清江隔河岩坝区杉木-南酸枣林的群落学特征

杉木—南酸枣林是清江隔河岩坝区的一种典型次生林。野外调查结果表明 ,该群落的组成与结构比较复杂 ,群落的区系组成以落叶阔叶树种为主 ,显示出由中亚热带向北亚热带过渡性植被地段次生群落的特征。该群落的物种多样性在同地区的次生林类型中处于较高水平 ,表明群落以前受到过中度干扰 ,目前的恢复状况较好 ,群落的演替趋势是常绿阔叶落叶阔叶混交林     

清江隔河岩坝区杉木—南酸枣林的群落学特征

杉木－南酸枣林是清江隔河岩坝区的一种典型次生林。野外调查结果表明,该群落的组成与结构比较复杂,群落的区系组成凤落叶阔叶树种主主,显示出由中亚热带向北亚热带过渡性植被地段次生群落的特征。该群落的物种多样性在同地区的次生林类型中处于较高水平,表明群落以前受到过中度干扰。目前的恢复状况较好,群落的演替趋势是常绿阔叶落叶阔叶混交林。     

珠江三角洲四种森林类型土壤CO_2通量特征研究

采用开路式土壤CO2通量测量系统Li-8100＆Li-8150对珠江三角洲地区尾叶桉（Eucalyptus urophylla）人工林、乡土树种恢复林、针阔叶混交林和常绿阔叶林4种林型的土壤CO2通量进行了观测。结果表明：4种森林类型年均土壤CO2通量为尾叶桉人工林（3.35μmol.m-2.s-1）〉针阔叶混交林（2.66μmol.m-2.s-1）〉乡土树种恢复林（2.09μmol.m-2.s-1）〉常绿阔叶林（1.86μmol.m-2.s-1）;旱季土壤CO2通量明显小于雨季。前3种森林类型凋落物呼吸处理表明,旱季对照组土壤CO2通量均小于相应的去除凋落物组、雨季则相反,全年的对比结果显示,3种森林类型的凋落物呼吸贡献分别达到1.3%、7.1%和10.8%。土壤CO2通量与10 cm土壤温度呈显著指数相关,且土壤CO2通量温度敏感指数表现为针阔叶混交林Q10最大（3.49）,尾叶桉人工林Q10最小（1.95）。     

珠江三角洲四种森林类型土壤CO2通量特征研究

采用开路式土壤CO2通量测量系统Li-8100&Li-8150对珠江三角洲地区尾叶桉(Eucalyptus urophylla)人工林、乡土树种恢复林、针阔叶混交林和常绿阔叶林4种林型的土壤CO2通量进行了观测。结果表明:4种森林类型年均土壤CO2通量为尾叶桉人工林(3.35μmol.m-2.s-1)>针阔叶混交林(2.66μmol.m-2.s-1)>乡土树种恢复林(2.09μmol.m-2.s-1)>常绿阔叶林(1.86μmol.m-2.s-1);旱季土壤CO2通量明显小于雨季。前3种森林类型凋落物呼吸处理表明,旱季对照组土壤CO2通量均小于相应的去除凋落物组、雨季则相反,全年的对比结果显示,3种森林类型的凋落物呼吸贡献分别达到1.3%、7.1%和10.8%。土壤CO2通量与10 cm土壤温度呈显著指数相关,且土壤CO2通量温度敏感指数表现为针阔叶混交林Q10最大(3.49),尾叶桉人工林Q10最小(1.95)。     

几种不同更新的森林群落碳储量结构特征分析

森林更新是维持和扩大森林资源的主要途径,也是森林结构调整、森林可持续经营和构建多功能高效的森林生态系统的过程。在安徽南部的岭南林场,选择了马尾松（Pinus massoniana Lamb）人工林（MP）、杉木（Cunninghamia lanceolata）人工林（CF）、阔叶混交天然次生林（MB）和针阔混交人工次生林（MN）等4种具有典型代表性的森林群落类型,研究了不同更新方式形成的森林群落的碳储量结构特征。结果表明：（1）针阔混交次生林树干生物量密度最大,为（67.32±56.57）mg.hm-2,杉木人工林生物量密度最小,为（43.79±9.13）mg.hm-2,而马尾松树干生物量所占比例最大,为（64.04±1.49）%。阔叶混交次生林碳储量最高,为（126.47±90.75）mg.hm-2;（2）4种群落类型中,阔叶混交林与马尾松群落碳密度最大,分别为95.67和98.21mg.hm-2,杉木群落碳密度最小,为55.41 mg.hm-2。阔叶混交林中的灌木层生物量碳密度最大,为（17.438±24.627）mg hm-2,马尾松林的草本层和枯落层生物量碳密度最高,分别为（1.326±0.431）、（5.517±2.846）mg.hm-2;（3）阔叶混交林群落的地下碳储量最高,为（10.5±9.8）mg.hm-2,群落地下碳储量从大到小的顺序是阔叶混交林〉针阔混交林〉杉木林〉马尾松林。相应的群落地上碳储量从大到小的顺序是阔叶混交林〉针阔混交林〉马尾松林〉杉木林。杉木林根茎比（R/S）最大,为0.21±0.01,杉木林群落中的灌木层根茎比（R/S）最大,为1.61±0.11;（4）在阔叶混交林中,株数密度与乔木层、草本层的碳比例正相关。在杉木林群落中,平均胸径、株数密度与乔木层碳所占比例成负相关。除杉木林群落外,灌木层碳含量之比与胸径及密度等调查因子都呈负相关。     

漓江流域红壤区生态恢复过程中植被结构动态和生物量变化

利用时空替代原理,选取漓江流域红壤区退化生态系统恢复过程中具有代表性的草丛、灌丛、针叶林、针阔混交林、常绿阔叶林5个阶段作为演替序列,研究自然恢复过程中各演替阶段的植被结构动态和生物量变化。结果表明：随着草丛→灌丛→针叶林→针阔混交林→次生常绿阔叶林正向演替的进行,在未形成成熟而稳定的顶极群落之前,物种丰富度、物种多样性指数、植被生物量及生产力都呈增大趋势。退化群落通过自然恢复总是向着结构更复杂、更完善的方向发展。根据恢复过程中植被的动态变化规律,提出了一些人工促进植被恢复的建议．     

季风常绿阔叶林演替系列菌根资源及其与群落多样性的关系

随着森林生态系统的正向演替,植物物种多样性、群落结构、生产力以及土壤条件均会发生显著的变化,这些变化对菌根类型和多样性会产生不同程度的影响。为了探讨群落结构和功能的变化对菌根资源可能产生的影响,选择季风常绿阔叶林及其演替系列上的代表性森林生态系统为对象,对菌根化根系、菌根类型和菌根真菌孢子密度进行调查,并结合已有的群落信息和土壤养分状况,分析在森林演替过程中菌根资源的变化情况和可能的影响因素。结果表明:季风常绿阔叶林各演替阶段的森林生态系统中菌根化比例接近70%,但不同演替阶段森林的优势菌根类型存在明显的差异。处于演替初期的马尾松(Pinus massoniana)林以丛枝菌根为主,占菌根总数的78%;演替中期的针阔叶混交林中的外生菌根占有绝对优势,占75%,是丛枝菌根的3倍;演替顶级的季风常绿阔叶林中的外生菌根和丛枝菌根的比例相当。马尾松林的菌根真菌孢子密度最高,每20 g风干土壤中的孢子数量高达2 925个,是针阔叶混交林的2.5倍,季风常绿阔叶林的2倍。演替系列上的森林生态系统的菌根类型的差异与植物物种多样性和群落结构,尤其是林下的灌木、草本层密度存在一定的相关性,同时也受土壤养分状况的影响。马尾松林具有较丰富的草本植物和较高的草本层密度,并且该森林的土壤相对贫瘠,这些条件都有利于丛枝菌根真菌侵染草本植物的根系形成丛枝菌根并产生大量孢子。针阔叶混交林中外生菌根的优势主要受该森林中外生菌根植物在群落组成上的绝对优势影响。季风常绿阔叶林的物种丰富,群落结构复杂,因此该森林呈现了两种类型菌根优势相当的现象。该文的结果表明,随着季风常绿阔叶林演替的进行,菌根资源在类型上会出现较大的分异,而这种变化受植物物种数量、群落结构的影响,与土壤养分状况存在一定的关系,并且不同演替阶段森林生态系统影响菌根组成的因素存在差异。     

株洲市城郊天然植物群落调查研究

植物群落是植物在自然因素综合作用下形成的一个有机体，是植物群体发展的自然属性．在不同的生态环境条件下产生了不同的群落类型．地处中亚热带丘陵地的株洲，地带性典型植物群落是常绿阔叶林，是以各类常绿树种为优势的植被类型．但是随着历史变迁，人类频繁活动，此类群落已不复存在，以人工群落和次生群落取而代之，其主要群落类型有青冈栎群落、石栎群落、苦槠、青冈栎群落、樟树群落、冬青群落、山杜英群落等12种．园林绿化作为人工群落，其园林植物选择和配置，设计建造人工群落都要遵循天然群落发生、发展规律及模拟其结构特征才能实现园林绿化低成本、高效益、高生产力、高生物量的总体目标．因此，开展对城郊区现有天然林的调查是非常必要的．其结果直接用于城市绿地系统规划和人工模拟地带性植物造景．     

泥石流频发区山地土壤环境因子与植被群落垂直梯度及其关系分析——以云南小江流域为例

海拔梯度和土壤环境是影响山地植被群落结构的关键因素,为揭示泥石流频发区植被群落的空间分布与演替规律,通过SPSS主成分分析、皮尔逊相关性分析和CANOCO5.0二维排序研究云南小江流域泥石流频发区山地生态系统土壤环境因子和植被群落的垂直梯度分异及其相互关系.结果表明:在海拔梯度上,土壤的垂直地带性分异规律与纬度地带性分异规律类似,从高到低依次为温带地带性土壤、北亚热带地带性土壤和亚热带地带性土壤;草本植被大致可以划分为鹅绒委陵菜(Potentilla anserina)–扭黄茅(Heteropogon contortus)群落、醡浆草(Oxalis corniculata)–牛尾蒿(Artemisia dubia)群落和苞茅(Hyparrhenia bracteata)群落3类;因该区地质灾害及人为干扰严重,生态环境恶化,原生乔木群落已极少分布,现以华山松、云南松人工林为高山主要植被类型,松柏混交林为亚高山主要植被类型,桉树、新银合欢人工林为低山主要植被类型.从典范对应分析(CCA)排序结果来看,不同植被群落与土壤环境因子之间的关系存在明显分异.综上,海拔梯度、土壤有机质、土壤全磷和重金属(铜、锰)含量是影响泥石流频发区植被群落格局的主要因素.图2表7参35     

不同演替阶段中黧蒴栲种群的大小结构与分布格局

在中亚热带常绿阔叶林,有代表性地选择三个黧蒴栲群落类型,即黧蒴栲纯林（常绿阔叶林皆伐地自然演替而成的黧蒴栲纯林,用生长锥对优势木进行随机抽查得其最大年龄为１３ａ）、以黧蒴栲为优势种的混交林（经优势木随机抽测其最大年龄为２４ａ）和黧蒴栲已不成为优势种的混交林（实为天然次生林,优势木随机抽测最大年龄为５３ａ）。测定分析结果表明,黧蒴栲群落在自然演替的前期即幼林阶段的种群大小级结构呈典型的三角状增长型;     

Response of a Group of Sichuan Snub-Nosed Monkeys to Commercial Logging in the Qinling Mountains, China

Abstract:  Habitat destruction is one of the greatest threats to primates worldwide. To understand the impact of forest logging on the habitat use of primates in temperate mixed forest, we compared the range, habitat used, population size, and diet of a troop (ERT) of Sichuan snub-nosed monkeys ( Rhinopithecus roxellana ) in the Qinling Mountains before (1989), during (1997), and after (2002–2003) commercial logging. Logging significantly changed the composition of the forest and the food supply for the troop. Some areas were heavily logged and formed patches in the forest that lacked canopy cover. The troop moved 7 km away from their original range when logging took place and returned to their original range after logging stopped, but they avoided heavily logged areas that lacked canopy cover. Their movement indicated some degree of site fidelity in this species. Diet and home range changed after logging, but the population size remained stable, which suggests that this species has some ability to adapt to habitat changes. Our results may reflect a natural flexibility in primates to adapt to the changing food resources in temperate areas with marked seasonal variations in food availability and distribution. This flexibility may have contributed to their higher degree of resilience to habitat alterations caused by human activities compared with tropical forest primates that have a more specialized diet. Our findings provide important baseline information that will help decision makers in their efforts to conserve primates, especially in temperate regions, and to sustainably manage primate habitat.     

Thermal ecology of the neotropical army ant Eciton burchellii.

I explored the thermal ecology of Eciton burchellii, a New World army ant, in primary forest and forest fragments in the Atlantic lowlands of Costa Rica in 2002 and 2003. My primary objective was to determine whether high surface temperatures in pastures surrounding forest fragments posed a thermal barrier to ant colonies within those fragments; secondarily, I assessed whether thermal gradients within continuous moist forest were sufficient to elicit avoidance reactions from foraging colonies. E. burchellii colonies in forest fragments avoided entering open pasture in full sun (51.3 degrees C) on 100% of all edge interactions; however, edges were readily crossed where artificial shaded areas had previously been installed. Ant raids in primary forest avoided artificially established temperatures >43 degrees C but tolerated 45.5 degrees C in the presence of prey baits. Captive ants held at 43 degrees C survived 18.5 min; at temperatures of 51.3 degrees C survival time was only 2.8 min. Ants running on established foraging trails increased running velocity by 18% when substrate temperature was raised from 28.4 degrees to 38.0 degrees C, and they abandoned trails at temperatures >43 degrees C. The standard deviation (s) of temperatures on active raid trails in continuous forest was 2.13 degrees C, while nearby systematic sampling revealed a greater background standard deviation of 4.13 degrees C. E. burchellii colonies in this region appear to be living surprisingly near their upper limits of thermal tolerance. The heat of open pastures alone is sufficient to prevent their exiting forest fragments, or entering similarly hot areas within continuous forest. Shaded vegetative corridors are sufficient to permit mobility between isolated fragments, and their preservation should be encouraged. Despite views that tropical lowland moist forests have an essentially homogenous microclimate, army ants appear to avoid local hot spots on the forest floor, steering daily foraging trails to follow cooler routes than would be expected by chance. As deforestation remakes tropical landscapes worldwide, it is important to consider the thermal consequences of these actions and their effect on keystone organisms such as army ants. Changes in global climate patterns are likely to affect even evergreen tropical systems whose organisms may be sensitive to finer microclimatic variation than previously suspected.     

Effects of Local Disturbance of Tropical Forests on Frugivores and Seed Removal of a Small-Seeded Afrotropical Tree

Abstract:  Small-scale, local disturbance of tropical forests, for example from selective logging, is widespread, but its effects on biodiversity and ecosystem function have rarely been studied. In 3 East African tropical rainforests, we investigated the effect of different levels of local forest disturbance on the frugivore community and on tree visitation and fruit removal rates of the small-seeded tree Celtis durandii. We quantified birds and primates in little and heavily disturbed sites, distinguishing between forest specialists, forest generalists, and forest visitors. We quantified frugivorous tree visitors and seed removal rates of C. durandii trees in the same sites. Forest disturbance reduced the species richness and density of the frugivore community and of forest specialists. Frugivorous species and individuals visiting the study trees were reduced significantly, which led to a marginally significant decline in fruit removal by all frugivores and a significant reduction in removal by forest specialists. Reduction in fruit removal by forest specialists was not compensated for by increases in removal by forest generalists or visitors. Results did not differ among the 3 rainforests, which suggests they were consistent at a regional scale. So local forest disturbance led to a loss of frugivores and their seed removal services. This suggests that large-seeded tree species and trees with small fruits are losing seed dispersers. Thus, local forest disturbance appears to have a more general negative impact on frugivores and their seed dispersal services than anticipated previously.     

Shrinking Tropical Forests, Human Agents of Change, and Conservation Policy

Abstract:  Human agents of landscape transformation in the tropics affect forests differently as the forests decline in size. Five agents of change—road builders, corporate concession holders, community forest managers, park advocates, and urban consumers—have different effects on large forests in remote tropical regions than they do on remnant forests in settled agricultural regions. Because forests vary so much in size across tropical regions, these differences in the effects of agents on forests have important implications for regional conservation efforts. To make these implications explicit, I compared the effects of the five agents in regions with large forests with their effects in regions with small forests. The comparisons indicated that, as forests declined in size, new roads no longer destroyed forests, corporate loggers left the forests, community forest managers became more effective, parks became less feasible as a means of conservation, and urban consumers initiated tree planting. My results suggest that awareness about the changing effects of humans on landscapes with shrinking forests can serve as a useful tool in formulating regionally appropriate policies for conserving tropical forests.     

Environmental stability and seasonality of a harpacticoid copepod community

The southwest monsoon on the west coast of India brings about dynamic changes in estuaries and coastal waters. The response of the meiofauna to monsoonal rain is obvious, but the impact of such environmental changes on the community structure of harpacticoid copepod species and their seasonality in the estuaries influenced by the tropical monsoon is poorly understood. In this study the spatial and temporal variability in abundance and community structure of meiobenthic copepods was investigated over an annual cycle (June 1983 to June 1984), in an estuary influenced by the tropical monsoon. Total meiofaunal abundance showed wide variations in space and time. Minimum and maximum densities were observed in the monsoon and pre-monsoon seasons, respectively. Quick recovery of harpacticoid populations in the early post-monsoon season indicated their recuperative power under adverse conditions. Of the 25 species recorded from lower, middle and upper reaches, eight comprised over 70% of the total copepod population. The peak and low occurrence of dominant species displayed striking correlations with the summer and rainy seasons, respectively. While other species were restricted in distribution, Stenhelia longifurca was recorded from all salinity regimes. The harpacticoid community was greatly influenced by the onset of the monsoon period, and their spatial and temporal variabilities were related with physico-chemical parameters and the variability of these parameters in the estuary.     

Effects of Pioneer Tree Species Hyperabundance on Forest Fragments in Northeastern Brazil

Abstract: Despite many studies on fragmentation of tropical forests, the extent to which plant and animal communities are altered in small, isolated forest fragments remains obscure if not controversial. We examined the hypothesis that fragmentation alters the relative abundance of tree species with different vegetative and reproductive traits. In a fragmented landscape (670 km²) of the Atlantic Forest of northeastern Brazil, we categorized 4056 trees of 182 species by leafing pattern, reproductive phenology, and morphology of seeds and fruit. We calculated relative abundance of traits in 50 1‐ha plots in three types of forest configurations: forest edges, small forest fragments (3.4–83.6 ha), and interior of the largest forest fragment (3500 ha, old growth). Although evergreen species were the most abundant across all configurations, forest edges and small fragments had more deciduous and semideciduous species than interior forest. Edges lacked supra‐annual flowering and fruiting species and had more species and stems with drupes and small seeds than small forest fragments and forest interior areas. In an ordination of species similarity and life‐history traits, the three types of configurations formed clearly segregated clusters. Furthermore, the differences in the taxonomic and functional (i.e., trait‐based) composition of tree assemblages we documented were driven primarily by the higher abundance of pioneer species in the forest edge and small forest fragments. Our work provides strong evidence that long‐term transitions in phenology and seed and fruit morphology of tree functional groups are occurring in fragmented tropical forests. Our results also suggest that edge‐induced shifts in tree assemblages of tropical forests can be larger than previously documented.     

降水变化、氮添加对鼎湖山主要森林土壤有机碳矿化和土壤微生物碳的影响

全球变化对土壤有机碳(SOC)存贮与分解的影响在全球碳(C)循环中具有重要地位.分别通过室内土壤培养法和氯仿熏蒸法,研究了降水变化和氮(N)添加处理对鼎湖山3种不同演替阶段的季风常绿阔叶林、针阔混交林和马尾松针叶林SOC矿化和土壤微生物量碳(SMBC)的影响.结果表明:1)降水量增加能够提高森林演替晚期SOC累积矿化量和矿化速率,而对森林演替早期SOC累积矿化量和矿化速率没有显著影响(P>0.05).2)干旱条件(降水量减少)降低森林SMBC含量,且在鼎湖山季风林表层土壤(0～10 cm)中SMBC的减少达到显著水平(P<0.05).3)N添加处理对鼎湖山3种森林类型SOC累积矿化量、矿化速率以及SMBC都没有显著影响(P>0.05).未来关于SOC矿化对全球变化响应的研究,要综合考虑土壤有机质质量、C/N比例、外源性氮输入等因素的作用.图4表2参37     

The Value of Primary, Secondary, and Plantation Forests for a Neotropical Herpetofauna

Abstract:  Plantation forests and second-growth forests are becoming dominant components of many tropical forest landscapes. Yet there is little information available concerning the consequences of different forestry options for biodiversity conservation in the tropics. We sampled the leaf-litter herpetofauna of primary, secondary, and Eucalyptus plantation forests in the Jari River area of northeastern Brazilian Amazonia. We used four complementary sampling techniques, combined samples from 2 consecutive years, and collected 1739 leaf-litter amphibians (23 species) and 1937 lizards (30 species). We analyzed the data for differences among forest types regarding patterns of alpha and beta diversity, species-abundance distributions, and community structure. Primary rainforest harbored significantly more species, but supported a similar abundance of amphibians and lizards compared with adjacent areas of second-growth forest or plantations. Plantation forests were dominated by wide-ranging habitat generalists. Secondary forest faunas contained a number of species characteristic of primary forest habitat. Amphibian communities in secondary forests and Eucalyptus plantations formed a nested subset of primary forest species, whereas the species composition of the lizard community in plantations was distinct, and was dominated by open-area species. Although plantation forests are relatively impoverished, naturally regenerating forests can help mitigate some negative effects of deforestation for herpetofauna. Nevertheless, secondary forest does not provide a substitute for primary forest, and in the absence of further evidence from older successional stands, we caution against the optimistic claim that natural forest regeneration in abandoned lands will provide refuge for the many species that are currently threatened by deforestation .     

Changing Drivers of Deforestation and New Opportunities for Conservation

Abstract: Over the past 50 years, human agents of deforestation have changed in ways that have potentially important implications for conservation efforts. We characterized these changes through a meta‐analysis of case studies of land‐cover change in the tropics. From the 1960s to the 1980s, small‐scale farmers, with state assistance, deforested large areas of tropical forest in Southeast Asia and Latin America. As globalization and urbanization increased during the 1980s, the agents of deforestation changed in two important parts of the tropical biome, the lowland rainforests in Brazil and Indonesia. Well‐capitalized ranchers, farmers, and loggers producing for consumers in distant markets became more prominent in these places and this globalization weakened the historically strong relationship between local population growth and forest cover. At the same time, forests have begun to regrow in some tropical uplands. These changing circumstances, we believe, suggest two new and differing strategies for biodiversity conservation in the tropics, one focused on conserving uplands and the other on promoting environmental stewardship in lowlands and other areas conducive to industrial agriculture.     

Synergistic Interactions between Habitat Fragmentation and Fire in Evergreen Tropical Forests

Abstract: The growing prevalence of fragmentation and fire in tropical forests makes it imperative to quantify changes in these disturbances and to understand the ways in which they interact across the landscape. I used a multitemporal series of Landsat images to study the incidence and coincidence of fire and fragmentation in two areas of Pará state in the eastern Brazilian Amazon: Tailândia and Paragominase. In both areas, deforestation and forest fires were quantified for time series of 6–10 years. The Tailândia study area typifies a landscape with the herringbone pattern of government-settled colonists, and the Paragominas area is dominated by large cattle ranches. In both areas, over 90% of the forests affected by fire were associated with forest edges. Although most burned forest occurred within 500 m of forest edges, some fires occurred in deep forest, several kilometers from any edge. The obvious synergism between forest fragmentation and fire poses serious risks to tropical ecosystems and has important implications for land management.