用随机决策树群算法进行高光谱遥感影像分类

摘要： 高光谱影像具有丰富的光谱信息,与全色、多光谱影像相比能更好地进行地面目标的分类识别. 该文对决策树分类算法的优劣进行分析,引入随机决策树群算法,对青海省祁连县Hyperion高光谱影像和IRS-P6影像数据进行实验,使用子空间划分和光谱距离进行降维后,分别采用支持向量机、神经网络、最大似然法进行分类,并与随机决策树群算法分类结果进行比较. 结果表明,该算法表现最优且无需降维预处理,可广泛应用于高光谱遥感领域.     

人为改造技术对豫南大别山区油茶产量的影响

在2010—2014年,采取不同的改造技术措施对8个不同品种的油茶产量进行研究.结果表明,采用撕皮嵌接的方法于5月份进行嫁接要优于拉皮切接(P0.05),密林疏伐可以有效地提高油茶的产量.选取的8个不同品种油茶中,亚2、亚5、亚21和湘17的单株产果量和人为改造后的产量明显高于其他品种(P0.05),建议作为豫南大别山区油茶低产林改造的主要品种.     

凉山州暗针叶林逆行演替特征分析

对植被逆行演替的分析有助干当今退耕还林植被恢复建设。凉山州暗针叶林分布较广,是西南林区的最主要森林类型之一。杜鹃-冷杉林逆行演替以林下杜鹃为主的下木层替代乔木层为特点,逐渐向杜鹃灌丛、高山草甸,甚至流石滩逆行演替;箭竹-云杉林或箭竹-冷杉林逆行演替表现为迅速被箭竹或悬钩子、蔷薇等灌丛占据,进而被柳叶菜（Epiobium．sp）替代。因此,在进行植被恢复的过程中,可详细调查原生植物群落,人为引入接近该地气候演替顶极的种源或种苗,并在改造地内密植,逐惭形成都闭的植物群落。     

青藏高原东部暗针叶林采伐迹地小气候及植被演替

暗针叶林主要分布在青藏高原东部的多条大江大河的上游和源头地区,具有重要的生态屏障功能,对于维护区域生态安全、促进经济可持续发展具有十分重要的作用。但自20世纪40年代以来,原始林被大规模采伐,形成大面积采伐迹地灌丛和草丛,其生态屏障功能逐步减弱,引起一系列生态环境因子变化。本文综述目前暗针叶林采伐迹地小气候、植被演替的研究现状,指出森林采伐后引起迹地小气候发生剧烈变化,导致迹地植被物种组成、盖度、生物量、生理生态因子等随着人为对其的不同干预也发生着相应的变化。指出今后应加强：（1）暗针叶林采伐迹地植被演替规律的研究;（2）加强人工造林树种的筛选;（3）采伐迹地0～1．5m下垫面小气候立体综合定位监测。     

Macroinvertebrate richness is lower in high-elevation lakes vs nearby streams: evidence from Grand Teton National Park,Wyoming

Mountain ecosystems will be strongly impacted by climate change, yet little is known of extant biodiversity in high-elevation lakes, particularly in North America. In this study, we sampled the littoral zone of six alpine and subalpine lakes in Grand Teton National Park (GRTE), Wyoming, to characterise invertebrate diversity and environmental variation in these climate change-threatened ecosystems. Overall, we collected 19 aquatic invertebrate taxa, and found that each lake harboured a unique assemblage of invertebrates despite close geographic proximity in some instances (e.g. less than 5 km). The results of this study complement previous efforts focused on macroinvertebrate diversity of streams in the Teton Range, highlighting much lower diversity in montane lakes vs nearby streams. Taken together, the two studies establish an important baseline understanding of mountain freshwater biodiversity in GRTE. With rapidly changing hydrologic inputs to mountain lakes driven primarily by the recession of alpine glaciers, these results may help target aquatic invertebrates to monitor as climate change affects the region. Moreover, these data clarify habitat factors, both biotic and abiotic, that influence high-elevation lake assemblages of the Teton Range.     

Taxonomic revision of the seasonal killifish genus Nothobranchius from Zanzibar,East Africa (Cyprinodontoidei: Aplocheilidae)

Nothobranchius guentheri and Nothobranchius melanospilus, the two seasonal killifishes of the genus Nothobranchius occurring in Zanzibar Island, Tanzania, were involved in past taxonomical mistakes and are still misidentified in museum collections. A historical review is herein presented and both species are redescribed on the basis of type material and recent collections. Nothobranchius guentheri, a popular aquarium fish, is endemic to Zanzibar, and N. melanospilus, geographically widespread in East Africa, occurring both in Zanzibar and in continental river basins. These species are distinguished by a series of morphological features not previously reported in the literature, including pre-dorsal length and relative position of the anterior portion of the dorsal-fin skeletal support and vertebrae; number of gill-rakers of the first branchial arch, caudal-fin rays, scales of the longitudinal series, series of scales around caudal peduncle, and vertebrae; frontal squamation; and arrangement and number of neuromasts of the supraorbital series. The present taxonomic revision comprising N. guentheri and N. melanospilus, the oldest species names of the genus in the East African biodiversity hotspot, is important to improve the knowledge of the genus in a region where its taxonomy is still problematic     

城市近郊林的减少率预测及保护对策

利用日本神奈川县1960-1995年的林业统计资料、农林业普查数据和森林面积与人口数量关系的数学模型,对该区域森林面积的减少趋势进行了分析.结果表明:随着人口的增加,居民人均森林面积在逐渐减少.在人口增加10%的情况下,该区36个市、镇、村的人均森林面积减少率分布为1%～92%.大部分市、镇、村的可决系数(r2)都在0.9以上.根据森林面积减少率的不同和政府财力的差异,笔者提出了通过政府购买,实现国有化、公有化,以及对土地开发行为进行长期监控,降低成本等对城市近郊林的保护对策.     

基于随机森林的企业信用评估模型

引入了一种能较好容忍噪声,且稳定性较高的组合分类器算法———随机森林(RF),建立企业信用评估模型;着重分析了适合RF的不平衡分类问题的处理方法,并介绍了模型参数的优化.通过与神经网络和支持向量机的对比实验,证实了该方法的有效性和优越性.     

陕北黄土高原森林地带油松林的主要类型及其动态关系

油松林系陕北黄土高原森林地带的气候顶极群落,共含11个类型,其中分布普遍的是:油松——多花胡枝子——大披针苔林;油松——柔毛绣线菊——大披针苔林;油松——虎椿子——大披针苔林;油松——胡枝子——大披针苔林;油松——杭子稍——大披针苔林;油松——大披针苔林。它们之间的演替关系和起源比较复杂,非单元和单演替顶极。     

斑尾榛鸡南迁及其与花尾榛鸡分布区间断成因探讨

更新世中期斑尾榛鸡的原始种群因冰川作用及相近种花尾榛鸡种群的竞争排挤南廷到青藏高原东部、东南部山地。当时这些地区的森林和适度的冰雪环境适于其生活，定居下来，经久进化。自然力和人类开发作用使东北平原，华北、黄土高原的原始森林消失，再加入类狩猎活动，致使两种榛鸡分布区间断。