Grassland productivity responds unexpectedly to dynamic light and soil water environments induced by photovoltaic arrays
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- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
- National Renewable Energy Laboratory Golden Colorado USA
- School of Geography, Development and Environment University of Arizona Tucson Arizona USA, Biosphere 2 University of Arizona Tucson Arizona USA
- Department of Biology and Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA, Long Term Ecological Research Network, National Center for Ecological Analysis and Synthesis University of California Santa Barbara Santa Barbara California USA
Abstract Agrivoltaic (AV) systems are designed to coproduce photovoltaic (PV) energy on lands simultaneously supporting agriculture (food/forage production). PV infrastructure in agroecosystems alters resources critical for plant growth, and water‐limited agroecosystems such as grasslands are likely to be particularly sensitive to the unique spatial and temporal patterns of incident sunlight and soil water inherent within AV systems. However, the impact of resource alteration on forage production, the primary ecosystem service from managed grasslands, is poorly resolved. Here, we evaluated seasonal patterns of soil moisture (SM) and diurnal variation in incident sunlight (photosynthetic photon flux density [PPFD]) in a single‐axis‐tracking AV system established in a formerly managed semiarid C 3 grassland in Colorado. Our goals were to (1) quantify dynamic patterns of PPFD and SM within a 1.2 MW PV array in a perennial grassland, and (2) determine how aboveground net primary production (ANPP) and photosynthetic parameters responded to the resource patterns created by the PV array. We hypothesized that spatial variability in ANPP would be strongly related to SM patterns, typical of most grasslands. We measured significant reductions in ANPP directly beneath PV panels, where SM and PPFD were both low. However, in locations with significantly increased SM from the shedding and redistribution of precipitation by PV panels, ANPP was not increased. Instead, ANPP was greatest in locations where plants were shaded in the afternoon but received high levels of PPFD in the morning hours, when air temperatures and vapor pressure deficits were relatively low. Thus, contrary to expectations, we found relatively weak relationships between SM and ANPP despite significant spatial variability in both. Further, there was little evidence that light‐saturated photosynthesis ( A sat ) and quantum yield of CO 2 assimilation (ϕCO 2 ) differed for plants growing directly beneath (lowest PPFD) versus between (highest PPFD) PV panels. Overall, the AV system established in this semiarid managed grassland did not alter patterns of ANPP in ways predictable from past studies of controls of ANPP in open grasslands. However, our results suggest that the diurnal timing of low versus high periods of PPFD incident on plants is an important determinant of productivity patterns in grasslands.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office; USDA National Institute of Food and Agriculture (NIFA)
- Grant/Contract Number:
- AC36-08GO28308; 2021-68012-35898 2021–2025; EE00034165
- OSTI ID:
- 1907141
- Alternate ID(s):
- OSTI ID: 1916518; OSTI ID: 1922628
- Report Number(s):
- NREL/JA-6A20-85177; e4334
- Journal Information:
- Ecosphere, Journal Name: Ecosphere Vol. 13 Journal Issue: 12; ISSN 2150-8925
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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