城市湖泊生态恢复与景观设计

按照从水生生态系统向陆地生态系统过渡的顺序，尝试提出了城市湖泊水生植被恢复与景观设计、湖滨带生态恢复与景观设计以及湖岸和连通沟渠生态恢复与景观设计的设计思路，并逐一进行分析。     

塔里木荒漠河岸林植物群落演替下的土壤理化性质研究

选择塔里木荒漠河岸林内典型、有代表性的不同演替阶段的群落,对其土壤理化性质进行研究。结果表明：土壤理化性质在演替方向和土壤剖面上表现出较强的规律性。演替后、中期表层土壤（0～20 cm）粘粒质量分数比初期分别减少了1.28%、64.29%、土壤砂粒质量分数分别增加了3.08%、17.23%,土壤明显变粗沙化。群落演替能明显增大土壤容重与非毛管孔隙度,降低土壤总孔隙度、毛管孔隙度、孔隙比、土壤水分质量分数、最大持水量、毛管持水量和最小持水量。演替后、中期表层土壤非毛管孔隙度比初期分别增大了33.78%、36.087%,土壤水分质量分数分别降低了85.57%、97.77%,演替后期最大持水量、毛管持水量分别比初期降低了40.28%、9.27%,导致土壤固相率减小,气相率增大,土壤持水供水能力与抗风蚀性能减弱。土壤有机质、全氮与碱解氮、全磷与速效磷、全钾与速效钾、盐分质量分数随群落演替呈降低趋势。演替后期表层土壤有机质、碱解氮、全磷与速效钾质量分数分别比初期降低了38.68%、60.71%、23.58%、66.93%,其土壤理化性质退化最显著。地下水位下降是引起荒漠河岸林植物群落逆向演替的驱动力。当前随人类干扰强度增强（水土资源开发）,塔里木荒漠河岸林土壤结构与土壤生态功能随之受到破坏与衰退,而保持合理的生态水位则是维持荒漠河岸林生态系统稳定的有效途径。     

退化滨水景观带植物群落生态修复技术研究进展

滨水带是重要的生态交错带,物质、养分和能量流动速率高,具有较高的生态、经济和美学价值。近年来,由于缺乏科学合理的生态规划意识,我国滨水带多被建成近直立人工护岸,加之自然、人为干扰力度的加强,滨水岸线生境破坏,生物群落丧失,滨水带退化,水岸生态环境日趋恶化。通过对滨水带生态景观功能分析,研究滨水带退化原因与机理,系统归纳了国内外退化滨水景观带植物群落生态修复相关技术的研究现状,深入探讨了生境恢复、生物廊道恢复、景观格局美化和水岸生态系统结构与功能优化等方面的研究内容,并提出今后滨水带生态修复技术研究方向,以及基于生态学、景观学、水力学、土力学、生物学、经济学等多学科背景的滨水景观带植物群落定量分析、配置方法。最后指出,滨水景观带植物群落生态修复技术研究需进一步分析我国水岸生态系统退化机理、细化滨水深槽-浅滩序列、量化滨水植被配置宽度与生物多样性关系、深化稳定化长效管理技术等,为我国退化滨水生态景观带植物群落生态修复集成技术的研究与实践提供参考,以全面有效的提高生态环境质量。     

Assessment of Temporal and Spatial Variation of Nitrate Removal in Riparian Zones

The aim of this study was to monitor long-term temporal and spatial groundwater NO₃^- removal efficiencies in different riparian zones via a limited number of sampling wells. Groundwater NO₃^- concentrations were measured fortnightly or monthly over a period of two years using transects of ground water sampling wells. Depending on the level of the NO₃^- load (up to 120mgNL^-1 at the input side of the riparian zone a distance of 10 to 30m was needed to remove NO₃^- from the groundwater below 11.3mgNL^-1. Considering all seasons, the mixed vegetation and grass riparian site succeeded to remove groundwater NO₃^- efficiently (92—100% within a distance of 30m. The forested riparian zone removed 72—90% of the total NO₃^- input within a distance of 30m. Evidence emerged that NO₃^- could also be removed actively at depths up to 2m, due to the presence of organically enriched layers of alluvial deposits or roots. Our four dimensional approach (three dimensional space and time), in combination with a limited number of sampling wells, was shown to be a useful monitoring tool to assess the variability of NO₃^- removal in riparian zones.     

The Aquatic Conservation Strategy of the Northwest Forest Plan

Abstract:  Implemented in 1994, the Aquatic Conservation Strategy of the Northwest Forest Plan was designed to restore and maintain ecological processes for aquatic and riparian area conservation on federal lands in the western portion of the Pacific Northwest. We used decision support models to quantitatively evaluate changes in the condition of selected watersheds. In the approximately 10 years since strategy implementation, watershed condition scores changed modestly, but conditions improved in 64% of 250 sampled watersheds, declined in 28%, and remained relatively the same in 7%. Watersheds that had the largest declines included some where wildfires burned 30–60% of their area. The overall statistical distribution of the condition scores did not change significantly, however. Much of the increase in watershed condition was related to improved riparian conditions. The number of large trees (>51 cm diameter at breast height) increased 2–4%, and there were substantial reductions in tree harvest and other disturbances along streams. Whether such changes will translate into longer-term improvements in aquatic ecosystems across broader landscapes remains to be seen.     

三峡水库消落带典型主动与被动修复策略对土壤饱和导水率的影响

人工造林的主动修复与退耕还林还草的被动修复是退化生态系统典型的生态修复策略.以三峡水库运行后形成的消落带为研究对象,研究不同生态修复策略对消落带土壤饱和导水率的影响,对生态脆弱带的水土保持效应具有重要意义.选取桑树+水杉复合林(主动修复)、自然草地(被动修复)、农田(对照)为研究样地,探究了两种不同生态修复策略下三峡水...     

Regeneration of Native Trees in the Presence of Invasive Saltcedar in the Colorado River Delta, Mexico

Abstract:  Many riparian zones in the Sonoran Desert have been altered by elimination of the normal flood regime; such changes to the flow regime have contributed to the spread of saltcedar ( Tamarix ramosissma Ledeb.), an exotic, salt-tolerant shrub. It has been proposed that reestablishment of a natural flow regime on these rivers might permit passive restoration of native trees, without the need for aggressive saltcedar clearing programs. We tested this proposition in the Colorado River delta in Mexico, which has received a series of large-volume water releases from U.S. dams over the past 20 years. We mapped the vegetation of the delta riparian corridor through ground and aerial surveys (1999–2002) and satellite imagery (1992–2002) and related vegetation changes to river flood flows and fire events. Although saltcedar is still the dominant plant in the delta, native cottonwood (  Populus fremontii S. Wats.) and willow ( Salix gooddingii C. Ball) trees have regenerated multiple times because of frequent flood releases from U.S. dams since 1981. Tree populations are young and dynamic (ages 5–10 years). The primary cause of tree mortality between floods is fire. Biomass in the floodplain, as measured by the normalized difference vegetation index on satellite images, responds positively even to low-volume (but long-duration) flood events. Our results support the hypothesis that restoration of a pulse flood regime will regenerate native riparian vegetation despite the presence of a dominant invasive species, but fire management will be necessary to allow mature tree stands to develop.     

河滨修复湿地不同植物配置对甲烷排放的影响

为了探讨河滨修复湿地在不同条件下CH₄的排放规律及降低CH₄排放的调控途径,以自行设计和建造的河滨湿地为研究对象,对植物种类配置及植株密度进行人为调控,运用静态箱-气相色谱法测定CH₄排放通量. 结果表明:①CH₄排放通量具有明显的季节性变化规律,其中夏季最大,占全年CH₄总排放量的50%以上;冬季最小,低于全年CH₄总排放量的5%. ②植物种植会明显增加CH₄的排放,不同植物类型通过改变w(SOC)(SOC为土壤有机碳)、气体传输机制以及产CH₄菌群落来改变湿地的CH₄排放,4种供试植物中,通气组织较发达的芦苇和水葱湿地CH₄排放通量分别为(1.98±0.78)和(1.41±0.58)mg/(m2·h),显著低于黄菖蒲的(6.77±1.92)mg/(m2·h). ③提高植株密度可以通过增加输气通道和提高w(SOC)来促进湿地CH₄排放,黄菖蒲植株密度为150株/m2时,CH₄平均排放通量为(10.31±2.56)mg/(m2·h),比植株密度为56株/m2时高出近30%. 因此,建议在新建和修复河滨湿地的设计和建造过程中,种植芦苇和水葱等通气组织较发达的植物,并在满足湿地修复、生态环境保护和景观营造等要求的前提下,适当控制植株密度,以有效减少CH₄排放.      

海河流域河流滨岸带入侵植物等级与分布特征

为了解海河流域河流生态系统的退化程度,进而为河流植被修复提供支撑,对河流滨岸带植被入侵物种开展调查,并分析其入侵等级、分布规律及成因. 调查了海河流域九大水系滨岸带402个样地的植物物种信息和主要环境因子,参照《中国入侵植物名录》确定入侵植物名单,根据物种的出现频率和以该物种为优势种的样地所占比例来评价植物入侵等级,并分析物种入侵与环境因子之间的关系. 结果表明:①海河流域河流滨岸带入侵植物共有48种,其中一年生草本植物占72.9%,并且以菊科、苋科、禾本科物种数最多. ②Ⅰ级入侵种为反枝苋(Amaranthus retroflexusn)、苘麻(Abutilon theophrasti)、小藜(Chenopodium serotinum)、鬼针草(Bidens pilosa)和鳢肠(Eclipta prostrata)共5个物种,出现频率超过25%;Ⅱ级入侵种为小蓬草(Conyza canadensis)、大狼杷草(Bidens frondosa)、圆叶牵牛(Pharbitis purpurea)等共11种;Ⅲ级入侵种共32种. ③各水系平均出现入侵植物23种,其中子牙河水系入侵植物种数最多,为33种;其次为滦河水系,为25种;漳卫河水系最少,为15种. ④海拔和堤外土地类型与植物入侵强度相关性最大,海拔与入侵植物的关系主要通过人口压力相关联.      

官厅水库库滨带非点源污染控制效应的遥感分析

选取官厅水库库滨带为研究区域,应用SPOT5遥感数据对其结构进行了解析,建立了高分辨率的Quick Bird遥感数据与SPOT数据的尺度转化关系,对SPOT信息提取结果进行了校核,以提高SPOT卫星对库滨带结构的解译精度;最后结合点上的实验结果对流域尺度上的库滨带的环境效益进行了分析.研究结果表明:(1)官厅水库陆相库滨带的结构不利于非点源污染的防治,应该适当增加林地的比例,同时提高林地、草地的植被覆盖度;(2)按照官厅水库流域非点源区年均TN量为188.1×104 t、TP量为101.2×104 t计算,库岸库滨带对TN、TP的去除率分别为11.6%和0.4%;(3)为了有效地防止官厅水库流域的非点源污染,必须加强水库流域的农业管理和库岸库滨带的科学建设与管理.