共查询到17条相似文献，搜索用时 125 毫秒
1.
择伐强度对天然林树种组成及物种多样性影响动态 总被引：3，自引：0，他引：3
定量分析不同强度采伐(弱度13.0%、中度29.1%、强度45.8%、极强度67.1%和皆伐)作业对天然针阔混交林乔木层树种组成及物种多样性的动态影响.结果表明:经过伐后10 a的恢复,弱度、中度择伐对优势种的影响不大,强度择伐和极强度择伐林分结构略有变化,而皆伐引起林分结构的变化最大,由此说明择伐作业基本上能保持原有的林分结构和种的数量,随着择伐强度的增大,林分结构的改变也随之增大;10 a后弱度择伐物种丰富度最大,而中度择伐多样性指数最高,各择伐样地多样性指数均超过伐前,而皆伐样地多样性指数则比伐前下降;均匀度指数随着择伐强度的增大而增大,生态优势度则呈相反趋势.对于天然针阔混交林的科学经营,从物种多样性的保护和发展出发,应尽量采取弱度或中度择伐方式. 相似文献
2.
山地森林采伐应注重经济、生态和社会效益的有机结合已成为共识.通过选取纯收益、土壤持水价值变化量、凋落物持水价值变化量、土壤养分价值变化量、凋落物养分价值变化量、固碳价值变化量和制氧价值变化量等7个效益指标,运用多目标决策分析方法,定量分析天然次生林5种不同强度(弱度13.0%、中度29.1%、强度45.8%、极强度67.1%和皆伐)采伐作业10 a后的经济和生态效益评价值以及它们的综合效益评价值.结果表明:随着采伐强度的增大,经济效益评价值增大,而生态效益评价值则下降,皆伐的经济效益评价值最大,为0.300,而其生态效益评价值最小,为0.070;弱度择伐的经济效益评价值最小,为0.030,而生态效益最大,为0.670;中度择伐的综合效益评价值最大,为0.713,皆伐的综合效益评价值最小,为0.370.因此,类似试验条件的林区应推行低强度(弱度或中度)择伐经营方式,以实现天然次生林可持续经营. 相似文献
3.
4.
在优化森林结构的同时保障其木材生产功能和生态功能,实现森林可持续经营,如何采取科学、合理的森林管理措施越来越受到人们的关注。本文选取采伐年龄、采伐斑块大小、采伐频率、采伐面积比例作为变量,以江西省泰和县为研究区,设定多种强度和方式的森林管理方案,耦合生态过程模型（PnET-II）和景观模型（LANDIS-II）模拟初始年（2009年）起,未来100年森林面积和生物量的动态变化情况。研究发现：① 森林对不同采伐变量的响应差异明显,采伐年龄对森林面积影响较小,采伐斑块面积仅对生物量有影响,采伐频率对面积和生物量均有较大影响,采伐面积比例是采伐变量中对森林影响最大的变量; ② 每10 a以20%的采伐面积比例,5 hm 2的采伐斑块,采伐21 a以上的杉木、26 a以上的松林、41 a以上的阔叶树种的采伐情景能够保证有林地的生物量较初始年有所增加,有效地保障红壤丘陵区人工林在木材生产的同时保持一定的生态功能。 相似文献
5.
6.
采伐影响下人工林木材生产与固碳功能权衡特征——以湖南会同森林生态实验站为例 总被引：2，自引：1，他引：1
中国人工林面积居世界首位,在全球气候变暖背景下,人工林在提供木材和固定CO2等方面同时具有重要意义。然而木材生产与碳储量之间存在此消彼长的权衡关系,如何综合考虑二者权衡过程,实现区域森林综合效益最大化,是中国森林生态建设中亟待解决的问题。选择会同森林生态实验站磨哨林场作为研究区,采用人工林固定样地多年观测数据以及InVEST模型,定量评估木材生产与碳储量,构建了不同管理模式下的权衡分析方法,提出了研究区森林生态系统综合效益最佳的权衡对策。研究发现：① 在采伐活动的影响下,木材生产与碳储量显著负相关（R = -0.907, P < 0.001）,表现出强权衡关系;② 随着采伐强度增加,木材生产与碳储量的综合效益逐渐增加,权衡值先下降后上升;每10年采伐总面积10%~20%的管理模式下,收获木材量和碳储量的综合效益相对较高且权衡值最低,是最佳森林管理模式;③ 研究区当前采伐强度略高于最佳采伐强度,适当降低采伐强度能够使森林获取更多的综合效益。因此,在明确森林管理目标的基础上,可借助基于标准差的权衡分析方法,提出中国南方人工林生态系统服务提升与可持续经营的权衡对策。 相似文献
7.
九华山森林生态系统生态服务价值评估 总被引：5，自引：0，他引：5
基于LY/T1721-2008((森林生态系统生态服务功能评估规范>,采用实证研究、意愿调查、文献研究等方法,估算了九华山森林生态系统生态服务价值,结果表明:2009年,九华山森林生态系统生态服务价值为84 208.50万元,实物生产价值为4 359.06万元,生态服务价值是实物生产价值的19.31倍.各项生态服务功能价值大小顺序为:涵养水源>保育土壤>生物多样性保护>固碳释氧>森林游憩>净化大气环境>积累营养物质.可为九华山管委会制定旅游、社会经济发展规划,合理开发九华山生态旅游资源,提供理论依据和数据支撑,也可增强人们对九华山森林资源保护的自觉性和主动性. 相似文献
8.
9.
10.
中国省际资源环境成本及生态负荷强度的时空演变分析 总被引：1，自引：0，他引：1
为了科学地评价区域生态系统对经济与社会发展的服务支撑能力,引入生态系统服务理论等构建资源环境成本及绿色GDP核算、生态负荷强度模型,计算出中国31个省区2001~2012年的资源环境成本、生态负荷强度,在此基础上利用探索性空间数据分析方法对2001年以来中国省区的生态负荷强度随时间演变的趋势及其空间分布特征进行分析和探讨（港澳台除外）。结果表明,在研究时段内中国省区的资源环境成本由16.83×1012元攀升到25.24×1012元（2001年可比价）,生态负荷强度由1.55下降到0.45;中国生态负荷强度呈西北、东部沿海地区集聚的空间分布特征,其中西北为高-高、东部沿海为低-低集聚区;这种西、东集聚现象的显著性在研究时段内逐渐减弱,空间负相关区域增加到11个、具有持续扩张的趋势,区域生态效益或经济效益持续向周边溢出。 相似文献
11.
12.
The transformation of tropical ecosystems by humans have resulted in forest loss, which, in turn, have caused negative impacts on biodiversity and the provisioning of ecosystem services. There is an urgent need to plan the restoration of these human-modified landscapes, using methodological approaches that consider key processes occurring at different spatial scales while engage local community participation, offering them the best possibilities of tangible benefits. In this study, was evaluated the landscape spatial pattern and local conservation status of existing forest remnants, showing an analysis of possible restoration scenarios for a human-modified landscape in La Montaña, an indigenous region in southwestern Mexico. Therefore, landscape and local scale approaches were linked to identify specific landscape elements where efforts to improve connectivity must be concentrated. Also, this approach allowed finding a set of species from reference sites that showed the best socioecological characteristics to be used in different restoration strategies. As expected, La Montaña region showed a spatial pattern typical of highly human-modified landscapes, i.e., several small (<21 ha) and irregular forest remnants with strong forest edge effects. Furthermore, these small and irregular forest fragments displayed forest structure, diversity and composition characteristics similar to those communities disturbed by selective harvesting or in an early successional phase. However, about 100 of woody species were found inside the fragments, some with important potential to provide ecosystem services. The landscape connectivity was very low, and an analysis of possible restoration scenarios showed that is equally important to restore the productive areas as well as open forest, to recover up to 47% of landscape connectivity. In this sense, it was proposed a productive restoration strategy to enrich open forests and create biodiversity-friendly habitat in agricultural areas, using species with high socioecological potential. We believe that the same approach could be applied to other highly human-modified tropical landscapes with similar socioecological problems. 相似文献
13.
Reed is one of the most frequent and dominant species in wetlands all over the world, with common reed (Phragmites australis (Cav.) Trin. ex Steud.) as the most widely distributed species. In many wetlands, P. australis plays a highly ambivalent role. On the one hand, in many wetlands it purifies wastewater, provides habitat for numerous species, and is a potentially valuable raw material, while on the other hand it is an invasive species which expands aggressively, prevents fishing, blocks ditches and waterways, and builds monospecies stands. This paper uses the eutrophic reed-swamp of Wuliangsuhai Lake in Inner Mongolia, northern China, as a case to present the multiple benefits of regular reed cutting. The reed area and aboveground biomass production are calculated based on field data. Combined with data about water and reed nutrient content, the impact of reed cutting on the lake nutrient budget (N and P) is investigated. Currently, at this lake around 100,000 tons of reed are harvested in winter annually, removing 16% and 8% of the total nitrogen and phosphorus influx, respectively. Harvesting all available winter reed could increase the nutrient removal rates to 48% and 24%, respectively. We also consider the effects of summer harvesting, in which reed biomass removal could overcompensate for the nutrient influx but could potentially reduce reed regrowth. 相似文献
14.
15.
地处半干旱/半湿润过渡带的河北丰宁坝上,华北落叶松(Larix principis-rupprechti)人工林的主要立地类型有:丘陵阳坡下部、丘陵阴坡、疏缓固定沙丘和风蚀劣地。土壤机械组成和养分含量对华北落叶松人工林的生长影响不大,而土壤风蚀和沙埋对其影响较大,但并不是通过搬运土壤细颗粒物质和养分来影响华北落叶松的生长。华北落叶松林下植物种类较多,长势较好,既可起到保护土壤作用,又可作打草用地。华北落叶松人工林防止坡地土壤侵蚀效益明显。在干旱的年份,固定沙丘华北落叶松林地土壤水分亏缺较大,但仍有一定的土壤有效水分节余,其立地土壤水分亏缺并不十分严重,林分相对稳定。除风蚀劣地外,30龄左右正值生长速生期,阴坡中部这一年龄段可以天然更新,其它立地也有天然更新的可能。因此,从人工林经营的经济效益和生态效益分析,此年龄段的华北落叶松人工林不宜采伐。 相似文献
16.
The Effects of Annual Harvesting on the Subsequent Phytomass and Species Composition of Grassland and Fernland: A Hong Kong Case 总被引：1，自引：0，他引：1
Anthropogenic grasslands mixed with fern and shrubland, on scales from metres to kilometres, are widespread in tropical Southeast Asia, and especially in southern China and adjoining regions where harvesting for domestic fuel is a major factor in their maintenance. Baseline surveys in grassland and fernland in 1989–90 and resurveys in 2001 of three 6 × 20 m plots in Wong Chuk Yuen, Hong Kong, showed substantial change in species composition and total aboveground phytomass as a result of annual harvesting, with more pronounced change in the fernland. Under harvesting pressure, the species composition of the grassland changed considerably, though the proportions of the various life‐forms did not. Ischaemum spp. and Miscanthus floridulus increased whereas Themeda gigantea died out while the proportion of other grass species remained much the same. Under the same regime the species composition and life‐forms of the fernland changed markedly. The proportion of Dicranopteris fern dropped substantially, though still comprising a third of the phytomass by 2001. The shrub Melastoma survived harvesting. A firebreak cut in the fernland became grassy under annual harvesting and remained grassy six years after cutting ceased. The annual harvests from the growth‐years 1991–2000 showed a substantial though variable increase in total phytomass. Analyses relating harvested phytomass with various climatic parameters showed no significant correlations. Some possible reasons for this are suggested. Although annual harvesting was clearly sustainable over the ten years of observation, the question of continued sustainability on sites harvested for centuries, the situation in much of southern China and parts of upland mainland Southeast Asia, remains unresolved. 相似文献