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61.
62.
天然橡胶产业生态系统管理是实现天然橡胶产业可持续发展的生态途径。本文在系统分析天然橡胶产业生态系统结构和功能的基础上,以海南为例,提出了天然橡胶产业生态系统管理的基本模式,其中重点探讨了天然橡胶产业生态系统管理的基本原则、管理步骤及管理途径,旨在为天然橡胶产业生态系统健康和可持续发展提供理论依据和实践指导。  相似文献   
63.
对安庆市南埂林场长江沿岸杨树抑螺防病林3年生、8年生和20年生林地上空间昆虫群落的种群组成和多样性进行了调查。结果表明,在3种不同林龄林分之间,地上空间昆虫种群组成的差异表现为,在目一级分类单元组成上,3种不同林龄林分具有很高的共性,在科和种的单元上,不同林龄林分之间的差异大小依次为:3年生与20年生林分之间>3年生与8年生林分之间>8年生与20年生林分之间。随着林分林龄的增加,林内地上空间昆虫丰富度指数、Shannon-Wiener指数明显降低。不同林龄林分地上空间昆虫种群的均匀度指数与林分林龄无明显的相关性,其中20年生林分昆虫种群的均匀度指数显著低于8年生和3年生的林分,而8年生和3年生林分之间没有显著差异。  相似文献   
64.
华南地区种植园地广泛分布,类型混杂多样,导致园地分布信息难以正确获取,为农业管理造成了较大困难。本研究基于Landsat8 OLI数据,通过数据融合、特征优化,应用随机森林算法构建面向对象的种植园地分类规则集,对华南地区典型经济作物香蕉、柑橘、葡萄、蒲葵、海枣、番木瓜和火龙果等进行类别识别,同时对比贝叶斯分类法、K最邻近分类法、支持向量机法、决策树分类法的分类效果。结果表明:数据融合会在一定程度上影响分类结果精度;植株形态、光谱特征接近,种植期交错是影响华南地区典型园地分类精度的重要原因;以中分辨率影像为数据源,面向对象的随机森林算法应用于种植园地分类研究总体精度可达88.05%,Kappa系数0.87,可以有效区分华南地区典型种植园地类别;相比于其他算法,随机森林算法在分类精度、可靠性和稳定性上具有一定优势,可为园地作物生长监测和种植管理提供科学依据。  相似文献   
65.
比较研究了杨梅园、地瓜山、柑桔园、李园 、普通山地等不同地类毛竹移栽母造林的新竹株数、新竹质量好坏、新竹最大扩展范围、竹鞭的质量及扩展范围差异。从造林的总体质量看,杨梅园、地瓜地坡耕地是最好的毛竹栽植地,柑桔园、李园的毛竹栽植效果也较好,但普通山地造林效果最差。  相似文献   
66.
BOOK REVIEWS     
Book Reviewed in this article: Development and Environment in Peninsular Malaysia . S. Robert Aiken, Colin H. Leigh, Thomas R. Leinbach, Michael R. Moss. The Rural-Urban Fringe: Canadian Perspectives . Ken B. Beesley and Lorne H. Russwurm, eds. Women and Development . Lourdes Benería, ed. The Border that Joins: Mexican Migrants and U.S. Responsibility . Peter G. Brown and Henry Shue, eds. Cities of the World: World Regional Urban Development . Stanley D. Brunn and Jack L. Williams, eds. Time Resources, Society, and Ecology: On the Capacity for Human Interaction in Space and Time (Vol. I, Preindustrial Societies). Tommy Carlstein. Urban Geography . David Clark. Spanish City Planning in North America . Dora P. Crouch, Daniel J. Garr, and Axel I. Mundigo. Not On Our Street: Community Attitudes to Mental Health Care . M. J. Dear and S. M. Taylor Unequal growth: Urban and Regional Employment Change in the U.K. Stephen Fothergill and Graham Gudgin. Agricultural Land in an Urban Society . Owen J. Furuseth and John T. Pierce. The Petroleum Industry in Oil-Importing Developing Countries . Fariborz Ghadar. Historical Understanding in Geography, An Idealist Approach . Leonard Guelke. Regional Planning in Europe . R. Hudson and J. R. Lewis, eds. Remote Sensing for Resource Management . Chris J. Johannsen and James L. Sanders, eds. Geography and The State . R. J. Johnston. Texas Graveyards: a Cultural Legacy . Tlrry G. Jordan. The Politics of Location: An Introduction . Andrew Kirby. A Social Geography of the City . David Ley. Energy and the Future . Douglas MacLean and Peter Brown, eds. The Natural Environment of Newfoundland Past and Present . A. G. Macpherson and J. B. Macpherson, eds. Tourism: Economic, Physical and Social Impacts . Alister Mathieson and Geoffrey Wall. Railroads and Land Grant Policy: A Study in Government Intervention . Lloyd J. Mercer. Progress in Rural Geography . Michael Pacione, ed. Progress in Urban Geography . Michael Pacione, ed. Models of Spatial Inequality: Settlement Patterns in Historical Archaeology . Robert Paynter. Natural Hazard Risk Assessment and Public Policy, Anticipating the Unexpected . William J. Petak and Arthur A. Atkisson. The Nature of Geomorphology . Alistair F. Pitty. Regional Conflict and National Policy . Kent A. Price Women and Spatial Change: Learning Resources for Social Science Courses . Arlene C. Rengert and Janice J. Monk, eds. Urban and Regional Analysis for Development Planning . Richard Rhoda. Rivers: Form and Process in Alluvial Channels . Keith Richards. This Remarkable Continent: An Atlas of United States and Canadian Society and Culture . John F. Rooney, Jr., Wilbur Zelinsky, and Dean R. Louder, gen. eds. The Origins of Open-Field Agriculture . Trevor Rowley, ed. Residential Location Determinants of the Older Population . Gundars Rudzitis. Borderland Sourcebook: A Guide to the Literature on Northern Mexico and the American Southwest . Ellwyn R. Stoddard, Richard L. Nostrand, and Jonathan P. West, eds. Arctic and Antarctic . David Sugden. Tall Timbers Ecology and Management Conference, February 22–24, 1979, Proceedings No. 16 . Graphic Communication and Design in Contemporary Cartography (Progress in Contemporary Cartography , Vol. II). D. R. Fraser Taylor, ed. Living with Energy Shortfall: A Future for American Towns and Cities . Jon Van Til. The United States: Habitation of Hope . J. Wreford Watson. Air Photo Interpretation for Archaeologists . D. R. Wilson. Urban and Rural Change in West Germany . Trevor Wild, ed. Population and Resources . Harry Robinson.  相似文献   
67.
The effects of environmental factors on carbon flux were analyzed, the spatial and temporal variation of carbon flux was studied at the two heights of 23 m and 39 m with the eddy covariance technique, and the carbon budget was evaluated for evergreen coniferous plantation in the red earth hilly area during the year 2003. The results showed that photosynthetically active radiation (PAR) and soil temperature are essential factors strongly affecting the net ecosystem exchange (NEE); in the daytime, the response of NEE to PAR shows a rectangular hyperbola trend, and in the nighttime, the significant correlation was observed between soil temperature and soil respiration which was filtered using friction velocity. This ecosystem appeared as a carbon sink along the whole year of 2003, and the carbon flux showed the obvious seasonal fluctuation and diurnal variability. The seasonal peak of NEE occurred in May and June with the daily sum about 0.61-0.67 mg · CO2 · m-2 · s-1. For the severe drought in the mid-summer, the daily sum was 0.40-0.44 mg · CO2 · m-2 · s-1 in July which was only 2/3 of that in the last two months. For the lasted drought of the year, the nadir of NEE happened in the winder with the daily sum about -0.29 to -0.35 mg · CO2 · m-2 · s-1. The sink intensity of the ecosystem was about -0.553 to -0.645 kg · Cm-2 per year in 2003.  相似文献   
68.
Alluvial fans are usually constructed through episodic flood events. Despite the significance of these ephemeral floods on the morphodynamics of alluvial fans, depositional responses to the variations in flood conditions are still poorly documented. This greatly limits the ability to interpret ancient sedimentary successions of fans and the associated flood hydrodynamics. The Quaternary Poplar Fan from endorheic Heshituoluogai Basin provides an optimal case for addressing this issue. Based on the variations in facies associations and flood conditions, three depositional stages – namely; lobe building stage, channel building stage and the abandonment stage – are identified. During the lobe building stage the Poplar Fan is predominately constructed through incised channel flood, sheetflood and unconfined streamflood, with coeval development of distal surficial ephemeral ponds. The channel building stage is characterized by the development of gravelly braided rivers. However, only scour pool fill deposits are preferentially preserved in the Poplar Fan. During the abandonment stage, erosional lags and aeolian sands randomly occur throughout the fan, while gully deposits can only be found in the distal fan. The distinctive facies architecture of the Poplar Fan is likely to be the result of periodicity of climate fluctuations between wetter and drier conditions during the Late Pleistocene to Holocene. The ephemeral floods formed under wetter conditions usually show high discharge and sediment concentrations which facilitate the lobe building processes. During the drier periods, only gravelly braided rivers can be developed through ephemeral floods as the intensity and frequency in precipitation, discharge and sediment concentrations of the flood flows significantly decrease. The abandonment stage of the fan may occur between recurring flood episodes or during the driest periods. Furthermore, the long-term (105 to 106 year) geomorphic evolution of the Poplar Fan shows the influence of tectonic activities. The ongoing thrust uplift tectonic activities have caused destruction of the fan but can also facilitate the fan-head trench/incision of the fan, which in turn facilitate the progradation of the fan. This study proposes a new depositional model for alluvial fans constructed through episodic flood events, which shows the character of both sheet-flood dominated and stream-flow dominated end members of alluvial fans. These findings supplement the understanding of the variability of the alluvial fans and provide means to characterize rock record of alluvial fans and their associated flood and climate conditions.  相似文献   
69.
秃杉人工林速生阶段的碳库与碳吸存   总被引:2,自引:0,他引:2  
对广西南丹山口林场速生阶段(11 a生)秃杉人工林的碳库与碳吸存进行了研究.结果表明,秃杉不同器官碳素含量为429.9~511.5 g/kg,各器官碳素含量排列顺序为树皮>树枝>树干>树根>树叶.草本层、灌木层和凋落物层平均碳素含量分别为452.9、407.7 g/kg和430.7 g/kg.土壤(0~80 cm)碳素含量为16.71 g/kg,随土层深度的增加各层次土壤碳素含量逐渐减少.秃杉人工林生态系统碳库为172.49 t/hm2,其中乔木层为39.06t/hm2,占生态系统碳库的20.92%;灌草层为0.20 t/hm2,占0.12%;凋落物层为0.98 t/hm2,占0.57%;土壤层为135.22 t/hm2,占78.39%.秃杉各器官的碳库与其生物量成正比例关系,树干的生物量最大,其碳库也最大,占乔木层碳库的52.06%.速生阶段秃杉林年净生产力为8.62 t/(hm2·a),碳素年净固定量为4.06 t/(hm2·a).  相似文献   
70.
基于树木年轮信息的千烟洲人工林碳蓄积的动态分析   总被引:2,自引:0,他引:2  
The authors developed a model to estimate annual tree growth based on tree-ring data (Abbr. TGTRing model) derived from the trunk at 0.5, 1.3 and 2.5 m height. This model was applied to estimate the annual biomass and carbon accumulation of a plantation in Qianyanzhou Red-Soil Hill Comprehensive Development Experimental Station of CAS in Taihe County, Jiangxi Province (Abbr. Qianyanzhou). The results showed that the inflexion points of the biomass and carbon accumulation curves occur at 17 and 18 years of age, respectively, in masson pine, whilst both inflexion points occurred at 15 years in slash pine and Chinese fir. The biomass and carbon accumulation in Chinese fir proved to be greater in the last 20 years than in the other species, with 171.697 t/hm2 and 92.29 tc/hm2, respectively. masson pine, with a biomass of 133.84 t/hm2 and a carbon accumulation of 73.92 tc/hm2 was the lowest whilst slash pine was intermediate with a biomass of 147.639 t/hm2 (unturpentined) and 135.743 t/hm2 (turpentined), and a carbon accumulation of 80.18 tc/hm2 (unturpentined) and 73.72 tc/hm2 (turpentined). In 2006, the total biomass and carbon storage of the tree stratum of masson pine in Qianyanzhou was 3324.43 t and 14,156.64 tc, respectively, whilst the values for Chinese fir were 1326.97 t and 713.27 tc. For slash pine the total biomass was 14,156.64 t (unturpentined) and 13,015.97 t (turpentined), and the total carbon storage was 7 688.21 tc (unturpentined) and 7068.78 tc (turpentined). Following the shaving of slash pine for resin, the total biomass was reduced by 1140.67 t and the total carbon storage fell by 619.43 tc.  相似文献   
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