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林分结构通过影响林内环境与生物因子,决定森林生态系统服务功能发挥;同时,通过调整林分结构亦可达到森林合理经营的目标。林分透光孔隙度(郁闭度)是决定林分结构的重要因子之一,它可以用来表征光、水等环境因子通过林冠进入林内的再分布状况。因此,合理、精确地确定林分内的郁闭状况,无论在森林经营与管理,还是在森林生态精细研究中,都显得十分重要。本文在以往研究的基础上,详细介绍了应用全天空照片(Hemispherical photograph/whole sky photograph)确定林分内一定高度(通常为1 m)的林分郁闭度或林分透光孔隙度(两者互补)的方法与步骤,重点讨论了在应用全天空照片确定林分郁闭度/透光孔隙度时选择的有效范围和应注意的实际问题。 相似文献
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Ernesto Gianoli Alfredo Saldaña Mylthon Jiménez‐Castillo Fernando Valladares 《植被学杂志》2010,21(1):66-73
Question: Are vines light‐demanding species? Location: Temperate evergreen rain forest of southern Chile (40°39′S, 72°11′W). Methods: In 45 plots of 25 m2 distributed in treefall canopy gaps, secondary forest stands and old‐growth forest (15 plots per light environment), all climbing and non‐supported vines were counted and identified to species level, and canopy openness was quantified using hemispherical photographs. Vine abundance and diversity (species richness and Simpson's index) were compared in the three light environments and similarity between vine communities was estimated using Jaccard's similarity coefficient. We also determined the relationship between light niche breadth and local dominance at the species level. Results: In total there were 2510 vine individuals of 14 species. Canopy openness was significantly different in the three light environments. Species richness, diversity, community composition and density of vines were similar in treefall gaps, secondary and old‐growth forest. Of the seven more common vine species, which accounted for 91% of all vines, three had even distribution, two were more abundant in the shaded understorey, and two had higher density in well‐lit sites. Local dominance of vine species and niche breadth were not significantly associated. Conclusions: Our study in a temperate rain forest questions the widespread notion of vines as pioneer‐like species, which may be a consequence of the abundance of some lianas in disturbed sites of tropical forests. Functional arguments are needed to justify a general hypothesis on light requirements of vines, which constitute a vast group of species. 相似文献
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Abstract. We studied gradients in field layer vegetation across ecotone‐type borderlines between 12 ancient woodlands and adjacent secondary deciduous woodlands on former arable land. The aim of the study was to determine how distance from the borderline influences species distributions as compared with soil factors and degree of canopy closure. Correspondence Analysis showed that distance from the borderline is closely related to the first ordination axis at all study sites. Canonical Correspondence Analysis with variation partitioning revealed that distance from the borderline was the single most important factor in explaining vegetation variation. In general, the results suggest the following order of decreasing importance: Distance from the borderline < Soil reaction < Soil nitrogen < Soil moisture < Canopy cover. However, the sum of soil variables, as estimated by weighted averages of Ellenberg indicator values for moisture, reaction and nitrogen, accounted for as much as ca. 50–70% of the total variation explained by environmental variables. Important gradients in field layer vegetation are due to a decrease in typical woodland species and an increase in other species with increasing distance from the ancient woodland. The results suggest dispersal limitation of woodland species as an important determinant of secondary forest succession. However, the importance of distance to species distributions decreases with increasing stand age as most woodland species gradually colonize the recent woodlands. After 70 yr, ca. 50 % of the woodland species present at a site showed complete colonization within 50 m from the ancient woodland border. 相似文献
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Florian Zellweger Andri Baltensweiler Patrick Schleppi Markus Huber Meinrad Küchler Christian Ginzler Tobias Jonas 《Ecology and evolution》2019,9(16):9149-9159
Light is a key driver of forest biodiversity and functioning. Light regimes beneath tree canopies are mainly driven by the solar angle, topography, and vegetation structure, whose three‐dimensional complexity creates heterogeneous light conditions that are challenging to quantify, especially across large areas. Remotely sensed canopy structure data from airborne laser scanning (ALS) provide outstanding opportunities for advancement in this respect. We used ALS point clouds and a digital terrain model to produce hemispherical photographs from which we derived indices of nondirectional diffuse skylight and direct sunlight reaching the understory. We validated our approach by comparing the performance of these indices, as well as canopy closure (CCl) and canopy cover (CCo), for explaining the light conditions experienced by forest plant communities, as indicated by the Landolt indicator values for light (Llight) from 43 vegetation surveys along an elevational gradient. We applied variation partitioning to analyze how the independent and joint statistical effects of light, macroclimate, and soil on the spatial variation in plant species composition (i.e., turnover, Simpson dissimilarity, βSIM) depend on light approximation methodology. Diffuse light explained Llight best, followed by direct light, CCl and CCo (R2 = .31, .23, .22, and .22, respectively). The combination of diffuse and direct light improved the model performance for βSIM compared with CCl and CCo (R2 = .30, .27 and .24, respectively). The independent effect of macroclimate on βSIM dropped from an R2 of .15 to .10 when diffuse light and direct light were included. The ALS methods presented here outperform conventional approximations of below‐canopy light conditions, which can now efficiently be quantified along entire horizontal and vertical forest gradients, even in topographically complex environments such as mountains. The effect of macroclimate on forest plant communities is prone to be overestimated if local light regimes and associated microclimates are not accurately accounted for. 相似文献
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Grime's CSR species life‐strategy theory (competition–stress–ruderality) provides a conceptual framework to classify species into competitive (growing under high productivity, low disturbance), stress‐tolerant (low productivity, low disturbance) and ruderal (high productivity, high disturbance). Importantly, this classification is based on the assumption that the niche space of disturbance and productivity is filled unevenly: while in productive habitats species can adapt to different disturbance regimes, species of low‐productivity and disturbed habitats do not exist, resulting in a triangular distribution of species optima along axes of disturbance and productivity. This assumption has often been criticised, but it has not yet been put under a rigorous test. Here we use existing data on niche positions of central European plant species to test this hypothesis, namely its prediction that species adapted to jointly stressed (low‐productive) and disturbed habitats do not exist. We use Ellenberg indicator values and newly developed indicator values for disturbance as proxies of species positions in the space of productivity and disturbance. We found that positions of species optima along the gradients of productivity and disturbance severity are not independent of each other, with very few species adapted to low‐productive and severely disturbed habitats. In contrast, there is no relationship between productivity and disturbance frequency; a number of species occur in low‐productive and frequently disturbed habitats. The relationship between productivity and disturbance severity can be either due to tradeoffs between life history traits responsible for response to disturbance and productivity (as originally assumed by Grime) or due to historical rarity of severely disturbed habitats in unproductive conditions and consequent absence of evolution of species adapted to them. Our data are based on one specific flora, shaped by glaciations and early introduction of agriculture, but the question of what causes this pattern can be resolved by future analyses of floras with different evolutionary and ecological histories. 相似文献
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Abstract Our study had the objective to examine whether the number of forest vascular plants in a forest-poor region may be indicative of total plant species richness and of the number of threatened plant species. We also related forest plant species richness to geological and soil variables. The analysis was based on a regional flora atlas from the Weser-Elbe region in northwestern Germany including incidence data of species in a total of 1109 grid cells (each ca. 2.8 × 2.8 km2). All taxa were classified either as forest or non-forest species. Total species richness in the grid cells ranged from 65 to 597, with a mean value of 308. The number of forest species varied between 20 and 309 (mean 176). Grid cells with or without particular geological units differed in total and forest species richness, with those containing peatland and marshland being particularly species-poor. Indicator value analysis showed that both total and forest species richness in the grid cells were related to soil acidity and nitrogen in a hump-backed manner, with the highest number of species found at moderately low values for nitrogen and at intermediate values of pH. Forest species richness was highly positively correlated with the number of non-forest species and threatened non-forest species. Indicators for high species richness were primarily those species that are confined to closed semi-natural forests with a varied topography and relatively base- and nutrient-rich soils. Grid cells including historically ancient forest exhibited a higher species richness than grid cells lacking ancient forest, indicating the importance of a long habitat continuity for a high phytodiversity. The “habitat coincidence” of high species richness is best explained by similar responses of forest species and species of other habitats to the main environmental gradients. It is suggested that the regional patterns found for the Weser-Elbe region can be transferred also to other forest-poor regions in Central Europe. 相似文献
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The composition of herbaceous vegetation was evaluated with the aim of characterizing forests at various ages of stand development. Herb stems were sampled in 250 4‐m² square plots distributed within six habitat types. A total of 36 herb species belonging to 15 families were recorded. Species richness did not significantly differ between habitat types. Most herb species occurred in all habitat types and were therefore generalists. However, a few indicator herb species were detected, and the results roughly suggested that herb species of the families Poaceae and Araceae were indicative of late successional forests; Zingiberaceae are indicative of early successional forests; and Commelinaceae, Costaceae, Cyperaceae and Marantaceae are indicators of flooded habitats. Species diversity and stem density of herbaceous plants did not change with forest succession as a decrease in abundance and frequency of occurrence of pioneer species in late successional forests was counterbalanced by the presence of generalist and late successional species. However, increasing proportions of dwarf stems in late successional forests translated to changes in the vertical structure of herbaceous plant communities. Herbivory pressure by gorillas did not have a notable effect on herbaceous plant community development. This study contributes to the definition of herbaceous ecological indicators of forest succession in different settings. 相似文献
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采用网格法在帽儿山温带落叶阔叶林通量塔风浪区(1500 m×400 m)内设置直径为20 m的圆形样地106个,运用地统计学方法和回归分析法研究了乔木生物量空间格局及其驱动因子。结果表明,风浪区总生物量平均值为153.63 Mg/hm~2,变异系数为37.89%;根冠比平均0.25(变化范围0.18—0.36)。总生物量、地上生物量和地下生物量的空间自相关显著,半方差模型的结构比分别为0.50、0.61和0.50,空间异质性尺度分别为276 m、198 m和375 m。硬阔叶林与杂木林的生物量组分和根冠比差异均不显著,但以胸高断面积(BA)为协变量,生物量组分差异显著。硬阔叶林和杂木林生物量组分与BA均呈极显著的线性正相关关系,BA可以解释总生物量和地上生物量空间变异的85%以上,表明局域尺度上BA可作为森林乔木生物量的预测因子。两种林型的生物量与优势高呈对数线性关系,但相关程度较低(R~20.41)。杂木林的各生物量组分与坡度显著正相关,但硬阔叶林的关系不显著。帽儿山落叶阔叶林乔木生物量受BA、优势高、林型、坡度和坡向共同驱动而存在空间变异,因此在整合通量塔与地面碳汇测量时需要考虑空间异质性。 相似文献
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M. Diekmann J. Brunet Å. Rühling U. Falkengren-Grerup 《Plant biology (Stuttgart, Germany)》1999,1(4):471-481
Abstract: We studied permanent plots in deciduous forests in two provinces of South Sweden, Skåne (127 plots) and Småland (116 plots). Vegetation data were sampled in 1983 and 1993 and used to calculate weighted averages of Ellenberg indicator values for light, reaction (pH) and nitrogen. Soil samples were collected from all plots in 1993 for determination of pH, organic matter content and potential net nitrogen mineralization (minN). Data on minN were also available for 66 plots in Skåne from 1983. Nitrogen deposition is considerably higher in Skåne than in Småland. The same holds true for total minN, minNH4 + , minNO3 - - , and the proportion of total minN due to nitrate (nitrification ratio). According to the comparison of average Ellenberg indicator values between 1983 and 1993, the stands had become darker (not in the heavily managed plots), more acid and nitrogen rich, except at the most acid sites where only minor changes could be observed. The nitrification ratio was significantly higher in 1993 than in 1983. Mean soil nitrification ratios were determined for the most common species in both regions. The means were higher in Skåne than in Småland. It is likely that nitrogen deposition causes an increase in nitrification rate and nitrification ratio. This ratio is a significant determinant of the species composition in deciduous forests. 相似文献
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Irena Axmanová Milan Chytrý David Zelený Ching‐Feng Li Marie Vymazalová Jiří Danihelka Michal Horsák Martin Kočí Svatava Kubešová Zdeňka Lososová Zdenka Otýpková Lubomír Tichý Vasiliy B. Martynenko El'vira Z. Baisheva Brigitte Schuster Martin Diekmann 《Global Ecology and Biogeography》2012,21(6):657-667
Aim In contrast to non‐forest vegetation, the species richness–productivity (SR‐P) relationship in forests still remains insufficiently explored. Several studies have focused on the diversity of the tree layer, but the species richness of temperate deciduous forests is mainly determined by their species‐rich herb layer. The factors controlling herb‐layer productivity may differ from those affecting tree layers or open herbaceous vegetation, and thus the SR‐P relationship and its underlying processes may differ. However, the few relevant studies have reported controversial results. Here we explore the SR‐P relationship in the forest herb layer across different areas from oceanic to continental Europe, and put the effect of habitat productivity on species richness into context with other key factors, namely soil pH and light availability. Location North‐western Germany, Czech Republic, Slovakia and southern Urals (Russia). Methods We measured herb‐layer species richness and biomass, soil pH and tree‐layer cover in 156 vegetation plots of 100 m2 in deciduous forests. We analysed the SR‐P relationship and the relative importance of environmental variables using regression models for particular areas and separate forest types. Results We found a consistent monotonic increase in the herb‐layer species richness with productivity across all study areas and all forest types. Soil pH and light availability also affected species richness, but their relative importance differed among areas. Main conclusions We suggest that the monotonically increasing SR‐P relationship in the forest herb layer results from the fact that herb‐layer productivity is limited by canopy shading; competition within the herb layer is therefore not strong enough to exclude many species. This differs fundamentally from open herbaceous vegetation, which is not subject to such productivity limits and consequently exhibits a unimodal SR‐P relationship. We present a conceptual model that might explain the differences in the SR‐P relationship between the forest herb layer and open herbaceous vegetation. 相似文献
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Frank R. Thompson III Melissa C. Roach Thomas W. Bonnot 《The Journal of wildlife management》2022,86(2):e22170
Chuck-will's-widow (Antrostomus carolinensis) and eastern whip-poor-will (Antrostomus vociferus) are nightjars in eastern North America that have declined 69% and 67%, respectively, in abundance since 1966, resulting in conservation concerns for these species. We investigated relationships between nightjar abundance and landscape composition, forest structure, and application of tree thinning and prescribed fire because of regional interest in woodland restoration and nightjar conservation. We conducted nocturnal nightjar surveys at 385 points in southern Missouri, USA, in 2014 and 2015 and related counts to pine (Pinus spp.) and hardwood basal area, canopy closure, percent forest cover, and percent of area thinned or burned within 500 m of survey points. We modeled abundance of chuck-will's-widow and eastern whip-poor-will using time-removal models that included a detection process and an abundance process within a hierarchical Bayesian framework. We detected 534 eastern whip-poor-will and 186 chuck-will's-widow during surveys. Our data supported global models that included all 6 vegetation and management variables for both species. Chuck-will's-widow abundance was negatively related to hardwood basal area and peaked at intermediate values of percent area burned and percent forest cover. Eastern whip-poor-will abundance was negatively related to hardwood basal area and canopy cover, positively related to percent forest cover and percent of area burned, and peaked at low to moderate levels of percent of area thinned. Relationships to forest structure and management activities generally supported the conclusion that woodland restoration benefits nightjars and that chuck-will's-widow select landscapes with less forest cover than eastern whip-poor-will. 相似文献
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林冠结构是研究森林生态系统众多关键生态功能和过程的重要参数,常绿阔叶林是亚热带林区具有代表性的森林类型,对其林冠结构及动态特征的研究还很不深入。在广西大明山中山区选择了一个斜坡水平长200 m、宽160 m的典型坡面,在整个坡面建立了80个20 m×20 m的样地,将样地均匀分为5个坡段,每个坡段包含16个连续的样地,在2009—2012年的生长季测定了林冠高度(CH)、林冠体积(CV)、林冠覆盖度(CC)、林冠上/下冠盖比(HLr)和林冠叶面积指数(LAI),分析了各林冠结构指标的坡位及年际动态,揭示了亚热带常绿阔叶林的林冠结构特征及短期动态规律。研究结果表明,大明山常绿阔叶林林冠结构的一般特征是:平均CH(12.09±0.05)m,平均CV(2642.51±278.33)m~3(每400 m~2样地),平均CC(59.90±3.29)%,平均HLr2.48±0.23,平均LAI 2.00±0.06。大明山常绿阔叶林的林冠结构存在多层性,上层林冠覆盖度平均为42.20%,中层为30.35%,下层为18.05%。大明山常绿阔叶林的林冠结构存在坡面和年际差异,坡面变异系数为CV(29.84%—55.89%)HLr(32.90%—53.52%)LAI(22.48%—43.89%)CC(16.61%—25.74%)CH(8.26%—12.77%);年际变异系数为HLr(47.33%—57.00%)CV(39.70%—49.06%)LAI(21.58%—48.13%)CC(20.35%—24.15%)CH(9.19%—12.59%),表明CH有较强的稳定性。林冠LAI存在明显的坡面尺度效应,即向下顺坡每滑动100 m冠层LAI升高0.34。坡位对CH、HLr有显著(P=0.022)和极显著(P0.001)影响;年份对HLr有显著影响(P=0.013),对CV和CC有极显著影响(P0.001);坡位×年份对CV和LAI的交互作用显著(P=0.016,P=0.017)。回归分析发现树冠面积与林木胸径呈极显著的线性关系。此研究结果表明大明山常绿阔叶林冠层高度较低、林冠体积较小、林冠覆盖度不高、上/下冠盖比和叶面积指数偏小,这与研究区域的海拔较高(934—1223 m),土层浅薄(30—45 cm)以及经常受到冰冻灾害(特别是2008年的特大冰冻灾害)的影响有关,是山地常绿阔叶林树冠结构与山地环境条件长期适应的结果。 相似文献
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1 We characterized and compared diversity patterns of canopy and understorey spiders (Arachnida: Araneae) on sugar maple ( Acer saccharum Marsh.) and American beech ( Fagus grandifolia Ehrh.) in hardwood forests of southern Québec, Canada.
2 We sampled canopies of 45 sugar maple and 45 American beech trees and associated understorey saplings in mature protected forests near Montréal. Samples were obtained by beating the crown foliage at various heights and by beating saplings around each tree.
3 Eighty-two species were identified from 13 669 individuals. Forty-eight species and 3860 individuals and 72 species and 9809 individuals were collected from the canopy and the understorey, respectively.
4 Multivariate analyses (NMDS ordination and NPMANOVA) showed the composition of canopy and understorey assemblages differed significantly, and canopy assemblages differed between tree species. Rank-abundance distribution models fitted to the canopy and understorey data indicated that different mechanisms structure the assemblages in both habitats. Three abundant spider species were significantly more common in the canopy; ten species were collected significantly more often in the understorey.
5 The forest canopy was shown to be an important reservoir for spider diversity in north-temperate forests. 相似文献
2 We sampled canopies of 45 sugar maple and 45 American beech trees and associated understorey saplings in mature protected forests near Montréal. Samples were obtained by beating the crown foliage at various heights and by beating saplings around each tree.
3 Eighty-two species were identified from 13 669 individuals. Forty-eight species and 3860 individuals and 72 species and 9809 individuals were collected from the canopy and the understorey, respectively.
4 Multivariate analyses (NMDS ordination and NPMANOVA) showed the composition of canopy and understorey assemblages differed significantly, and canopy assemblages differed between tree species. Rank-abundance distribution models fitted to the canopy and understorey data indicated that different mechanisms structure the assemblages in both habitats. Three abundant spider species were significantly more common in the canopy; ten species were collected significantly more often in the understorey.
5 The forest canopy was shown to be an important reservoir for spider diversity in north-temperate forests. 相似文献