英语翻译AbstractDespite the numerous values of riparian areas an

英语翻译
Abstract
Despite the numerous values of riparian areas and the recognition of fire as a critical natural disturbance,few studies have investigated the behavior,properties,and influence of natural fire in riparian areas of thewestern USA.Riparian areas frequently differ from adjacent uplands in vegetative composition and structure,geomorphology,hydrology,microclimate,and fuel characteristics.These features may contribute to different fire environments,fire regimes,and fire properties (frequency,severity,behavior,and extent) in riparian areas relative to uplands.In certain forested riparian areas,fire frequency has generally been lower,and fire severity has been more moderate than in adjacent uplands,but in other areas,fires have appeared to burn riparian areas with comparable frequency.Impacts of land use and management may strongly influence fire properties and regimes in riparian areas.Fire suppression,livestock grazing,logging,damming and flow regulation,agricultural diversions,channel modifications,and introduction of invasive species have led to shifts in plant species composition,structure and distribution of fuel loads,and changes in microclimate and areal extent of riparian areas.Cumulative impacts of human alterations are likely to exert the most pronounced influence on fire behavior during periods of drought and under conditions of extreme fire weather.Riparian plant species possess adaptations to fluvial disturbances that facilitate survival and reestablish-ment following fires,thus contributing to the rapid recovery of many streamside habitats.Given the critical resource values of riparian zones,additional data are needed to understand interactions between fire and riparian ecosystems,and how riparian zones affect spatial and temporal patterns of fires at the landscape scale.An improved understanding of fire ecology and effects in riparian areas is needed to prescribe ecologically sound rehabilitation projects following fire.# 2003 Elsevier Science B.V.All rights reserved.

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摘要
尽管我们知道河岸地区具有众多价值,并已确认火灾是一个关键的自然干扰因素,但鲜有研究调查了美国西部河岸地区自然火灾的行为、特征和影响.河岸地区与邻近山地在植被组成结构、地形、水文、微气候和燃料特点经常不同.这些不同特点导致了河岸地区火灾在环境、机制、特征（频率、严重性、行为、范围）方面与相应的山地地区的不同.与邻近的山地相比,某些河岸森林地区的火灾频率较低、严重性（破坏程度）也偏弱,但是在其他地区,火灾在河岸区域的发生频率不相上下.
土地的利用和管理产生的作用会严重影响河岸地区火灾的特征和机制.禁火、放牧、伐木、筑坝、水流调节、农业转换、渠道改变和外来物的引入,这些活动已导致了河岸地区在植被物种的组成结构、燃料储量的分布、微气候的改变及区域范围方面的转变.
人类对环境长期改变的作用累积起来,可能会对火灾活动发挥深远的影响,特别是在干旱时期和极端火险天气条件下.河岸地区植被有能力适应河流作用的干扰,促进火灾后的生存和重建,从而使得许多河岸地区环境能够迅速恢复.考虑到河岸地区重要资源的价值,我们还需要更多的资料以便更好的认识火灾和河岸地区生态环境的相互作用,以及河岸地区在地形范围上怎样影响火灾的空间和时间模式.我们还需要对河岸地区火灾生态和影响有更进一步的认识,这样可以在火灾后生态环境彻底恢复工程中做到对症下药.