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Abstract Forests significantly influence regional and global water cycles through transpiration, which is affected by meteorological variables, soil water availability, and stand and site characteristics. Variable retention harvesting (VRH) is a forest management practice in which varying densities of trees, such as 55% and 33%, are retained after thinning or harvesting. These trees can be grouped together or evenly distributed. VRH aims to enhance forest growth, improve biodiversity, preserve ecosystem functions, and generate economic revenue from harvested timber. Application of VRH treatment in forest ecosystems can potentially impact the response of forest transpiration to environmental controls. This study analyzed the impacts of four different VRH treatments on sap flow velocity (SV) in an 83‐year‐old red pine (Pinus resinosa Ait.) plantation forest in the Great Lakes region in Canada. These VRH treatments included 55% aggregated (55A), 55% dispersed (55D), 33% aggregated (33A), and 33% dispersed (33D) basal area retention, and an unharvested control (CN) plot, 1 ha each. Analysis of counterclockwise hysteresis loops between SV and meteorological variables showed larger hysteresis areas between SV and photosynthetically active radiation (PAR) than vapor pressure deficit (VPD) and air temperature (Tair), particularly in clear sky and warm temperatures in the summer. It demonstrated that PAR was the primary control on SV across VRH treatments, followed by VPD andTair. Larger hysteresis loop areas and higher SV values were observed in the CN and 55D treatments, with lower values found in the 55A, 33D, and 33A plots. This suggests that maintaining dispersed retention of 55% basal area (55D) is the optimal forest management practice that can be utilized to enhance transpiration and forest growth. These findings will assist forest managers and other stakeholders to adopt sustainable forest management practices, thereby enhancing forest growth, water use efficiency, and resilience to climate change. Additionally, these practices will contribute to nature‐based climate solutions.
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Synoptic Patterns Associated with Turbulent Fluxes of Water Vapor and Carbon Dioxide in Northern New England
Abstract Synoptic-scale weather patterns affect local meteorological variables, such as vapor pressure deficit (VPD), temperature, and insolation, that are known to influence evapotranspiration (ET) and net CO2flux (FC). However, little research exists that links synoptic-scale patterns to ET and FC. In this study, we seek to understand how synoptic-scale patterns influence ET and FC for the temperate mixed-hardwood forest at Hubbard Brook Experimental Forest (HBEF) in New Hampshire, United States. We use self-organizing maps to identify the most common synoptic pattern types impacting HBEF during the 2016–21 growing seasons and determine how ET and FC vary with these synoptic pattern types. Our analysis reveals that high ET and most negative FC days occur for the weather pattern phases starting after the departure of a low pressure system and through the approach of a high pressure system. ET and the magnitude of FC remain high if the latitude of the high is south of HBEF but moderate (especially for ET) if the high is to the north and causes east winds to advect a humid maritime air mass over the region. ET is lowest when HBEF is located between high pressure to the east and low pressure to the west, which causes humid southerly flow to decrease VPD and insolation. Meanwhile, FC magnitude may remain high when this pattern occurs in June–July when photosynthetic capacity is at its highest. Our results suggest that future changes in the frequency of passing low pressure systems and pathways of high pressure systems could impact the fluxes of water and CO2from this forest. Significance StatementFor decades, we have understood that local meteorological variables, such as insolation, temperature, and relative humidity, have a strong influence on a forest ecosystem’s use of water and carbon dioxide, two important greenhouse gases. We also understand that large-scale weather patterns and their interactions with forests shape these local meteorological conditions. This research advances knowledge of the relationship between various large-scale weather patterns and their impacts on forest’s use of water and carbon dioxide via local meteorological variables for a mixed-hardwood forest in the Northeastern United States. Connecting these results to the frequency of these various large-scale weather pattern types projected by global climate models will help us predict how forest ecosystems will influence water vapor and carbon dioxide concentrations and thus impact global climate.
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- Award ID(s):
- 2224545
- PAR ID:
- 10594127
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Journal of Hydrometeorology
- Volume:
- 26
- Issue:
- 6
- ISSN:
- 1525-755X
- Format(s):
- Medium: X Size: p. 661-673
- Size(s):
- p. 661-673
- Sponsoring Org:
- National Science Foundation
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