Trophic plasticity,environmental gradients and food‐web structure of tropical pond communities

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南宁老虎岭林区多种外来植物入侵程度与影响因子模型解释

了解森林环境中多种外来植物对多种环境因子的互作效应,可以更有针对性地应对外来入侵威胁。在南宁老虎岭林区分6个区进行样方调查,以样方所有外来植物的相对百分比作为外来植物入侵程度,利用以分区为随机截距的混合效应模型和一般线性模型来分析有关因素对入侵的影响,用R-effects包的互作效应图形化和数据提取来解释互作效应的复杂变化。多因素混合效应模型分析表明,路边对入侵的主效应为正且极显著(P=0.000),林冠郁蔽度和优势最大株高对入侵的主效应为负(P=0.000),土著物种丰富度对入侵的主效应不显著,但土著物种丰富度与路边的互作对入侵的效应极显著(P=0.007);路边的土著物种丰富度明显提升入侵抵抗性,但林内的土著物种丰富度只能微弱增加入侵抵抗性;林冠郁蔽度和优势最大株高的互作对入侵的效应极显著(P=0.004),但两个因素对入侵的限制作用非可加。一般线性模型分析表明,林龄和抚育时间对外来植物入侵的影响趋势不明显;未发现引进树种造林与乡土树种造林的林下外来植物入侵程度有差异;相对于林道的样方位置高低影响入侵程度,林道下方的样方较易被入侵。在监测或防控林业外来植物时,重点应放在低于林道的森林。     

Arthropod Abundance,Canopy Structure,and Microclimate in a Bornean Lowland Tropical Rain Forest1

This study applies a novel, vertically stratified fogging protocol to document arthropod abundance, density, and biomass across a vertical gradient in a primary, lowland dipterocarp forest canopy in Borneo. We fogged arthropods at 5 m vertical intervals and 20 m horizontal intervals along six full‐canopy transects and measured leaf surface areas along the same transects. The results show that arthropod biomass in the aboveground regions was 23.6 kg/ha, the abundance was 23.9 million individuals/ha, and the density on leaf surfaces was 280 individuals/m² leaf area. All three numbers are five to ten times higher than estimated by previous surveys of tropical lowland rain forest canopies using mass‐collection techniques. Arthropod abundance and biomass were analyzed in relation to canopy structure, composition, vapor pressure deficit (VPD), photosynthetic photon flux density (PPFD), and height. Using stepwise regression we found that 13 of 14 arthropod groups had significant positive relationships with one‐sided leaf area, 11 had significant negative relationships with VPD, 3 had significant relationships with height, and none showed positive relationships with light. Classifying the 14 taxa based on their responses to leaf area and VPD created three groups that corresponded roughly to the biology of these taxa. This study suggests that the biomass and abundance, and perhaps therefore—by extrapolation—the biodiversity, of tropical canopy arthropods may be very much higher than previously estimated.     

Estimating Canopy Structure in an Amazon Forest from Laser Range Finder and IKONOS Satellite Observations1

Canopy structural data can be used for biomass estimation and studies of carbon cycling, disturbance, energy balance, and hydrological processes in tropical forest ecosystems. Scarce information on canopy dimensions reflects the difficulties associated with measuring crown height, width, depth, and area in tall, humid tropical forests. New field and spaceborne observations provide an opportunity to acquire these measurements, but the accuracy and reliability of the methods are unknown. We used a handheld laser range finder to estimate tree crown height, diameter, and depth in a lowland tropical forest in the eastern Amazon, Brazil, for a sampling of 300 trees stratified by diameter at breast height (DBH). We found significant relationships between DBH and both tree height and crown diameter derived from the laser measurements. We also quantified changes in crown shape between tree height classes, finding a significant but weak positive trend between crown depth and width. We then compared the field‐based measurements of crown diameter and area to estimates derived manually from panchromatic 0.8 m spatial resolution IKONOS satellite imagery. Median crown diameter derived from satellite observations was 78 percent greater than that derived from field‐based laser measurements. The statistical distribution of crown diameters from IKONOS was biased toward larger trees, probably due to merging of smaller tree crowns, underestimation of understory trees, and overestimation of individual crown dimensions. The median crown area derived from IKONOS was 65 percent higher than the value modeled from field‐based measurements. We conclude that manual interpretation of IKONOS satellite data did not accurately estimate distributions of tree crown dimensions in a tall tropical forest of eastern Amazonia. Other methods will be needed to more accurately estimate crown dimensions from high spatial resolution satellite imagery.     

森林覆被率等因子与PM2.5的时间滞后效应的研究

利用黑龙江省13个市（区）的170 820个数据，运用2SLS方法以森林覆被率等11个影响因素为指标，建立了3个不同时间段的静态面板和动态面板回归模型，探究了森林覆被率等影响因素与PM_2.5时间滞后效应的关系。结果表明：①PM_2.5的时间滞后效应是当期PM_2.5浓度积累的影响因素，且随着时间的推移，PM_2.5时间滞后效应对当期PM_2.5浓度积累的促进作用逐渐减弱；②随着PM_2.5时间滞后效应的逐渐减弱，森林覆被率、气温对PM_2.5浓度积累所起的阻碍作用逐渐增强，PM₁₀、CO对PM_2.5浓度积累的促进作用逐渐增强，而风速对当期PM_2.5浓度积累所起的阻碍作用逐渐减弱；③PM_2.5时间滞后效应呈现出惯性的同时，森林覆被率、PM₁₀、CO、气温、风速对PM_2.5的作用也具有了惯性。     

国内外森林与水质研究综述

近几十年来,随着大面积的森林被不合理的采伐利用,使生态环境遭受巨大破坏。同时,近些年来,受全球气候异常的影响,水、旱灾频繁,水土流失严重,且由于环境污染,造成水质不断恶化,水质型缺水日益严重。为保护水资源,森林与水环境,森林与水质已成为近十年来森林水文学研究的重点和热点。国内外的一些专家、学者经过多年来的观测和研究,已取得很多成果。1　关于森林和水质的研究现状大约从本世纪50年代,我国开始关注森林对水质的影响[1]。不过国内绝大多数的研究是着重于森林对河流悬移泥沙含量的影响。直到七十八十年代,我国的一些科研院所,如…     

Forest Structure and Biomass of a Tropical Seasonal Rain Forest in Xishuangbanna,Southwest China1

Xishuangbanna is a region located at the northern edge of tropical Asia. Biomass estimates of its tropical rain forest have not been published in English literature. We estimated forest biomass and its allocation patterns in five 0.185–1.0 ha plots in tropical seasonal rain forests of Xishuangbanna. Forest biomass ranged from 362.1 to 692.6 Mg/ha. Biomass of trees with diameter at 1.3 m breast height (DBH) ≥ 5 cm accounted for 98.2 percent of the rain forest biomass, followed by shrubs (0.9%), woody lianas (0.8%), and herbs (0.2%). Biomass allocation to different tree components was 68.4–70.0 percent to stems, 19.8–21.8 percent to roots, 7.4–10.6 percent to branches, and 0.7–1.3 percent to leaves. Biomass allocation to the tree sublayers was 55.3–62.2 percent to the A layer (upper layer), 30.6–37.1 percent to the B layer (middle), and 2.7–7.6 percent to the C layer (lower). Biomass of Pometia tomentosa, a dominant species, accounted for 19.7–21.1 percent of the total tree biomass. The average density of large trees (DBH ≥100 cm) was 9.4 stems/ha on two small plots and 3.5 stems/ha on two large plots, illustrating the potential to overestimate biomass on a landscape scale if only small plots are sampled. Biomass estimations are similar to typical tropical rain forests in Southeast Asia and the Neotropics.     

滹沱河湿地石家庄段水鸟群落结构及多样性

2003年3月～2006年4月,对滹沱河湿地石家庄段水鸟进行了调查。共记录水鸟80种,隶属于7目16科。其中候鸟73种(夏候鸟、冬候鸟和旅鸟),留鸟7种;古北种62种,东洋种11种,广布种7种;国家Ⅰ、Ⅱ级重点保护鸟类11种。鸻形目和雁形目鸟类占优势,各占水鸟种数的35.00%和30.00%。水鸟种类和数量高峰出现在4月和11月,低谷在1月和2月。多样性分析表明,冶河-黄壁庄水库和滹沱河-岗南水库Shannon-Weiner指数和G-F指数均高于石板水库,这与湿地面积和生境的多样性有关。滹沱河湿地石家庄段作为许多水鸟,尤其是黑鹳的重要栖息地,需进一步加强监测和保护。     

Regional Fragmentation of Rain Forest in West Africa and Its Effect on Local Dung Beetle Assemblage Structure

Data from Ghana and Côte d'Ivoire, for local dung beetle assemblages of rain forest, plantations, and savanna, suggest that a subset of the savanna fauna has expanded its range across the Eastern Guinean Forest ecoregion, presumably in response to its conversion from continuous rain forest into an archipelago of forest fragments within a disturbance matrix of less shady plantation and farmland vegetation that more resembles moist savanna.     

Effects of Logging and Oil Palm Expansion on Stream Frog Communities on Borneo,Southeast Asia

The conversion of tropical rain forests to oil palm plantations is a major threat to Southeast Asia's rich biodiversity. Fostering forest species communities in secondary forests, agroforestry systems, and plantations is therefore increasingly becoming a conservation focus. This study uses standardized transect‐based sampling to compare species richness, density and community composition of stream anuran assemblages among primary forests, repeatedly logged forests and oil palm plantations in northern Borneo. In primary forest streams, we recorded an average of 19 frog species, compared to 15 species in logged forests and 11 species in oil palm plantation streams. However, the high percentage of canopy cover above the plantation streams mitigated this loss to some extent. This study corroborates numerous studies that oil palm plantations have mainly negative effects on the region's biodiversity. However, our results also demonstrate the high conservation value of logged forests for Bornean stream‐dependent anurans. We conclude that palm plantations have a largely unused potential to promote regional anuran biodiversity.     

Germination and Establishment of Tillandsia eizii (Bromeliaceae) in the Canopy of an Oak Forest in Chiapas, Mexico

We assessed the effectiveness of repopulating the inner canopy and middle canopy of oak trees with seeds and seedlings of the epiphytic bromeliad Tillandsia eizii. Canopy germination was 4.7 percent, considerably lower than in vitro (92%). Of the tree-germinated seedlings, only 1.5 percent survived 6 mo. In contrast, 9.3 percent of transplanted laboratory seedlings survived 15 mo. To repopulate trees, we recommend transplanting laboratory-grown seedlings, as large as practically possible, to branches in the middle canopy.     

Influence of Forest Type and Tree Species on Canopy‐Dwelling Beetles in Budongo Forest,Uganda1

Beetles were collected on 64 trees of four species (Cynometra alexandri C. H. Wright, Rinorea beniemis (Welwitsch ex Olivier) Kuntze, Teclea nobilis Delile, and Trichilia rubescens Olivier) in Budongo Forest, Uganda, using an insecticidal fogging technique. Selected tree species were abundant, taxonomically not closely related, and different in the shape of leaves, growth form, and size, with heights between 7 and 35 m. Trees were fogged in an old primary forest stand, in an area of secondary forest where selective logging was performed, and in a swamp forest. Eight conspecific trees per forest type were fogged. A total of 29,736 beetles were collected from all trees that could be assigned to 1433 (morpho)‐species; 41.6 percent were singletons and 89.6 percent of species were found with less than ten individuals. Abundant beetle taxa included Latridiidae (N= 4093), Chrysomelidae (3952), Staphylinidae (2931), Apioninae (2621), and Curculionidae (2457). Most species‐rich groups were Staphylinidae (N= 196 spp.), Curculionidae (189), and Chrysomelidae (148). Abundance increased in the order: primary < secondary < swamp forest. Due to the relatively high dominance of some species in the secondary forest, species richness increased in the order: secondary < primary < swamp forest. Beta diversity measures and factor analysis showed distinct differences among forest types but higher similarity of beetle communities on different tree species within one forest type. The taxonomic distribution of beetles in the secondary forest was more heterogeneous than in the primary forest. Analyses of the data revealed low host specificity even for phytophagous beetles, underlining the importance of habitat structure and chance effects on the spatial distribution of beetles in the canopy of Budongo Forest.     

Herpetofaunal Richness and Community Structure of Offshore Islands of Sulawesi,Indonesia1

We examined the distribution and broad habitat associations of the herpetofauna on three offshore islands of southeast Sulawesi, Indonesia. A total of 74 amphibian and reptile taxa were recorded, comprising 13 frogs, 29 lizards, 29 snakes, 1 freshwater turtle, and 1 crocodile. Of the total taxa, 38 percent were endemic to Sulawesi, 13 were new undescribed taxa. Range extensions were also recorded for one taxon previously not known from Sulawesi. Herpetofauna of these islands is largely derived from that of mainland Sulawesi, and as for Sulawesi generally, is depauperate compared with herpetofaunal assemblages in Borneo, Java, and Thailand. Taxon richness was much higher in minimally disturbed forest and forest habitats with only moderate disturbance levels than in highly modified or disturbed habitats, such as secondary forests, plantations, and villages. Disturbed habitats were characterized by widespread, habitat generalists and human commensals. Forests were characterized by endemic and habitat‐specialist taxa. Little discrimination of taxon composition or endemism was found between minimally and moderately disturbed forest habitats. These results reaffirm the need for more general biological survey and research in this region. Taxa most likely to be displaced by human impacts tend to be endemic taxa, for which there exists little or no ecological information. The similarity in the herpetofaunal community structure between habitats with minimal and moderate disturbance levels has important implications for our understanding of ecological resilience in tropical herpetofaunal communities.     

Post-Frontier Forest Change Adjacent to Braulio Carrillo National Park, Costa Rica

Effective biodiversity conservation in national parks depends to a large extent on adjacent forest cover. While deforestation and forest fragmentation as a result of colonization and agriculture have been widespread in neotropical countries over the past few decades, in some places agricultural intensification, wage labor, and rural to urban migration are becoming the most important emerging trends. Changes like this have resulted in forest recovery in other places, mostly in temperate zones, but there have been few studies of this phenomenon in the tropics. This paper presents a case study from a national park buffer zone in Costa Rica. An expansion of Braulio Carrillo National Park (BCNP) in 1986 forced the closing of a frontier that had been characterized by spontaneous colonization and widespread forest-to-pasture conversion. After that time, the Sarapiquí region surrounding the northern sector of BCNP underwent a dramatic social and economic transformation. Population more than doubled, new roads created easy access to a coastal port and the capital city (San José), industrial agriculture and ecotourism enterprises expanded, and population and urbanization along major highways increased. In spite of government reforestation and forest protection programs and changes in rural people's attitudes favoring forest conservation, we find that there has been only slight detectable forest recovery in satellite imagery and that forest fragmentation continued, even in remote rural areas near BCNP with stable or shrinking population. We attribute this to the consolidation of landholdings into large cattle ranches and smaller hobby ranches, driven by an inflow of capital from urban areas and developed countries. This pattern has important implications for the management of this and other national park buffer zones. We suggest that strategies focused only on sustainable land use inside buffer zones are unlikely to succeed when carried out in a context of certain macro-level changes. Conservation of endangered biological resources will only be possible if we broaden our thinking about national parks and adjacent lands in the tropics to address new land ownership and use patterns that are occurring as a result of globalization, urbanization, and expanding wage labor employment.

Conifer Cover Increase in the Greater Yellowstone Ecosystem: Frequency,Rates, and Spatial Variation

Extensive fires in recent decades in the Greater Yellowstone Ecosystem (GYE) garnered much attention for causing a significant decrease in the extent of conifer forest cover. Meanwhile, conifer forests in unburned parts of the GYE have continued to increase in extent and density. Conifer cover increase has been well documented by repeat historical photography, but the average rate of increase and the spatial variation remain unquantified. We examined changes in conifer cover across biophysical gradients in the GYE based on stratified random samples from aerial photographs. The percent conifer cover for samples in 1971 and 1999 was quantified to determine the frequency and rate of conifer cover change. A slight majority of samples (56%) showed no change, whereas increases (22%) were balanced by decreases (22%). However, among samples that were not recently burned or logged, or already closed-canopy, nearly 40% increased in conifer cover, at an average annual rate of 0.22%. We quantified significant variability in the frequency and rate of conifer cover increase across gradients of elevation, aspect, vegetation type, and proximity to nearby conifer forest. The most dynamic locations were low density conifer woodlands on northerly aspects at lower elevations, with average annual rates of increase up to 0.51%. This study is significant because it demonstrates that rates of conifer cover increase vary across biophysical gradients, an important consideration for management of dynamic forest ecosystems. Improved understanding of this variability helps us to better understand what factors ultimately cause conifer cover increase. It is also a critical step towards accurate quantification of the magnitude of carbon uptake by conifer cover increase.     

Climatic,ecological, and socioeconomic factors associated with West Nile virus incidence in Atlanta,Georgia, U.S.A.

The integrated effects of the many risk factors associated with West Nile virus (WNV) incidence are complex and not well understood. We studied an array of risk factors in and around Atlanta, GA, that have been shown to be linked with WNV in other locations. This array was comprehensive and included climate and meteorological metrics, vegetation characteristics, land use / land cover analyses, and socioeconomic factors. Data on mosquito abundance and WNV mosquito infection rates were obtained for 58 sites and covered 2009–2011, a period following the combined storm water – sewer overflow remediation in that city. Risk factors were compared to mosquito abundance and the WNV vector index (VI) using regression analyses individually and in combination. Lagged climate variables, including soil moisture and temperature, were significantly correlated (positively) with vector index as were forest patch size and percent pine composition of patches (both negatively). Socioeconomic factors that were most highly correlated (positively) with the VI included the proportion of low income households and homes built before 1960 and housing density. The model selected through stepwise regression that related risk factors to the VI included (in the order of decreasing influence) proportion of houses built before 1960, percent of pine in patches, and proportion of low income households.     

Activity of a Methanotrophic Consortium Isolated from Landfill Cover Soil: Response to Temperature,pH, CO2, and Porous Adsorbent

A robust, naturally evolving methanotrophic community in landfill cover soil (LFCS) can be the simplest way to mitigate landfill methane emission. In this study, bacterial community composition in LFCS and methane oxidation potential of enriched methanotrophic consortium, in comparison to that of axenic Methylosinus sporium, was investigated. Growth and methane oxidation of the consortium was studied in liquid phase batch experiments under varying temperature (20–40°C), pH (5–10), headspace CO2, and in presence of porous adsorbent (1.3 cm³ sponge cubes). The 16S rRNA gene analysis revealed presence of both type-I and type-II methanotrophs along with few obligate methylotroph in LFCS. Though the optimal growth condition of the consortium was at 30°C and pH 7, it was more resilient in comparison to M. sporium. With increasing availability of porous adsorbent, methane consumption by the consortium was significantly improved (p < 0.001) reaching a maximum specific methane oxidation rate of 11.4 μmol mg^?1 biomass h^?1. Thus, inducing naturally thriving methanotrophs in LFCS is a better alternative to axenic methanotrophic culture in methane emission management.     

Upland Forest Linkages to Seasonal Wetlands: Litter Flux, Processing, and Food Quality

The flux of materials across ecosystem boundaries has significant effects on recipient systems. Because of edge effects, seasonal wetlands in upland forest are good systems to explore these linkages. The purpose of this study was to examine flux of coarse particulate organic matter as litter fall into seasonal wetlands in Minnesota, and the relationship of this flux to development of mosquitoes (Aedes aegypti). We hypothesized that litter flux into seasonal wetlands was dominated by upland plant litter that was lower quality and slower to breakdown than wetland litter, and that development rate of mosquitoes reared on upland litter was less than those reared on wetland litter. Of total litter fall into the wetlands, 71% originated in upland forest. Carbon to nitrogen ratios differed between upland litter (mostly sugar maple (Acer saccharum) and trembling aspen (Populus tremuloides) leaves) and wetland litter (mostly black ash (Fraxinus nirgra) leaves), averaging 63.9 and 47.7, respectively over two years. Breakdown rate of black ash leaves was faster than upland leaves (k (day⁻¹) = 0.00329 and 0.00156, respectively), based on the average between wetland margins and centers. Development of mosquito larvae fed black ash leaves was faster than larvae fed upland leaves. Our results demonstrate linkages between upland forests and seasonal wetlands through litter fall. The abundance of upland litter in the wetlands may influence litter breakdown and carbon assimilation by invertebrates. Wetlands receiving high amounts of upland versus wetland litter may be lower quality habitats for invertebrates that depend on detrital pools for their development.