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91.
大兴安岭天然白桦林群落结构特征及其物种多样性 总被引:1,自引:0,他引:1
基于2011年大兴安岭地区的样地调查数据,分别用大小比数、混交度和角尺度来衡量林分空间结构特征;用Simpson生态优势度指数、Margalef丰富度指数、Shannon多样性指数以及Pielou均匀度指数来衡量群落的物种多样性水平。研究结果表明:随着白桦优势度的提高,群落的物种多样性、丰富度和均匀度指数均显著下降;从林分的空间结构特征来看,混交林的水平分布格局呈随机分布,林分的混交程度高,林木的生长水平整体处于中庸状态;各项指标均表明,白桦混交林具有较高的物种多样性和群落的稳定性,对白桦林向松桦混交林过渡的群落演替趋势研究有重要意义。 相似文献
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【目的】研究不同抚育强度对锐齿栎林光合特性的影响,为秦岭南坡锐齿栎林的森林抚育间伐提供理论依据。【方法】在秦岭南坡火地塘林区锐齿栎林内设置13块样地进行间伐,其中抚育强度5%,10%,15%,20%的样地各3块,对照样地1块,测定不同间伐强度样地内的环境因子及锐齿栎的光合生理生态因子,并进行方差分析、回归分析和相关分析。【结果】抚育后的林内环境因子和光合生理生态因子都发生了变化,抚育强度15%,20%的林内光强(PAR)、大气温度(Ta)、大气CO2浓度(Ca)、净光合速率(Pn)、蒸腾速率(Tr)、气孔限制值(Ls)、水分利用效率(WUE)有极显著或显著提高,而相对湿度(RH)极显著或显著降低,气孔导度(Gs)在抚育强度15%的林内极显著降低,胞间CO2浓度(Ci)经抚育后显著降低,但在不同抚育强度间无明显差异;通过光合光响应曲线拟合可知,抚育强度15%和20%的林内最大净光合速率(Pmax)较高;通过假设检验可知,Pn与环境因子PAR、Ta、Ca、RH在α=0.01的水平上存在显著的回归关系;Pn与PAR、Ta呈极显著正相关,而与Gs、Ci呈极显著负相关;抚育后林内的光合同化量有所提高,其中抚育强度15%的林内光合同化量最高。【结论】秦岭南坡锐齿栎林的抚育强度设置在15%为宜。 相似文献
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95.
报道了中国小兴安岭云杉树上一种新干基白腐病,其病原菌为鳞片昂氏多孔菌Onnia leporina(Fr.)H.Jahn。该病主要发生在成熟林分,造成受害木干基白腐,被侵染树木极易风折或风倒而死亡。根据中国的材料对该病病菌进行了宏观和微观的详细描述,并与欧洲的材料进行了对比。 相似文献
96.
Kenji Ohse Kenji Tamura Haruo Tanaka Teruo Higashi 《Soil Science and Plant Nutrition》2005,51(1):37-42
At Mt. Hirugatake in the Tanzawa Mountains, Kanto district, Japan, the deciduous broadleaved forests have rapidly declined. In our previous studies, we reported that the amount of soil organic matter had significantly decreased at the early and final stages of forest decline, and that the soil microbial biomass also showed a large decrease at these stages, suggesting that the composition of soil organic matter might have also changed with forest decline. To clarify the influences of forest decline on the composition of soil organic matter, the amount of humic substances, optical properties of humic acid, and the amount of soil carbohydrates in surface soils at different stages of forest decline were investigated. The amounts of humic acid and fulvic acid decreased to a lesser extent at the early and middle stages of forest decline, and showed a significant decrease at the final stage. As the amount of humin significantly decreased at the early stage, it was plausible that the distinct decrease in the total carbon content of the soil surface horizons at the early stage of forest decline was induced by the decrease in the amount of humin, and at the final stage, by the decrease in the amounts of humic acid and fulvic acid. The amount of soil carbohydrates did not change appreciably with forest decline although the soil organic matter content markedly decreased. It was suggested that most of the carbohydrates in the soil surface horizons were in a stabilized form consisting of complexes with humic substances, metals, and minerals, and would not be affected by the environmental changes associated with forest decline. 相似文献
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98.
以秦岭火地塘林区油松和漆树倒木为研究对象,采用国际倒木腐烂等级划分方法,测定其 5 个腐烂等级的6种化学元素( C,N,P,K,Ca,Mg) 的含量,分析倒木对土壤化学元素的影响。结果表明: 油松倒木5个腐烂等级间 C 含量没有显著差异,而漆树倒木 C 含量随着分解显著递减; 漆树和油松Ⅴ级倒木的 N 含量随着分解显著递增; Mg 含量在油松倒木分解过程中无显著差异,在漆树倒木分解后期显著增加; P,K,Ca 含量在漆树和油松分解过程中都无显著差异,但 P 和 Ca 含量随着油松和漆树倒木的腐烂呈线性增加,K 含量随油松和漆树倒木分解呈线性下降。油松和漆树倒木下土壤 C 含量随着土层加深而显著减少,K,Ca,Mg 含量随土层加深无显著差异; 土壤 C含量随倒木腐烂显著递增,N,P,Ca,Mg 含量随倒木分解无显著差异。该研究揭示倒木分解过程中各种化学元素的变化规律,对促进秦岭森林生态系统物质循环和制定林木更新措施有重要的参考价值。 相似文献
99.
旅游干扰对祁连山风景区土壤性质的影响 总被引:1,自引:0,他引:1
本研究以祁连山大野口风景区为研究对象,初步探讨了旅游干扰对该区域土壤性质的影响。研究结果表明:祁连山风景区游客主要集中在5—8月,游客大多选择自驾游方式,以野炊、烧烤式旅游为主。旅游活动对核心区表层土壤的pH、体积质量、含水量及有机质影响较大。随着旅游活动干扰程度的降低,0~10 cm土层土壤pH逐渐上升,10~20 cm土层pH变化不大。土壤体积质量表现出:核心区缓冲区背景区,而土壤含水量则为:背景区缓冲区核心区。核心区和缓冲区土壤表层有机质含量受游客活动影响较大,显著低于背景区,分别占背景区的63.6%和60.1%。表层土壤全氮、全磷、全钾含量均表现出:背景区缓冲区核心区,而10~20 cm土层全量含量差异不大。不同区域土壤速效养分0~10 cm土层含量高于10~20 cm土层含量。核心区表层土壤水解氮、速效磷含量偏高,而深层土壤速效磷含量较高。各个有效微量元素在0~10 cm土层含量普遍高于10~20 cm土层,且在核心区含量均较高。 相似文献
100.
Plant species-level research that comprises inventories, impact studies and monitoring is necessary if plant resources are to be harvested sustainably by human populations living adjacent to protected areas in sub-Saharan Africa. This research assessed the extraction of plant products from two montane forest ecosystems, Uzungwa Scarp Forest Reserve (USFR) and Bwindi Impenetrable National Park (BINP), East Africa. In USFR, data from vegetation sampling and interviews with local people were used to understand the ecological and socio-economic aspects of non-timber forest product (NTFP) harvesting. The densities of eight commonly harvested tree species, most of which were used as building poles, were approximately 2.4-4.5 times lower in disturbed versus undisturbed habitats across all four sites in USFR. Interviews with 91 women and 54 men suggested that most species were harvested for medicinal uses (57 species) and building purposes (50 species). In BINP, the liana Loeseneriella apocynoides (Apocynaceae), is harvested for basketry weaving. Evidence suggested that the liana was harvested in both protected and unprotected areas of BINP. Data collected suggested a negative impact on this species in an unprotected versus a protected area, with stem diameters larger than 1 cm significantly more abundant in the protected area. This study reveals that harvesting of NTFPs occurs even in these two protected forest areas, and that over-exploitation not only threatens species of high-demand, but could also alter forest structure and composition. Management practices that encourage the monitoring of sustainable harvesting levels of species and promote alternative plants for the same uses should be considered as part of conservation strategies. 相似文献