Microhabitats associated with solar energy development alter demography of two desert annuals

Abstract

Political and economic initiatives intended to increase energy production while reducing carbon emissions are driving demand for solar energy. Consequently, desert regions are now targeted for development of large-scale photovoltaic solar energy facilities. Where vegetation communities are left intact or restored within facilities, ground-mounted infrastructure may have negative impacts on desert-adapted plants because it creates novel rainfall runoff and shade conditions. We used experimental solar arrays in the Mojave Desert to test how these altered conditions affect population dynamics for a closely related pair of native annual plants: rare Eriophyllum mohavense and common E. wallacei. We estimated aboveground demographic rates (seedling emergence, survivorship, and fecundity) over 7 yr and used seed bank survival rates from a concurrent study to build matrix models of population growth in three experimental microhabitats. In drier years, shade tended to reduce survival of the common species, but increase survival of the rare species. In a wet year, runoff from panels tended to increase seed output for both species. Population growth projections from microhabitatspecific matrix models showed stronger effects of microhabitat under wetter conditions, and relatively little effect under dry conditions (lack of rainfall was an overwhelming constraint). Performance patterns across microhabitats in the wettest year differed between rare and common species. Projected growth of E. mohavense was substantially reduced in shade, mediated by negative effects on aboveground demographic rates. Hence, the rare species were more susceptible to negative effects of panel infrastructure in wet years that are critical to seed bank replenishment. Our results suggest that altered shade and water runoff regimes associated with energy infrastructure will have differential effects on demographic transitions across annual species and drive population-level processes that determine local abundance, resilience, and persistence.

Standardized metrics to quantify solar energy-land relationships: A global systematic review

“…Several studies have found that ground-mounted solar energy, specifically PV, can impact air temperature, photosynthetically available radiation, rate of photosynthesis (Armstrong et al, 2016;Choi et al, 2020;Guoqing et al, 2021). Additionally, solar energy can impact plant diversity, abundance, and demography (Hernandez et al, 2020a;Tanner et al, 2020), and soil moisture creating unique microclimates under and around solar arrays (Tanner et al, 2020(Tanner et al, , 2021. For example, Grodsky and Hernandez (2020) found that development decisions for a 392 megawatt (MW) concentrating solar energy power plant in the Mojave Desert reduced cover and structure of desert perennial plants and their ecosystem services and facilitated the growth of invasive grass species.…”

Statistical inference for seed mortality and germination with seed bank experiments

“…However, there is no standard statistical approach for estimating seed mortality and germination from field experiments, and even observations from the same kind of experiment are often analyzed in disparate ways. For instance, three recent studies that used seed bag burial experiments each analyzed the observations differently: by regressing seeds in year on seeds in year (Kurkjian et al, 2017), fitting an exponential curve (Lommen et al, 2018), or estimating the proportion of surviving seeds (Tanner et al, 2021).…”

Solar Energy-driven Land-cover Change Could Alter Landscapes Critical to Animal Movement in the Continental United States

“…Major knowledge gaps remain in our understanding of the relationship between solar energy infrastructure and wildlife. ,, To date, empirical research has documented direct negative impacts on biodiversity for plants and animals within large, ground-mounted facility footprints during the construction and operation of PV and concentrating solar power facilities. ,− Other studies have reported avian richness in large, ground-mounted solar facilities to be comparable to that of active pasture/cropland, but less than that of abandoned cropland, as well as lower species density and richness inside of large, ground-mounted solar facilities compared to that of facility boundary zones and unaltered controls. − Beyond these studies, there is little data regarding other topics such as solar infrastructure’s influence on species ranges, behavior, occupancy/density, and, critically, movement. One study describes negative impacts of solar development on ungulates, including barrier effects on both resident and migratory populations as well as direct and indirect habitat loss, but more data are needed to characterize the relationship between solar energy infrastructure and animal movement.…”