Conservation prioritization requires knowledge about organism distribution and density. This information is often inferred from models that estimate the probability of species occurrence rather than from models that estimate species abundance, because abundance data are harder to obtain and model. However, occurrence and abundance may not display similar patterns and therefore development of robust, scalable, abundance models is critical to ensuring that scarce conservation resources are applied where they can have the greatest benefits. Motivated by a dynamic land conservation program, we develop and assess a general method for modeling relative abundance using citizen science monitoring data. Weekly estimates of relative abundance and occurrence were compared for prioritizing times and locations of conservation actions for migratory waterbird species in California, USA. We found that abundance estimates consistently provided better rankings of observed counts than occurrence estimates. Additionally, the relationship between abundance and occurrence was nonlinear and varied by species and season. Across species, locations prioritized by occurrence models had only 10-58% overlap with locations prioritized by abundance models, highlighting that occurrence models will not typically identify the locations of highest abundance that are vital for conservation of populations.

Groundwater is a critical water supply around the world and is increasingly under threat from pumping that exceeds natural replenishment. California is taking on this challenge with the Sustainable Groundwater Management Act (SGMA) of 2014, which seeks to reliably manage groundwater to meet current and future water needs for the economy, communities and environment. Successful implementation of SGMA depends on the ability of local agencies to work with stakeholders to develop plans and implement projects that reduce groundwater use, increase recharge and efficiently allocate pumping. With more than 250 local agencies undertaking actions to address groundwater overdraft, California serves as a unique laboratory for testing new ways to achieve groundwater management. At the same time, economic tools are increasingly being utilized to secure or deliver water to the environment. For the past several years, The Nature Conservancy has been testing ways that economic tools can help achieve groundwater sustainability. This paper presents case studies that illustrate how two forms of Payment for Ecosystem Services (PES) — a groundwater market and a multi-benefit recharge incentive program — are being used in California to achieve groundwater sustainability to simultaneously meet the water needs of people and nature.

No abstract