Long-Term Conservation Effects of Protected Areas in Stochastic Population Dynamics

Abstract

Terrestrial and marine protected areas are essential tools in mitigating anthropogenic impacts and promoting population persistence and resource sustainability. Adequately implemented protected areas (PAs) aim to promote conservation by increasing population size and reducing its variability. To resolve how these effects depend on PA features, I develop and analyze new models of stochastic processes that encompass the fluctuations generated by demographic or environmental stochasticity in PAs management. The stochastic model is built upon individual processes. In the model, density-independent mortality, migration between PAs and non-PAs, organism preference for PAs, and size characterize the features of the PA. The effect of PAs size is also examined. The long-term conservation effects are quantified using the coefficient of variation (CV) of population size in PAs, where a lower CV indicates higher robustness in stochastic variations. The results from this study demonstrate that sufficiently reduced density-independent mortality in PAs and high site preference for PAs and immigration rate into PAs are likely to decrease the CV. However, different types of stochasticity induce rather different consequences: under demographic stochasticity, the CV is always reduced because PAs increase the population size therein, but an increased population size by PAs does not always decrease the CV under environmental stochasticity. The deterministic dynamics of the model are investigated, facilitating effective management decisions.

A perspective on biodiversity data and applications for spatio-temporally robust spatial planning for area-based conservation

“…We introduced a reserve score to characterize the temporal efficacy of protected areas and evaluated how the reserve score varies under spatiotemporal ecosystem dynamics. While the conservation efficiency of a protected area at a given point in time can be evaluated by the reserve score, the long-term variation is evaluated by its coefficient of variation (CV) in order to evaluate the degree of variation of conservation efficiency by considering the effect of the mean value as in Takashina [22]. Figure 4 represents the dynamics of reserve score as well as its frequency under four different data resolutions (2 − 4 , 2 − 2 , 2 0 , or 2 2 km 2 ).…”

“…In most cases, the existing optimization algorithms for SCP are based on snapshot data and potentially involve this problem. However, species distribution status fluctuates due to inherent stochasticity in nature, and hence conservation efficacy also varies over time [22]. Previous studies have argued the importance of dynamics mainly from the viewpoint of future predictions focusing on climatic and land-use changes.…”