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1.
陆地生态系统碳循环、氮循环和水循环是全球变化科学研究的三大主题,而陆地生态系统碳氮水耦合循环过程及其生物调控机制则是全球变化生态学研究的前沿性科学问题。目前,对陆地生态系统碳氮水耦合循环过程及其调控机制认识的不足是制约评估陆地增汇/减排效果,预测分析全球变化对生态系统生产力和固碳功能影响的瓶颈性问题。本文在综合分析陆地生态系统碳氮水循环的耦合过程基础上,论述了制约生态系统碳氮水循环空间格局耦联关系的生物地理学机制,制约典型生态系统碳氮水循环耦合关系的生物生理生态学机制,以及典型生态系统碳氮水耦合循环的关键生物物理和生物化学过程。重点评述了生态系统碳氮水耦合循环的主要过程及其生物调控机制研究进展,包括:(1)植物叶片冠层生物学过程和根系冠层生物学过程及其对生态系统碳氮水耦合循环控制机制,以及二者之间的关联与互作关系;(2)土壤微生物功能群网络及其对碳氮循环过程的影响;(3)生态系统碳氮水交换通量的时空变化规律,以及生态系统的生态化学计量学理论与实践。本文最后还简要介绍了国家基金委重大研究项目"森林生态系统碳氮水耦合循环的生物控制机制"的研究思路及其主要研究内容。期望能够通过这些探讨对推动我国该研究领域的基础理论建设和新技术发展有所贡献。  相似文献
2.
Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for their ecological group classifications, and that earthworm species interactions would affect mineralization through competition and facilitation effects. A mesocosm experiment was conducted to investigate the effect of three earthworm species, representative of different ecological groups (epigeic: Lumbricus rubellus; endogeic: Aporrectodea caliginosa tuberculata; and anecic: Lumbricus terrestris), and their interactions on the bacterial community, and on nitrogen mineralization from 15N-labelled crop residue and from soil organic matter.Our results indicate that L. rubellus and L. terrestris enhanced mineralization of the applied crop residue whereas A. caliginosa had no effect. On the other hand, L. rubellus and A. caliginosa enhanced mineralization of the soil organic matter, whereas L. terrestris had no effect. The interactions between different earthworm species affected the bacterial community and the net mineralization of soil organic matter. The two-species interactions between L. rubellus and A. caliginosa, and L. rubellus and L. terrestris, resulted in reduced mineral N concentrations derived from soil organic matter, probably through increased immobilization in the bacterial biomass. In contrast, the interaction between A. caliginosa and L. terrestris resulted in increased bacterial growth rate and reduced total soil C. When all three species were combined, the interaction between A. caliginosa and L. terrestris was dominant. We conclude that the effects of earthworms on nitrogen mineralization depend on the ecological traits of the earthworm species present, and can be modified by species interactions. Knowledge of these effects can be made useful in the prevention of nutrient losses and increased soil fertility in agricultural systems, that typically have a low earthworm diversity.  相似文献
3.
丁昌璞 《土壤学报》2010,47(3):451-457
应用多学科研究手段,研究了低分子量有机还原性物质的化学性质。主要结果是,该类物质含-COOH和-C-=NOH2功能团、酚类化合物、挥发性有机酸,等电点变动在3.5~9.5。不同还原强度组份的峰电位大多分布在0.00~0.70 V,负电荷有机还原性物质可占总量的70%~80%,表观分子量小于500~1 000,在电极过程中具有明显的伏安行为。  相似文献
4.
长期定位施肥对无石灰性潮土生物环境影响研究   总被引:2,自引:0,他引:2       下载免费PDF全文
科尔沁沙地草地退化、沙漠化发展中的沙质草场阶段,植被丰富度、盖度可很好地拟合为球状模型,都具有明显的空间结构特征,在所研究范围内,盖度变异幅度明显高于丰富度,但在变程范围内植被丰富度空间变异性强,盖度的空间变异性弱,依赖性强。群落生物量及各功能群生物量的空间自相关范围在9.390~252.690 m范围内变化,相差近30倍,表明影响功能群生物量的生态过程和格局起作用的尺度效应明显。多年生草本和中生植物生物量的结构方差与基台值的比值小于60%,不具有空间结构特征,随着距离的增大,半方差函数值达到一个稳定的极限值后,开始下降并呈现出减小的趋势,但是受牲畜活动等随机因素影响,在5 m取样尺度内不存在局部格局,而可能受更大尺度的格局控制。群落中其它功能群生物量表现出随着距离的增大空间变异性增强的趋势,但超过其变程后半方差函数值稳定在一个极限值附近。群落中生态功能群旱生植物的波动变化不仅对群落盖度、草场的生产力有直接的影响,而且对草场群落及其生态系统的稳定和生态功能的发挥具有重要作用。  相似文献
5.
The influences of arbuscular mycorrhizal fungi (MF, Acaulospora spp. and Glomus spp.), rice straw and earthworms (RE, Eisenia foetida) on nematode communities and arsenic (As) uptake by maize (Zea mays L.) in As-contaminated soils were examined in a field experiment conducted in Wujiang, Jiangsu Province, China. The experiment was designed as a 2 × 2 factorial with the factors of MF (inoculated or uninoculated) and RE (added or not added). The results demonstrated that MF inoculation led to significantly higher root colonization of MF and root dry weight. Plants inoculated with both MF and RE had the highest As concentrations in root. The number of total nematodes increased with MF inoculation when RE was absent, and decreased with RE addition when MF was inoculated. The improved abundance of nematodes with the MF treatment implied that the tested MF acted as food sources for fungivores. The abundances of omnivores-predators and plant parasites were reduced by earthworm activity. Twenty-seven genera of nematodes were identified, with Filenchus dominant in all treatments. Trophic diversity (TD), Shannon-Weaver diversity (H′), Simpson dominance index (λ), and species richness (SR) indicated higher species diversity, more proportionate species composition, evenly distributed species, and more food sources in the MF, RE, and their interaction treatments. Maturity index (MI) showed a moderately disturbed environment due to As pollution. Besides enhancing plant uptake of contaminants, MF and RE amendments could also improve soil health by restoring the structure of soil communities, as reflected by more stable nematode community structure.  相似文献
6.
芦苇定居后铜尾矿细菌群落结构的变化   总被引:1,自引:0,他引:1  
Soil samples were collected from both bare and vegetated mine tailings to study the changes in bacterial communities and soil chemical properties of copper mine tailings due to reed (Phragmites communis) colonization. The structures of bacterial communities were investigated using culture-independent 16S rRNA gene sequencing method. The bacterial diversity in the bare mine tailing was lower than that of the vegetated mine tailing. The former was dominated by sulfur metabolizing bacteria, whereas the latter was by nitrogen fixing bacteria. The bare mine tailing was acidic (pH = 3.78), whereas the vegetated mine tailing was near neutral (pH = 7.28). The contents of organic matter, total nitrogen, and ammonium acetate-extractable potassium in vegetated mine tailings were significantly higher than those in the bare mine tailings (P < 0.01), whereas available phosphorus and electrical conductivity were significantly lower than those in the bare mine tailings (P < 0.01). The results demonstrated that 16S rRNA gene sequencing could be successfully used to study the bacterial diversity in mine tailings. The colonization of the mine tailings by reed significantly changed the bacterial community and the chemical properties of tailings. The complex interactions between bacteria and plants deserve further investigation.  相似文献
7.
为了揭示紫胶玉米混农林对地表蚂蚁群落多样性及功能群的影响,采用陷阱法调查了云南省绿春县紫胶林、紫胶玉米混农林和玉米旱地3种类型样地的地表蚂蚁物种组成、物种多样性、群落结构相似性、指示物种和功能群等。结果显示,紫胶玉米混农林模式具有较高的地表蚂蚁物种数和稀有物种数,与玉米旱地相比,紫胶玉米混农林的蚂蚁物种数增加41%,稀有物种数增加85%。紫胶玉米混农林与紫胶林具有更高的蚂蚁多样性,其物种丰富度和 ACE 估值均显著高于玉米旱地,而紫胶玉米混农林的多度显著高于紫胶林和玉米旱地。地表蚂蚁物种组合在3种类型样地中有差异,与紫胶林和紫胶玉米混农林相关联的物种与玉米旱地不同。3种样地的指示物种不同,玉米旱地的指示种为扁平虹臭蚁和伊大头蚁,紫胶玉米混农林为凹头臭蚁、西昌刺结蚁和中华小家蚁,紫胶林为费氏盘腹蚁、立毛举腹蚁、阿普特铺道蚁、贝卡盘腹蚁和西氏拟毛蚁。紫胶玉米混农林蚂蚁功能群组成比例介于玉米旱地和紫胶林之间,其中机会主义者(OPP)、从属弓背蚁族(SC)、隐蔽物种(C)及气候特化种(CS)的蚂蚁物种数、多度及比例明显高于玉米旱地。紫胶玉米混农林生境较为复杂,对地表蚂蚁多样性保护具有积极作用,是平衡环境保护和经济可持续发展的较好模式。  相似文献
8.
The species richness and frequency of occurrence of bryophytes within taxonomic and functional groups was examined in relation to the size of 20 old-growth patches (size range: 0.6-63.6 ha) remaining after logging in temperate rainforests of coastal British Columbia. At the centre of each remnant patch, bryophytes were sampled in sixty-three 10 cm × 30 cm microplots on three substrate-types (forest floor, downed logs and tree bases). Generalized linear models demonstrated that the species richness and frequencies of some bryophyte functional groups were related to patch size. In particular, some dispersal-limited groups (perennial stayers) and microclimate-sensitive groups (closed canopy species, epixylic (log-dwelling) species, and liverworts) showed significant declines in either richness or frequency as patch size decreased. In contrast, colonists and open canopy species showed little association with patch size. Many, but not all, of the significant patch size relationships disappeared when the three smallest patches (0.6-1.8 ha) were eliminated from the analysis. These results suggest that patches sized 3.5 ha or larger may provide habitat capable of sustaining a diverse array of bryophyte functional groups in temperate rainforest landscapes.  相似文献
9.
This paper provides a quantitative review of the consequences of disturbance on epiphytic lichens in boreal and near boreal forests, focusing on disturbance effects on lichen persistence, growth, and colonization, and on the development (recovery rates) of lichen diversity over time. Lichen persistence, growth, and colonization were examined by reviewing studies on e.g. edge-effects, lichen transplants, and logging experiments. Recovery rates were examined by reviewing studies on relationships between lichen diversity and stand age. The results from the reviewed studies were analysed by various meta-analysis methods. The review showed e.g. overall negative effects of disturbance on lichen persistence, but that persistence depend on the magnitude of the disturbance (e.g. forest edge orientation and clearcut size). However, many lichens seem to persist disturbance, and growth rates were as good in disturbed as in intact forest. The review also showed that lichen populations may need long time to recover, but that species richness does not necessarily increase over time. However, disturbance origin (logging or natural disturbance) is important to explain lichen diversity but is often confounded with stand age. The results are promising for the potential to restore and maintain lichen diversity by forest management methods based on natural disturbance regimes. Further research is needed to e.g. separate the effects of time since disturbance and disturbance type, to examine edge-effects under varying edge conditions, and to examine the influence of landscape context on stand level lichen diversity.  相似文献
10.
Anthropogenic modification of natural habitat is resulting in a widespread loss of biodiversity. One of the primary responses of human societies to biodiversity loss has been the creation of protected areas. Two of the most important questions in conservation biology are: (1) whether protected areas are playing their intended role as reservoirs of biodiversity; and (2) whether habitat outside protected areas, particularly in agricultural landscapes, plays a significant role in maintaining biodiversity and the ecosystem services that it provides. Even though empirical evidence is still lacking on the exact mapping from functional group richness to specific ecosystem services, functional groups are good indicators of ecosystem functioning and thus service provision. We classified the South African avifauna into nine functional groups and tested at a coarse grain for differences in functional group composition between landscapes containing predominantly agricultural vs. protected areas. We used a matched pair sampling design to control for confounding variance. We found that avian functional groups respond in quantitatively and qualitatively distinct ways to agriculturally dominated landscapes. Raptors and scavengers displayed the most consistent losses, while nutrient dispersers and grazers tended to increase. Spatial detrending and randomisation tests suggested that only raptors and scavengers are negatively affected by agricultural landscapes independently of spatial autocorrelation. Thus, protected area landscapes are serving as important reservoirs of functionally important upper trophic populations while agricultural landscapes facilitate the presence of species that link aquatic and terrestrial systems. These results demonstrate the potential for complementary facets of functional diversity to exist on landscapes containing vastly different land-uses.  相似文献
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