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草地灌丛化对植被与土壤的影响 被引量:11
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作者 邢媛媛 王永东 雷加强 《干旱区研究》 CSCD 北大核心 2017年第5期1157-1163,共7页
位于东非高原低海拔区的埃塞俄比亚博拉娜区草地正遭受着灌丛化的威胁。本文将博拉娜区灌丛化草地按灌木盖度分成3个等级,研究不同灌丛化程度草地植被及土壤理化性质的差异。结果表明:随灌丛化程度增加,灌木冠幅和种类增加,高度先增加... 位于东非高原低海拔区的埃塞俄比亚博拉娜区草地正遭受着灌丛化的威胁。本文将博拉娜区灌丛化草地按灌木盖度分成3个等级,研究不同灌丛化程度草地植被及土壤理化性质的差异。结果表明:随灌丛化程度增加,灌木冠幅和种类增加,高度先增加后降低,密度先降低后增加;草本植物的盖度、高度、优势种盖度下降,但优势种有所增加;含水量、黏粒含量下降,其中轻度灌丛化草地(灌木盖度40%~60%)含水量达22.36%,容重和紧实度先下降后上升,中度灌丛化草地(灌木盖度在60%~80%)容重达1.23 g·cm^(-3);有机质、全磷、速效磷、pH先增加后降低,在中度灌丛化草地分别为4.73%、0.73 g·kg^(-1)、16.86 mg·kg^(-1)、8.19;全氮和无机氮含量增加,在重度灌丛化草地(灌木盖度>80%)高达1.85 g·kg^(-1)、12.29 mg·kg^(-1)。 展开更多
关键词 灌丛化 植被盖度 土壤理化性质 博拉娜区 埃塞俄比亚
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光学与雷达遥感协同的大尺度草地灌丛化监测研究 被引量:8
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作者 邵京 李晓松 +1 位作者 杨珺婷 刘代超 《干旱区资源与环境》 CSSCI CSCD 北大核心 2021年第2期130-135,共6页
受全球变化及人类利用方式强度影响,草地灌丛化已成为干旱半干旱地区草原生态系统最为突出问题之一。准确掌握大尺度草地灌丛化信息,对草地可持续利用管理及气候变化响应分析具有重要的意义。极化合成孔径雷达在地表粗糙度、灌木生物量... 受全球变化及人类利用方式强度影响,草地灌丛化已成为干旱半干旱地区草原生态系统最为突出问题之一。准确掌握大尺度草地灌丛化信息,对草地可持续利用管理及气候变化响应分析具有重要的意义。极化合成孔径雷达在地表粗糙度、灌木生物量等估算上已经展现出了一定潜力,其与多光谱光学影像的结合从理论上来说具备开展草原灌丛化监测的可能,然而目前严重缺乏这方面的研究。本研究选择锡林郭勒草原为研究区,以欧空局Sentinel-1与Sentinel-2时间序列影像及地面草原灌丛化样地观测数据为数据源,通过相关性分析及随机森林等模型方法,开展了锡林郭勒草原的灌丛覆盖度估算研究。研究结果表明:(1)光学数据与草地总覆盖度显著相关,但对草地灌丛化特性不敏感,相对来说3月份的红边植被指数与6月份的光学植被指数与灌丛覆盖度相关性略高。(2)极化合成孔径雷达数据对于灌丛覆盖度有较强敏感性(VH极化好于VV极化),且高相关性贯穿了整个生长期,其中6月份的VH极化数据与灌丛覆盖度相关性可达0.64。(3)联合光学与雷达数据的随机森林模型可以实现较高精度草地灌丛覆盖度估算(R^(2)=0.76,RMSE=0.05),其中雷达数据Sentinel-1的贡献度为71.54%,光学数据Sentinel-2的贡献度为28.47%。 展开更多
关键词 草地灌丛化 合成孔径雷达 随机森林 灌丛覆盖度
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Spatial and Temporal Habitat Use by GPS Collared Male Cheetahs in Modified Bushland Habitat
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作者 Matti Nghikembua Jacob Harris +1 位作者 Tom Tregenza Laurie Marker 《Open Journal of Forestry》 2016年第4期269-280,共12页
Cheetahs and other apex predators are threatened by human-wildlife conflict and habitat degradation. Bush encroachment creates one of the biggest forms of habitat change, thus it is important to understand the impact ... Cheetahs and other apex predators are threatened by human-wildlife conflict and habitat degradation. Bush encroachment creates one of the biggest forms of habitat change, thus it is important to understand the impact this has on habitat use. We investigated habitat preferences of five male cheetahs in Namibian farmlands degraded by bush encroachment. Cheetahs were tracked using satellite based Global System for Mobile (GSM) collars providing a higher resolution on ranging behavior. We aimed to investigate: 1) habitat characteristics;2) evidence for habitat selection;3) temporal activity partitioning;and 4) whether revisits to locations were related to habitat type. There were differences in habitat characteristics, showing that cheetahs were able to utilise different habitats. Fecal pellet counts revealed that warthog, oryx, scrub hare and kudu were most abundant. The cheetahs spent more time in high visibility shrubland, suggesting they selected rewarding patches within predominantly bush-encroached landscapes. The usage in marginal habitat was strikingly influenced by habitat type, with both previously cleared and open vegetated areas showing high proportions in edge use. Individuals exhibited significant temporal activity partitioning, showing peaks between late afternoon and early morning hours. This finding could be key to managing human-wildlife conflict by showing that increased protection such as the use of herders and livestock guarding dogs should be used as mitigation methods to minimize the impact of cheetah specific temporal patterns at all times as defined in this research. Visits to the same locations were not correlated to habitat type;revisits may be dictated by other reasons such as social interaction, prey density or avoidance of other predators. Findings from this study will help build existing knowledge on the effects bush encroachment has on cheetah habitat preference. 展开更多
关键词 bush encroachment CHEETAH CONSERVATION Land Use Management
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