Bats limit insects in a neotropical agroforestry system

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.     

Colonization lessons from a tropical forest

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.     

热带森林植被冠层CO2储存项的估算方法研究

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...     

Species loss and aboveground carbon storage in a tropical forest

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.     

Tree dispersion, abundance, and diversity in a tropical dry forest

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.     

昆明城区大学校园与公园绿地植物组成研究

目的以种间关系原理为基础,探究河南鸡公山落叶阔叶林中藤本植物是否对林冠下其他物种的生存产生抑制或促进的效应,为理解林冠下的种间关系和共存机制提供指导。方法林冠下藤本及非藤本植物的Shannon-Wiener指数及密度采用样方法进行调查,土壤温湿度采用土壤温湿度监测仪测定。结果该地区落叶阔叶林林冠下总物种及非藤本植物Shannon-Wiener指数随着藤本植物密度的增加而显著下降,林冠下非藤本植物的Shannon-Wiener指数变异受到物种总密度、距离最近树的胸径和土壤温度的综合调节。林冠下非藤本植物的密度随着藤本植物密度的增加而下降,非藤本植物的密度受到物种总密度、土壤温度和距离最近树的胸径大小的影响。结论中国华中地区落叶阔叶林中的藤本植物对林冠下非藤本植物的Shannon-Wiener指数产生显著抑制效应,同时显著降低了个体的数量,这主要归因于藤本植物较强的扩散和生存能力及其对环境资源较强的占据能力,本研究对于提高森林生态系统中物种多样性及共存机制有重要参考价值。     

Reproductive dominance of pasture trees in a fragmented tropical forest mosaic

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.     

Restoration of degraded tropical forest landscapes

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.     

Tritium movement in soil of tropical rain forest

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.     

Genetic consequences of tropical second-growth forest regeneration

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.     

Coadapted competitors: the flowering seasons of hummingbird-pollinated plants in a tropical forest

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.     

海南热带雨林沟谷植物群落区系地理研究

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.     

Biomass of tropical forests: a new estimate based on forest volumes

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.     

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

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.     

西双版纳热带季节雨林与橡胶林凋落物的持水特性

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。