نتایج جستجو برای: canopy gap
تعداد نتایج: 154523 فیلتر نتایج به سال:
Tropical forest structural variation across heterogeneous landscapes may control above-ground carbon dynamics. We tested the hypothesis that canopy structure (leaf area and light availability) - remotely estimated from LiDAR - control variation in above-ground coarse wood production (biomass growth). Using a statistical model, these factors predicted biomass growth across tree size classes in f...
Tree regeneration was compared among closed-canopy sites and 4±11-year old natural and felling gaps in a selectively logged semideciduous tropical forest in southeastern Mexico. Closed-canopy sites and gaps were selected strati®ed randomly. In addition, all large natural and felling gaps encountered were sampled. All stems 5 cm dbh were sampled in sets of 10 m plots in closed-canopy sites and g...
Hemispherical photography (HP) is extensively used for both canopy architecture such as leaf area index (LAI), and solar radiation regime determinations under forest canopies. This is done mainly by assuming that foliage elements occur in a spatially random manner. However, the majority of world forests occur in heterogeneous ecosystems and topography with rather complex canopy architecture. To...
BACKGROUND AND AIMS Acer saccharum and Fagus grandifolia are among the most dominant late-successional tree species in North America. The influence of sapling growth responses to canopy gaps on the co-dominance of the two species in an old-growth forest in southern Quebec, Canada was examined. Two predictions were evaluated: (a) F. grandifolia is more shade tolerant than A. saccharum due to gre...
Canopy Gaps in an Upper Mississippi River floodplain plot were measured as part of a songbird nest-site selectivity study. Two methods of measuring floodplain forest canopy gaps were compared. One method used a ground crew to sweep the plot and record spatial and botanical information of canopy gaps > 10 meters in diameter. The second method used 1:15,000 scale color infrared stereoscopic aeria...
We evaluate the potential of deriving a vegetation leaf area index (LAI) from small footprint airborne laser scanning data. Based on findings from large area histograms of discrete laser returns for two contrasting plots, LAI is estimated from the fraction of first to last and single returns inside the canopy. The canopy returns are classified using thresholding of LIDAR raw data heights subtra...
Delineating canopy gaps and quantifying gap characteristics (e.g., size, shape, and dynamics) are essential for understanding regeneration dynamics and understory species diversity in structurally complex forests. Both high spatial resolution optical and light detection and ranging (LiDAR) remote sensing data have been used to identify canopy gaps through object-based image analysis, but few st...
The forests of Rangatira Island (218 ha) in the Chatham Islands are a critical breeding site for a number of rare and threatened forest bird species, but are also home to more than three million seabirds, which could significantly affect forest regeneration processes. We surveyed the forests of Rangatira Island by establishing 40 permanent forest plots, estimated seabird density through burrow ...
T ropical deforestation is occurring at unprecedented rates, contributing as much as a fifth of annual global carbon emissions and imparting significant impacts on biodiversity, ecosystem function, livelihoods, and climate (1–3). Selective logging, removal of 1–25 canopy trees per hectare with associated levels of harvesting damage, is predicted to greatly exceed tropical deforestation in exten...
Little is known about the gap pattern of primeval beech forests, since large-scale studies with continuous coverage are lacking. Analyses of forest structural patterns have benefitted from advances in remote sensing, especially with the launch of satellites providing data of submetric ground resolution. These developments can strongly advance our knowledge of natural forest dynamics and disturb...
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