pest we studied. Both exclusion treatments (all three vertebrates as well as only birds/bats) showed an increased abundance of the coffee leafminer (Leucoptera coffeella; Lepidoptera: Lyonetiidae), whereas no effect was seen for the coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae). We found that the predation of Petrusa epilepsis was highest on farms with a medium amount of shade and that the predation of the coffee leafminer was highest on medium- and low-shade farms. Other pests did not show a significant difference across shade levels. Bird and anole abundance and diversity was highest in medium and high shade farms. We show that vertebrates can be important predators of coffee pests but their effect varies and depends on both the type of pest, especially in regards to its level of conspicuousness, and the management intensity of the farm. Although values of biocontrol and biodiversity vary largely depending on the organism, we found that overall farms with medium levels of shade provide the highest provision of both biocontrol and biodiversity conservation.
International Journal of Plant Sciences, Jun 1, 2013
ABSTRACT Premise of research. The lianoid habit is found in 125 extant plant families and is most... more ABSTRACT Premise of research. The lianoid habit is found in 125 extant plant families and is most diverse and abundant in structurally complex forests, such as tropical forests. A stem with lianoid anatomy is described from Cretaceous sediments of Hornby Island, British Columbia. Methodology. The stem segment, 2.5 cm in diameter and 2.8 cm long, was studied using the cellulose acetate peel technique and SEM. Anatomy was documented and compared to fossil and modern taxa. Pivotal results. The stem lacks distinct growth increments, and the fibrous wood is dissected by large (>10 cells wide) rays. Wood is diffuse porous with mostly solitary vessels, rarely in tangential multiples (2–4). Vessel elements have a mean tangential diameter of 198 μm and mean length of 527 μm, bearing medium to large, crowded, elliptical to flat-elliptical alternate pits. Axial parenchyma is diffuse and vessels are surrounded by vasicentric tracheids with alternate bordered pitting. Rays are homocellular and >2 cm tall. Phloem rays are dilated, protruding into the xylem rays; thick-walled ray cells contain prismatic crystals. Periderm is composed of thin-walled cells interspersed with sclerotic nests. Wood anatomy of the fossil shows the most similarity to that of lianas in the Menispermaceae, Lardizabalaceae, and Ranunculaceae. Conclusions. The Hornby Island stem represents a new taxon, Atli morinii gen. et sp. nov. (Ranunculales). This liana specimen expands our knowledge of Cretaceous biodiversity and points to the presence of structurally complex forests on Hornby Island in the Campanian. Anatomy of Atli and other Cretaceous liana stems combines characteristics of several families in Ranunculales, documenting past anatomical diversity and possible stem lineage mosaicism. The most diverse lianoid lineages currently known from the Cretaceous and Paleogene are early-divergent eudicots, particularly Ranunculales and Vitales that account for more than 50% of described lianoid species during this key time period of angiosperm diversification.
ABSTRACT Background/Question/Methods As atmospheric CO2 levels continue to rise, whether we can r... more ABSTRACT Background/Question/Methods As atmospheric CO2 levels continue to rise, whether we can rely on forests as carbon sinks (45% of terrestrial carbon) depends on our ability to understand the dynamics behind terrestrial and atmospheric interactions. One concern is the increase in the abundance, size, and dominance of native lianas (woody climbing vines) in tropical forests. Lianas are associated with an increased risk of tree mortality, and may alter forest species composition by disproportionately colonizing non-pioneer tree species. Moreover, lianas have more efficient water transport systems and may have deeper roots, thus are capable of extending growth in the canopy during periods of seasonal drought when many tropical trees are photosynthetically less active, deciduous, or otherwise water-stressed. Our goal is to determine whether there is any difference in the growth and physiological response of tropical lianas and trees grown under elevated CO2, and whether any response differs between the wet and dry seasons. We are investigating 8 locally abundant tropical liana and tree species growing in open-top chambers in Panama. Results/Conclusions Preliminary results suggest that, during the wet season, lianas exhibit a larger response (change in stem height and diameter) than trees to elevated CO2 concentrations when compared to ambient concentrations. Lianas also respond with higher rates of photosynthesis and stomatal conductance. However, during the first six weeks of the dry season, the results are mixed: elevated CO2 leads to greater growth in liana diameter and leaf productivity than trees, yet trees exhibit the larger change in stem height. The liana and tree responses are each controlled by a subset of species, instead of a uniform response within growth form. This is the first study to assess whether the combination of increasing CO2 and seasonal drought is a viable explanation for the observed increase in liana size and abundance in the tropics.
A new species of asymmetrically winged fruit is described from Miocene sediments of Andean Ecuado... more A new species of asymmetrically winged fruit is described from Miocene sediments of Andean Ecuador. The new fruit is readily placed in the genus Loxopterygium of the Anacardiaceae based on the size, position of the stigma, wing venation, and serration of the wing tip. The new fossil species is very similar to extant species of Loxopterygium now distributed in dry
To assess the degree to which forest litter reflects the source forest, three 1-ha plots of tempe... more To assess the degree to which forest litter reflects the source forest, three 1-ha plots of temperate deciduous forest were mapped and litter accumulating in these forests was sampled. Identity, position, and diameter of all stems 2 cm or larger diameter at breast height are known for each forest. Composition of the leaf litter is governed by two key factors: (1) abscised leaves are deposited primarily on the forest floor directly underneath the canopy that produced them, and (2) the leaf mass of a species is highly correlated with its stem cross-sectional area. These factors produce autochthonous litter samples that correspond closely in composition to the forest within a circle of canopy-height radius or less. Even relatively small litter samples (350 leaves) consistently contained all the common species in the local area. However, the rarer tree species were seldom recovered in the litter samples. Correlation coefficients for litter mass and basal area by species are typically over .80.These observations have three important implications for interpreting autochthonous compression-fossil assemblages. First, approximate relative abundances of locally dominant and subdominant forest taxa can be obtained from relatively small samples of autochthonous compression-fossil assemblages. Second, representation of rare forest species, even in large fossil samples, will be fortuitous. For this reason, complete species lists and consistent estimates of richness cannot be derived directly from most existing samples of autochthonous compression-fossil assemblages. Third, the strong tendency for leaves to fall beneath the canopy of the tree that sheds them suggests that properly sampled autochthonous fossil leaf assemblages may yield information on crown size of individual trees and the spatial distribution of individuals and species, aspects of vegetational structure that have been thought accessible only in well-preserved “fossil forests” with standing trunks.
Page 1. RESEARCH LETTERS Forest Litter Preserved by Volcanic Activity at El Chich6n, Mexico: A Po... more Page 1. RESEARCH LETTERS Forest Litter Preserved by Volcanic Activity at El Chich6n, Mexico: A Potentially Accurate Record of th( Pre-Eruption Vegetatic ROBYN J. BURNHAM Department of Botany KB-15 University of Washington ...
We found six species of the genus Gurania that are described here as new records for the state of... more We found six species of the genus Gurania that are described here as new records for the state of Mato Grosso, Central Brazil. The species of Gurania recorded here occur in the north of Mato Grosso state, Brazil in the biome recognized as "Floresta Amazônica". This is an area of southern Amazonia that has been poorly inventoried. We carried out the surveys in permanent plots using the RAPELD-PPBio system and along trails giving access to the permanent plots.
Recent studies indicate that lianas are increasing in size and abundance relative to trees in neo... more Recent studies indicate that lianas are increasing in size and abundance relative to trees in neotropical forests. As a result, forest dynamics and carbon balance may be altered through liana-induced suppression of tree growth and increases in tree mortality. Increasing atmospheric CO2 is hypothesized to be responsible for the increase in neotropical lianas, yet no study has directly compared the relative response of tropical lianas and trees to elevated CO2 . We explicitly tested whether tropical lianas had a larger response to elevated CO2 than co-occurring tropical trees and whether seasonal drought alters the response of either growth form. In two experiments conducted in central Panama, one spanning both wet and dry seasons and one restricted to the dry season, we grew liana (n = 12) and tree (n = 10) species in open-top growth chambers maintained at ambient or twice-ambient CO2 levels. Seedlings of eight individuals (four lianas, four trees) were grown in the ground in each ch...
Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terrestrial su... more Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terrestrial surface, and increased agricultural intensification has resulted in the degradation of biodiversity and various ecosystem services associated with agriculture. However, individual agroecosystems have varying impacts on ecosystem services, and attention is turning to methods of agricultural management that are capable of providing not only food, but also multiple services. In determining how to optimize food production and ecosystem service provision, it is crucial to first understand what ecological factors—both at a local- and landscape-level scale—are most influential in providing these services. I addressed the question of how pest predation by vertebrates and biodiversity conservation are influenced by local- and landscape-level heterogeneity in Puerto Rican coffee farms. Central to this question is whether plant diversity or simply vegetation structure has a stronger influence on serv...
ABSTRACT Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terre... more ABSTRACT Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terrestrial surface, and increased agricultural intensification has resulted in the degradation of biodiversity and various ecosystem services associated with agriculture. However, individual agroecosystems have varying impacts on ecosystem services, and attention is turning to methods of agricultural management that are capable of providing not only food, but also multiple services. In determining how to optimize food production and ecosystem service provision, it is crucial to first understand what ecological factors—both at a local- and landscape-level scale—are most influential in providing these services. I addressed the question of how pest predation by vertebrates and biodiversity conservation are influenced by local- and landscape-level heterogeneity in Puerto Rican coffee farms. Central to this question is whether plant diversity or simply vegetation structure has a stronger influence on service provision. At the farm level, we recorded various plant diversity and vegetation structure metrics, while at the landscape-level we measured the surrounding area in different landuses. To assess biocontrol of insect pests on coffee bushes, we excluded birds and bats in one treatment and birds, bats, and anoles in another treatment. To determine biodiversity conservation, we surveyed parasitoid wasps, ground-foraging ants, birds, and anoles. Results/Conclusions Based on the vertebrate predator exclusions, we observed an additive effect of bird, bat, and anole predation on Petrusa epilepsis (Hemiptera: Flatidae), the largest coffee pest we studied. Both exclusion treatments (all three vertebrates as well as only birds/bats) showed an increased abundance of the coffee leafminer (Leucoptera coffeella; Lepidoptera: Lyonetiidae), whereas no effect was seen for the coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae). We found that the predation of Petrusa epilepsis was highest on farms with a medium amount of shade and that the predation of the coffee leafminer was highest on medium- and low-shade farms. Other pests did not show a significant difference across shade levels. Bird and anole abundance and diversity was highest in medium and high shade farms. We show that vertebrates can be important predators of coffee pests but their effect varies and depends on both the type of pest, especially in regards to its level of conspicuousness, and the management intensity of the farm. Although values of biocontrol and biodiversity vary largely depending on the organism, we found that overall farms with medium levels of shade provide the highest provision of both biocontrol and biodiversity conservation.
International Journal of Plant Sciences, Jun 1, 2013
ABSTRACT Premise of research. The lianoid habit is found in 125 extant plant families and is most... more ABSTRACT Premise of research. The lianoid habit is found in 125 extant plant families and is most diverse and abundant in structurally complex forests, such as tropical forests. A stem with lianoid anatomy is described from Cretaceous sediments of Hornby Island, British Columbia. Methodology. The stem segment, 2.5 cm in diameter and 2.8 cm long, was studied using the cellulose acetate peel technique and SEM. Anatomy was documented and compared to fossil and modern taxa. Pivotal results. The stem lacks distinct growth increments, and the fibrous wood is dissected by large (>10 cells wide) rays. Wood is diffuse porous with mostly solitary vessels, rarely in tangential multiples (2–4). Vessel elements have a mean tangential diameter of 198 μm and mean length of 527 μm, bearing medium to large, crowded, elliptical to flat-elliptical alternate pits. Axial parenchyma is diffuse and vessels are surrounded by vasicentric tracheids with alternate bordered pitting. Rays are homocellular and >2 cm tall. Phloem rays are dilated, protruding into the xylem rays; thick-walled ray cells contain prismatic crystals. Periderm is composed of thin-walled cells interspersed with sclerotic nests. Wood anatomy of the fossil shows the most similarity to that of lianas in the Menispermaceae, Lardizabalaceae, and Ranunculaceae. Conclusions. The Hornby Island stem represents a new taxon, Atli morinii gen. et sp. nov. (Ranunculales). This liana specimen expands our knowledge of Cretaceous biodiversity and points to the presence of structurally complex forests on Hornby Island in the Campanian. Anatomy of Atli and other Cretaceous liana stems combines characteristics of several families in Ranunculales, documenting past anatomical diversity and possible stem lineage mosaicism. The most diverse lianoid lineages currently known from the Cretaceous and Paleogene are early-divergent eudicots, particularly Ranunculales and Vitales that account for more than 50% of described lianoid species during this key time period of angiosperm diversification.
ABSTRACT Background/Question/Methods As atmospheric CO2 levels continue to rise, whether we can r... more ABSTRACT Background/Question/Methods As atmospheric CO2 levels continue to rise, whether we can rely on forests as carbon sinks (45% of terrestrial carbon) depends on our ability to understand the dynamics behind terrestrial and atmospheric interactions. One concern is the increase in the abundance, size, and dominance of native lianas (woody climbing vines) in tropical forests. Lianas are associated with an increased risk of tree mortality, and may alter forest species composition by disproportionately colonizing non-pioneer tree species. Moreover, lianas have more efficient water transport systems and may have deeper roots, thus are capable of extending growth in the canopy during periods of seasonal drought when many tropical trees are photosynthetically less active, deciduous, or otherwise water-stressed. Our goal is to determine whether there is any difference in the growth and physiological response of tropical lianas and trees grown under elevated CO2, and whether any response differs between the wet and dry seasons. We are investigating 8 locally abundant tropical liana and tree species growing in open-top chambers in Panama. Results/Conclusions Preliminary results suggest that, during the wet season, lianas exhibit a larger response (change in stem height and diameter) than trees to elevated CO2 concentrations when compared to ambient concentrations. Lianas also respond with higher rates of photosynthesis and stomatal conductance. However, during the first six weeks of the dry season, the results are mixed: elevated CO2 leads to greater growth in liana diameter and leaf productivity than trees, yet trees exhibit the larger change in stem height. The liana and tree responses are each controlled by a subset of species, instead of a uniform response within growth form. This is the first study to assess whether the combination of increasing CO2 and seasonal drought is a viable explanation for the observed increase in liana size and abundance in the tropics.
A new species of asymmetrically winged fruit is described from Miocene sediments of Andean Ecuado... more A new species of asymmetrically winged fruit is described from Miocene sediments of Andean Ecuador. The new fruit is readily placed in the genus Loxopterygium of the Anacardiaceae based on the size, position of the stigma, wing venation, and serration of the wing tip. The new fossil species is very similar to extant species of Loxopterygium now distributed in dry
To assess the degree to which forest litter reflects the source forest, three 1-ha plots of tempe... more To assess the degree to which forest litter reflects the source forest, three 1-ha plots of temperate deciduous forest were mapped and litter accumulating in these forests was sampled. Identity, position, and diameter of all stems 2 cm or larger diameter at breast height are known for each forest. Composition of the leaf litter is governed by two key factors: (1) abscised leaves are deposited primarily on the forest floor directly underneath the canopy that produced them, and (2) the leaf mass of a species is highly correlated with its stem cross-sectional area. These factors produce autochthonous litter samples that correspond closely in composition to the forest within a circle of canopy-height radius or less. Even relatively small litter samples (350 leaves) consistently contained all the common species in the local area. However, the rarer tree species were seldom recovered in the litter samples. Correlation coefficients for litter mass and basal area by species are typically over .80.These observations have three important implications for interpreting autochthonous compression-fossil assemblages. First, approximate relative abundances of locally dominant and subdominant forest taxa can be obtained from relatively small samples of autochthonous compression-fossil assemblages. Second, representation of rare forest species, even in large fossil samples, will be fortuitous. For this reason, complete species lists and consistent estimates of richness cannot be derived directly from most existing samples of autochthonous compression-fossil assemblages. Third, the strong tendency for leaves to fall beneath the canopy of the tree that sheds them suggests that properly sampled autochthonous fossil leaf assemblages may yield information on crown size of individual trees and the spatial distribution of individuals and species, aspects of vegetational structure that have been thought accessible only in well-preserved “fossil forests” with standing trunks.
Page 1. RESEARCH LETTERS Forest Litter Preserved by Volcanic Activity at El Chich6n, Mexico: A Po... more Page 1. RESEARCH LETTERS Forest Litter Preserved by Volcanic Activity at El Chich6n, Mexico: A Potentially Accurate Record of th( Pre-Eruption Vegetatic ROBYN J. BURNHAM Department of Botany KB-15 University of Washington ...
We found six species of the genus Gurania that are described here as new records for the state of... more We found six species of the genus Gurania that are described here as new records for the state of Mato Grosso, Central Brazil. The species of Gurania recorded here occur in the north of Mato Grosso state, Brazil in the biome recognized as "Floresta Amazônica". This is an area of southern Amazonia that has been poorly inventoried. We carried out the surveys in permanent plots using the RAPELD-PPBio system and along trails giving access to the permanent plots.
Recent studies indicate that lianas are increasing in size and abundance relative to trees in neo... more Recent studies indicate that lianas are increasing in size and abundance relative to trees in neotropical forests. As a result, forest dynamics and carbon balance may be altered through liana-induced suppression of tree growth and increases in tree mortality. Increasing atmospheric CO2 is hypothesized to be responsible for the increase in neotropical lianas, yet no study has directly compared the relative response of tropical lianas and trees to elevated CO2 . We explicitly tested whether tropical lianas had a larger response to elevated CO2 than co-occurring tropical trees and whether seasonal drought alters the response of either growth form. In two experiments conducted in central Panama, one spanning both wet and dry seasons and one restricted to the dry season, we grew liana (n = 12) and tree (n = 10) species in open-top growth chambers maintained at ambient or twice-ambient CO2 levels. Seedlings of eight individuals (four lianas, four trees) were grown in the ground in each ch...
Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terrestrial su... more Background/Question/Methods Agricultural lands currently cover ~40% of the earth’s terrestrial surface, and increased agricultural intensification has resulted in the degradation of biodiversity and various ecosystem services associated with agriculture. However, individual agroecosystems have varying impacts on ecosystem services, and attention is turning to methods of agricultural management that are capable of providing not only food, but also multiple services. In determining how to optimize food production and ecosystem service provision, it is crucial to first understand what ecological factors—both at a local- and landscape-level scale—are most influential in providing these services. I addressed the question of how pest predation by vertebrates and biodiversity conservation are influenced by local- and landscape-level heterogeneity in Puerto Rican coffee farms. Central to this question is whether plant diversity or simply vegetation structure has a stronger influence on serv...
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