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On the difference in the net ecosystem exchange of CO2 between deciduous and evergreen forests in the southeastern United States
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The southeastern United States is experiencing a rapid regional increase in the ratio of pine to deciduous forest ecosystems at the same time it is experiencing changes in climate. This study is focused on exploring how these shifts will affect the carbon sink capacity of southeastern US forests, which we show here are among the strongest carbon sinks in the continental United States. Using eight-year-long eddy covariance records collected above a hardwood deciduous forest (HW) and a pine plantation (PP) co-located in North Carolina, USA, we show that the net ecosystem exchange of CO2 (NEE) was more variable in PP, contributing to variability in the difference in NEE between the two sites (DNEE) at a range of timescales, including the interannual timescale. Because the variability in evapotranspira- tion (ET) was nearly identical across the two sites over a range of timescales, the factors that determined the variabil- ity in DNEE were dominated by those that tend to decouple NEE from ET. One such factor was water use efficiency, which changed dramatically in response to drought and also tended to increase monotonically in nondrought years (P < 0.001 in PP). Factors that vary over seasonal timescales were strong determinants of the NEE in the HW site; however, seasonality was less important in the PP site, where significant amounts of carbon were assimilated outside of the active season, representing an important advantage of evergreen trees in warm, temperate climates. Additional variability in the fluxes at long-time scales may be attributable to slowly evolving factors, including canopy structure and increases in dormant season air temperature. Taken together, study results suggest that the carbon sink in the southeastern United States may become more variable in the future, owing to a predicted increase in drought frequency and an increase in the fractional cover of southern pines.
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Pensacola and Perdido Bays Estuary Program
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Pensacola and Perdido Bays Estuary Program serves as a trusted source for residents, businesses, industry, and the community on issues relating to preserving, restoring, improving and maintaining the natural habitat and ecosystem of the bays, estuaries and watersheds of Pensacola and Perdido Bays.
PPBEP strives to achieve a healthy and collaborative environment by:
1. Elevating and increasing the importance, awareness and understanding of environmental quality.
2. Employing rigorous, unbiased and scientifically sound science to inform and guide decisions, policies, and initiatives.
3. Funding programs and projects that protect the environment, increase ecological resilience.
4. Building a network of inclusive, multi-stakeholder partnerships that takes into account factors affecting the environment, the economy, and the community-at-large for the benefit of improving the quality of life for all.
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Seeing the landscape for the trees: Metrics to guide riparian shade management in river catchments
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Rising water temperature (Tw) due to anthropogenic climate change may have serious conse- quences for river ecosystems. Conservation and/or expansion of riparian shade could counter warming and buy time for ecosystems to adapt. However, sensitivity of river reaches to direct solar radiation is highly het- erogeneous in space and time, so benefits of shading are also expected to be site specific. We use a network of high-resolution temperature measurements from two upland rivers in the UK, in conjunction with topo- graphic shade modeling, to assess the relative significance of landscape and riparian shade to the thermal behavior of river reaches. Trees occupy 7% of the study catchments (comparable with the UK national aver- age) yet shade covers 52% of the area and is concentrated along river corridors. Riparian shade is most ben- eficial for managing Tw at distances 5–20 km downstream from the source of the rivers where discharge is modest, flow is dominated by near-surface hydrological pathways, there is a wide floodplain with little land- scape shade, and where cumulative solar exposure times are sufficient to affect Tw. For the rivers studied, we find that approximately 0.5 km of complete shade is necessary to off-set Tw by 18C during July (the month with peak Tw) at a headwater site; whereas 1.1 km of shade is required 25 km downstream. Further research is needed to assess the integrated effect of future changes in air temperature, sunshine duration, direct solar radiation, and downward diffuse radiation on Tw to help tree planting schemes achieve
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Significant anthropogenic-induced changes of climate classes since 1950
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Anthropogenic forcings have contributed to global and regional warming in the last few decades and likely affected terrestrial precipitation. Here we examine changes in major Köppen climate classes from gridded observed data and their uncertainties due to internal climate variability using control simulations from Coupled Model Intercomparison Project 5 (CMIP5). About 5.7% of the global total land area has shifted toward warmer and drier climate types from 1950–2010, and significant changes include expansion of arid and high-latitude continental climate zones, shrinkage in polar and midlatitude continental climates, poleward shifts in temperate, continental and polar climates, and increasing average elevation of tropical and polar climates. Using CMIP5 multi-model averaged historical simulations forced by observed anthropogenic and natural, or natural only, forcing components, we find that these changes of climate types since 1950 cannot be explained as natural variations but are driven by anthropogenic factors.
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Slow and Steady: Bog Turtles at Home on Private Lands
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As a result of the Delaware Watershed Conservation Fund, agricultural landowners in New Jersey are changing management practices on their land to support the bog turtle, a species listed as threatened in the northern part of its range under the federal Endangered Species Act.
The beauty is, farmers aren’t just changing their practices because it’s good for the turtle; they are changing their practices because it’s good for business.
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St. Andrew and St. Joseph Bays Estuary Program
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The St. Andrew Bay Watershed in the central Florida Panhandle covers 1,156 square miles that includes the interconnected estuary system of both St. Andrew Bay (West, North, and East bays) and St. Joseph Bay. This gem of an estuary and watershed is one of the most biologically diverse bays in North America and the only watershed in Northwest Florida located entirely in the state of Florida.
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Stream & Watershed Restoration Design & Implementation Workshop
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Participants will learn about developing and implementing stream and watershed restoration programs at the district level. Restoration in watershed analysis context, and effective stream restoration programs will also be covered. Scheduled for May 2023, pending COVID.
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Tennessee River Basin Partnership Overview
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An overview on the Tennessee River Basin as a priority landscape for the Appalachian LCC.
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July 13-15, 2015 Appalachian LCC Steering Committee Meeting
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Tennessee Valley Authority Watershed Protection and Improvement
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This presentation details how TVA is providing adequate data for sound decision-making, identifying and build partnerships, partnering to prioritize watersheds and projects, and implementing projects to protect water quality and biodiversity.
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Past SC Meetings and Materials
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July 13-15, 2015 Appalachian LCC Steering Committee Meeting
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The global volume and distribution of modern groundwater
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Groundwater is important for energy and food security, human health and ecosystems. The time since groundwater was recharged—or groundwater age—can be important for diverse geologic processes, such as chemical weathering, ocean eutrophication and climate change. However, measured groundwater ages range from months to millions of years. The global volume and distribution of groundwater less than 50 years old—modern groundwater that is the most recently recharged and also the most vulnerable to global change—are unknown. Here we combine geochemical, geologic, hydrologic and geospatial data sets with numerical simulations of groundwater and analyse tritium ages to show that less than 6% of the groundwater in the uppermost portion of Earth’s landmass is modern. We find that the total groundwater volume in the upper 2 km of continental crust is approximately 22.6 million km3 , of which 0.1–5.0 million km3 is less than 50 years old. Although modern groundwater represents a small percentage of the total groundwater on Earth, the volume of modern groundwater is equivalent to a body of water with a depth of about 3 m spread over the continents. This water resource dwarfs all other components of the active hydrologic cycle.
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