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为探讨桂东丘陵区森林小气候效应,选择苍梧县具代表性的几种人工林作为研究对象,对其林内外的小气候进行观测。结果表明,荷木湿地松(Schima superba×Pinus elliotti)混交林内的气温、大气相对湿度与林外的差值较大;湿地松大叶栎(Pinus elliotti×Castanopsis fissa)混交林光合有效辐射最大,达1663.8μmol/(m^2·s),与光合有效辐射最低的竹林相差97.4%。初步认为,林分类型和结构对林分小气候及森林防火、防虫等生态效应有着重要影响。 相似文献
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长江中上游防护林体系初建以来,为定量化反映出不同林分在保护环境中的作用,以端坊溪小流域为试验点,针对鄂西三峡库区6种优良林分,从林地的小气候观测及影响森林小气候的主要林分因子等方面进行了小气候效益研究。研究表明:1.森林对林内光照、地温、空气温度、湿度及林地水汽蒸发具有明显的影响作用;2.林分因子中,影响森林小气候的主要是郁闭度,平均林分高及林冠层厚度等;3.林分结构不同,对小气候的影响程度较大。 相似文献
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酸雨区亚热带针阔混交林的冠层淋溶特征 总被引:2,自引:0,他引:2
2001年1月至2002年6月在湖南韶山对亚热带针阔混交林4个采样区进行酸雨监测,分析林内穿透水中主要离子的淋溶特征.结果表明:大气降水经过森林冠层后pH值明显升高,亚热带针阔混交林对SO2-4、NO3-、Mg2 、NH4 和Na 具有吸收作用,SO2-4、Ca2 和Mg2 的冠层淋溶百分率随降雨量的增加明显减少.Ca2 、K 和Cl-的冠层淋溶百分率随着pH值增加而增加.韶山地区在常年酸沉降作用下,森林冠层对酸性离子SO2-4、NO3-的吸收作用最强.根据18个月离子浓度平均值来计算,韶山地区森林冠层离子的淋溶序列为:K >Ca2 >Cl->Mg2 >SO2-4>NO3->NH4 >Na . 相似文献
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对22a生柠檬桉×木荷×杉木复层混交林、木荷×杉木单层混交林及杉木纯林调查分析表明:柠檬桉×木荷×杉木复层混交林能合理利用营养空间,提高林分生产力,林分蓄积量比木荷×杉木单层混交林提高了30.6%,比杉木纯林提高了119.3%。柠檬桉由于树体高大,与木荷、杉木混交,其密度的增加并不会影响乡土树种的树高、胸径、材积生长。柠檬桉×木荷×杉木复层混交林林下植被丰富,生物多样性高于荷×杉单层混交林和杉木纯林。 相似文献
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杉木酸枣人工混交林生产力和林木生长规律的研究 总被引:14,自引:7,他引:7
本文分析比较了20年生杉木与酸枣人工混交林以及杉木纯林、酸枣纯林生产力和林木生长规律。结果表明:杉木与酸枣人工混交林乔木层生物量为168.74t/hm2>杉木纯林乔木层生物量135.95t/hm2>酸枣纯林乔木层生物量107.01t/hm2;杉木与酸枣混交林林分蓄积量为355.113m3/hm2>杉木纯林蓄积量301.672m3/hm2>酸枣纯林蓄积量173.150m3/hm2;杉木与酸枣混交可改变树种单调状况,防止地力衰退,提高林地生产力。 相似文献
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南亚热带马尾松红椎人工林群落结构、物种多样性及基于自然的森林经营 总被引:4,自引:0,他引:4
研究广西凭祥伏波林场28年生马尾松纯林、红椎纯林及红椎×马尾松混交林的群落结构与物种多样性,根据培育人工大径材和满足生态服务功能的发展目标,提出基于自然的森林经营方向.结果表明:马尾松纯林可划分为2层(Ⅰ层13 ~24 m优势种为马尾松,Ⅱ层2~9m优势种为红椎),红椎纯林可划分为2层(Ⅰ层:12~17 m,优势种为红椎;Ⅱ层:2~8 m,优势种也为红椎),红椎×马尾松混交林可划分为3层(Ⅰ层:20~25 m,优势种为红椎;Ⅱ层:13~20 m,优势种为马尾松;Ⅲ层:4~7 m,优势种为红椎);胸径大于1 cm的乔木物种数表现为马尾松纯林(11种)>红椎×马尾松混交林(7种)>红椎纯林(4种);胸径大于1 cm的林木株数表现为马尾松纯林(1949株·hm-2)>红椎纯林(825株·hm-2)>红椎×马尾松混交林(383株·hm-2);胸高断面积表现为马尾松纯林(30.05 m2·hm-2)>红椎×马尾松混交林(17.48 m2·hm-2)>红椎纯林(12.35 m2·hm-2);平均胸径表现为红椎×马尾松混交林(21.7 cm)>红椎纯林(9.9 cm)>马尾松纯林(9.7 cm);除丰富度指数外,红椎×马尾松混交林灌木层的Shannon-Wiener指数、Simpson指数和Pielou指数均显著低于2种纯林(P<0.05);红椎纯林草本层多样性指数最低,但3种林分之间差异不显著(P>0.05).对于该地区的马尾松纯林,通过林分结构调整,充分依靠林下天然更新,适当补植阔叶树种,最终形成以阔叶树为主的异龄、复层针阔混交林;对于红椎纯林,根据目标树经营体系,通过林分结构调整,补植部分阔叶树种,最终形成异龄、复层阔阔混交林;对于红椎×马尾松混交林,根据目标树经营要求对妨碍目标树生长的林木进行砍伐,促进林下马尾松和红椎更新,最终形成异龄、复层针阔混交林. 相似文献
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Temperate and boreal forests act as major sinks for atmospheric CO2. To assess the magnitude and distribution of the sinks more precisely, an accurate estimation of forest biomass is required. However, the determinants of large-scale biomass pattern (especially root biomass) are still poorly understood for these forests in China. In this study, we used 515 field measurements of biomass across the northeast part of China, to examine factors affecting large-scale biomass pattern and root–shoot biomass allocation. Our results showed that, Picea & Abies forest and coniferous & broadleaf mixed forest had the highest mean biomass (178–202 Mg/ha), while Pinus sylvestris forest the lowest (78 Mg/ha). The root:shoot (R/S) biomass ratio ranged between 0.09 and 0.67 in northeast China, with an average of 0.27. Forest origin (primary/secondary/planted forest) explained 31–37% of variation in biomass (total, shoot and root), while climate explained only 8–15%, reflecting the strong effect of disturbance on forest biomass. Compared with shoot biomass, root biomass was less limited by precipitation as a result of biomass allocation change. R/S ratio was negatively related to water availability, shoot biomass, stand age, height and volume, suggesting significant effects of climate and ontogeny on biomass allocation. Root–shoot biomass relationships also differed significantly between natural and planted forests, and between broadleaf and coniferous forests. Shoot biomass, climate and forest origin were the most important predictors for root biomass, and together explained 83% of the variation. This model provided a better way for estimating root biomass than the R/S ratio method, which predicted root biomass with a R2 of 0.71. 相似文献
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我国森林生态系统枯落物现存量研究进展 总被引:3,自引:0,他引:3
在参考大量相关文献的基础上,对我国森林生态系统枯落物现存量研究进展进行了归纳总结。我国枯落物现存量的研究主要集中在亚热带和温带,热带相对较少;枯落物现存量的研究主要采用收获法,但取样样方的布设、面积、数量及取样时间等尚没有统一的规定;在大区域尺度上,气候是影响森林枯落物现存量变化的主导因子,不同气候带森林枯落物现存量的大小顺序为温带>亚热带>热带;森林枯落物现存量还受林分起源、群落组成和结构、群落发育阶段、土壤、地形条件及干扰的影响。文中还针对全球变化背景下我国森林枯落物现存量研究中存在的问题及今后的研究方向进行了探讨。 相似文献
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Renewable energy sources have received significant attention in European countries as a result of increasing dependence on energy imports and concerns over high prices of fuels and climate change. Although private forests in Croatia account for less than one quarter of all forests, they may play an important role in woody biomass energy production, due to their underutilized exploitation. The objective of this paper is to identify the willingness of private forest owners to supply woody biomass and to understand how this willingness is affected by certain owner, management and forest property characteristics. A survey conducted in Croatia in 2012 of a random sample of 350 private forest owners shows that almost half of them were willing to supply woody biomass. A random utility model was used to determine the factors influencing private forest owners’ willingness to supply woody biomass. The results showed that willingness to supply woody biomass was influenced by property size, management objectives (production of fuel wood for personal needs and using the forest for outdoor recreation), cooperation with other forest owners and owner age. In order to enhance woody biomass mobilization from private forests it is important to identify the owners who are willing to supply it and to provide them with financial and administrative support using a mix of developed forest policy instruments. 相似文献
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[目的]分析德国推行近自然森林经营20年来的经营效果,总结德国推行近自然森林经营的经验。[方法]在明晰近自然森林经营原则的基础上,基于两期(间隔期10年)资源清查数据对比,对德国大面积推行近自然森林经营20年的经营效果进行分析。[结果]两期资源清查数据表明,德国采用近自然经营20年后,针叶林如挪威云杉和欧洲赤松的面积显著减少,阔叶林和针阔混交林面积持续增加;阔叶树种蓄积平均增长量约为15 m~3·hm~(-2),针叶树种蓄积平均增长4 m~3·hm~(-2),挪威云杉是唯一蓄积下降的树种,下降了5 m~3·hm~(-2);近自然度等级变化表明,人工林面积在减少,而近自然森林的面积在增加,甚至符合原始林等级的森林面积也在增加。[结论]实现近自然森林经营的目标是一个长期的过程,联邦政府促进和保护森林的政策以及林场主所采用的先进的森林经营技术也是德国森林每公顷蓄积达到336 m~3的重要原因;在近自然森林经营的原则下,德国森林中针阔混交林比例显著增加;将近自然程度不高的人工林经营转化为近自然的森林生态系统是德国森林经营所面临的主要问题。 相似文献
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Forest dynamics after timber harvesting is a major issue for tropical forest managers and communities. Timber harvesting provides income to communities and governments and resources to industry but it has also been identified as a potential contributor to deforestation and degradation of tropical forests. In Papua New Guinea (PNG) harvesting is primarily occurring in accessible primary forests however, the fate of these forests under current harvesting practices is poorly understood.In this study we investigated the impacts of selective harvesting on stand structure, growth and dynamics, recovery and degradation, and species diversity. We also assessed the impacts of forest fire after the 1997-98 El Nino on basal area (BA) growth and mortality rates of natural tropical forests in PNG. For this study we used data from 118 (105 in selectively harvested and 13 in un-harvested forest), one-hectare permanent sample plots distributed across the country and measured for over 15 years by the PNG Forest Research Institute (PNGFRI). We analysed data from 84 of these plots in harvested forest to examine temporal trends in stand condition following harvesting. Mortality rates were investigated in 10 of the 21 plots in harvested forest that were burned during the 1997-98 El Nino drought with sufficient data for analyses. We tested a model developed in Queensland tropical forests to determine whether or not a critical threshold residual BA existed for the recovery of harvested tropical forests in PNG. Results from a logarithmic regression analysis of the relationship between starting BA (BA at first census) and stand BA increment after selective harvesting showed a positive increase in BA growth (r2 = 0.74, p < 0.05). However, there was no critical threshold in residual BA that determined whether a harvested forest was likely to degrade or recover BA growth after harvesting. Our analyses suggested that the response to harvesting was variable, with the majority of un-burned plots (75%) showing an increase in BA and remainder a decrease. Average BA of selectively-harvested tropical forests was about 17 m2 ha−1 ± 4.17 (SD). Average annual increment in BA across the 84 un-burned plots was 0.17 m2 ha−1 year−1 ± 0.62 (SD). Thus these forests generally show capacity to recover after selective harvesting even when the residual BA is low. A proportion of the BA increment is made up of non-commercial pioneer species that originate in significant gaps after harvesting. On burned plots, BA is affected by high mortality rates. The fate of these forests will depend on the degree of future harvesting, potential conversion to agriculture and the impact of fire and other disturbances. 相似文献
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将碳达峰、碳中和纳入我国生态文明建设整体布局是中共中央作出的重大战略选择。森林是陆地生态系统最重要的贮碳库,对实现碳中和具有重要作用。森林的扰动与碳储量和碳汇关系密切,目前由于森林扰动资料的缺乏,导致区域森林碳汇与碳源的估算精度不准确,建立和完善适用于中国森林的扰动检测方法具有重要的理论意义和应用价值。文中在分析国内外森林扰动遥感检测文献的基础上对分类后比较法、直接分析法、时间序列分析法与深度学习法进行对比,分析每一类方法的技术特点和应用效果,指出森林扰动检测方法存在的问题,展望今后发展方向,以期能够为森林扰动检测相关研究提供参考。 相似文献
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[目的]利用星载激光雷达波形数据对森林类型识别时,受地形、噪声和林层结构等因素影响,针叶林、阔叶林和混交林森林类型识别精度较低,为提高森林类型识别精度,需提取与森林类型相关的波形特征参数.[方法]结合回波仿真原理与林分冠层特征对GLAS回波波形进行理论分析,提出了与森林类型相关的波形特征参数147R-cafit-、K1... 相似文献
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