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Dirzo, R.

Publications and source records attributed to Dirzo, R..

2 recordsLinked to original sources

Risky home with easy food: Denning of a generalistic and widely distributed carnivore red fox

Dens are crucial for the survival of all canids, however, for a meso-carnivore like red fox, denning is of greater importance as they utilize dens all throughout the year for protection, resting and breeding. The red fox known for its generalist and opportunistic behavior and extremely good adaptability to the dynamic anthropogenic changes is the most widespread and successful wild land carnivore. With an ever-growing human population the choice of space for wild animals is limited and such adaptability is important for species survival. In this study we examined the denning preferences and den characteristics of red fox. Intensive surveys were conducted across two study sites Chiktan and Changthang. Foxes preferred to den on mountain slopes (43.70 {+/-} 3.38 SE) where human disturbances were minimal. The red fox chose den sites closer to human settlements, water and road as compared to random points (Pillais trace = .487, F= 31.014 and P = 3.497e-14), which are risky and may expose the pups to humans but also provide the advantage of procuring anthropogenic food subsidies. In Changthang, foxes preferred to den at a greater distance (936 {+/-} 223 meters) from human settlements as compared to Chiktan (403 {+/-} 50 meters). The present research is of broad significance, given the increasing presence of human settlements within original animal ranges, even in remote harsh environments like the Trans-Himalaya.

ecology

Assessing sustainability in North America’s ecosystems using criticality and information theory

Sustainability is a key concept in economic and policy debates. Nevertheless, it is usually treated only in a qualitative way and has eluded quantitative analysis. Here, we propose a sustainability index based on the premise that sustainable systems do not lose or gain Fisher Information over time. We test this approach using time series data from the AmeriFlux network that measures ecosystem respiration, water and energy fluxes in order to elucidate two key sustainability features: ecosystem health and stability. A novel definition of ecosystem health is developed based on the concept of criticality, which implies that if a systems fluctuations are scale invariant then the system is in a balance between robustness and adaptability. We define ecosystem stability by taking an information theory approach that measures its entropy and Fisher information. Analysis of the Ameriflux consortium big data set of ecosystem respiration time series is contrasted with land condition data. In general we find a good agreement between the sustainability index and land condition data. However, we acknowledge that the results are a preliminary test of the approach and further verification will require a multi-signal analysis. For example, high values of the sustainability index for some croplands are counter-intuitive and we interpret these results as ecosystems maintained in artificial health due to continuous human-induced inflows of matter and energy in the form of soil nutrients and control of competition, pests and disease.

ecology