共查询到20条相似文献,搜索用时 15 毫秒
1.
Exclosure experiments have demonstrated the effects of bird predation on arthropods. In a Mexican coffee plantation, we excluded foliage-gleaning bird and bat predators from coffee plants. Effects of bats and birds were additive. In the dry season, birds reduced arthropods in coffee plants by 30%; birds and bats together reduced arthropods by 46%. In the wet season, bats reduced arthropods by 84%, whereas birds reduced them by only 58%. We conclude that previous "bird" exclosure experiments may have systematically underestimated the effects of bats. 相似文献
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Smith NJ 《Science (New York, N.Y.)》1981,214(4522):755-761
The decade-old Transamazon Highway provides a useful stage for examining some of the major issues related to frontier conquest and the impact of pioneer settlement on one of the world's richest biomes. The highway project is an ambitious colonization scheme and the lessons that can be drawn from it, ranging from the environmental effects of stripping back the tree cover to the spread of diseases, will be useful in guiding development policy in other tropical regions. 相似文献
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热带森林植被冠层CO2储存项的估算方法研究 总被引:1,自引:0,他引:1
评价植被冠层CO2储存项有助于提高森林-大气层面净生态系统CO2交换量(FNEE)的估算精度.基于西双版纳热带季节雨林2年完整的涡度相关系统和CO2廓线的同步观测资料,详细分析涡度相关法(Fs-EC)和廓线法(Fs-PM)CO2储存项估算结果和变化趋势.结果表明:1)廓线法CO2储存项年平均日变化曲线相比涡度相关法能更... 相似文献
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Species loss and aboveground carbon storage in a tropical forest 总被引:1,自引:0,他引:1
Bunker DE Declerck F Bradford JC Colwell RK Perfecto I Phillips OL Sankaran M Naeem S 《Science (New York, N.Y.)》2005,310(5750):1029-1031
Tropical forest biodiversity is declining, but the resulting effects on key ecosystem services, such as carbon storage and sequestration, remain unknown. We assessed the influence of the loss of tropical tree species on carbon storage by simulating 18 possible extinction scenarios within a well-studied 50-hectare tropical forest plot in Panama, which contains 227 tree species. Among extinction scenarios, aboveground carbon stocks varied by more than 600%, and biological insurance varied by more than 400%. These results indicate that future carbon storage in tropical forests will be influenced strongly by future species composition. 相似文献
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Hubbell SP 《Science (New York, N.Y.)》1979,203(4387):1299-1309
Patterns of tree abundance and dispersion in a tropical deciduous (dry) forest are summarized. The generalization that tropical trees have spaced adults did not hold. All species were either clumped or randomly dispersed, with rare species more clumped than common species. Breeding system was unrelated to species abundance or dispersion, but clumping was related to mode of seed dispersal. Juvenile densities decreased approximately exponentially away from adults. Rare species gave evidence of poor reproductive performance compared with their performance when common in nearby forests. Patterns of relative species abundance in the dry forest are compared with patterns in other forests, and are explained by a simple stochastic model based on random-walk immigration and extinction set in motion by periodic community disturbance. 相似文献
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Tropical forest fragmentation threatens biodiversity, yet basic information on population responses for major groups such as plants is lacking. Hypervariable genetic markers were used to reconstruct a population-level pedigree in fragmented tropical forest for the tree Symphonia globulifera. Though seedlings occurred only in remnant forest, the pedigree showed that most seedlings had been produced by sequentially fewer adults in pasture, creating a genetic bottleneck. The pedigree also implicated shifts in the foraging of animals that disperse pollen and seed in a secondary constriction of the bottleneck. These results suggest that tropical conservation strategies should anticipate complex, cryptic responses to fragmentation. 相似文献
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Terborgh J 《Science (New York, N.Y.)》1983,222(4626):920-921
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Restoration of degraded tropical forest landscapes 总被引:5,自引:0,他引:5
The current scale of deforestation in tropical regions and the large areas of degraded lands now present underscore the urgent need for interventions to restore biodiversity, ecological functioning, and the supply of goods and ecological services previously used by poor rural communities. Traditional timber plantations have supplied some goods but have made only minor contributions to fulfilling most of these other objectives. New approaches to reforestation are now emerging, with potential for both overcoming forest degradation and addressing rural poverty. 相似文献
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Tritiated water applied to the surface of soil in a tropical rain forest was found in free water of the litter and top 18 centimeters of soil as long as 7 months after the application. Plant roots, even in the high-rainfall environment of a tropical rain forest, therefore are exposed to tritiated water for considerable periods of time after release. 相似文献
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Secondary forests are more extensive than old-growth forests in many tropical regions, yet the genetic composition of colonizing populations is poorly understood. We analyzed the parentage of a founder population of 130 individuals of the canopy palm Iriartea deltoidea in a 24-year-old second-growth forest in lowland Costa Rica. Among 66 trees in adjacent old-growth forest, only two individuals contributed 56% of the genes in founders. Second-growth trees had lower genetic diversity and larger patches of similar genotypes than old-growth trees. Recovery of genetic diversity of populations in tropical second-growth forests may take many generations and will require continued dispersal from genetically diverse source populations. 相似文献
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Stiles FG 《Science (New York, N.Y.)》1977,198(4322):1177-1178
A system of compensating phenological responses of different species to unusual rainfall conditions may play a major role in maintaining an orderly, staggered sequence of flowering peaks among the hummingbird-pollinated plants of a Costa Rican rain forest. Quantitative phenological studies over several years may be essential to understanding the temporal organization of many tropical communities. 相似文献
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海南热带雨林沟谷植物群落区系地理研究 总被引:1,自引:0,他引:1
海南岛热带沟谷雨林物种丰富,分别在霸王岭和黎母山的5 000 m2样地调查中,发现树种703株,两地共有树种36科,其中樟科、夹竹桃科、大戟科、楝科、山矾科和桃金娘科等共有科占有的树种数量超过60%,表明两个样地相似度较高;霸王岭和黎母山沟谷雨林群落树种都以热带分布型为优,霸王岭沟谷雨林热带科成分占85.4%,热带属成分占78.5%,黎母山沟谷雨林热带科成分占88.9%,属成分占92.6%,黎母山沟谷雨林热带科属成分比霸王岭均高,反映了较强的热带性质. 相似文献
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Recent assessments of areas of different tropical forest types and their corresponding stand volumes were used to calculate the biomass densities and total biomass of tropical forests. Total biomass was estimated at 205 x 10(9) tons, and weighted biomass densities for undisturbed closed and open broadleaf forests were 176 and 61 tons per hectare, respectively. These values are considerably lower than those previously reported and raise questions about the role of the terrestrial biota in the global carbon budget. 相似文献
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海南热带山地雨林森林循环不同阶段光、温环境的测定与分析 总被引:4,自引:1,他引:4
臧润国 《北京林业大学学报》2002,24(5):125-130
以海南岛典型的热带山地雨林为对象,测定了森林循环不同阶段林分斑块内的光照、空气温度以及土壤不同层次内的温度因子,分析了其日变化规律,讨论了森林群落内环境因子异质性对群落内物种共存和多样性维持的意义.海南岛热带山地雨林森林循环不同阶段斑块内光照与温度的日变化规律不同.林隙阶段内光照的强度及其变动幅度都远大于其它3个阶段,而且林隙内不同部位光照的日变化规律也存在着明显的差异.森林循环各阶段斑块内光照强度及其变动幅度的大小顺序为林隙阶段(G)>衰退阶段(D)>建立阶段(B)≥成熟阶段(M).不同斑块之间的气温基本上呈现出M>B>D>G的总趋势.不同阶段斑块内土壤表面温差变动幅度的大小顺序为G>D>B>M.不同阶段斑块类型在土壤不同层次中温度的日变化不同,但各类型斑块在同一时刻同一土壤层次内的温度差异大都不超过1℃.森林循环不同阶段斑块内环境因子的时空差异,为不同生态特性树种在群落中的共存奠定了基础. 相似文献
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为了比较热带季节雨林和橡胶林2种植被类型凋落物层的持水能力差异,在云南西双版纳选取了这2种森林,收集了地表凋落物,对比研究2种植被类型的凋落物地表现存量、持水率、持水速率、最大持水量和有效持水量等持水特性的差异。结果表明:橡胶林凋落物地表现存量(3.79 ±0.34)t· hm-2显著高于热带季节雨林(2.19 ±0.14)t·hm-2(独立样本t检验,P=0.012);橡胶林凋落物的最大持水量(12.50 t·hm-2)显著高于热带季节雨林(5.53 t·hm-2)(独立样本t检验,P=0.000);同时,橡胶林和热带季节雨林凋落物的有效最大持水量分别为10.63和4.71 t·hm-2,橡胶林具有显著更高的有效最大持水量(独立样本t检验,P=0.000)。因此,橡胶林凋落物无论在数量上还是持水能力上都优于热带季节雨林,橡胶林凋落物具有相对较好的生态持水效果。 相似文献