VALUING ECOSYSTEM SERVICES OF CHILEAN TEMPERATE RAINFORESTS

The Valdivian Rainforest Ecoregion (35°–48° S) in southern South America is among the ecosystems with highest conservation priority worldwide due to its rich diversity, degree of endemism, and critical conservation status. Temperate rainforests in this vast area are essential as source of biological resources and to maintain different ecosystem services which remain largely unmeasured and unvalued. Consequently, the benefits they provide are not reflected in decision-making regarding forest management and conservation. Based on existing studies and results from ongoing research we describe selected ecosystem services and provide estimates of their economic value. Timber benefits for secondary forests expressed as net present stumpage values were US$ 3742 ha⁻¹ and US$ 3093 ha⁻¹ for sustainable forest management (SFM) and unsustainable harvesting, respectively. Timber benefits for old growth forests␣equaled US$ 4546 ha⁻¹ and US$ 5718 ha⁻¹, for SFM and unsustainable harvesting, respectively, using an 8% discount rate. Annual benefits from recreation were US$ 1.6 ha⁻¹ and US$ 6.3 ha⁻¹ for the two most important national parks located in the study area. The annual value of maintaining soil fertility was US$ 26.3 ha⁻¹ using the replacement cost of nutrient losses due to soil erosion. The annual economic value of water supply for human consumption using the production function method was US$ 235 ha⁻¹. These results provide valuable information on the kind and magnitude of values that could be relevant in decision-making concerning conservation and management of native forests in the Valdivian Rainforest Ecoregion.     

Multiscale Spatial and Small-Scale Temporal Variation in the Composition of Riverine Fish Communities

We studied the multiscale (sites, river reaches and rivers) and short-term temporal (monthly) variability in a freshwater fish assemblage. We found that small-scale spatial variation and short-term temporal variability significantly influenced fish community structure in the Macquarie and Namoi Rivers. However, larger scale spatial differences between rivers were the largest source of variation in the data. The interaction between temporal change and spatial variation in fish community structure, whilst statistically significant, was smaller than the variation between rivers. This suggests that although the fish communities within each river changed between sampling occasions, the underlying differences between rivers were maintained. In contrast, the strongest interaction between temporal and spatial effects occurred at the smallest spatial scale, at the level of individual sites. This means whilst the composition of the fish assemblage at a given site may fluctuate, the magnitude of these changes is unlikely to affect larger scale differences between reaches within rivers or between rivers. These results suggest that sampling at any time within a single season will be sufficient to show spatial differences that occur over large spatial scales, such as comparisons between rivers or between biogeographical regions.     

重视全球化带来的生态安全问题

本文从自然生态系统动态平衡的角度出发，分析了在全球化进程加快的背景下，外来干扰与胁迫加剧，区域生态系统的物理环境与生物群落所受到的外来安全影响，叙述了外源性影响导致的环境，群落，基因三种尺度的安全问题，探讨了生态系统持续进化的相应对策。     

Competition between Populations in the Consumer–Producer Trophic Chain in a Closed Aquatic System

The functioning of a closed aquatic consumer–producer system with spatially separated links, with each link consisting of two species, is considered. Competition between the consumers (infusorians Paramecium caudatum and rotifers Brachionus sp.) feeding on a mixed algal culture (Chlorella vulgaris and Scenedesmus sp.) and competition between these algae under conditions of limited nitrogen supply are analyzed. It is shown that Scenedesmus algae have an advantage over C. vulgaris in terms of competitiveness, and their metabolic products have an adverse effect on reproduction in infusorians.     

崇明东滩沿海湿地生态系统健康评价

以生态系统健康及压力-状态-响应（PSR）模型作为研究方法，根据沿海湿地生态系统的特点，建立一套沿海湿地生态系统适用的健康评价指标体系。以现有研究数据和统计资料为基础，对长江口崇明东滩湿地进行单因子和综合评价，分别计算其健康度、压力综合指数和响应综合指数。揭示崇明东滩湿地的生态系统健康状况以及形成原因，并提出保护对策和可持续利用的相关建议。研究结果表明：①崇明东滩湿地生态系统的健康度、压力综合指数和响应综合指数分别为0．72、0．64和0．79，总体上仍处于一个较为健康的状态；②崇明东滩湿地生态系统目前的主要压力并不直接来源于土地围垦，而是来源于水环境污染和外来生物入侵。     

广州市土地利用总体规划与生态脆弱性的耦合分析

以广州市为例，利用2005年的TM影像．并结合DEM、水土流失现状图、地质灾害图、有机质含量分布图及社会经济等数据。分析全市生态环境脆弱性的空间格局特征，并将生态脆弱性区分区圈与土地利用规划图进行空间叠加分析。结果表明：①研究区生态环境优越。生态良好区占85．96％；②人类活动对生态脆弱性格局具有重要的影响。各生态脆弱性类型区的分布有一定的规律性．平原地区好于山区。城区好于郊区；③新一轮土地利用规划结构调整和布局已经充分考虑生态环境因素影响。符合广州市生态环境保护和经济发展的需要。规划实施有利用于提升环境生态服务功能。     

基于生态系统服务功能价值评估的土地利用总体规划环境影响评价研究

随着全国性、地区性土地利用总体规划的制定与实施，探讨适台于土地利用总体规划环境影响评价的技术方法显得相当重要。在对生态系统服务功能价值评估研究进展进行评述的基础上。分析了生态系统服务功能价值评估在土地利用总体规划环境影响评价中应用的必要性．并结合实例对其应用方法进行了探讨．实例分析表明，生态系统服务功能价值评估在土地利用总体规划环评中的应用具有把土地利用的生态效益转化为简单易懂的货币形式．可为决策者提供直观的生态信息及生态系统服务功能价值。可作为一项量化指标。对土地利用总体规划目标及规划方案的生态效益进行综合评估，且核算简单。有助于节省规划环评的时间和资源等优势，本文还指出了进一步研究的方向。     

长江河口淡水资源利用与避咸蓄淡水库

开发利用长江口的淡水资源 ,首先要研究河口水质的污染程度以及咸潮入侵的时空变化规律。长江河口水质除边滩存在局部污染外 ,主槽水质良好。长江口南支、南港、北港盐水来源主要有北支倒灌和外海盐水直接入侵两种形式 ,盐水入侵具有周日、半月、季节和年际变化规律 ,由于北支倒灌咸水团的影响 ,低盐度值往往出现在大潮期和涨憩附近。通过修建边滩水库 ,达到控制引水时间、避咸蓄淡的目的。最长连续超标天数的推算是确定水库库容的关键问题 ,采用数理统计、二维数值模拟、ARMAX模型 +Markov模型等方法推算 ,几种方法相互印证 ,计算结果基本上符合实际情况。“避咸潮取水 ,蓄淡水保质” ,这是宝钢干部、科技人员总结出来的长江河口引水经验。长江口取水工程由取水系统、调蓄水库和输水系统等三大部分组成。长江口避咸蓄淡水库的成功经验 ,对沿海潮汐河口的淡水资源开发利用具有示范作用。     

淹水增加对闽江河口淡水潮汐湿地孔隙水地球化学特征及CO2和CH4排放通量的影响

海平面上升使得河口潮汐湿地淹水高度增加,对CO_2和CH_4的排放通量产生重要影响,但目前绝大多数研究集中在淹水增加对河口盐沼湿地的影响,淹水增加对于河口淡水潮汐湿地的影响缺乏数据.鉴于此,本研究利用模拟潮汐池和中型生态系,研究淹水增加15 cm和30 cm后对闽江河口淡水潮汐湿地孔隙水(NH_4+、NO_3-、DOC、溶解性CH_4和DIC)浓度及CO_2和CH_4排放通量的影响.结果表明,淹水高度增加15 cm和30 cm后,CO_2的排放通量分别下降28. 53%和36. 56%;淹水增加15 cm时,CH_4的排放通量没有显著变化,增加至30 cm后,CH_4的排放通量显著增加29. 27%;淹水高度增加15 cm和30 cm,孔隙水CH_4的浓度分别增加47. 83%和73. 91%.淹水增加对孔隙水DOC浓度变化影响不显著.淹水增加促进孔隙水NH_4+浓度,并降低孔隙水DIC和NO_3-的浓度.淹水增加降低CO_2和CH_4排放通量的温度敏感性.根据研究结果,未来海平面上升50 a和100 a后,闽江河口淡水潮汐湿地的综合增温潜势将分别降低28%和35%.