The importance of matrix quality in fragmented landscapes: Understanding ecosystem collapse through a combination of deterministic and stochastic forces

Increasing fragmentation of natural landscapes due to anthropogenic forces are changing the ecological structure of many systems. The corpus of literature has addressed the fact that there are many complex mechanisms that may lead to population and ecosystem collapse. Here, we propose an additional mechanism that combines the deterministic framework of complex oscillatory phenomena with the stochastic framework based on the spatial phenomena of island biogeography and metapopulation theory. Combining these two frameworks, which we believe exist in disturbed natural systems, we construct a situation in which collections of competitors are controlled by specialist natural enemies. Species are isolated in fragmented habitats separated by a matrix of decreasing ecological quality, which will determine immigration potential. In this system, species are exposed to stochastic extinction of spatial immigration potential and deterministic extinction of standard oscillatory frameworks. Through the combination of these extinction events, we see that many natural systems may become increasingly unstable and subject to unexpected consequences with changes to the matrix environment. The combined effect of these two extinctions pathways highlights the need to maintain high immigration rates in order to offset possible ecosystem collapse in fragmented systems. The results highlight the importance of landscape conservation efforts, especially towards maintaining matrix environments with greater ecological integrity.