湿地地形恢复研究概述

湿地地形反映了一定范围内湿地地貌起伏的状况。在湿地恢复工程中, 适宜的地形处理有利于丰富景观要素、形成景观层次、创造出多种生境类型, 达到加强湿地艺术性和改善环境的目的。文中介绍了湿地地形在湿地恢复中的作用, 阐述了湿地地形的不同类型, 综述了典型湿地地形的恢复方式, 主要有浅滩、弯型岸带、生境岛、深水区、开敞水面、急流带和滞水带等7种类型。     

基于植被恢复潜力的强度石漠化地区立地因子研究

 石漠化地区立地分类及其植被恢复潜力评价是石漠化地区生态修复的重要基础,立地因子研究是立地分类与评价的前提。通过对典型强度石漠化地区毕节石桥小流域和花江峡谷立地条件调查,利用成因分析与统计分析方法,研究强度石漠化地区影响植被恢复潜力的主要立地因子。结果表明：岩性和坡性是强度石漠化地区基于植被恢复潜力的主导立地因子。研究结果可为强度石漠化地区立地分类的建立与植被恢复潜力评价提供依据。     

Activities of extracellular enzymes in physically isolated fractions of restored grassland soils

Extracellular enzymes degrade complex organic compounds and contribute to carbon turnover in soils. We used physical fractionation procedures to investigate whether soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay-sized fraction. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in particulate organic matter (POM) fractions than in bulk soil, consistent with the rapid turnover of POM fractions. Polyphenol oxidase activity in the clay-sized fraction was 3 times that in the bulk soil, despite a higher mean residence time for carbon in the clay-sized fraction. For most enzymes, differences in activity among fractions and across the restoration chronosequence diminished when adjusted for differences in carbon concentrations. However, glycine aminopeptidase activity per unit carbon increased four-fold across the chronosequence in the clay fraction, while polyphenol oxidase activity declined by 40%. These results suggest that enzyme production and carbon turnover occur rapidly in POM fractions, but slowly in mineral-dominated fractions where enzymes and their carbon substrates are immobilized on mineral surfaces. Soil carbon accumulation in mineral fractions and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular to micron scale, rather than exclusion of enzymes from entire soil fractions. Based on these mechanisms, land managers could increase soil C stocks by reducing the physical disruption of soil structure associated with cultivation.     

宁夏干旱区甘草不同采挖方式及强度对植物群落恢复及稳定性的影响

针对近些年来野生甘草因滥采、乱挖导致草场大面积退化的现象,通过研究野生植物资源甘草不同采挖利用强度对土壤风蚀、养分、植物群落结构特征以及植物多样性变化的影响研究,结果表明:对野生甘草的采挖采用点挖方式要好于条挖,对恢复区植被破坏较小,恢复期短,且以秋末冬初采挖最好。     

大型水生植物修复受损水环境机理及进展

利用大型水生植物修复受损水环境成为研究的热点.在阐述生态修复目标的基础上,深入分析了净化富营养化水体生态修复的多方面作用机理及其效果,探讨了大型水生植物修复受损水环境研究的发展方向和研究重点,可为大型水生植物修复受损水环境的相关研究和工程提供一定的参考.     

乙烯对叶菜衰老的影响及光对乙烯作用的增效作用

采用气流系统用4ppm乙烯对结球生菜和菠菜分别在光照和黑暗条件下连续处理5天,结果发现:无论在光照和黑暗条件下,与对照相比,乙烯处理均使这两种叶菜的叶绿素和可溶性蛋白质含量减少,使过氧化物酶活力增强;同样乙烯处理,在光照条件下要比在黑暗条件下效果明显;乙烯处理不改变过氧化物酶同工酶酶谱,但使结球生菜可溶性蛋白质区带数目由对照的5条增加到7条;光照条件下乙烯处理的结球生菜叶片锈褐色明显比黑暗条件下乙烯处理的严重.     

Sedimentation-induced eutrophication in large river floodplains – An obstacle to restoration?

Conservation and restoration of floodplain ecosystems and their specific functions often suffer from a deficient knowledge on basic processes and dynamics such as sedimentation and related nutrient inputs. In this study, we present the results of a joint analysis of site conditions and vegetation of alluvial meadows along a gradient of increasing distance to the main channel of the river Rhine. In particular we scrutinized whether the flooding frequency mediated by the ground elevation or the distance to the river channel determines the degree of eutrophication by river water and sediments.We found a remarkably strong transversal gradient in the functional floodplain. Extremely high concentrations of CAL-soluble phosphorous (more than 150 mg kg⁻¹) were measured in close proximity to the main channel. These sites were characterized by low vascular plant species richness and a significantly higher proportion of species with high nutrient demands. At a distance of 300 m from the main channel P concentrations in the soil dropped to a quarter of this figure, whereas the average species richness per plot strongly increased. Contrary to our expectations, the influence of the flooding duration was of minor importance for the nutrient status. We can specify that strong eutrophication effects induced by sediment deposits are confined to the close proximity to the main channel within a distance of 200–300 m. At more distant sites, target vegetation of flood meadows was obviously not affected by recent nutrient input in the course of flooding. Concerns by conservationists that the restoration of active floodplains by the removal of dykes will generally lead to unwanted eutrophication by river water and sediments require revision and thorough specification.     

不同栽培方式下苹果纺锤形冠层光照分布及产量品质效应

为探讨渭北南部苹果产区不同栽培方式苹果纺锤形冠层光照分布对果实产量品质的影响,以9年生细长纺锤形的双矮富士、矮化富士和自由纺锤形乔化富士树为试材,测定了不同冠层枝类组成、光照分布、产量和品质等指标.结果表明,3种栽培方式树体适宜光合区比例分别为67.84%、64.58%和56.28%,按株产折合产量分别为4078.4、3 499.8和2 183.6 kg/667 m2.双矮富士的果实产量和品质优于矮化富士和乔化富士,矮化富士的果实产量和品质优于乔化富士.细长纺锤形双矮富士和矮化富士树冠光照好,果实产量高,品质优,是生产上值得大力推广的树形和栽培方式.     

尾叶桉和邓恩桉的光合和蒸腾特性对光强的响应

[目的]探讨桉树的光合特性及其对环境光强变化的响应和适应性。[方法]设10个光照强度梯度:2 000、1 500、1 000、800、500、200、100、50、20和0μmol(/m2.s),利用LI-6400测定了尾叶桉(Eucalyptus urophylla)和邓恩桉(E.dunnii)幼苗的光合特性和蒸腾特性对光强的响应。[结果]尾叶桉和邓恩桉的光饱和点分别为1 500和1 000μmol/(m2.s),光补偿点分别为24.87和25.16μmol(/m2.s),表观量子效率分别为0.058 0和0.050 6,暗呼吸速率分别为1.44和1.27μmol(/m2.s)。两种桉树叶片Ci随光强的上升呈现出下降的趋势,气孔导度随光强的上升呈现出上升的趋势。水分利用率随光照强度增加呈抛物线状变化,光强在500μmol(/m2.s)以内时几乎呈直线上升并在500μmol/(m2.s)时达到最大值,然后随着光强的继续增强而出现了略有下降的趋势。[结论]该研究为桉树引种、速生丰产和制定栽培管理措施提供理论依据。     

生态恢复与重建研究综述

生态恢复与重建是当前学术界关注的热点问题之一。对生态恢复与重建的相关概念、理论基础、研究现状、问题进行了分析,并指出了未来研究的趋势。