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91.
92.
Zsolt Vgvri Orsolya Valk Balzs Dek Pter Trk Sndor Konyhs Bla Tthmrsz 《Land Degradation \u0026amp; Development》2016,27(4):910-918
Increasing agricultural activities have been shown to affect soil and vegetation changes leading to serious biodiversity declines throughout the world. These effects are amplified in dry grassland areas, where resulting changes in habitat structure affect threatened animals on long temporal scales. Great bustards (Otis tarda) inhabit open landscapes where fire and grazing have been a part of the natural disturbance regime since historical times. Even fire and grazing are hypothesized to be important factors in the lifecycle of the species, studies are still missing on disturbance‐related lekking distribution patterns of great bustards. We analyzed the importance of fires and grazing on the spatial distribution of lekking bustards controlling for habitat types, habitat diversity, distance from roads and social effects. Our standardized dataset spanned 31 years, being one of the largest datasets on bustard lekking. During the 31 years we observed 10 118 individuals at 639 observation points in Hortobágy National Park, East‐Hungary. One of the most important predictors for total number of birds and number of males was the area burnt in previous years. We found that increased habitat diversity had a positive effect on female numbers. Models fit on second‐ and third‐year burn data detected no substantial role of burning on lekking distribution. Our results suggest that introduction of a patch‐burning management system in lekking areas could increase the availability of optimal lek sites for bustards. As an effective management tool, we suggest applying patch‐burning annually in a spatially mosaic structure inside the area occupied by each sub‐population unit. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
93.
Considerable differences observed in the home-range size of individual three-toed woodpeckers (Picoides tridactylus) may be linked to variation in resource availability. We used radio-telemetry to test this hypothesis in an alpine mountain forest in southeastern Germany between 1994 and 2000. Stepwise backward multiple-regression showed that adaptive kernel home-range size using 95% use distribution (n=24 woodpeckers) was positively related to forest extent and tree-species diversity. Conversely, we found smaller home ranges with increasing density of potential cavity trees, and with increasing dbh-range of trees at breast height. The habitat variables shown to effect home range selection were attributes of mature boreal forests. This implied that maintaining a boreal-like habitat (i.e. spruce-dominated autochthonous forests including their natural disturbance regime) would be the best option for successful conservation of the alpine subspecies of the three-toed woodpecker. 相似文献
94.
Methane emissions from different vegetation zones in a Qinghai-Tibetan Plateau wetland 总被引:1,自引:0,他引:1
Mitsuru Hirota Yanhong Tang Shigeki Hirata Wenhong Mo Shigeru Mariko 《Soil biology & biochemistry》2004,36(5):737-748
We measured methane (CH4) emissions in the Luanhaizi wetland, a typical alpine wetland on the Qinghai-Tibetan Plateau, China, during the plant growth season (early July to mid-September) in 2002. Our aim was to quantify the spatial and temporal variation of CH4 flux and to elucidate key factors in this variation. Static chamber measurements of CH4 flux were made in four vegetation zones along a gradient of water depth. There were three emergent-plant zones (Hippuris-dominated; Scirpus-dominated; and Carex-dominated) and one submerged-plant zone (Potamogeton-dominated). The smallest CH4 flux (seasonal mean=33.1 mg CH4 m−2 d−1) was observed in the Potamogeton-dominated zone, which occupied about 74% of the total area of the wetland. The greatest CH4 flux (seasonal mean=214 mg CH4 m−2 d−1) was observed in the Hippuris-dominated zone, in the second-deepest water area. CH4 flux from three zones (excluding the Carex-dominated zone) showed a marked diurnal change and decreased dramatically under dark conditions. Light intensity had a major influence on the temporal variation in CH4 flux, at least in three of the zones. Methane fluxes from all zones increased during the growing season with increasing aboveground biomass. CH4 flux from the Scirpus-dominated zone was significantly lower than in the other emergent-plant zones despite the large biomass, because the root and rhizome intake ports for CH4 transport in the dominant species were distributed in shallower and more oxidative soil than occupied in the other zones. Spatial and temporal variation in CH4 flux from the alpine wetland was determined by the vegetation zone. Among the dominant species in each zone, there were variations in the density and biomass of shoots, gas-transport system, and root-rhizome architecture. The CH4 flux from a typical alpine wetland on the Qinghai-Tibetan Plateau was as high as those of other boreal and alpine wetlands. 相似文献
95.
高寒矮嵩草草甸地面热源强度及与生物量关系的初步研究 总被引:1,自引:0,他引:1
在青藏高原海北高寒矮嵩草草甸地区,依据2002年涡度相关法观测的能量平衡各分量资料和6-10月植物地上、地下生物量测定值,分析了高寒矮嵩草草甸近地表热量平衡、地面热源强度的变化特征,讨论了地面热源强度与植物生物量季节变化过程中的相互关系。结果表明:在青藏高原海北高寒矮嵩草草甸地区,年内地面均为热源,热源强度季节变化明显,地面热源强度年平均为88.5 W/m2;地上生物量季节变化与热源强度具有显著的正相关关系,而地下生物量季节变化与热源强度关系不明显。 相似文献
96.
Weixing Liu Wenhua Xu Yi Han Changhui Wang Shiqiang Wan 《Biology and Fertility of Soils》2007,44(2):259-268
Temporal dynamics of microbial biomass and respiration of soil and their responses to topography, burning, N fertilization,
and their interactions were determined in a temperate steppe in northern China. Soil microbial indices showed strong temporal
variability over the growing season. Soil microbial biomass C (MBC) and N (MBN) were 14.8 and 11.5% greater in the lower than
upper slope, respectively. However, the percentage of organic C present as MBC and the percentage of total N present as MBN
were 16.9 and 26.2% higher in the upper than lower slope, respectively. Neither microbial respiration (MR) nor metabolic quotient
(qCO2) was affected by topography. Both MBC and MBN were increased by burning, on average, by 29.8 and 14.2% over the growing season,
and MR and qCO2 tended to reduce depending on the sampling date, especially in August. Burning stimulated the percentage of organic C present
as MBC and the percentage of total N present as MBN in the upper slope, but did not change these two parameters in the lower
slope. No effects of N fertilization on soil microbial indices were observed in the first growing season after the treatment.
Further research is needed to study the long-term relationships between changes in soil microbial diversity and activity and
plant community in response to burning and N fertilization. 相似文献
97.
不同放牧强度对滩羊生产性能影响的研究 总被引:1,自引:0,他引:1
五种不同放牧强度,历期154d的滩羊放牧试验结果表明:滩羊的采食量随着放牧强度的加重而降低,同一放牧强度下,随着放牧时间的推移,采食量先是逐渐增大,尔后又下降;不同放牧强度下,滩羊的体重随着时间的推移总体上都呈增加的趋势,但放牧强度轻的处理日增重峰值较高,持续时间较长:滩羊个体增重与放牧强度之间存在着强的负相关,单位草地面积(1hm^2)增重与放牧强度之间呈强的正相关:随着放牧强度的加重,饲料报酬先增大后减小,在同一放牧强度下,饲料报酬随着时间的推移先升高后降低;当放牧强度超过0.750只/hm^2以后,滩羊出现了空怀、产羔率降低和推迟怀孕的现象。综合考虑各研究指标,本类草地放牧强度以不超过0.750只/hm^2为宜。 相似文献
98.
在内蒙古锡林郭勒高原东部的贝加尔针茅草原上,选择丘间宽阔平地设置研究样地,在围栏封闭条件下,以群落为研究对象,采用固定双样方随机区组的方法,于1998年5月-1999年9月,对植物进行了不同强度和不同时间的刈割研究,观察植物营养生长和生殖生长因不同处理而发生的变化,从而判断对整个群落植物生长与繁殖的影响。结果表明,从群落主要种到整个草群,其处理当年及返青后的高度、盖度、植株数量等指标基本上随刈割强度加大和刈割时间推后而降低,繁殖活动状态也是依相同的顺序而变差,1年1次处理的效果即很明显且有残效。为合理安排草地的利用计划提供了参考依据。 相似文献
99.
在连续2a处理的基础上,于1999年秋集中观察了草群、羊草和贝加尔针茅生长状况的变化。结果表明,经过2次重复处理之后,累加效应显著。草群和主要种的高度、盖度随处理时间的推移和留茬高度的降低而呈直线或波动性下降;单位面积羊草植株数和单位株丛贝加尔针茅植株数也以相同的方式减少。下降和减少的程度比第la处理后加大。与CK相比,所有时间和留茬处理的生长指标都明显降低,揭示了不同利用方式对草地的不同影响。 相似文献
100.
1992年4~9月在内蒙古呼伦贝尔盟草甸草原上,选择15种牧草进行了牧草贮藏养分积累与消耗规律的研究。采用3.5-二硝基水杨酸比色法对野外采集的样品进行贮藏碳水化合物的定量分析。试验结果表明,双子叶植物贮藏碳水化合物含量的季节变化呈U型曲线,而禾本科植物的一般为双峰或多峰型曲线。根据试验结果,作者指出了该草地类型放牧利用的适宜时期。 相似文献