Shifting bottom-up and top-down regulation of oak recruitment across a regional resource gradient

2013 ◽  
Vol 22 (6) ◽  
pp. 718-727 ◽  
Author(s):  
Blair C. McLaughlin ◽  
Erika S. Zavaleta
Ecology ◽  
1994 ◽  
Vol 75 (8) ◽  
pp. 2227 ◽  
Author(s):  
A. P. Gutierrez ◽  
N. J. Mills ◽  
S. J. Schreiber ◽  
C. K. Ellis

2014 ◽  
Vol 51 (3) ◽  
pp. 814-824 ◽  
Author(s):  
Ted D. Center ◽  
F. Allen Dray ◽  
Elizabeth D. Mattison ◽  
Philip W. Tipping ◽  
Min B. Rayamajhi

BioScience ◽  
2013 ◽  
Vol 64 (1) ◽  
pp. 26-39 ◽  
Author(s):  
David B. Bunnell ◽  
Richard P. Barbiero ◽  
Stuart A. Ludsin ◽  
Charles P. Madenjian ◽  
Glenn J. Warren ◽  
...  

2021 ◽  
Author(s):  
Renee L. Brawata

ABSTRACT The removal of apex carnivores from ecosystems can impact the abundance and diversity of species in lower trophic levels. In arid ecosystems, where “bottom up” forces of primary productivity and resource availability strongly affect trophic interactions, the role of “top down” effects is still much debated. This study explored the potential role of an apex predator, the dingo, as a “top down” trophic regulator in Australian arid ecosystems under different levels of primary productivity and dingo management regimes. Consistent with the theory of top down regulation, strong relationships were found between dingo management, dingo activity and fox activity. Dingoes appeared to suppress fox activity where dingoes were uncontrolled or only opportunistically controlled. At sites where dingoes were absent or in low numbers, fox activity was higher, and this inverse relationship persisted regardless of rainfall. The activity of rabbits and small mammals was lower where dingoes were absent and fox activity was high, while the activity of macropods was higher in the absence of dingoes. Feral cat activity did not differ significantly between sites under different dingo management or between years. These results suggest that management of dingoes is a key determinant of fox activity and the activity of some prey under varying levels of productivity. Evidence from this research showed that while the strength of trophic regulation by dingoes may fluctuate, top down effects occurred both prior to and post significant rainfall events. Following this, top down regulation of fox populations during dry periods at sites where dingoes are retained may enable higher and more stable “baseline” densities of small vertebrates, from which a larger and more rapid rate of increase of these prey during the “boom” periods can occur. Understanding the relative strength and interactions of top down and bottom up forces in regulating populations, and under what ecological states the importance of each changes, is important for the long-term conservation of biodiversity in arid regions.


2019 ◽  
Vol 11 (19) ◽  
pp. 5364 ◽  
Author(s):  
Belinskij ◽  
Iho ◽  
Paloniitty ◽  
Soininen

Animal agriculture is shifting toward larger farms and regional agglomerations in many countries. In step with this development, manure nutrients have started accumulating regionally, and are leading to increasing eutrophication problems. Nevertheless, the same trend may also prompt innovations in manure treatment. For example, Valio Ltd (the largest dairy processer in Finland) is planning a network of facilities that would remove water from manure, fraction the nutrients in it, and produce biogas from the excess methane. One of the main hurdles in developing this technology is that the current regulatory framework does not support a shift from diffuse loading, which is seen in the traditional application of manure on fields, to point-source loading; the regulations may even prevent such a change. This article analyzes a governance framework that addresses this dilemma in EU–Finland, and discusses how the governance described could curtail the nutrient loading of agriculture to waters. The approach is based on adaptive governance theory. We argue that traditional top–down regulation, which emphasizes food security, contains serious shortcomings when it comes to managing agricultural nutrient loading to waters, and that the current regulatory framework does not necessarily have the adaptive capacity to facilitate new, bottom–up solutions for manure treatment. Interestingly, the strict water quality requirements of the EU Water Framework Directive (2000/60/EC) open new windows of opportunity for such solutions, and thus for improving the overall sustainability of animal agriculture.


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