Soil respiration (R_s), the largest carbon emission flux in ecosystems, is usually modeled as an empirically parameterized function of temperature, and sometimes water availability. The likely contribution by other factors, such as carbohydrate substrate supply from photosynthesis, has been recognized, but modeling capacity to use this information is limited. Wavelet transformations of the residuals of a seasonal Q₁₀ temperature response model indicated structure at different temporal scales. We hypothesize that this indicates the lack of explicit representation of relevant processes in the models. Using cross‐spectral analysis, we found that time series of photosynthetically active radiation explained most of the diurnal variation, temperature, explained variability at multiple time scales (diurnal‐synoptic), whereas volumetric soil water content correlated with variability in R_s at scales 15‐30 days. The results suggest that the time domains of influence for different driving variables of R_s are discrete, and largely nonoverlapping, and represent functional relationships between soil biological activity and its constraints. Analysis of phase angles showed that R_s lagged photosynthetically active radiation by 1.5‐3.0 hr. As this time lag was the same in both young and mature trees, with more than fivefold difference in transport distances, we hypothesize that this finding adds to the body of literature that support the pressure‐concentration‐wave model of carbohydrate availability in plants.

Forest water use efficiency (WUE), the ratio of gross primary productivity (GPP) to evapotranspiration (ET), is an important variable to understand the coupling between water and carbon cycles, and to assess resource use, ecosystem resilience, and commodity production. Here, we determined WUE for managed loblolly pine plantations over the course of a rotation on the coastal plain of North Carolina in the eastern U.S. We found that the forest annual GPP, ET, and WUE increased until age ten, which stabilized thereafter. WUE varied annually (2–44%), being higher at young plantation (YP, 3.12 ± 1.20 g C kg⁻¹ H₂O d⁻¹) compared to a mature plantation (MP, 2.92 ± 0.45 g C kg⁻¹ H₂O d⁻¹), with no distinct seasonal patterns. Stand age was strongly correlated with ET (R² = 0.71) and GPP (R² = 0.64). ET and GPP were tightly coupled (R² = 0.86). Radiation and air temperature significantly affected GPP and ET (R² = 0.71 − R² = 0.82) at a monthly scale, but not WUE. Drought affected WUE (R² = 0.35) more than ET (R² = 0.25) or GPP (R² = 0.07). A drought enhanced GPP in MP (19%) and YP (11%), but reduced ET 7% and 19% in MP and YP, respectively, resulting in a higher WUE (27–32%). Minor seasonal and interannual variation in forest WUE of MP (age > 10) suggested that forest functioning became stable as stands matured. We conclude that carbon and water cycles in loblolly pine plantations are tightly coupled, with different characteristics in different ages and hydrologic regimes. A stable WUE suggests that the pine ecosystem productivity can be readily predicted from ET and vice versa. The tradeoffs between water and carbon cycling should be recognized in forest management to achieve multiple ecosystem services (i.e., water supply and carbon sequestration).

Co‐production practices are increasingly being adopted in research conducted for the purpose of societal impact. However, the ways in which co‐production is conducted can perpetuate long‐standing inequity and inequality. This study investigates which principles of co‐production design are perceived to advance more equitable processes and outcomes based on the experiences of participants in three projects funded by U.S. federal programs that support decision‐relevant climate science, along with others engaged in co‐production efforts. We found three distinct perspectives: (a) Ways of Knowing and Power; (b) Participants and Interactions; and (c) Science as Capacity Building. Each viewpoint differentially weights the salience of statements associated with five dimensions of co‐production practices: (a) outcomes; (b) power; (c) place‐based, community rights and respect; (d) audiences and participation; and (e) interactions. In the final stage of the study, we hosted a workshop of participants representing various roles in co‐production efforts to vet and discuss each perspective. We found that the perspectives remained distinct after each of the groups selected core statements that reflect their views. The degree of variation across the three perspectives suggests that co‐production processes would benefit from an initial discussion of, and decisions about, rules of engagement to ensure that participants view the process as equitable.

Search this collection of freely available full text articles on the science behind sustainable management of forests and rangelands, restoration of native plants, wildlife, fish and ecosystems, protecting against wildfires and invasive species, and improving the resilience of our lands in the face of climate change.

Hurricanes are one of the most significant threats to coastal plain forest ecosystems and urban communities of the southeastern U.S., but their implications for watershed hydrology are unclear. Hurricanes have the potential to alter water balances, causing extensive flooding, biogeochemical cycle disruption, and water quality degradation, saltwater intrusion, and increased nutrient sedimentation export in coastal watersheds. This case study focused on Hurricane Michael, a recent catastrophic event that impacted the Gulf coast, the Florida panhandle, southwestern Georgia, and southeastern Alabama. Through empirical (Double Mass Curve) and process-based ecohydrological modeling (WaSSI model) on long-term streamflow data, we explored whether vegetation damage caused by this hurricane resulted in an increase in streamflow two years after the extreme event. We found that monthly streamflow from the Chipola River watershed with an area of 2023 km² did not change (<6%) appreciably during the first two years following the storm, arguably because only a fraction of the gauged watershed lost substantial tree cover. However, spatially explicit hydrological modeling suggested that several sub-watersheds with the highest decreases in the Normalized Difference Vegetation Index (NDVI) significantly increased their monthly streamflow in 2019 by up to 22%. These modeled streamflow anomalies subsided by the second growing season when vegetation recovered. Overall, this study suggests that changes in vegetation cover after Hurricane Michael did not have lasting impacts on the hydrology of this watershed, and the hydrology of coastal watersheds may be more resilient to hurricane disturbances than previously thought.