The effect of lands surrounding fragmented landscapes: theory development and novel experimental tests

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Species are declining across the world. The destruction of plant and animal habitat is a well-known cause for such declines. It is less appreciated that lands surrounding remaining suitable habitats, termed "the matrix" can be important for species. Observations suggest that in many situations, these lands can be necessary for the survival of species. Understanding why these effects occur is important for advancing our knowledge on land-use change. This research will address these issues by providing novel field experiments to understand both habitat and non-habitat effects on species. The results will be used to provide solutions for mitigating the deleterious effects of habitat destruction on natural populations of species. It will also provide broader impacts to society by developing videos on the findings which will be presented to the public at a natural history museum. In this project, the researchers will conduct field experiments designed to elucidate effects of the matrix on populations. They will also develop theoretical models of this study system which can be applied to other similar systems in which species typically live in habitats surrounded by unsuitable lands (the matrix). The study system consists of two species of insect herbivores that specialize on prickly pear cactus and vary in dispersal ability. The cactus plants are the suitable habitats, occurring in clumps surrounded by a variety of grass species which is the matrix. The experiments will manipulate habitat size, degree of fragmentation (number of habitats and distance between habitats) and quality of the matrix land to test how each of these factors affects the population dynamics of the subject species. The results will be used to evaluate the importance of matrix effects relative to the well-known effects of habitat loss and fragmentation. Model development will contextualize these results and will provide new solutions for predicting the effects of the matrix on connectivity and population dynamics.