In a reserved forest parcel in a virgin eastern Hyrcanian mixed beech forest,80 ha was surveyed to determine the pit and mound topography,canopy gaps and dead trees.The aim was to investigate the spatial patterns and ...In a reserved forest parcel in a virgin eastern Hyrcanian mixed beech forest,80 ha was surveyed to determine the pit and mound topography,canopy gaps and dead trees.The aim was to investigate the spatial patterns and correlation of pit and mound features with canopy gaps.Seventy-five canopy gaps and 61 pit and mound features were identified.The univariate first order nearest neighbor(R_(CE))and bivariate second order test(Ripley’s K)statistic were applied.R_(CE) statistics highlighted a general aggregation pattern for canopy gaps and pits and mounds,while pits and mounds alone were more clumped.Distances between canopy gaps were 130 m average,whereas distances between pit and mound features and dead trees were 60 and 78 m,respectively.Spatial positive correlation of canopy gaps with pits and mounds were observed with all distances.The result of spatial correlations between canopy gaps with pits and mounds confirmed that windthrows cause micro successions in fallen tree ecosystem-scale correlated with gap phase dynamics in the forest community-scale.展开更多
This article describes how the cartographic depth-to-water (DTW) index in combination with other variables can be used to quantify, model and map the distribution of common forest floor bryophytes, at 1 m resolution. ...This article describes how the cartographic depth-to-water (DTW) index in combination with other variables can be used to quantify, model and map the distribution of common forest floor bryophytes, at 1 m resolution. This was done by way of a case study, using 12 terrain and climate representative locations across New Brunswick, Canada. The presence/absence by moss species was determined at each location along upland-to-wetland transects within >10-m spaced 1-m2 forest floor plots. It was found that Bazzania trilobata, Dicranum polysetum, Polytrichum commune, Hylocomium splendens, and Pleurozium schreberi had greater probabilities of occurrence in well-drained forested areas, whereas Sphagnum fuscum and Sphagnum girgensohnii dominated in low-lying wet areas. The presence/absence of each species was quantified by way of logistic regression analyses, using DTW, slope, canopy closure, forest litter depth, ecosite type (8 classes), nutrient regime (4 classes, poor to rich);vegetation type (deciduous, coniferous, mixed, and shrubs), and macro- and micro-topography (upland, wetland;mounds, pits) as predictor variables. Among these, log10DTW and forest litter depth were the most consistent predictor variables, followed by mound versus pit. For the mapping purpose, only log10DTW and already mapped classifications for upland versus wetland and vegetation type were used to predict the probability of occurrences for the most frequent moss species, namely, D. polysetum, P. schreberi and Sphagnum spp. The overall accuracy for doing this ranged from 67% to 83%, with false positives and negatives amounting to 18% to 42%. The overall classification accuracy exceeded the probability by chance alone at 76.8%, with the significance level reached at 75.3%. The average level of probability by chance alone was 60.3%.展开更多
基金supported by Gorgan University of Agricultural Sciences and Natural Resources
文摘In a reserved forest parcel in a virgin eastern Hyrcanian mixed beech forest,80 ha was surveyed to determine the pit and mound topography,canopy gaps and dead trees.The aim was to investigate the spatial patterns and correlation of pit and mound features with canopy gaps.Seventy-five canopy gaps and 61 pit and mound features were identified.The univariate first order nearest neighbor(R_(CE))and bivariate second order test(Ripley’s K)statistic were applied.R_(CE) statistics highlighted a general aggregation pattern for canopy gaps and pits and mounds,while pits and mounds alone were more clumped.Distances between canopy gaps were 130 m average,whereas distances between pit and mound features and dead trees were 60 and 78 m,respectively.Spatial positive correlation of canopy gaps with pits and mounds were observed with all distances.The result of spatial correlations between canopy gaps with pits and mounds confirmed that windthrows cause micro successions in fallen tree ecosystem-scale correlated with gap phase dynamics in the forest community-scale.
文摘This article describes how the cartographic depth-to-water (DTW) index in combination with other variables can be used to quantify, model and map the distribution of common forest floor bryophytes, at 1 m resolution. This was done by way of a case study, using 12 terrain and climate representative locations across New Brunswick, Canada. The presence/absence by moss species was determined at each location along upland-to-wetland transects within >10-m spaced 1-m2 forest floor plots. It was found that Bazzania trilobata, Dicranum polysetum, Polytrichum commune, Hylocomium splendens, and Pleurozium schreberi had greater probabilities of occurrence in well-drained forested areas, whereas Sphagnum fuscum and Sphagnum girgensohnii dominated in low-lying wet areas. The presence/absence of each species was quantified by way of logistic regression analyses, using DTW, slope, canopy closure, forest litter depth, ecosite type (8 classes), nutrient regime (4 classes, poor to rich);vegetation type (deciduous, coniferous, mixed, and shrubs), and macro- and micro-topography (upland, wetland;mounds, pits) as predictor variables. Among these, log10DTW and forest litter depth were the most consistent predictor variables, followed by mound versus pit. For the mapping purpose, only log10DTW and already mapped classifications for upland versus wetland and vegetation type were used to predict the probability of occurrences for the most frequent moss species, namely, D. polysetum, P. schreberi and Sphagnum spp. The overall accuracy for doing this ranged from 67% to 83%, with false positives and negatives amounting to 18% to 42%. The overall classification accuracy exceeded the probability by chance alone at 76.8%, with the significance level reached at 75.3%. The average level of probability by chance alone was 60.3%.
