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Rune Østergaard Pedersen 《Scandinavian Journal of Forest Research》2016,31(2):206-221
This paper presents new methods for plot edge bias (PEB) correction of individual tree competition indices (CIs) using airborne laser scanning (ALS) as auxiliary information in multivariate ratio and multivariate regression models. I applied the methods to 557 plots from the Norwegian National Forest Inventory located in Hedmark County in South East Norway and compared them to the benchmarks methods linear expansion and simulated annealing by studying the individual tree growth predictions before and after PEB correction. Generally, the simulated annealing method seemed to improve growth prediction most and overall the existing methods performed better than those based on ALS. All PEB-correction methods tested gave minor changes in growth predictions and the absolute change in percent in adj. R2 and Akaike's Information Criterion (AIC) was numerically small, with an average percentage change for the tested CIs between 1.8 for adj. R2 and 0.6 for AIC of the observed values in the original data. The small differences in the results between the original data and the PEB-corrected data show that on average PEB remains a minor problem for individual tree growth prediction. Whether the results are valid for forests with significantly different spatial composition than that of this database remains to be confirmed. 相似文献
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Sławomir Mitrus Grzegorz Hebda Tomasz Wesołowski 《Scandinavian Journal of Forest Research》2016,31(2):135-139
A previously unknown association of ants with birds breeding in tree holes is described. Ants Lasius brunneus Latreille (Hymenoptera: Formicidae) were found in c. 15% of nests of Parus major L. and Poecile palustris L. (Paridae) breeding in tree holes in the primeval deciduous forest located in the Bia?owie?a National Park (Poland). The ants preferably used holes located higher above the ground. As such holes are warmer than the unused holes or other nest sites, it is suggested that the ants cohabit holes utilized by the tits to gain thermal benefits. 相似文献
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大山包自然保护区越冬黑颈鹤对觅食地选择的初步研究 总被引:5,自引:0,他引:5
对云南大山包黑颈鹤国家级自然保护区越冬黑颈鹤种群所选用的觅食地进行了调查和初步研究。研究结果表明:在其越冬黑颈鹤的家庭鹤与集群鹤两种类群中对觅食地的8种生境因子(坡度、坡向、坡位、植被型、植被盖度、植被高度、最近水源距离和最近干扰距离)及其相对应的项目均表现出有相同的选择性。除家庭鹤更偏好选用上坡位(54.4%)作觅食地,而集群鹤更偏好选用下坡位(44.5%)作觅食地外;对其他因子的选择频次相差不大。对大山包自然保护区越冬黑颈鹤觅食地进行了因子分析,提取了主成分。其结果表明:对越冬黑颈鹤觅食地影响较大的生境因子为植被盖度、植被高度、水源距离和干扰距离。对其两种类群而言,对家庭鹤影响较大的生境因子为植被盖度、坡向、干扰距离和植被高度;而对集群鹤影响较大的生境因子为水源距离、坡向和植被高度。越冬黑颈鹤所选择的觅食地的主要特征具体表现为开阔(植被高度3~10 cm,上坡位(54.5%))、距离水源较近(100~500 m)、植被盖度适中(>40%~<60%)、背风〔东北坡向(45.4%)和西南风(63.6%)〕、缓坡(<30°)、附近有人类活动(距100~700 m)的鸭茅草草地。大山包自然保护区越冬黑颈鹤中家庭鹤与集群鹤对觅食地选用的差别主要表现在水源距离、植被盖度和干扰距离上。 相似文献
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Obtaining accurate estimates of national belowground and whole tree biomass is important to better understand the global carbon cycle and to quantify biomass stocks and changes. However, the availability of individual tree belowground biomass functions is generally low due to the difficulty of extracting roots. Allometric birch (Betula pubescens Ehrh. and Betula pendula Roth) biomass functions were derived from 67 trees for belowground and whole tree biomass using diameter at breast height (dbh) and height as the independent variables. The sampled trees spanned a dbh range from 4.0 to 45.5?cm and the functions provided a good fit to the data (RMSE?=?14.2?kg for BG and 40.7?kg for whole tree with dbh as predictor). Belowground, total stem, live crown, and dead branch biomass comprised 29.2%, 52.2%, 18.1%, and 0.5% of the whole tree biomass, respectively. Observed root-to-shoot ratios were between 0.21 and 0.88 with a mean of 0.42. Comparisons with existing belowground birch biomass functions from Fennoscandia indicated considerable differences in estimates between existing functions. The derived data-set for belowground birch biomass is the largest in Fennoscandia and the developed functions are likely the best available for estimating national birch biomass stock and stock change in Norway. 相似文献
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通过野外调查和查阅文献资料,得出石门国家森林公园共有野生观赏植物122科267属377种,其中蕨类植物19科23属28种,裸子植物4科5属7种,被子植物99科239属342种。分析了石门国家森林公园野生观赏植物资源的基本特征和用途,并探讨其保护和开发利用。 相似文献
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