A Comparison of Logging Systems and Bat Diversity in the Neotropics

Abstract:  Evaluating logging systems to determine which are most compatible with the maintenance of biodiversity is of prime importance if tropical forests are to be managed in a sustainable way. Bats are model taxa for this purpose. Two different logging systems are used in the natural forest of the Victoria-Mayaro Forest Reserve in Trinidad: open range and periodic block. Open range is a continuous harvesting system and, in common with most methods used to log tropical forests worldwide, has few harvest controls other than girth limits for selected species. Periodic block is a polycyclic system, with felling based on ecological criteria assumed to be compatible with the maintenance of biodiversity. To compare the effects of periodic block and open-range systems on biodiversity, we determined bat species richness and abundance in each system and in primary forest. We caught bats in mist nets set at ground level and in the canopy and in harp traps. In total 1959 individuals representing 38 species were captured. Species richness was similar among primary forest and logged forest habitats, although bat diversity was lower in logged forest. The distributions of bat species abundance did not differ significantly between logged forest and primary forest. We found, however, that both logging systems lead to a decrease in gleaning animalivores and an increase in frugivores. The increase in frugivores was likely the result of an increase in the abundance of bat-dispersed pioneer fruiting plants in logged forest. Bats of periodic-block-managed forest were more similar to those of primary forest than those of forest logged using the open-range system, indicating that the periodic-block system is more compatible with the maintenance of bat diversity. Our results support the suggestion that the measured use of tropical forests can largely be compatible with biodiversity conservation.     

Nutrients in soil solution following selective logging of a humid tropical ‘terra firme’ forest north of Manaus,Brazil

Sustainable use of the Amazon forest for timber production is conditioned by the effect of logging on the system's nutrient cycling. This paper reports the results of a soil moisture and soil water chemistry monitoring campaign before and immediately after a selective logging which removed 35 m³ wood/ha. Soil moisture was measured using tensiometers, and soil water chemistry using suction samplers in five disturbance classes: tractor tracks, clearing centres, clearing edges, forest edges and untouched forest. The results show that the soil under the tractor tracks and clearings contained more moisture than under the untouched forest. The suction samplers extracted substantially more nitrate, ammonium, calcium, magnesium and potassium from the clearing centres, the tractor tracks and the clearing edges than from the forest sites. The results are explained in terms of altered microbial activity, changes in crown interception and uptake by roots.     

热带人工林生物物理参数及生物量对RADARSAT SAR信号响应研究

合成孔径侧视雷达穿透冠层而获得树干信息的特点使得其具有在南方NDVI易饱和地区的生物量估测方面优于光学遥感。文章利用地面实测调查数据,首次系统地研究了热带人工林生物物理参数及生物量对RADARSAT-SAR信号响应。结果表明:RADARSAT-SAR后向散射系数与森林生物量、树高、胸径可以用对数模型模拟。对于本实验区人工速生林来说,在森林生物量小于40 t.hm-2时RADARSAT-SAR后向散射系数与森林生物量具有较强相关性。桉树树高与后向散射系数的相关系数大于桉树胸径与后向散射系数关系。松树胸径与后向散射系数相关系数高于树高与后向散射系数的相关系数。研究结果为SAR在热带森林研究中的应用提供了一定的理论基础。     

台风过程珠江三角洲边界层特征及其对空气质量的影响

利用2006年7月珠江三角洲南北向3个点为期1个月的小球测风、低空探空资料及9个地面气象站逐时风向、风速资料,通过计算和分析风、温梯度资料,研究了台风过程珠江三角洲边界层特征及其对珠江三角洲地区空气质量的影响,重点分析了台风下沉气流影响导致灰霾天气期间的边界层结构.结果表明,2006年7月珠江三角洲地区空气质量主要受2个台风过程影响,当台风中心位于粤东及福建以东海域时,台风外围的下沉气流会对珠江三角洲地区的空气质量产生强烈影响,出现灰霾天气.在台风登陆前出现灰霾日时,珠江三角洲被均压场所控制,大部分区域为静小风,沿海地区会出现局地的海陆风,边界层风速较小.在200~500m低空会出现逆温层,同时最大混合层高度迅速下降到不足500m.     

Testing Hypotheses of Bird Extinctions at Rio Palenque,Ecuador, with Informal Species Lists

Abstract: Informally gathered species lists are a potential source of data for conservation biology, but most remain unused because of questions of reliability and statistical issues. We applied two alternative analytical methods (contingency tests and occupancy modeling) to a 35‐year data set (1973–2007) to test hypotheses about local bird extinction. We compiled data from bird lists collected by expert amateurs and professional scientists in a 2‐km² fragment of lowland tropical forest in coastal Ecuador. We tested the effects of the following on local extinction: trophic level, sociality, foraging specialization, light tolerance, geographical range area, and biogeographic source. First we assessed extinction on the basis of the number of years in which a species was not detected on the site and used contingency tests with each factor to compare the frequency of expected and observed extinction events among different species categories. Then we defined four multiyear periods that reflected different stages of deforestation and isolation of the study site and used occupancy modeling to test extinction hypotheses singly and in combination. Both types of analyses supported the biogeographic source hypothesis and the species‐range hypothesis as causes of extinction; however, occupancy modeling indicated the model incorporating all factors except foraging specialization best fit the data.     

贵州南部河谷热带性植物资源及开发利用

贵州南部河谷热带性植物共计464种、2变种。主要构成3种植被类型:大型羽状复叶林、稀树草坡灌丛与肉质多刺灌丛。可分为11类经济用途:药用(139种)、纤维(38种)、野果(21种)、观赏(21种)、鞣料(18种)、饲料(13种)、油脂(13种)、淀粉(12种)、紫胶虫寄主(11种)、芳香(6种)、染料(5种)。资源流失与环境变化,使现存资源的保护与深层次利用成为当前的主要问题。     

Soil erosion under different vegetation covers in the Venezuelan Andes

This comparative study of soil erosion considered different environments in an ecological unit of the Venezuelan Andes. The soils belong to an association of typic palehumults and humic dystrudepts. Soil losses were quantified by using erosion plots in areas covered by four types of vegetation, including both natural and cultivated environments. The highest soil erosion rate evaluated corresponded to horticultural crops in rotation: reaching a value of 22 Mg ha^–1 per year. For apple tree (Malus sylvestris Miller) plots, soil losses reached values of 1.96 Mg ha^–1 per year. Losses from pasture (Pennisetum clandestinum Hochst. ex Chiov.) plots, without livestock grazing, were as high as 1.11 Mg ha^–1 during the second year of the experiment. The highest soil losses generated from plots under natural forest were equal to 0.54 Mg ha^–1 per year. Environmental factors such as total and effective rainfall, runoff, and some soil characteristics as those related to soil losses by water erosion were evaluated. The type of management applied to each site under different land use type and the absence of conservation practices explain, to a large extent, the erosive processes and mechanisms.     

The Water Quality of some Tropical Freshwater Bodies in Uyo (Nigeria) Receiving Municipal Effluents, Slaughter-House Washings and Agricultural Land Drainage

The water quality of some tropical fresh-water bodies in Uyo (Nigeria) was investigated for two years in relation to point and non-point source city effluents and slaughter-house washings discharged into them. Streams which received city effluents and slaughter-house washings were degraded in quality with acidic water (pH =5.26±0.83 to 6.20±0.56), low oxygenation (2.46±1.30 to 3.88±0.29 mgl^–1), high biochemical oxygen demand (4.96±0.66 to 8.20±0.82 mgl^–1) and chemical oxygen demand (88.60±3.50 to 146.36±9.86 mgl^–1) than non-effluent receiving streams. High acidity in streams is due mainly to the acidic nature of underground water which replenishes the streams. Nutrient levels were high indicating enrichment from highly fertilized farmlands and slaughter-house washings. The concentrations of most of the hydrochemical variables were significantly lower in non-effluent than effluent-receiving streams. Some of the hydrochemical variables (total alkalinity, dissolved oxygen, nitrate, phosphate and conductivity) exhibited pronounced seasonality regimes with significant correlations with rainfall indicating its influence on the chemical hydrology of the water bodies. Land use in the catchment influenced water quality through inflow of nutrients, organic and inorganic contaminants and siltation. Pollution in the impacted streams is attributed mainly to episodic events.