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B.d. Bricker - One of the best experts on this subject based on the ideXlab platform.
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Interspecific variation in tree seedling establishment in Canopy Gaps in relation to tree density
Journal of Vegetation Science, 1995Co-Authors: Richard J Reader, T.e. Duralia, Stephen P Bonser, B.d. BrickerAbstract:Abstract. We tested whether interspecific variation in tree seedling establishment in Canopy Gaps was significantly related to interspecific variation in tree density, for seven deciduous forest tree species (Quercus alba, Hamamelis virginiana, Acer rubrum, Sassafras albidum, Quercus rubra, Prunus serotina, Ostrya virginiana). For each species, seedling establishment was calculated as the difference in seedling density before experimental gap creation versus three years after gap creation. In each of the six experimentally-created gap types (33 % or 66 % removal of tree basal area from 0.01-ha, 0.05-ha or 0.20-ha patches), differences in seedling establishment among species were significantly related to differences in their density in the tree Canopy. A regression model with loge tree density as the independent variable accounted for between 93 % and 98 % of interspecific variation in seedling establishment. Our results provide empirical support for models of tree dynamics in Gaps that assume seedling establishment depends on Canopy tree density.
Alvaro Promis - One of the best experts on this subject based on the ideXlab platform.
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solar radiation transmission in and around Canopy Gaps in an uneven aged nothofagus betuloides forest
International Journal of Biometeorology, 2009Co-Authors: Alvaro Promis, Dirk Schindler, Albert Reif, Gustavo CruzAbstract:The transmission of direct, diffuse and global solar radiation in and around Canopy Gaps occurring in an uneven-aged, evergreen Nothofagus betuloides forest during the growing season (October 2006–March 2007) was estimated by means of hemispherical photographs. The transmission of solar radiation into the forest was affected not only by a high level of horizontal and vertical heterogeneity of the forest Canopy, but also by low angles of the sun’s path. The below-Canopy direct solar radiation appeared to be variable in space and time. On average, the highest amount of transmitted direct solar radiation was estimated below the undisturbed Canopy at the southeast of the gap centre. The transmitted diffuse and global solar radiation above the forest floor exhibited lower variability and, on average, both were higher at the centre of the Canopy Gaps. Canopy structure and stand parameters were also measured to explain the variation in the below-Canopy solar radiation in the forest. The model that best fit the transmitted below-Canopy direct solar radiation was a growth model, using plant area index with an ellipsoidal angle distribution as the independent variable (R2 = 0.263). Both diffuse and global solar radiation were very sensitive to Canopy openness, and for both cases a quadratic model provided the best fit for these data (R2 = 0.963 and 0.833, respectively). As much as 75% and 73% of the variation in the diffuse and global solar radiation, respectively, were explained by a combination of stand parameters, namely basal area, crown projection, crown volume, stem volume, and average equivalent crown radius.
Richard J Reader - One of the best experts on this subject based on the ideXlab platform.
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Interspecific variation in tree seedling establishment in Canopy Gaps in relation to tree density
Journal of Vegetation Science, 1995Co-Authors: Richard J Reader, T.e. Duralia, Stephen P Bonser, B.d. BrickerAbstract:Abstract. We tested whether interspecific variation in tree seedling establishment in Canopy Gaps was significantly related to interspecific variation in tree density, for seven deciduous forest tree species (Quercus alba, Hamamelis virginiana, Acer rubrum, Sassafras albidum, Quercus rubra, Prunus serotina, Ostrya virginiana). For each species, seedling establishment was calculated as the difference in seedling density before experimental gap creation versus three years after gap creation. In each of the six experimentally-created gap types (33 % or 66 % removal of tree basal area from 0.01-ha, 0.05-ha or 0.20-ha patches), differences in seedling establishment among species were significantly related to differences in their density in the tree Canopy. A regression model with loge tree density as the independent variable accounted for between 93 % and 98 % of interspecific variation in seedling establishment. Our results provide empirical support for models of tree dynamics in Gaps that assume seedling establishment depends on Canopy tree density.
David J Mladenoff - One of the best experts on this subject based on the ideXlab platform.
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emergent properties of downed woody debris in Canopy Gaps a response of the soil ecosystem to manipulation of forest structure
Soil Biology & Biochemistry, 2020Co-Authors: Lili Perreault, Jodi A Forrester, Nina Wurzburger, David J MladenoffAbstract:Abstract Natural forest disturbance events can influence soil biogeochemical processes in two ways - by creating downed woody debris (DWD; fallen tree boles or branches) and by creating Canopy Gaps that alter forest microclimate. DWD represents a substrate for microbial growth and a persistent store of carbon and nutrients, but microbial activity is also sensitive to temperature and moisture. We studied the potential interaction of DWD and Canopy Gaps on soil microbial processes, and wondered if microclimatic conditions resulting from the manipulation of forest structure would be enough to inhibit production, thereby altering a critical ecosystem process. Gaps and DWD (>10 cm diameter) were added to a maturing, even-aged, second-growth northern hardwood forest (the Flambeau Experiment; N Wisconsin, USA) to enhance structural complexity and promote key ecosystem processes typically associated with late-successional forests. We investigated the influence of DWD and Gaps on soil microbial community composition, extracellular enzyme activity and soil characteristics. Soils were sampled near intermediately and highly decayed DWD and 2 m away from DWD (control) in Gaps and closed Canopy a decade after manipulation. DWD decomposition influenced the surrounding soil differentially depending on decay class and Canopy condition. Mean C- and P-potential extracellular enzyme activities (BG, BX and AP) were enhanced near highly decayed DWD in Gaps. The relative abundance of bacteria (actinomycete, anaerobic, gram-negative and -positive) remained constant in Gaps but decreased from May to August in closed Canopy. In Gaps, soil total exchangeable cations increased by 34.6%, available phosphorus by 152% and fungal to bacterial ratios by 23.3% but temperatures decreased by 3.42% suggesting that Canopy condition continues to affect soil properties and microbial processes a decade after gap creation. These results highlight the contribution of DWD to the forest floor and the influence of decaying wood characteristics on belowground ecosystems critical to future forest productivity. Retaining or adding heterogeneously distributed DWD of varying decay status may be essential to maintain ecosystem functions associated with nutrient cycling and microbial community dynamics in managed forests.
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spatial patterns of soil surface c flux in experimental Canopy Gaps
Ecosystems, 2012Co-Authors: Jason Schatz, Jodi A Forrester, David J MladenoffAbstract:To explore within-gap spatial patterns of soil surface CO2 flux, we measured instantaneous soil surface CO2 flux, soil surface temperature, and soil moisture in north–south transects across Canopy Gaps and in adjacent contiguous forest from April to November 2010 in a second-growth northern hardwood forest in Wisconsin, USA. Throughout the growing season, soil surface CO2 flux was higher in the northern 1/3 and northern edge of Gaps compared to the central and southern portions. These patterns were driven primarily by within-gap variation in soil temperature, which was itself driven by within-gap patterns of insolation. Most locations in the northern 1/3 and northern edge of Gaps had significantly higher modeled total growing season C flux (mean 725 g C m−2) compared to the contiguous forest (mean 706 g C m−2), whereas C flux in the central and southern portions of Gaps (mean 555 g C m−2) was significantly lower than both the contiguous forest and the northern portions of Gaps.
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interactions of temperature and moisture with respiration from coarse woody debris in experimental forest Canopy Gaps
Forest Ecology and Management, 2012Co-Authors: Jodi A Forrester, David J Mladenoff, Stith T Gower, Jennifer L StoffelAbstract:Coarse woody debris (CWD) and Canopy Gaps are thought to be important structural components that influence forest ecosystem processes, yet few studies have assessed whether these features interact to influence decay dynamics, and we know of none that does so under controlled experimental Canopy gap conditions. By manipulating forest structure to create Canopy openings, we tested whether Canopy Gaps, through their influence on microclimate, affect the respiration rate of CWD in a mature second- growth northern hardwood forest of Wisconsin, USA. We sought to determine the relative contribution of moisture or temperature as predictors of respiration, and to provide estimates of the annual C emission from CWD in these treatments. Differences in the surface temperature of CWD were apparent immedi- ately following gap treatments, with debris in Gaps staying significantly warmer than beneath undis- turbed Canopy. Coarse woody debris moisture content differed more between Gaps and undisturbed Canopy in the second post-treatment year due to higher insolation and temperature in Gaps relative to undisturbed Canopy. The gap treatment increased respiration rates and altered the relationship with CWD temperature and moisture in complex ways. The impacts of gap creation on C fluxes from CWD depended on the range of temperature and moisture being examined. The interaction of the temperature and moisture of the debris in combination with the decay class explained 60% of the observed variation in CWD respiration beneath undisturbed canopies. In Gaps, only 23% of the variation of flux could be explained by environmental variables. Annual C fluxes were 128.2 g C kg � 1
Gustavo Cruz - One of the best experts on this subject based on the ideXlab platform.
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solar radiation transmission in and around Canopy Gaps in an uneven aged nothofagus betuloides forest
International Journal of Biometeorology, 2009Co-Authors: Alvaro Promis, Dirk Schindler, Albert Reif, Gustavo CruzAbstract:The transmission of direct, diffuse and global solar radiation in and around Canopy Gaps occurring in an uneven-aged, evergreen Nothofagus betuloides forest during the growing season (October 2006–March 2007) was estimated by means of hemispherical photographs. The transmission of solar radiation into the forest was affected not only by a high level of horizontal and vertical heterogeneity of the forest Canopy, but also by low angles of the sun’s path. The below-Canopy direct solar radiation appeared to be variable in space and time. On average, the highest amount of transmitted direct solar radiation was estimated below the undisturbed Canopy at the southeast of the gap centre. The transmitted diffuse and global solar radiation above the forest floor exhibited lower variability and, on average, both were higher at the centre of the Canopy Gaps. Canopy structure and stand parameters were also measured to explain the variation in the below-Canopy solar radiation in the forest. The model that best fit the transmitted below-Canopy direct solar radiation was a growth model, using plant area index with an ellipsoidal angle distribution as the independent variable (R2 = 0.263). Both diffuse and global solar radiation were very sensitive to Canopy openness, and for both cases a quadratic model provided the best fit for these data (R2 = 0.963 and 0.833, respectively). As much as 75% and 73% of the variation in the diffuse and global solar radiation, respectively, were explained by a combination of stand parameters, namely basal area, crown projection, crown volume, stem volume, and average equivalent crown radius.