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Watershed managers require accurate, high-spatial-resolution evapotranspiration (ET) data to evaluate forest susceptibility to drought or catastrophic wildfire, and to determine opportunities for enhancing streamflow or forest resilience under climate warming. We evaluate an easily calculated product by using annual gridded precipitation (P) and measured discharge (Q), together with a gridded ET product developed from ET and P measured at flux towers plus Landsat NDVI (normalized difference vegetation index) to evaluate uncertainties in water balances across 52 watersheds with stream-gauge measurements in the Central Sierra Nevada. Watershed areas ranged from 5 to 4823 km2, and the study-area elevation range was 52–3302 m. Study-area P, ET, and Q averaged 1263, 634, and 573 mm yr–1 respectively, with precipitation at higher elevations up to five times that at lower elevations. We assessed uncertainty in water-balance components by applying a multiplier to P or Q values across the period of record for each watershed to align annual P-ET and Q values, resulting in average P-ET-Q = 0. Most year-to-year values of annual change in storage (ΔS), calculated as P-ET-Q for watersheds with well-constrained water balances, were within about + 300 mm. Across the study area we found that for each of 37 watersheds, applying a constant multiplier to either annual P or Q resulted in well-constrained water balances (average annual P-ET-Q = 0). Multiplicative adjustment of ET values for each watershed did not improve average water balances over the period of record, and would result in inconsistent values across adjacent and nested watersheds. For a given watershed, ET was relatively constant from year to year, with precipitation variability driving both interannual and spatial variability in runoff. These findings highlight the importance of evapotranspiration as a central metric of water-balance change and variability, and the strength of using high-confidence spatial- evapotranspiration estimates to diagnose uncertainties in annual water balances, and the components contributing to those uncertainties.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been detected in multiple animal species, including white-tailed deer (WTD), raising concerns about zoonotic transmission, particularly in environments with frequent human interactions. To understand how human exposure influences SARS-CoV-2 infection in WTD, we compared infection and exposure prevalence between farmed and free-ranging deer populations in Florida. We also examined the timing and viral variants in WTD relative to those in Florida's human population. Between 2020 and 2022, we collected respiratory swabs (N = 366), lung tissue (N = 245), retropharyngeal lymph nodes (N = 491), and serum specimens (N = 381) from 410 farmed and 524 free-ranging WTD. Specimens were analyzed using RT-qPCR for infection and serological assays for exposure. SARS-CoV-2 infection was detected in less than 1% of both northern Florida farmed (0.85%) and free-ranging (0.76%) WTD. No farmed deer possessed virus-neutralizing antibodies, while one free-ranging WTD tested positive for SARS-CoV-2 antibodies (3.45%). Viral sequences in infected WTD matched peaks in human cases and circulating variants, indicating human-to-deer spillover but at a lower frequency than reported elsewhere. Our findings suggest a reduced risk of SARS-CoV-2 spillover to WTD in northern Florida compared to other regions, highlighting the need for further research on transmission dynamics across North America. [ABSTRACT FROM AUTHOR]

Natural climate solutions (NCS) and transitioning to clean energy can reduce greenhouse gases and contribute to mitigating climate change. Private landowners with large holdings, such as conservation organizations like The Nature Conservancy, have set ambitious goals to reduce net emissions and increase sequestration on their lands by implementing NCS. We assessed the potential carbon dioxide-equivalent (CO2e) reduction from feasible NCS, specifically implementing new restoration and agricultural management activities, and transitions to clean energy on The Nature Conservancy, California chapter's fee-owned and conservation easement properties. We compared the total CO2e reduction from potential new NCS activities to the impact from ongoing NCS activities, the chapter's 2030 goal, and the state's reduction goal for natural and working lands to understand how the organization can contribute to climate mitigation. We found that implementing NCS on 37 fee-owned properties (63,175 MTCO2e year –1) and clean energy on 10 fee-owned properties (488 MTCO2e year –1) combined would not reach the chapter's 2030 goal (72,000 MTCO2e year –1), and there can be tradeoffs between maximizing CO2e reduction and protecting conservation values. However, ongoing changes to forest management on a single conservation easement property, where another non-profit harvests timber and sells carbon credits, currently contributes 147,749 MTCO2e year –1, more than two times the 2030 goal and representing 7.4% of the state's annual goal. Our results suggest that The Nature Conservancy, California chapter would need to implement NCS on some of the conservation easements or consider future land protection deals with carbon rich ecosystems or high impact NCS to reach their CO2e reduction goal. [ABSTRACT FROM AUTHOR]