Trophic Cascade

The tritrophic interactions between plants, herbivores and avian predators are complex and prone to trophic cascades. We conducted a meta-analysis of original articles that have studied birds as predators of invertebrate herbivores, to compare top-down trophic cascades with different plant responses from different environments and climatic areas. Our search found 29 suitable articles, with a total of 81 separate experimental study set-ups. The meta-analysis revealed that plants benefited from the presence of birds. A significant reduction was observed in the level of leaf damage and plant mortality. The presence of birds also positively affected the amount of plant biomass, whereas effects on plant growth were negligible. There were no differences in the effects between agricultural and natural environments. Similarly, plants performed better in all climatic areas (tropical, temperate and boreal) when birds were present. Moreover, both mature plants and saplings gained benefits from the presence of birds. Our results show that birds cause top-down trophic cascades and thus they play an integral role in ecosystems.

Gray wolves are essential keystone species  that regulate a biological ecosystem. (Estes, Terborgh, Brashares, Power, Berger, Bond and Wardle, 2011) There are many reasons why maintaining a healthy population of keystone species  in the wild is essential. Gray wolves: 1) Are family pack animals that work together as a team, (San Diego Wolf Conservation Center, 2019) 2) Create a trophic cascade , (Estes et al., 2011) 3) Are meant to be in the lower 48 states based on historical range, (Colorado Wolf and Wildlife Center, 2019) 4) Have been unfairly eradicated by humans in the past, 5) Have been identified as endangered species during specified times, 6) Have a symbiotic relationship with birds, 7) Serve an essential purpose warranting conservation , 8) Are the ancestors of domesticated dogs, 9) Have a fear of humans and tend to stay away from them (Colorado Wolf and Wildlife Center, 2019), and 10) Rarely attack humans. Some species transform our planet through their existence.

Despite scientific evidentiary support respecting the ecological importance of gray wolves, the canine continues to be a problem for many humans. If the problem is that there is a coexistence concern for gray wolves in the wild and humans living together, then a reason for this should be obtained if people are willing to share. Perception  is essential when deriving reasons for why coexistence is problematic for competing species. Humans reluctance to coexist with apex predators has consequences, some of which humans are already experiencing.

This study involved interviews with various human individuals in Idaho, surrounding states and countries, regarding their experience and knowledge of gray wolves. The interviews were conducted as informational interviews, where the interviewees were either directly or indirectly aware of their participation, and/or as in-depth surveys. Observational data was also obtained through visits at gray wolf sanctuaries, and locations where historic and/or current gray wolf habitat could be found. After reviewing the findings, a longer-term sustainability solution was developed to conserve these species, and to mitigate the negative effects of human interference. The results indicated that a long-term sustainability solution depends on: 1) humans ability to minimize their own unchecked growth and development, in order to allow wild keystone species to live with the land, 2) the human species ability to change their perspective on wild species, thereby allowing them to live peacefully, in an ecologically balance manner, 3) the human species ability to adapt to new norms and implement protection strategies that ensure planetary health and human health, simultaneously, and 4) wolves ability to stay away from humans and their livestock. Coexistence between gray wolves and humans is dependent on mostly the human species ability to implement planetary health and human health measures, simultaneously.

***Please note that the quote:

“Wolves, like other wildlife, have a right to exist in a wild state. This right is in no way related to their known value to mankind. Instead, it derives from the right of all living creatures to coexist as part of the natural ecosystem.” – Summary of Public Comment (SPC), 2007

Comes from the source:

Bangs, Ed. (Bangs), and U.S. Fish Wildlife Service. Gray Wolf EIS. The Reintroduction of Gray Wolves to Yellowstone National Park and Central Idaho: Final Environmental Impact Statement. Helena, Mont.: U.S. Fish and Wildlife Service, Gray Wolf EIS, 1994. Retrieved from
https://search.library.oregonstate.edu/permalink/f/ueodtl/CP71114360520001451

While the 2007 date refers to the source:

Idaho Fish and Wildlife Service (SPC). 2007. Wolf Population Management Plan: Species Management Plan 2008 - 2012. Boise, ID. Retrieved from https://catalog.boisestate.edu/vwebv/holdingsInfo?searchId=205&recPointer=0&recCount=25&searchType=1&bibId=684784

These two sources were accidentally combined in the writing of this paper.***

Large ‘apex’ predators influence ecosystems in profound ways, by limiting the density of their prey and controlling smaller ‘mesopredators’. The loss of apex predators from much of their range has lead to a global outbreak of mesopredators, a process known as ‘mesopredator release’ that increases predation pressure and diminishes biodiversity. While the classifica- tions apex- and meso-predator are fundamental to current ecological thinking, their definition has remained ambiguous. Trophic cascades theory has shown the importance of predation as a limit to population size for a variety of taxa (top–down control). The largest of predators however are unlikely to be limited in this fashion, and their densities are commonly assumed to be determined by the availability of their prey (bottom–up control). However, bottom–up regulation of apex predators is contradicted by many studies, particularly of non-hunted populations. We offer an alternative view that apex predators are distinguishable by a capacity to limit their own population densities (self-regulation). We tested this idea using a set of life-history traits that could contribute to self-regulation in the Carnivora, and found that an upper limit body mass of 34 kg (corresponding with an average mass of 13–16 kg) marks a transition between extrinsically- and self- regulated carnivores. Small carnivores share fast reproductive rates and development and higher densities. Large carnivores share slow reproductive rates and development, extended parental care, sparsely populated territories, and a propensity towards infanticide, reproductive suppression, alloparental care and cooperative hunting. We discuss how the expression of traits that contribute to self-regulation (e.g. reproductive suppression) depends on social stability, and highlight the importance of studying predator–prey dynamics in the absence of predator persecution. Self-regulation in large carnivores may ensure that the largest and the fiercest do not overexploit their resources.

This work, illustrates the development of 2 GHz Low Noise Amplifier (LNA) interfaced with square truncated edge-fed
right circularly polarized patch antenna. The LNA is simulated on Agilent ADS platform with TSMC 130nm RF CMOS
process. The development of cascode amplifier and its optimization has been further exemplified. The developed LNA is
tuned for 2 GHz and the performance is tuned for high stability factor of 4, Gain of 19 dB which is essential for any
mobile device, Noise Figure (NF) of 1.15 dB with a P1dB point at -9 dBm. Further a truncated patch antenna with
right circular polarization has been simulated on EMpro. The antenna has a gain of 6.1 dB in the azimuth plane. The
simulated system can be further integrated to form the RF front end of TDD2000 LTE standard mobile device.

The thylacine (Thylacinus cynocephalus) was one of Australia's largest predators, but became extinct in mainland Australia soon after the arrival of a new predator, the dingo (Canis lupus dingo) around 3500 bp. Evidence implicating the dingo in the thylacine's extinction has been equivocal, largely because thylacines are thought to be considerably larger than dingoes. Thus, other concurrent factors, such as shifts in human technology and population increase as well as climate change, have been cited to explain their extinction. Here we present new morphological evidence that female mainland Holocene thylacines were actually smaller than dingoes. We discuss these findings against archaeological and contemporary ecological evidence concerning dingoes' environmental impacts, and provide evidence that, as novel predators, dingoes induced a trophic cascade that had dramatic impacts on the fauna and economy of Holocene Australia. We suggest that dingoes, owing to their larger brains and body size, were likely a primary agent for the extinction of the thylacine from mainland Australia.

Novel assemblages of native and introduced species characterize a growing proportion of ecosystems worldwide. Some introduced species have contributed to extinctions, even extinction waves, spurring widespread efforts to eradicate or control them. We propose that trophic cascade theory offers insights into why introduced species sometimes become harmful, but in other cases stably coexist with natives and offer net benefits. Large predators commonly limit populations of potentially irruptive prey and mesopredators, both native and introduced. This top-down force influences a wide range of ecosystem processes that often enhance biodiversity. We argue that many species, regardless of their origin or priors, are allies for the retention and restoration of biodiversity in top-down regulated ecosystems.

... Our understanding of eutrophication and its management has evolved from simple control of nutrient sources to recognition that it is often a cumulative effects problem that will require protection and restoration of many features of a lake's community and its catchment. ...

Rewilding is a strategy for the conservation of complete, self-sustaining ecosystems, primarily involving the protection and, where necessary, reintroduction, of populations of keystone species in large, connected reserve networks. A potential method of preserving ecosystem functions and biodiversity, it is now receiving a great deal of practical and political attention, particularly in North America. In Scotland, where many native species

... Blaire Van Valkenburgh is a paleobiologist and functional morphologist in the Department of Ecology and Evolutionary Biology at the University of ... predation-driven direct effects or fear-driven indirect effects on communities and ecosystems (Ripple and Beschta 2004, Ray et al. ...