集合生态系统研究15年回顾与展望

集合生态系统(meta-ecosystem)由法国的Loreau教授等于2003年提出,是指"由跨生态系统边界的物质流、能量流和生物体流所连接起来的一系列生态系统的集合",是对只关注生物体(organism)迁移交换的集合种群(meta-population)和集合群落(meta-community)概念的外推,也是为了给生态系统空间异质性研究提供一个重要的分析路径,对研究和理解生态系统的结构、过程、功能和异质性具有重要意义。通过对相关文献的梳理分析,简述了集合生态系统研究的基本状况,分析了对集合生态系统概念的狭义和广义两种理解,指出了探讨集合生态系统结构的两个方向,构建了分析集合生态系统研究的六维整体框架,综述了研究集合生态系统的两类方法,探讨了经验化的集合生态系统(empirical meta-ecosystem)的3种空间结构和两种构建路径。将集合生态系统概念和理论引入流域复合生态系统(integrated watershed ecosystem)的分析,为流域生态学研究提供新的概念框架。     

Hydrology,water chemistry and nutrient accumulation in the Biebrza fens and floodplains (Poland)

The composition, structure and above-ground biomass production of floodplain- and fen-vegetation of the Biebrza valley (N.E. Poland) are strongly correlated with water flow characteristics and water chemistry. Groundwater flow and flooding are the major conditioning factors for the vegetation in the valley.The highly productive vegetation is restricted to the dynamic floodplain where it receives nutrient-rich river water during spring floods. The non-flooded parts of the valley contain rich fen and transitional fen vegetation that have a lower biomass production. The rich fen is fed by calcareous and phosphate-poor groundwater coming from the moraines. In the transitional fen, where rainwater infiltrates, phosphate availability is large.Annual nutrient accumulation in the above-ground biomass of the floodplains is estimated to be about 8–9 § 10³ kg/km² for N and K and 1 § 10³ kg/km² for P. For the less-productive fens these figures are 60 to 70% lower. The total annual nutrient accumulation by vegetation of both floodplains and fens for the entire Biebrza valley is estimated to be about 5600 × 10³ kg N, 560 × 103 kg P and 4500 × 10³ kg K. This is high compared to the loading rates in the river near to where the Biebrza River discharges into the Narew River (N-, P- and K-loading rates are c. 900, 200 and 3000 × 103 kg/y, respectively). This implies that floodplain and fen vegetation are important sinks for nutrients, especially for N and P.This paper was presented at the INTECOL IV International Wetlands Conference in Columbus, Ohio, 1992, as part of a session organized by Prof. S. E. Jørgensen and sponsored by the International Lake Environment Committee.Corresponding Editor: J. Kvt     

降水中的PH值和金属元素在松柏混交林内变化动态

 本文以日本滋贺县大津市桐生自然保护区的日本赤松(Pinus densiflora)、黑松(Pinus thunbergii)、扁柏(Chamaecypari sobtusa)混交林小流域为研究地,以若女自然保护区内荒山小流域为对照地。通过对两个小流域为期一年的定位观测研究,测定了林外降水、流出水、穿透水、树干流中的pH值、电导率、钾、钠等14种金属元素以及硅、硼非金属元素。研究结果表明,松柏混交林生态系统和花岗岩发育形成的土壤对雨水的pH值和金属元素等均具有较大的影响,但松柏混交林生态系统对其影响大于荒山。此外,系统内大多数元素的收入大于支出,呈积累趋势。     

Identifying wetland meadows in Grand Teton National Park using remote sensing and average wetland values

Six spectrally and ecologically distinct montane meadow community types were identified and mapped within Grand Teton National Park by analysis of Indian IRS-1B LISS-II imagery. A distinct to-xeric-hydric gradient among the meadow types was predicted by analysis of the satellite data. Thirty sites (five replicates for each of six meadow typ were selected for intensive field sampling. At each of the 30 sites, meadow vegetation was sampled in 20 m by 20 m square plots for canopy cover of all species. Using wetland indexes (on a scale of 1–5, where obligate wetland species = 1, facultative land = 2, facultative = 3, facultative upland = 4 and upland species = 5), average wetland values were calculated and ranged from 1.88 for A-type meadows and 2.86 for B meadows to 4.40, 4.49, 4.74, and 4.43 for C, D, E and F meadows, respectively. Because average wetland values of A and B meadows were < 3.00, they were determined to be indicative of wetlands. Eight out of ten obligate wetland plants had their greatest cover on A meadows (the wettest of the gradient) and had significant cover differe among meadow types using the non-parametric Kruskal-Wallis test. Average wetland values and plant species cover were used, in conjunction with remotely sensed data, to identify as wetlands 1,258 hectares of A meadows and 1,711 hectares of B meadows in Grand Teton National Park.     

土地利用变化情景下浑河-太子河流域的非点源污染模拟

近年来非点源污染已经成为水污染的主要来源,对非点源污染发生机理和控制方法的研究有着重要的科学和现实意义.为了研究不同土地利用方式对非点源污染的影响,本文基于土地利用变化模型CLUE-S模拟了城市规划、历史趋势和生态保护3个预案下浑河-太子河流域土地利用未来变化.应用SWAT模型对非点源污染进行了模拟研究,并结合实测数据对模拟结果进行了评价.结合两个模型研究了3个土地利用预案下非点源污染对土地利用和景观格局变化的响应.结果表明: SWAT模型在浑河-太子河流域模拟精度较高,该模型在研究区具有适用性.城市规划和历史趋势预案下非点源污染负荷不断增加,城市规划方案下最高,生态保护预案下非点源污染负荷呈不断下降趋势.不同土地利用和景观格局对非点源污染有一定的影响,科学合理的生态建设能够有效减少非点源污染负荷.研究结果可以为流域的非点源污染研究提供案例,为非点源污染防治和最佳管理措施的制定提供科学依据,为相关政策制定提供参考.     

黄土高原典型流域种植业发展模式的能值分析

为客观评估和比较退耕还林后黄土高原典型小流域不同种植业发展模式的稳定性和可持续性,本研究通过能值分析方法,定量分析了粮食和果树兼作、粮食生产为主和果树种植为主3种典型流域种植业系统的能值投入和产出情况,建立能值分析指标体系,在自然资源压力、社会和经济发展水平方面进行比较,进而对3种模式的系统可持续性进行评估.结果表明: 黄土高原典型流域不同类型种植业系统外部辅助能值均占总能值投入的75%以上,且其中不可更新能值所占比例远大于可更新能值,由此造成了能值自给率低而环境承载率高的特点;流域粮食种植业生产具有高投入、低产出的特点,而水果种植和粮果兼作具有高投入、高产出的特点,3种模式能值密度均达到全国农业经济系统平均水平2倍以上,其中,粮食生产为主的模式净能值产出率最低而粮果兼作型最高;流域种植业能值可持续发展指数均<1,能值/环境可持续指标均远低于全国农业系统平均水平,可持续发展能力较低,以粮食和果树兼作的模式可持续发展指数最高.3种模式比较发现,粮果兼作发展模式在流域种植业发展中具有相对较好的发展能力和较高的系统稳定性,能值生产效率适中且可持续性最高,因此黄土高原地区以流域为单元的农业发展应该更加偏向于考虑多产业综合的复合结构生产方式.     

基于“源-汇”理论的流域非点源污染控制景观格局调控框架——以厦门市马銮湾流域为例

基于“源-汇”理论对景观格局进行调控与优化是一种较为经济、有效的流域非点源污染控制新方法,目前尚处在探索阶段.在景观生态学及相关理论与前人已有研究的基础上,以流域整体为对象,从2个层次构建基于“源-汇”理论的流域非点源污染控制景观格局调控框架: 1)流域层次:在分析流域“源-汇”景观合理的基本组合与空间布局方式的基础上,建立了流域景观格局整体调控与优化方法;2)景观斑块类型层次:将关键“源”景观作为重点调控与优化对象,建立了包含景观单位面积污染负荷、景观坡度、起传输作用的狭长“源”景观、临河“源”景观单位岸线长度污染负荷等4项关键“源”景观识别准则,并遵循镶嵌“汇”景观、局部增补带型“汇”景观、提高原有“汇”景观消纳污染物的能力等3项调控与优化原则,针对农村地区与城区不同的关键“源”景观类型,制定了9类调控与优化方法.最后将该框架应用到厦门市马銮湾流域,基于GIS平台及研究区遥感图像与数字高程模型,制定了马銮湾流域景观格局整体调控与优化模式及3个片区关键“源”景观调控与优化方案.     

基于增强回归树的流域非点源污染影响因子分析

地表水的非点源污染在点源污染不断得到控制的前提下已经成为水环境污染的首要问题.非点源污染影响因子的复杂性及不确定性一直是流域非点源污染研究的重点和难点.本文利用SWAT(Soil and Water Assessment Tool)模型,以辽河子流域汎河流域为例,模拟了2003—2012年的非点源污染状况,对其空间分布状况进行了分析,并应用增强回归树的方法定量分析各种影响因子(坡度、土地利用类型、高程和土壤类型)对该流域非点源污染的贡献率.结果表明: 在汎河流域,非点源污染呈现较高的空间异质性,其中总氮的空间分布差异较大,总磷的空间分布差异较小.坡度因子与载体泥沙、总氮和总磷均呈极显著正相关关系(P<0.01),对泥沙和总磷有显著影响,其贡献率分别为46.5%、38.2%;土地利用因子对载体泥沙、总磷的负荷量有重要影响,其贡献率分别达到27.2%、35.3%;高程较低、坡度较缓的耕地地区易产生较高的总磷负荷量;褐色土壤最易流失总磷,而草甸土易流失总磷,且易受泥沙侵蚀.本研究利用增强回归树模型克服了流域非点源污染影响因子的复杂性,可加深对非点源污染产生机制的理解.     

Low ratios of silica to dissolved nitrogen supplied to rivers arise from agriculture not reservoirs

Coastal marine systems are greatly altered by toxic marine algae, eutrophication and hypoxia. These problems have been linked to decreased ratios of dissolved silica to inorganic nitrogen (Si : DIN) delivered from land. Two mechanisms for this decline under consideration are enhanced nitrogen (N) fertiliser losses from agricultural lands or Si sequestration in reservoirs. Here we examine these mechanisms via nutrient concentrations in impoundments receiving water from 130 watersheds in a landscape representative of the agriculture that often dominates coastal nutrient inputs. Decreased Si : DIN was correlated with agriculture, not impoundment. Watersheds with > 60% agricultural land yielded highest DIN, whereas Si was uncorrelated with agricultural intensity. Furthermore, eutrophic lakes were dominated by Cyanobacteria that use little Si, so reservoirs did not diminish Si : DIN. Instead, Si : DIN increased slightly as reservoir residence time increased. These data suggest that impoundments in agricultural watersheds may enhance the water quality of coastal ecosystems, whereas fertiliser losses are detrimental.