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Spatiotemporal changes in forest loss and its linkage to burned areas in China 被引量:3
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作者 Zhiwei Wu Saijia Yan +1 位作者 Lei He Yanlong Shan 《Journal of Forestry Research》 SCIE CAS CSCD 2020年第6期2525-2536,共12页
Fire-induced forest loss has substantially increased worldwide over the last decade.In China,the connection between forest loss and frequent fi res on a national scale remains largely unexplored.In this study,we used ... Fire-induced forest loss has substantially increased worldwide over the last decade.In China,the connection between forest loss and frequent fi res on a national scale remains largely unexplored.In this study,we used a data set for a time-series of forest loss from the Global Forest Watch and for a MODIS-derived burned area for 2003–2015 to ascertain variations in forest loss and to explore its relationship with forest fi res(represented by burned areas)at the country-and forest-zone levels.We quantifi ed trends in forest loss during 2003–2015 using linear regression analysis and assessed the relation between forest loss and burned areas using Spearman’s correlation.Forest loss increased signifi cantly(264.8 km 2 a−1;R 2=0.54,p<0.01)throughout China,with an average annual increase of 11.4%during 2003–2015.However,the forest loss trend had extensive spatial heterogeneity.Forest loss increased mainly in the subtropical evergreen broadleaf forest zone(315.0 km 2 a−1;R 2=0.69,p<0.01)and tropical rainforest zone(38.8 km 2 a−1;R 2=0.66,p<0.01),but the loss of forest decreased in the cold temperate deciduous coniferous forest zone(−70.8 km 2 year−1;R 2=0.75,p<0.01)and the temperate deciduous mixed broadleaf and coniferous forest zone(−14.4 km 2 a−1;R 2=0.45,p<0.05).We found that 1.0%of China’s area had a signifi cant positive correlation(r≥0.55,p<0.05)with burned areas and 0.3%had a signifi cant negative correlation(r≤−0.55,p<0.05).In particular,forest loss had a signifi cant positive relationship with the burned area in the cold temperate deciduous coniferous forest zone(16.9% of the lands)and the subtropical evergreen broadleaf forest zone(7.8%).These results provide a basis for future predictions of fi re-induced forest loss in China. 展开更多
关键词 forest loss forest fire Burned area Spatiotemporal variability Correlation analysis
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Rapid Urbanization Induced Extensive Forest Loss to Urban Land in the Guangdong-Hong Kong-Macao Greater Bay Area, China 被引量:3
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作者 YANG Chao LIU Huizeng +7 位作者 LI Qingquan CUI Aihong XIA Rongling SHI Tiezhu ZHANG Jie GAO Wenxiu ZHOU Xiang WU Guofeng 《Chinese Geographical Science》 SCIE CSCD 2021年第1期93-108,共16页
China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot ... China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation. 展开更多
关键词 forest loss to urban land urbanization spatiotemporal pattern remote sensing Guangdong-Hong Kong-Macao Greater Bay Area(GBA)
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Simulating long-term effect of Hyrcanian forest loss on phosphorus loading at the sub-watershed level 被引量:1
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作者 Fatemeh RAJAEI Abbas E SARI +4 位作者 Abdolrassoul SALMANMAHINY Timothy O RANDHIR Majid DELAVAR Reza D BEHROOZ Alireza M BAVANI 《Journal of Arid Land》 SCIE CSCD 2018年第3期457-469,共13页
Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus(P) nutrient, thus impacting the water quality. Modeling the effect of forest los... Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus(P) nutrient, thus impacting the water quality. Modeling the effect of forest loss on surface water quality provides valuable information for forest management. This study predicts the future impacts of forest loss between 2010 and 2040 on P loading in the Tajan River watershed at the sub-watershed level. To understand drivers of the land cover, we used Land Change Modeler(LCM) combining with the Soil Water Assessment Tool(SWAT) model to simulate the impacts of land use change on P loading. We characterized priority management areas for locating comprehensive and cost-effective management practices at the sub-watershed level. Results show that agricultural expansion has led to an intense deforestation. During the future period 2010–2040, forest area is expected to decrease by 34,739 hm^2. And the areas of pasture and agriculture are expected to increase by 7668 and 27,071 hm^2, respectively. In most sub-watersheds, P pollution will be intensified with the increase in deforestation by the year 2040. And the P concentration is expected to increase from 0.08 to 2.30 mg/L in all of sub-watersheds by the year 2040. It should be noted that the phosphorous concentration exceeds the American Public Health Association′s water quality standard of 0.2 mg/L for P in drinking water in both current and future scenarios in the Tajan River watershed. Only 30% of sub-watersheds will comply with the water quality standards by the year 2040. The finding of the present study highlights the importance of conserving forest area to maintain a stable water quality. 展开更多
关键词 PHOSPHORUS land use change modeling forest loss prioritizing management area Tajan River Iran
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LOSS ASSESSMENT OF BURNED FOREST USING REMOTE SENSING AND GEOGRAPHICAL INFORMATION TECHNIQUES
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作者 Zhou Hongze Ye Ronghua Northeast Forestry University 《Journal of Northeast Forestry University》 SCIE CAS CSCD 1991年第2期89-94,共6页
After forest fire, it is very needed to locate fire position and assess the loss of forest resources. In this paper, a method of burned forest assessment with satellite remote sensing data and over-laying techniques i... After forest fire, it is very needed to locate fire position and assess the loss of forest resources. In this paper, a method of burned forest assessment with satellite remote sensing data and over-laying techniques is discussed and used in the assessment of the burned forest in Malin Forest Farm after the large forest fire of May, 1987. 展开更多
关键词 Assessment method forest loss forest fire Geographic information techniques
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Swamp Forest Use and Loss in the Niger Delta: Contextual and Underlying Issues 被引量:1
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作者 Nwabueze Ikenna Igu 《Open Journal of Forestry》 2017年第1期34-47,共14页
Forest ecosystems are vital not only for the ecosystem and biogeochemical processes, but also for the livelihood of forest dependent communities for which its continual existence is a necessity. This study explored th... Forest ecosystems are vital not only for the ecosystem and biogeochemical processes, but also for the livelihood of forest dependent communities for which its continual existence is a necessity. This study explored the pattern of forest use in the hinterlands of the Niger Delta and sought to elucidate the drivers of forest loss and how the ownership and management of the forest plots influenced the changes in the forest ecosystem. Ecosystem services reduction and forest loss/degradation were found to be increasing over the years due to crude oil activities, urbanization/developments, population increase, agricultural activities and natural causes like flood. While each factor contributed to forest loss directly and indirectly, and varied from community to community, agricultural activities and population growth were responsible for most of the losses across the landscape. Even though agricultural activities were essential and thrived in the region, sustainable forest (land) uses could have reduced the associated implications of such land uses;but this was however hampered by the farming practises (shifting cultivation) across most of the communities. Lack of proper, effective and sustainable forest management structures, poor individual commitment and monitoring of forest activities were found to encourage forest loss at different spatial scales. Provision of alternative sources of livelihood and ensuring that suitable guidelines on forest abstraction and harvest are enforced across the region, are steps to promoting biodiversity conservation and resource management. 展开更多
关键词 Community forest MANAGEMENT Ecosystem Services forest loss Resilience Sustainable MANAGEMENT
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Measuring economic loss caused by ecological damages: a case study of China's forest ecosystem in 2005
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作者 CAO Ying 《Ecological Economy》 2010年第1期45-50,共6页
At present about 60% of ecosystem has been damaged and degraded severely, resulting in enormous eco logical loss globally. The essential cause is the irrational utilization of ecosystem by humankind, so it is the key ... At present about 60% of ecosystem has been damaged and degraded severely, resulting in enormous eco logical loss globally. The essential cause is the irrational utilization of ecosystem by humankind, so it is the key to changing improper environmental performance of humankind so as to prevent ecosystem from being damaged. The quantitative valuation on the loss of ecological damage is an effective tool to guide human eco environmental per formance. In this paper, the concepts related to the valuation on ecological damage cost are introduced; uncertain ties that might arise in the valuation on the loss of ecological damage such as area coverage of valuation, ecological damage quantity, borders of ecological damage cost and data support are analyzed; and the valuation approaches for the loss of ecological damage are also discussed. As a case study, the economic losses of ecological damage of forest in 2005 in China are valuated. 展开更多
关键词 森林生态系统 生态破坏 经济损失 中国 人类生态 破坏损失 环保性能 估价方法
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福建省县域森林损失时空演变特征及其影响因素分析
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作者 朱玮晗 林金煌 +3 位作者 杨舒棋 陈梅英 戴永务 朱艳萍 《生态与农村环境学报》 CAS CSCD 北大核心 2024年第4期499-512,共14页
森林是陆地生物圈重要的生态资源,厘清区域长期森林损失状况及其影响因素,对森林资源保护和社会经济协调发展具有重要意义。基于全球森林变化(Global Forest Change)数据集,利用ArcGIS 10.8空间分析技术,对2001—2019年福建省58个县域... 森林是陆地生物圈重要的生态资源,厘清区域长期森林损失状况及其影响因素,对森林资源保护和社会经济协调发展具有重要意义。基于全球森林变化(Global Forest Change)数据集,利用ArcGIS 10.8空间分析技术,对2001—2019年福建省58个县域森林损失的时空演变特征进行分析,并结合时空地理加权回归模型,探究县域森林损失的主要影响因素及其时空分异特征。结果表明:(1)2001—2019年福建省县域森林损失率呈波动上升的基本态势,森林损失面积累计达112.89万hm^(2),森林损失情况可划分为显著上升阶段、先降后升阶段和显著下降阶段。(2)整体上,福建省县域森林损失具有较强的空间正相关性和空间集聚性特征,相邻区域森林损失率的空间相关性显著,而其空间集聚效应呈现西北低、东南高的基本态势。(3)城镇化率、人均GDP、公路通车里程、人口密度和木材产量对福建省县域森林损失均具有一定的影响,但存在明显的时空异质性特征。该研究有效揭示了福建省县域森林损失时空动态特征及其影响因素,可为森林资源可持续经营提供理论依据。 展开更多
关键词 森林损失 时空演变 影响因素 时空地理加权回归 福建省
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中国农田磷流失风险评价及其关键驱动因素
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作者 郑博福 刘海燕 +4 位作者 吴汉卿 吴之见 刘忠 朱锦奇 万炜 《农业工程学报》 EI CAS CSCD 北大核心 2024年第2期332-343,共12页
农田面源磷流失是农业面源污染的重要原因之一,识别流域内农田磷流失风险的关键源区及其影响因子是面源污染控制的重要手段。基于磷指数模型开展2000—2020年中国农田磷流失风险评估,选取土壤有效磷含量、磷肥施用量为源因子,土壤侵蚀... 农田面源磷流失是农业面源污染的重要原因之一,识别流域内农田磷流失风险的关键源区及其影响因子是面源污染控制的重要手段。基于磷指数模型开展2000—2020年中国农田磷流失风险评估,选取土壤有效磷含量、磷肥施用量为源因子,土壤侵蚀模数、年径流深、农田和水体间归一化距离指数为迁移因子,结合GIS技术评估了中国农田磷流失的关键源区;在此基础上,利用随机森林法分析影响中国农田磷流失的关键因子,并通过结构方程模型揭示了农田磷流失风险指数与各因子的关系。结果表明:1)2000—2020年中国农田的磷流失的低、中、高、极高风险面积分别占农田总面积的43.8%、40.5%、13.4%、2.4%。2)中国农田磷流失在2000、2005、2010、2015、2020年高风险和极高风险总面积的年平均占比从大到小依次为:淮河流域、长江流域、珠江流域、东南诸河流域、松辽河流域、西南诸河流域、黄河流域、内陆河流域、海河流域。3)影响农田磷流失风险的关键源因子和迁移因子分别为土壤有效磷含量和归一化距离指数,其重要性特征值分别为129.53和65.12,土壤有效磷含量是农田磷流失最主要影响因子。4)磷流失风险指数与源因子指数、迁移因子指数呈极显著正相关,选取的14个指标对磷指数的解释度达0.62,其中源因子和迁移因子对磷指数的贡献率分别为0.77、0.19(P <0.001)。研究结果可为中国农田磷流失风险评估提供科学参考,对中国农业面源污染的宏观防控及战略决策具有重要意义。 展开更多
关键词 农田 面源污染 磷指数模型 磷流失 风险评价 关键因子 随机森林 结构方程模型
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基于RF-FL-LightGBM算法的信用风险评估模型研究
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作者 苗月 吴陈 《计算机与数字工程》 2024年第3期808-813,共6页
为了解决大数据环境下高维度稀疏的客户信用特征以及样本不平衡问题,从而提高客户的信用评估准确度,论文提出了基于RF-FL-LightGBM算法的信用风险评估模型。首先利用随机森林(RF)对高维数据进行重要性排序和筛选,剔除容易引起模型过度... 为了解决大数据环境下高维度稀疏的客户信用特征以及样本不平衡问题,从而提高客户的信用评估准确度,论文提出了基于RF-FL-LightGBM算法的信用风险评估模型。首先利用随机森林(RF)对高维数据进行重要性排序和筛选,剔除容易引起模型过度拟合和冗余无效的特征;其次将基于Focal Loss函数改进后的二分类平衡交叉嫡损失函数(FL)作为LightGBM模型的损失函数,以此改善正负样本不平衡导致模型准确度降低的情况,从而提高模型的分类性能。使用某金融租赁公司的历史客户数据集进行实验,结果表明,RF-FL-LightGBM模型的F1值、AUC值都明显高于XGBoost和LigthGBM模型。RF-FL-LightGBM算法不仅有效处理了高维稀疏不平衡样本数据,还提高了客户属性的分类精确度且执行效率更高。 展开更多
关键词 信用风险评估 随机森林 特征选取 Focal loss LightGBM算法
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改良剂对红壤水土流失恢复林地土壤细菌群落结构的影响
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作者 袁华光 章仕斌 《亚热带水土保持》 2024年第2期1-5,24,共6页
为探究不同改良剂对红壤恢复林地土壤细菌群落结构的影响差异,提高红壤恢复林地的土壤质量和水土保持效能,本研究以亚热带红壤区马尾松(Pinus massoniana Lamb.)恢复林地为研究对象,设置原状林地(CK)和施加有机改良剂(OF)、生物炭(BF)... 为探究不同改良剂对红壤恢复林地土壤细菌群落结构的影响差异,提高红壤恢复林地的土壤质量和水土保持效能,本研究以亚热带红壤区马尾松(Pinus massoniana Lamb.)恢复林地为研究对象,设置原状林地(CK)和施加有机改良剂(OF)、生物炭(BF)、复合改良剂(CF)3种处理,研究其土壤化学性质、土壤细菌群落相对丰度与多样性,探讨红壤区侵蚀退化恢复林地土壤肥力与细菌群落结构微生物群落结构对不同土壤改良剂的响应,分析土壤化学性质与细菌群落结构间的相关性。结果表明:(1)不同改良剂使土壤pH值与有机碳含量分别显著(P<0.05)提高了4.20%~6.72%与40.20%~102.37%,有机改良剂使土壤全磷含量提高了56.98%(P<0.05),生物炭使土壤全氮含量提高了73.09%(P<0.05),复合改良剂使土壤全磷与全氮含量分别提高了64.57%与72.09%(P<0.05);(2)施加不同改良剂土壤细菌群落优势菌门均为变形菌门、放线菌门与酸杆菌门,优势菌纲均为酸杆菌纲、α-变形菌纲与放线菌纲;(3)所有土壤改良剂均降低了细菌群落多样性,而施加生物炭提高了土壤细菌群落丰富度;(4)土壤全磷含量对细菌群落组成产生显著影响,有机碳含量与细菌群落多样性呈负相关;(5)施加复合改良剂提高了土壤细菌群落新陈代谢通路相对丰度。本研究结果可为提升红壤区恢复林地土壤肥力,合理调节细菌群落结构提供理论支撑与数据支撑。 展开更多
关键词 水土流失 红壤 恢复林地 土壤改良剂 细菌群落结构 高通量测序技术
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Effects of acid deposition on forests in south China
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作者 Feng Zong wei, Tao Fu lu Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1998年第4期122-126,共5页
Acid deposition has caused serious damage to the forests of China. In this paper, the quantification theory I is used to calculate the forest volume loss caused by acid disposition in seven provinces of south China. T... Acid deposition has caused serious damage to the forests of China. In this paper, the quantification theory I is used to calculate the forest volume loss caused by acid disposition in seven provinces of south China. The results showed that contribution rates of acid deposition to forest volume loss in seven provinces of south China vary from 24 5% to 37 91%; the volume loss rates range from 7% to 20%. Total volume losses per year are 1 0145×10 6 m 3, of which Zhejiang Province is the greatest, totalling 3 841×10 5 m 3, while Anhui Province is the least, amounting to 1 59×10 4 m 3. 展开更多
关键词 acid deposition DAMAGE forest volume loss.
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Response of Nitrogen Leaching to Nitrogen Deposition in Disturbed and Mature Forests of Southern China 被引量:5
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作者 FANG Yun-Ting M. YOH +2 位作者 MO Jiang-Ming P. GUNDERSEN ZHOU Guo-Yi 《Pedosphere》 SCIE CAS CSCD 2009年第1期111-120,共10页
Current nitrogen (N) leaching losses and their responses to monthly N additions were investigated under a disturbed pine (Pinus massoniana) forest and a mature monsoon broadleaf forest in southern China. N leaching lo... Current nitrogen (N) leaching losses and their responses to monthly N additions were investigated under a disturbed pine (Pinus massoniana) forest and a mature monsoon broadleaf forest in southern China. N leaching losses from both disturbed and mature forests were quite high (14.6 and 29.2 kg N ha-1 year-1, respectively), accounting for 57% and 80% of their corresponding atmospheric N inputs. N leaching losses were substantially increased following the first 1.5 years of N applications in both forests. The average increases induced by the addition of 50 and 100 kg N ha-1 year-1 were 36.5 and 24.9 kg N ha-1 year-1, respectively, in the mature forest, accounting for 73.0% and 24.9% of the annual amount of N added, and 14.2 and 16.8 kg N ha-1 year-1 in the disturbed forest, accounting for 28.4% and 16.8% of the added N. Great N leaching and a fast N leaching response to N additions in the mature forest might result from long-term N accumulation and high ambient N deposition load (greater than 30 kg N ha-1 year-1 over the past 15 years), whereas in the disturbed forest, it might result from the human disturbance and high ambient N deposition load. These results suggest that both disturbed and mature forests in the study region may be sensitive to increasing N deposition. 展开更多
关键词 大气氮沉积 氮增加 氮流失 氮饱和 亚热带森林
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Land Cover Change in a Freshwater Swamp Forest Landscape: Implications for Biodiversity Conservation
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作者 Nwabueze I. Igu Joseph O. Duluora 《Journal of Environmental Protection》 2019年第12期1578-1590,共13页
Forest landscapes are under much pressure globally due to changes in land use and their biodiversity and services are threatened at increasing magnitude especially in the tropics. Biodiversity and ample forest cover s... Forest landscapes are under much pressure globally due to changes in land use and their biodiversity and services are threatened at increasing magnitude especially in the tropics. Biodiversity and ample forest cover still remain in freshwater forest landscapes in the Niger basin of Nigeria, but are declining at astronomical scales across the region. To better understand the changes and modifications going on in the ecosystem at the landscape level, a thirty-year study (1987-2017) was conducted using remotely sensed Landsat imageries. These were processed and used to verify the dynamics in land cover changes and their major drivers. Land use change across the region reduced the forest extent and forest cover (up to 50.2 percent) of the natural ecosystems which served as the habitats for the indigenous species. Sparse vegetation and bare soil/farmlands increased over the study period and were seen as the major indices for modifications and forest loss in the area. Since land use indices such as agricultural activities were seen as one of the major factors of land cover change, sustainable forest use and management practices that accommodate agricultural practices were advocated. While the forest cover and ultimately their biodiversity and conservation prospects reduced following forest loss in the region, efforts should be targeted at conserving the pockets of vegetation seen in the sparsely vegetated zones and also maximize the potentials that the biodiversity in the agro-forested locations offers. 展开更多
关键词 BIODIVERSITY Carbon CLIMATE CHANGE forest loss Land Use CHANGE Modification
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Effects of litter quality and climate change along an elevational gradient on litter decomposition of subalpine forests, Eastern Tibetan Plateau, China 被引量:7
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作者 Zhenfeng Xu Jianxiao Zhu +3 位作者 Fuzhong Wu Yang Liu Bo Tan Wanqin Yang 《Journal of Forestry Research》 SCIE CAS CSCD 2016年第3期505-511,共7页
Temperature and freeze-thaw events are two key factors controlling litter decomposition in cold biomes.Predicted global warming and changes in freeze-thaw cycles therefore may directly or indirectly impact litter deco... Temperature and freeze-thaw events are two key factors controlling litter decomposition in cold biomes.Predicted global warming and changes in freeze-thaw cycles therefore may directly or indirectly impact litter decomposition in those ecosystems. Here, we conducted a2-year-long litter decomposition experiment along an elevational gradient from 3000 to 3600 m to determine the potential effects of litter quality, climate warming and freeze-thaw on the mass losses of three litter types [dragon spruce(Picea asperata Mast.), red birch(Betula albosinensis Burk.), and minjiang fir(Abies faxoniana Rehd. et Wild)]. Marked differences in mass loss were observed among the litter types and sampling dates. Decay constant(k) values of red birch were significantly higher than those of the needle litters. However, mass losses between elevations did not differ significantly for any litter type.During the winter, lost mass contributed 18.3-28.8 % of the net loss rates of the first year. Statistical analysis showed that the relationships between mass loss and litter chemistry or their ratios varied with decomposition periods. Our results indicated that short-term field incubations could overestimate the k value of litter decomposition.Considerable mass was lost from subalpine forest litters during the wintertime. Potential future warming may not affect the litter decomposition in the subalpine forest ecosystems of eastern Tibetan Plateau. 展开更多
关键词 Alpine forest Elevational gradient FREEZE-THAW Global warming Mass losses
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Optimal plot design in a multipurpose forest inventory
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作者 Helena M.Henttonen Annika Kangas 《Forest Ecosystems》 SCIE CSCD 2016年第1期37-50,共14页
Background: We explore the factors affecting the optimal plot design (size and type as well as the subsample tree selection strategies within a plot) and their relative importance in defining the optimal plot desig... Background: We explore the factors affecting the optimal plot design (size and type as well as the subsample tree selection strategies within a plot) and their relative importance in defining the optimal plot design in amultipurpose forest inventory. The factors include time used to lay out the plot and to make the tree measurements within the plot, the between-plot variation of each of the variables of interest in the area, and the measurement and model errors for the different variables. Methods: We simulate different plot types and sizes and subsample tree selection strategies on measuredtest areas from North Lapland. The plot types used are fixed-radius, concentric and relascope plots. Weselect the optimal type and size first at plot level using a cost-plus-loss approach and then at cluster level byminimizing the weighted standard error with fixed budget. Results: As relascope plots are ve~/efficient at the plot level for volume and basal area, and fixed-radius plots for stems per ha, the optimal plot type strongly depends on the relative importance of these variables. The concentric plot seems to be a good compromise between these two in many cases. The subsample tree selection strategy was more important in selecting optimal plot than many other factors. In cluster level, the most important factor is the transfer time between plots. Conclusions: While the optimal radius of plots and other parameters were sensitive to the measurement times and other cost factors, the concentric plot type was optimal in almost all studied cases. Subsample tree measurement strategies need further studies, as they were an important cost factor. However, their importance to the precision was not as clear. 展开更多
关键词 SAMPLE PLOT forest inventory MEASUREMENT COST loss
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Runoff and sediment concentration of different parts of a road in Hyrcanian forests 被引量:1
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作者 Majid LOTFALIAN Aidin PARSAKHOO +1 位作者 Ataollah KAVIAN Seyed Ataollah HOSSEINI 《Forestry Studies in China》 CAS 2013年第2期144-151,共8页
Road prisms, such as cutslopes, fillslopes and road surfaces, can be important contributors of sediment to streams in forested watersheds. In this study rainfall simulations were carried out on cutslopes, fillslopes, ... Road prisms, such as cutslopes, fillslopes and road surfaces, can be important contributors of sediment to streams in forested watersheds. In this study rainfall simulations were carried out on cutslopes, fillslopes, road surfaces and forest grounds in hardwood forests of Lolet and Lat Talar, Iran. Water at intensity of 32.4 mm·h-1 was sprayed from a nozzle onto a square area of 0.48 m2. Runoff was collected by water gauge every 4 min and then runoff and sediment parameters were measured in each plot. Results indicated that on road surfaces, the runoff coefficient was 63.28%. On the cutslopes and fillslopes, the runoff coefficients were 35.14% and 10.23%, respectively. On the forest ground as a control, the runoff coefficient was 5.90%. Runoff volume was 2.73 mL·s^-1 on the road surfaces and 1.52 mL·s^-1 on cutslopes. On fillslopes the runoff volume was 0.44 mL·s^-1 and on the forest ground 0.25 mL·s^-1 The greatest rate of soil loss was found on the cutslope (280.79 g·m-2·h-1). The total soil loss from the cutslopes was two times higher than that from the road surfaces and six times higher than that from the fillslopes. We conclude that cutslopes can be considered the main source of sediments in our study sites, but the function of road surface as a source of runoff generation is more important. 展开更多
关键词 RUNOFF soil loss road prism rainfall simulation Hyrcanian forest
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Analysis of Land Use Change and Associated Implications on Soil Ecosystem Functions in South Eastern Nigeria
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作者 Nwabueze I. Igu Chinero N. Ayogu +1 位作者 Chidimma C. Umeogu Michael C. Obikwelu 《Journal of Geoscience and Environment Protection》 2023年第5期126-134,共9页
Land use change affects soil functions and its capacity to provide ecosystem services. Though much of the tropics are experiencing accelerated increases in land use change, associated impacts of such changes are poorl... Land use change affects soil functions and its capacity to provide ecosystem services. Though much of the tropics are experiencing accelerated increases in land use change, associated impacts of such changes are poorly understood and studied. This study assessed the extent to which land use changes affect the soil ecosystem functions in a rainforest zone of south eastern Nigeria. Soil samples were collected from 24 sample locations in selected natural forest, cashew and palm plantations. Samples were analyzed in triplicate in the laboratory for geochemical analysis, after which the result was subjected to statistical analysis—ANOVA, correlation and regression. Forest carbon had higher % mean carbon content;though there was no significant difference (F (2, 21) = .246, p = .784) in carbon level across land uses. R value of .301 showed low correlation between % carbon, organic matter and % loss in ignition. Furthermore, R<sup>2</sup> value of 9.1% total variation in the dependent variable could only be explained by the independent variables. CEC, Nitrogen, Potassium and Phosphorus content of the land uses did not differ significantly: CEC (F (2, 21) = .844, p (.44);Nitrogen (.243), p (.79), Potassium (.140), p (.87), Phosphorus (.783), p (.47). This showed that there was no significant variation in soil fertility of the land uses, although natural forest had higher concentrations for these variables. Across the land uses, soil texture equally had no significant variations: % sand (F (2, 21) = .320, p (.729) % clay (.430), p (.656), % silt (.043), p (.958). Soil carbon was seen to be more enhanced in natural forest ecosystems than other land uses. Though plantations had reduced capacities to provide ecosystem functions, establishing such in modified landscapes is still advocated as they can coexist with such and yet ensure ecosystem functions. 展开更多
关键词 Climate Change Ecosystem Services forest loss Modification Soil Processes
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Assessment of Past and Future Land Use/Land Cover Dynamics of the Old Kumasi Metropolitan Assembly and Atwima Nwabiagya Municipal Area, Ghana
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作者 Addo Koranteng Bernard Fosu Frimpong +2 位作者 Isaac Adu-Poku Jack Nti Asamoah Tomasz Zawiła-Niedźwiecki 《Journal of Geoscience and Environment Protection》 2023年第3期44-69,共26页
Ghana like all countries in Sub-Saharan region of Africa have long been undergoing intense land use land cover changes (LULCC) which have given rise to extensive forest loss (deforestation and degradation), loss of ar... Ghana like all countries in Sub-Saharan region of Africa have long been undergoing intense land use land cover changes (LULCC) which have given rise to extensive forest loss (deforestation and degradation), loss of arable land and land degradation. This study assessed the past LULCC in the Atwima Nwabiagya which contains the Barekese and Owabi Headworks) and the old Kumasi Local Assemblies’ areas in Ghana and projected the scenario in 2040 for business-as-usual (BAU). The synergies of satellite imagery of 1990, 2000, 2010 and 2020 were classified with an overall accuracy of 90%. Markov Cellular-Automata method was used to forecast the future LULC pattern after detecting main driving forces of LULCC. The findings showed an extensive increase in built up areas from 11% in 1990 to 39% in 2020 owing largely to 23% decrease in forest cover and 6% decrease in agricultural lands within the past 30 years (1990-2020). The projected LULC under the BAU scenario for 2040 showed built-up surge from 39% to 45% indicating additional forest loss from 43% in 2020 to 40% and decreasing agricultural land from 17% to 14%. The main driver for the LULCC is clearly anthropogenic driven as the human population in the study area keeps rising every censual year. This study exemplifies the fast-tracked forest loss, loss of arable land and challenges on ecosystem sustainability of the Barekese-Owabi-Kumasi landscape. The current and projected maps necessitate the apt implementation of suitable interventions such as reforestation, protection measures and policy decision in deliberate land use planning to mitigate further loss of forest cover and safeguard the Barekese and Owabi headworks. 展开更多
关键词 forest loss Random forest Classifier Change Detection URBANIZATION Markov-Cellular Automata
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Urbanization and Other Land Use Land Cover Change Assessment in the Greater Kumasi Area of Ghana
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作者 Addo Koranteng Isaac Adu-Poku +3 位作者 Bernard Fosu Frimpong Jack Nti Asamoah John Agyei Tomasz Zawiła-Niedźwiecki 《Journal of Geoscience and Environment Protection》 2023年第5期363-383,共21页
Urbanization posits the expression of urban expanse expansion due to population growth, rise in built-up areas, high population density and its correspondingly urban way of life. Unrestrained impetus of development an... Urbanization posits the expression of urban expanse expansion due to population growth, rise in built-up areas, high population density and its correspondingly urban way of life. Unrestrained impetus of development and land use land cover change (LULCC) portent several issues such as unlawful urban sprawl, loss of agricultural land, forest loss and other associated complications. This study analyzed the dynamics of urbanization and other LULCC in Ghana’s Greater Kumasi area via Landsat images (TM 1986, OLI 2013 and OLI 2023) using ERDAS Imagine, Idrisi and ArcGIS software. Implementing supervised classification technique, the Maximum Likelihood Classifier (MLC) procedure was employed to categories the study area into five LULC classes. Accuracy assessment undertaken on the resultant LULC maps was deemed very satisfactory. The results from 1986-2023 pointed to an upsurge in a built-up extent as of 8% to 41%, a decrease in Closed Forest from 9% to 4%, another decrease in Open Forests from 64% to 33%, a slight increase from 16% to 20% in farmlands and a stable level of water share. Further analysis indicated that the study area had undergone LULCC within the periods 1986-2013 and 2013-2023 at 60% and 37% respectively. The findings showed uncontrolled urban sprawling along major roads and forest loss as deforestation outside protected areas and degradation in protected forest. The monitoring of urbanization and other LULCC is important for local, and national governments and other bodies charged with the implementation of programs and policies that manage and utilize natural resources. Development adapts to mitigate the effect on the environment. 展开更多
关键词 URBANIZATION Maximum Likelihood Classifier (MLC) Urban Sprawl Change Detection forest loss
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Characterization of Forest Degradation beyond Canopy Cover Change in Mau Forest, Kenya
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作者 Merceline Awuor Ojwala Felix Mutua Mwangi James Kinyanjui 《Open Journal of Forestry》 2022年第4期393-407,共15页
Monitoring Forest degradation is evidence enough to show a country’s commitment to monitor the forest trend both for national and local decision-making and international reporting processes. Unlike deforestation whic... Monitoring Forest degradation is evidence enough to show a country’s commitment to monitor the forest trend both for national and local decision-making and international reporting processes. Unlike deforestation which is easier to point out, monitoring forest degradation is quite a challenge since there is no universal definition and thus no clear monitoring methods apart from the canopy cover change. This research, therefore, sought to look at the degradation trends in the Mau forest complex between 1995-2020 with the aim of finding out whether monitoring canopy density changes over time and quantifying these changes in terms of biomass loss could be a good approach in monitoring forest degradation. Forest Canopy Density (FCD) model was adopted focusing on using vegetation indices describing biophysical conditions of Vegetation, Shadow and Bareness to monitor changes in canopy density as a parameter for describing forest degradation in the forest blocks of Maasai Mau and Olpusimoru in Mau forest complex. Results indicated how different vegetation indices responded to changes in the vegetation density and eventually changes in the canopy density values which were converted in terms of biomass loss. The forest Canopy Density model proved to be a good tool for monitoring forest degradation since it combines different biophysical indices with different characteristics capturing what is happening below the canopy. 展开更多
关键词 forest Degradation Canopy Density Vegetation Indices Biomass loss MONITORING
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