五彩河采风

2002年国庆假期,笔者相约几位摄影友租车去新疆北端的布尔津五彩河岸摄影采风。 五彩河岸是一处由棕色、红色、橘黄色、浅黄色、绿色、紫黑色、乳白色的泥岩、砂岩组成的雅丹地貌。五彩斑斓的山丘河岸约     

黄土高原区景观生态特征与景观生态建设

黄土高原是黄河中游的黄土分布区 ,人类开发历史悠久 ,自然环境变化显著。长期以来 ,由于土地的不合理利用 ,水土流失严重 ,资源被破坏 ,生态环境日益恶化 ,属于生态脆弱区。人类活动强烈干扰 ,超过了生态系统的稳定极限而使之退化是该区的显著特征之一。景观生态学理论体系中的景观动态与演进、景观规划与建设以及景观保护等都是黄土高原生态环境所面临的主要问题。所以 ,强调人类活动对景观结构与生态过程影响 ,可为黄土高原地区生态环境建设提供理论依据。1　黄土高原区景观生态特征黄土高原位于我国西北荒漠区的前沿 ,北与毛乌素沙漠相…     

黄河源区景观格局与生态功能的动态变化

利用20世纪70年代、80年代与90年代三期遥感资料,选取有代表性的9个有关度量景观空间结构与景观异质性的定量指标,通过FRAGSTATS计算方法,系统研究了黄河源区景观生态结构与景观格局变化,表明在近30a来,区域景观空间格局趋于破碎化和多样化,其形成与发展的主要内在因素是高寒稀疏化草原草地、黑土化与杂类草草地和沙化草地等景观类型的迅速发展,其景观面积分别增加了384.16％、66.63％和421.09％;选取景观生物生产力、景观土壤养分、景观植被覆盖度等景观功能的表征参数,提出了景观格局动态演变下分析景观功能变化的定量方法及其数学模型。在明确近30a来区域景观格局演变特征的基础上,研究了黄河源区不同时段不同景观类型间生态功能的转移流动特征及其区域生态环境效应,表明：近30a来,黄河源区景观功能变化强烈;区域景观动态演变将形成区域内部景观功能向减退与增强两个方向的变化,两个方向的强度均衡将形成区域整体生态功能的特征。研究区域景观格局的动态变化所引起的区域生态功能演变特征,可充分认识区域生态系统变化的内在因素和演变趋势。     

不同地震烈度对灾区景观生态破坏程度的评价

利用地震前后的遥感资料和区域基础数据,结合地震对区域景观生态的破坏特征,分析地震前后景观生态系统过程变化以及不同地震烈度下的景观生态异质性。从景观稳定性和景观异质性出发,运用层次分析法,建立景观生态破坏评价的指标体系,对不同地震烈度下区域景观生态破坏程度进行评价,得出以下结论：（1）地震使大面积林地、耕地和草地破坏,山体滑坡、崩塌严重,裸地、裸岩面积大量增加。在大于Ⅸ级烈度区域,地震后,有林地和耕地面积减少了458．48km^2和91．16km^2,裸地（岩）面积增加了496．23km^2。（2）通过对Ⅸ级以上地震区的景观格局指标分析得出：地震前,区域整体的景观生态的多样性、均匀性、景观破碎度和优势度值均反映出区域的生态系统较为脆弱,地震造成了明显的景观空间异质,加速了生态环境退化。（3）运用层次分析法,从景观稳定性和景观异质性两个方面对不同烈度下景观生态破坏进行评价。得出：Ⅸ、Ⅹ和Ⅺ级地震烈度区域景观生态破坏程度综合值为0．42、0．66和0．80,即中度破坏、重度破坏和极度破坏。根据以上综合分析得出,Ⅷ级地震区域应属于轻微破坏级,建议“5．12”汶川大地震灾害生态环境恢复从建工作应重点考虑Ⅸ级以及Ⅸ级以上区域。     

不同地貌条件下景观对河流水质的影响差异

景观对河流水质的影响在不同地区、不同空间尺度上存在差异。以赤水河流域为研究对象,根据地貌特征将研究区分为喀斯特地貌和非喀斯特地貌,在划分的29个子流域内采集测试水质数据,所选用的水质指标有溶解氧(DO)、电导率(EC)、总氮(TN)和总磷(TP),运用空间分析及数理统计方法,分析流域内不同地貌区景观之间的差异,探究不同空间尺度上景观与水质指标之间的关系。结果表明:(1)流域内景观组成以林地和灌草为主,建设用地和耕地次之,景观组成在不同地貌区各空间尺度上存在差异。建设用地和耕地对水质具有负面影响,且在碳酸盐岩地区更显著;林地对水质具有正面影响;灌草对水质的影响相对复杂。(2)流域内水质表现为碳酸盐岩地区优于碎屑岩地区。景观破碎化指数与总氮(TN)、总磷(TP)呈正相关,是水质变化的重要影响因素;景观聚集度指数与溶解氧(DO)呈正相关;景观破碎化指数和景观聚集度指数与电导率(EC)的关系在两个地区呈相反的结果。(3)不同地貌区景观对河流水质具有不同程度的影响。在两个地区,景观组成对河流水质解释能力最大空间尺度均为河岸带尺度,解释率分别为53.4%和59.1%;景观格局对河流水质解释能力最大...     

基于地貌类型的中国东海大陆海岸带景观动态分析

基于东海地貌信息数据和6期景观数据,研究1990—2015年东海大陆海岸带地貌类型与景观动态变化特征,分析各地貌类型下景观格局时空分布规律。结果表明:(1)东海海岸带以丘陵地貌为主,其次是小起伏山地、平原、台地和中起伏山地。景观类型林地占主导,其次为耕地和建设用地。(2)平原、台地和丘陵地貌景观变化以耕地转为建设用地为主,小和中起伏山地则以草地转林地为主。(3)不同地貌单元下的景观变化剧烈程度依次为:平原>台地>丘陵>小起伏山地>中起伏山地,2005—2015年景观变化叠合度小于1990—2005年,景观变化剧烈程度下降。(4)地貌类型对景观分维数和稳定性指数影响差异较大,平原上水域分维数值最大,台地和丘陵耕地分维数最大,小起伏山地未利用地分维数最大,中起伏山地建设用地分维数最大,稳定性指数相反。耕地在海拔较低的地貌类型中趋于稳定,林地和草地多分布在海拔较高丘陵和山地,水域和建设用地在平原地区分维数最大,稳定性更强。     

城市边缘区景观生态规划的人工神经网络模型

景观生态规划是景观生态学的一个重要应用领域,本文在地理信息系统的辅助下引入了人工神经网络这一新兴应用技术,建立了城市边缘区景观生态规划的BP神经网络模型,模型以区域的高程、高程离差、坡度、坡度离差、地貌分区、离黄河距离、居民点数七个要素作为输入变量,选取斑块密度、分维数、Shannon多样性指数和聚集度指数作为输出变量,精心采集了20个样本对网络进行训练,结果表明网络收敛效果理想,泛化能力强,为景观生态规划提供了一个新的模拟分析手段。     

新疆荒漠中的梭梭和白梭梭（下）

生态地位和利用价值 梭梭和白梭梭适应干旱环境的能力很强,是荒漠地区防风固 沙和维护生态安全不可多得的优良树种。在实施西部大开发战略的生态环境保护和建设中,具有不可替代的生态地位和重要利用价值。它们所形成的天然植被,为许多荒漠动物提供了栖息环境,也是荒     

矿区废弃地复垦的景观生态规划与设计

景观生态学属于宏观尺度生态空间研究范畴,理论信心集中表现为空间异质性和生态整体性两方面。基于景观生态规划与设计的生态重建就是使采矿废弃地具有具体利用方式和一定水平的生产力,维持相对稳定的生态平衡,与周围景观牲相协调,最终达到生态整体性目标。矿区废弃地有多种类型,冰同类型具有不同的生态重建途径。矿区废弃地隶属各种尺度的景观类型,只有按照景观生态学原理,在宏观上设计出合理的景观格局,在微观上创造出适合     

Using Wind Tunnels to Predict Bird Mortality in Wind Farms: The Case of Griffon Vultures

Background

Wind farms have shown a spectacular growth during the last 15 years. Avian mortality through collision with moving rotor blades is well-known as one of the main adverse impacts of wind farms. In Spain, the griffon vulture incurs the highest mortality rates in wind farms.

Methodology/Principal Findings

As far as we know, this study is the first attempt to predict flight trajectories of birds in order to foresee potentially dangerous areas for wind farm development. We analyse topography and wind flows in relation to flight paths of griffon vultures, using a scaled model of the wind farm area in an aerodynamic wind tunnel, and test the difference between the observed flight paths of griffon vultures and the predominant wind flows. Different wind currents for each wind direction in the aerodynamic model were observed. Simulations of wind flows in a wind tunnel were compared with observed flight paths of griffon vultures. No statistical differences were detected between the observed flight trajectories of griffon vultures and the wind passages observed in our wind tunnel model. A significant correlation was found between dead vultures predicted proportion of vultures crossing those cells according to the aerodynamic model.

Conclusions

Griffon vulture flight routes matched the predominant wind flows in the area (i.e. they followed the routes where less flight effort was needed). We suggest using these kinds of simulations to predict flight paths over complex terrains can inform the location of wind turbines and thereby reduce soaring bird mortality.     

African Ethnicity as Mirage? Historicizing the Essence of the Igbo in Africa and the Atlantic Diaspora

The enslavement of Africans, which gave birth to the African Diaspora in the Atlantic world, scattered people who shared the same cultural and linguistic affinity but often lumped them together in identifiable regional patterns. A significant consequence of the pattern of trade was the emergence of identifiable “ethnic” and cultural patterns in the diaspora. Attention, therefore, has for a long time focused on the pattern of dispersion and the impact of the Atlantic slave trade on the emergence of New World cultures. This paper addresses what I call the “question of Igbo history, ethnicity and identity,” with a view to presenting a synthesis and a framework for understanding the essence of ndiIgbo as flexible in both Africa and the Atlantic Diaspora. The case of the Igbo suggests that identities are multi-layered, self imposed, as well as ascribed by others and as such require a critical analysis to avoid the essentialism that have bedeviled much of the discourse on African identity in the diaspora     

The Effect of Wind Speed on Assimilation Rate--a Re-assessment

Deneke concluded from wind-tunnel experiments that CO₂ uptakeis increased by wind, but that this stimulation is proportionatelyless at higher wind speeds, and that above Ioo m./min. (I₆₇cm./sec.) no further increase results. His data in fact indicatea linear relationship between wind and assimilation rate overthe whole range investigated. The wind speeds he used were ofthe same order as those occurring in vegetation in the field. Published experiments on the effect of wind on dry-weight increase,on the other hand, show that wind reduces growth; but theseexperiments have used winds equivalent to 'gale' or 'hurricane',and at such speeds other, harmful effects of wind become important. Wind-tunnel investigations on stands of Brassica napus reconcilethese observations by showing growth-rates to increase withwind speed up to an optimum near 30 cm./sec., and to fall offat higher speeds. It is considered that the stimulating effectof wind on assimilation shown by Deneke's and these experimentsis likely to be significant in the field.