A central tenant of ecohydrology in drylands is that runoff redistribution concentrates the key limiting resource of water, which can then enhance vegetation growth and biomass. Conversely, a reduction in vegetation patches can lead to a threshold-like response: bare patches become highly interconnected, triggering an increase in hillslope runoff and erosion. However, assessing how maximization of runon to vegetation patches relates to minimization of hillslope runoff, and applying these principles to improve the woodland management requires additional research. To illustrate how runoff redistribution potentially changes in response to conversion of vegetation patches to bare ones, we used a spatially distributed model, SPLASH (Simulator for Processes at the Landscape-Surface-Subsurface Hydrology), with an example of a semiarid pi?on-juniper woodland hillslope with seven combinations of bare and vegetation patch cover, culminating in complete loss of herbaceous patches, for a 1-year design storm. The amount of hillslope runoff increased curvilinearly with reductions in herbaceous cover as runoff per cell increased from bare patches and runon per cell increased for herbaceous patches. Notably, total amount of runon to herbaceous patches was greatest when amount of bare cover was intermediate, highlighting a tradeoff between source and sink area. Our results certainly depends on several site-specific conditions, but the general nature of the response may be indicative of a general type of response applicable to many woodland. We suggest that the assessing of the optimal source: sink area ratio could be valuable for managing woodland, preventing hillslope-scale degradation and, potencially, maximizing productivity.

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