坡度对香根草护坡植物群落早期特征的影响

对不同坡度的相邻两边坡上香根草(Vetiveria zizanioides)护坡植物群落早期阶段连续2年的调查与分析,结果显示:(1)菊科(Compositae)、禾本科(Gramineae)、豆科(Lentil)3类物种最早在群落中定居,3类物种数占物种总数比例为56.00%～84.62%。(2)香根草种植两年后两坡面上植物群落开始出现分化。其中,1#坡面(坡度小)有利于香根草种群的发展,但也有利于乡土植物种在其中定居,植物群落保水效果也较好。(3)秋季植物群落特征规律明显,表现为:1#坡面(坡度小)植物群落丰富度指数R、多样性指数H′、均匀度指数J′随时间上升,植物群落优势度指数C′则呈现随时间下降;而2#坡面(坡度大)表现规律则相反。(4)植物群落丰富度指数R与群落中香根草物种优势度呈显著线性负相关;多样性指数H′和均匀度指数J′与群落中香根草物种优势度呈极显著线性负相关;优势度指数C′均与群落中香根草物种优势度呈极显著线性负相关。     

贵州喀斯特山区草地生态系统类型转变对土壤有机碳的影响

为探明喀斯特生态脆弱区土地利用方式转变对土壤有机碳的影响,以贵州省不同海拔梯度下的草地及其相应开垦的农田为研究对象,采用成对设计的方法研究了不同海拔梯度下草地、农田的有机碳特征及草地生态系统类型转变对土壤有机碳的影响。结果表明:研究区草地、农田土壤体积质量随土层深度增加显著升高(P <0.05),增幅为17.85%～45.74%,草地转变为农田后土壤体积质量均显著增加,增幅为5.09%～10.88%。研究区草地、农田土壤有机碳含量随土层深度的增加而显著降低,表层(0～10 cm)土壤有机碳含量占整个研究区(0～50 cm)的54.93%,呈表层富集现象。草地生态系统类型转变导致整个研究区土壤有机碳含量显著下降,降幅为19.64%～57.12%,且降幅随着海拔高度的增加而增大;草地转变为农田使土壤有机碳密度下降,降幅12.22%～50.73%。     

不同牧压梯度下高寒草甸演替及植物物种多样性分异特征

通过对不同牧压梯度导致的4个相邻高寒草甸植物群落物种多样性的调查,探讨了放牧驱动下高寒草甸演替及植物物种多样性分异特征,以期为高寒草甸合理利用提供依据。结果表明:矮嵩草时期与小嵩草草毡表层开裂期的多样性指数D差异不显著,其他3个阶段间差异显著(P0.05);多样性指数H除禾草矮嵩草时期与小嵩草草毡表层开裂期,矮嵩草时期与小嵩草草毡表层加厚期差异不显著外,其他均差异显著(P0.05);均匀度指数除矮嵩草时期与小嵩草草毡表层加厚期差异不显著,其他3个时期差异均达到显著水平(P0.05);放牧明显改变了高寒草甸的主要建群种和优势种,伴随牧压强度增大,植物群落发生更替,莎草科重要值增大,禾本科重要值减小,草甸植物群落由禾草矮嵩草时期向矮嵩草时期、小嵩草草毡表层加厚期、小嵩草草毡表层开裂期演替。     

Soundscapes of urban parks: An innovative approach for ecosystem monitoring and adaptive management

Urban foresters are addressing the challenge of urban biodiversity loss through management plans in the context of rapid urbanization. Protecting the integrity of the urban ecosystem requires long-term monitoring and planning for resilience as well as effective management. The soundscape assessment has attracted attention in this field, but applying the soundscape assessment in urban ecological monitoring requires a protocol that links soundscapes to the impact of resource management on biodiversity over time. The effective processing and visualization of large-scale data also remains an important challenge. The aim of this study was to better understand the relationship between soundscape and physical environment, and examine the feasibility of this innovative soundscape approach in highly urbanized areas. Soundscape recordings were collected for 20 urban parks twice on 4 consecutive days in Spring. A total of 691,200 min of sound material were automatically obtained. In order to track the spatio-temporal patterns of a soundscape and determine its potential suitability for ecosystem monitoring, our study characterized soundscape information by adopting 4 widely used acoustic indices: acoustic diversity index (ADI), bioacoustic index (BIO), normalized difference vegetation index (NDSI), and power spectral density (PSD). Daily patterns of PSD have provided a potential connection between soundscapes and bird songs, and 1–2 kHz presented a similar pattern that was linked to human activity. Through further modeling, we tested the relationship of soundscapes to physical environment characteristics. The results showed the importance of habitat vegetation structure for acoustic diversity. More vertical heterogeneity, with an uneven canopy height or multilayered vegetation, was associated with more acoustic diversity. This suggests that clearing ground cover may have a significant negative impact on wildlife. Our results suggest that soundscape approaches provide a way to quickly synthesize large-scale recording data into meaningful patterns that can track changes in bird songs and ecosystem conditions. The proposed approach would enable regular assessment of urban parks and forests to inform adaptive planning and management strategies that can maintain or enhance biodiversity.     

长白山北坡主要建群种种群结构及重要值沿海拔梯度的变化

From 700 m to 1900 m on the northern slope of Changbai Mountain, 13 plots with an interval of 100 m in elevation were investigated to study the variations of population structure and important value of the main edificators along the elevation gradient. In their core distribution areas, most of the edificators had healthy population structure and could regenerate smoothly except Larix olgensis, but important value of Larix olgensis had no obvious variations with elevation changes, which showed that Larix olgensis had its own particularity and strong adaptability. At high elevation above 1800 m, Betula ermanfi was the only species that could form a mono-dominant community. Important values of Pinus koraiensis and Acer mono had similar changing trends, and they had the similar ecological adaptabilities.     

长白山阔叶红松林CO2廓线和CO2贮存的动态

从1999年8至10月,2000年的4至6月,2002年8月至2003年9月,在平均树高为26米的长白山阔叶红松林内,用红外气体分析仪(2250D,LI-CORInc.和LI-COR,820)测定了不同高度的二氧化碳浓度。根据测定的数据,分析了阔叶红松林二氧化碳廓线的日变化和季节变化动态。结果表明:CO2浓度的垂直分布在白天和夜间是不同的,在接近地面处CO2浓度始终最大。从季节CO2廓线看出,在植物生长季节林冠处CO2浓度有明显的成层现象,不同高度(60~2.5m)的CO2浓度3月份变化较小差值为10mmol穖ol-1,而在7月份变化较大,差值为60mmol穖ol-1。7月份林冠处(22,26,32m)CO2浓度梯度较大,浓度差为8mmol穖ol-1。计算位于涡度相关仪器之下的40米高空气柱中CO2贮存状况表明,年际贮存是负值,但对NEE的贡献很小。图4参11。     

宝天曼植物群落物种多样性研究

对宝天曼保护区植物群落物种多样性进行了研究。结果表明 ,物种丰富度指数、多样性指数和均匀度指数在群落梯度上的分布趋势基本一致 ,较好地反映了不同植物群落类型在物种组成方面的差异。草本层物种丰富度指数明显高于乔木层和灌木层 ,草本层物种丰富度指数在群落梯度上的变异最大 ,灌木层次之 ,乔木层最小。乔木层物种多样性指数小于灌木层和草本层 ,草本层和乔木层物种多样性指数在群落梯度上的变异程度明显大于灌木层。灌木层物种均匀度指数大于乔木层和草本层 ,草本层和乔木层均匀度指数在群落梯度上的变异程度大于灌木层。物种丰富度指数和多样性指数的较大值出现在高海拔和低海拔群落 ,较小值多出现在中等海拔群落。物种均匀度指数的较小值多出现在中等海拔群落 ,但其较大值在各海拔群落都有分布。草本层物种丰富度指数和多样性指数的较高值多分布在低海拔群落 ,较小值多分布在中等海拔群落 ;乔木层和灌木层的各种指数以及草本层的物种均匀度指数在海拔梯度上的分布规律不明显     

Soil desiccation for Loess soils on natural and regrown areas

In the Loess Plateau, soil desiccation has become a serious problem for forest and grass vegetation. Soil desiccation leads to the formation of a dried soil layer (DSL). This paper presents the results of research carried out in the central part of the Loess Plateau. The objective of the research was to produce a statistically supported set of indicators for evaluating soil desiccation of forestlands, to present a heuristic idea for soil desiccation and to supply scientific support for replacing farmland with forest or grass in the Loess Plateau and other regions of China. Here, we suggest that more attention should be paid to soil desiccation and its effects on the ecosystem of the region in the future. The results showed that natural Quercus liaotungensis forestlands (NQF) retained more water content than regrown Robinnia pseudoscacia forestlands (RRF). Significant DSLs were formed in the RRF but not in the NQF. A possible reason for no formation of DSL in NQF could be due to the presence of an arbor–shrub–herb stand structure and large humus and litter accumulation, which increased the natural forest's (NF) adaptability to the environmental conditions. Soil water content in the north-facing slope was significantly larger than in the south-facing slope. DSLs formed in the 0–500 cm layer of the south-facing slope. When slope gradient was greater than 25°, soil water content deceased sharply and showed significant difference compared with 9°, 15° and 20° (P < 0.05). So, we conclude that plant species, aspect and slope angle could be the predicators for the formation of DSLs. The analysis on soil physical properties of 0–60 cm layer indicated that plant species, aspect and slope angle also have significant effects on bulk density, porosity, plant-available capacity, and hydraulic conductivity, especially in the 0–20 and 20–40 cm layers. In the NQF and RRF with north-facing slope, soil physical properties were improved.     

Vertical profiles of environmental factors within tropical rainforest, Lambir Hills National Park, Sarawak, Malaysia

Environmental factors, such as global solar radiation, wind speed, air temperature, humidity, and CO₂ concentration, were measured above and within the canopy of a tropical rainforest in Lambir Hills National Park, Sarawak, Malaysia. Few data concerning the environment of this forest have been reported. Intensive observations were carried out in 1998, 1999, and 2000 with the following results: (1) The fraction of global solar radiation reaching the upper layer of the canopy varied with global solar radiation above the canopy. Even though the global solar radiation above the canopy fluctuated, the fraction of that reaching the lower canopy and the ground was constantly approximately 5%. (2) The fraction of wind speed reaching each layer of the canopy increased with wind speed above the canopy. Little wind was usually present at the lower canopy. (3) The daytime air temperature at the canopy top was higher than that near the ground. The maximum difference between the air temperature at the canopy top and that at the ground was about 5°C, and the diurnal temperature ranges at the canopy top and those at the ground were about 8°C and about 5°C, respectively. The highest daytime water vapor pressure occurred within the canopy and particularly near the ground. Vertical gradients of water vapor pressure during the day were steep, probably because of high transpiration. (4) In the 1998 observation the minimum and the maximum CO₂ concentrations were 360 ppm in the day and 450 ppm at night, while in the 2000 observation the minimum and the maximum CO₂ concentrations were 350 ppm in the day and 540 ppm at night. The higher CO₂ concentration in the daytime and the lower concentration at night observed during the 1998 observation period were probably due to reduced photosynthesis and soil respiration caused by exceptional dry conditions during the observation period.     

贺兰山西坡鼠种内脏重量与海拔梯度关系研究

采用铗日法对贺兰山西坡鼠类的内脏重量与海拔梯度关系情况进行了细致研究。选取8条典型沟道为样线,共布设有效铗日18 748个,捕获鼠类235只。阿拉善黄鼠和大林姬鼠在所有海拔梯度均有分布,其次是社鼠、灰仓鼠和短尾仓鼠,海拔分布范围最小的是高山鼠兔和东方田鼠。阿拉善黄鼠的肺脏和肾脏重量高海拔重量远高于低海拔重量,显示出了其对外界环境的超强适应能力。