The Urban Funnel Model and the Spatially Heterogeneous Ecological Footprint

Urban ecological systems are characterized by complex interactions between the natural environment and humans at multiple scales; for an individual urban ecosystem, the strongest interactions may occur at the local or regional spatial scale. At the regional scale, external ecosystems produce resources that are acquired and transported by humans to urban areas, where they are processed and consumed. The assimilation of diffuse human wastes and pollutants also occurs at the regional scale, with much of this process occurring external to the urban system. We developed the urban funnel model to conceptualize the integration of humans into their ecological context. The model captures this pattern and process of resource appropriation and waste generation by urban ecosystems at various spatial scales. This model is applied to individual cities using a modification of traditional ecological footprint (EF) analysis that is spatially explicit; the incorporation of spatial heterogeneity in calculating the EF greatly improves its accuracy. The method for EF analysis can be further modified to ensure that a certain proportion of potential ecosystem services are left for in situ processes. Combining EF models of human appropriation with ecosystem process models would help us to learn more about the effects of ecosystem service appropriation. By comparing the results for food and water, we were able to identify some of the potentially limiting ecological factors for cities. A comparison of the EFs for the 20 largest US cities showed the importance of urban location and interurban competition for ecosystem services. This study underscores the need to take multiple scales and spatial heterogeneity into consideration to expand our current understanding of human–ecosystem interactions. The urban funnel model and the spatially heterogeneous EF provide an effective means of achieving this goal. Received 17 October 2000; accepted 31 May 2001.     

基于生态系统服务的广西水生态足迹分析

针对传统生态足迹对于水域仅考虑渔业生产功能的缺陷,研究者提出了水生态足迹.但当前水生态足迹基础理论与模型均存在较大不足.为此,提出了基于生态系统服务的水生态足迹概念和模型,并以2003-2010年的广西为例进行了计算与分析.结果表明:(1)水域-渔业账户中,淡水渔业生态足迹呈上升趋势,淡水渔业生物承载力较高且比较稳定,淡水渔业生态盈余较多同时淡水渔业生态压力较小;(2)水资源账户中,淡水生态足迹先较快上升随后缓慢下降,水资源承载力较高但2007-2010年波动幅度较大,水资源生态盈余较多同时水资源生态压力较小;(3)水环境账户中,水污染生态足迹先缓慢上升随后大幅下跌之后逐渐回升,水环境承载力变化趋势与水资源承载力相同,绝大多数年份表现为水环境生态赤字和水环境生态不安全;(4)淡水渔业生态压力＜水资源生态压力＜水环境生态压力,淡水生态系统基本已处于生态不安全状态.模型克服了传统模型的诸多缺陷与不足,是对广西近年来淡水生态系统服务供需及水生态安全状况的较客观全面的反映.     

基于生态系统服务价值的生态足迹模型均衡因子及产量因子测算

均衡因子和产量因子是生态足迹模型中的关键参数,现有的测算方法多根据物质生产和消费实现,忽略生态系统提供服务的能力。本研究提出基于生态系统服务价值的均衡因子和产量因子测算方法,并以1990、2005和2015年北京市门头沟区为例,研究生态涵养发展区生态承载力,并与通用因子计算结果对比。结果表明:(1)基于生态系统服务价值获取的均衡因子:水域林地耕地。水域均衡因子最高,平均值达到8.37。耕地均衡因子最低,平均值仅为0.24。林地均衡因子高于耕地,均衡因子平均值为0.71。说明该方法较好的表现了不同生态系统提供生态服务能力的差异;(2)基于该研究方法获取的不同生态系统的产量因子接近:耕地林地水域,均值分别为0.90,0.87和0.86,且呈逐年递减趋势;(3) 1990年到2015年,门头沟区生态承载力先降低后提高,生态足迹先提高,再降低,2005年出现生态赤字,其森林、耕地和区域生态承载力与生态足迹小于通用因子生态足迹模型结果,水域生态承载力和生态足迹高于通用因子生态足迹模型结果。与通用因子相比,基于生态系统服务价值的均衡因子和产量因子更好的体现了研究区内各类生态系统生态服务的承载力。     

森林生态系统服务价值及其补偿校准——以马尾松林为例

森林补偿资金分配与生态系统服务脱钩,是长期以来制约森林生态保护制度发挥作用的关键因素。建立森林生态保护成效与资金分配挂钩的激励约束机制,对于完善生态补偿制度、保障国家生态安全具有重要意义。以马尾松林为例,运用野外调查、实验室实验等方法,精准计量评价马尾松林的固碳、水源涵养、固土保肥、生物多样性等4种主要生态系统服务;以皮尔(R.Pearl)生长曲线为基础构建生态补偿算法,测算基于生态系统服务价值的马尾松林补偿标准。第一,马尾松林生态系统服务价值为10335.86—16358.06元hm~(-2)a~(-1),固碳价值为165.93—521.03元hm~(-2)a~(-1),水源涵养价值为5024.47—11788.30元hm~(-2)a~(-1),固土保肥价值为3597.84—6405.04元hm~(-2)a~(-1),生物多样性价值为178.57—1346.15元hm~(-2)a~(-1)。第二,固碳价值、固土保肥价值在空间上呈现出随纬度增加而减小的格局,水源涵养价值、生物多样性价值与前两者分布格局相反。植被类型、经营方式影响马尾松林生态系统服务价值,混交林生态系统服务价值大于纯林,间伐补植的马尾松林生态系统服务价值高于皆伐后营造的林分。第三,马尾松林生态系统服务补偿标准为0.15×10~3—1.43×10~3元hm~(-2)a~(-1),大小主要受生态系统服务单价影响。本研究为森林生态系统服务精确计量评价、森林生态系统服务补偿标准的确定提供科学量化的依据。     

贵州草海湿地生态系统服务价值评估

贵州草海是中国三大高原淡水湖泊之一,其湿地生态系统能给人类提供产品和服务,为社会可持续发展提供基础,由于其价值没有被量化,人们对其重要性缺乏直观认识,导致了湿地的不合理开发及利用。根据草海湿地的特征,运用市场价值法、影子工程法、问卷调查法等定量评估了2010年草海湿地生态系统最终服务价值,包括供给服务、调节服务和文化服务。结果表明,草海湿地生态系统服务总价值为4.39×108元,其中供给服务价值为0.74×108元,调节服务价值为1.14×108元,文化服务价值为2.51×108元;所计算的10项服务按其价值大小排序为:休闲娱乐生物多样性与景观资源保护水资源供给调蓄洪水气候调节补给地下水大气组分调节原材料生产水质净化食物生产;单位面积服务价值为16.40×104元/hm2,是2010年贵州省威宁县单位面积GDP产值的16.91倍。从研究结果来看,草海湿地生态系统服务价值较大,为草海湿地的管理及保护提供了一定参考依据。     

三江源区基于生态系统服务价值的生态补偿额度

以青海三江源区为例,探讨了基于生态系统服务价值的生态补偿额度测算方法。以分析和筛选生态补偿需求下的生态系统服务价值评估指标为前提,估算了生态保护和建设活动实施前(2005年)三江源区草地生态系统服务价值,并采用专家咨询法提出的不同退化程度草地的生态功能系数对其进行修正,得到未退化、轻度退化、中度退化和重度及重度以上退化草地的单位面积生态价值分别为74.70×104、59.76×104、37.35×104元/km2和14.94×104元/km2。根据三江源区草地退化现状和生态恢复的目标,确定该区基于退化草地完全恢复的生态补偿总量为911.62×108元。     

江苏省陆地和生态红线区域生态系统服务价值

生态红线是最为关键的生态保护区域边界,是生态安全的底线。以2013年江苏省划定的生态红线区域为研究对象,在土地利用现状分析的基础上,对生态系统服务价值进行了评价。结果显示:江苏省陆域生态红线区域的生态系统服务价值为564.15亿元/a,占全省陆地生态系统服务总价值的48.69%,其中水体的生态系统服务价值最大,占生态红线区域的比例高达78.34%;生态红线区域的土地平均生态系统服务单位面积价值为2.47万元/hm~2,是全省平均的2.18倍,其中湿地最高,生态系统服务单位面积价值达5.55万元/hm~2,是全省平均的4.89倍,其次是水体、林地和草地;在已划定的生态红线区域中,各类生态系统占全省相应土地类型的面积比例排序与生态系统的单位面积价值排序完全一致,显示出生态系统类型的单位面积价值越大,受保护的程度越高。     

Expanding ecological appropriation approach: Solar space method and a case study in Yangzhou city,East China

In this paper, the authors made an attempt to measure appropriation of ecosystems more reasonably and effectively based on examining the advantages and disadvantages of emergy analysis and ecological footprint. By combining emergy analysis with ecological footprint (EF) in terms of spatial equivalent of energy productivity, a new method of solar space (SS) and its calculating framework was proposed, and some necessary parameters for this method of analysis were calculated. A case study was followed under this calculating framework for Yangzhou city, Jiangsu province, Eastern China, using the data of the year 2000. The main results are as follows: (1) The ecological space in Yangzhou city includes earth surface space and solar space, and their demands were bigger than their supply. In the year of 2000, the earth surface space had an absolute deficit of 2.3063E?02 Ga-ha per capita (global hectares), and the solar space had an absolute deficit of 1.4944E?04 Sa-ha per capita (solar hectares). (2) There was a relative ecological deficit of 3.68% in earth surface space, and that of 154.86% in solar space. (3) Only freshwater areas and built-up areas were in a state of surplus, and there was a relative ecological surplus of 82.66% for freshwater areas, being greater than that for built-up areas. (4) The ranking of absolute ecological deficit in a descending order was as follows: solar space > arable land > pasture > forest > marine area > garden land, while the relative ecological deficit was the following: solar space > pasture land > forest land > arable land > garden land, except marine areas.A qualitative comparison of methodology was made between solar space method and ecological footprint according to their capability to describe the temporal-spatial characteristics of ecosystems appropriation. Moreover, a quantitative comparison was also conducted to show their differences in applicability to the assessment of ecosystems appropriation. It was shown that the calculating results from solar space method were bigger than that from ecological footprint because the former supplemented additional items of appropriation omitted by the later and included some new items of indirect appropriation that were excluded by the later. It is found that the new measure of solar space operates well as an indicator of the city's appropriation to ecosystems.     

Evaluation of ecosystem services of Chinese pine forests in China

Evaluation of forest ecosystem services is a hot topic, both in China and at abroad, but it has not yet obtained a consistency of evaluation indicator systems and evaluation methods. Under the framework of evaluation criteria to be implemented for forest ecosystem services, years of consecutive observation data from Long Term Ecological Research Stations affiliated to Chinese Forest Ecosystem Research Network (CFERN), forest resource inventory and public data were applied to carry out a detailed and dynamic evaluation on the physical quantity and value of ecosystem services of Chinese pine forests in China. The results showed that the above services had the total value and unit value of 1144.9640 billion (1.1449640×10¹²) RMB and 52.074 thousand RMB per hectare per year, respectively during the 9th Five-year Plan (1996–2000), and of 1190.5461 billion RMB and 52.101 thousand RMB per hectare per year, respectively, during the 10th Five-year Plan (2001–2005). For Chinese pine forests, water conservation was 40.40 hundred million cubic meters annually, soil conservation was 67 million tons and C fixation 9 million tons annually, production of healthful negative ions was 1.96×10²⁰, absorption of SO₂ was 5.02 hundred million kilograms and dust-catching was 759.10 hundred million kilograms. Among the 15 provinces of China with Chinese pine forests, the biggest beneficiary from ecosystem services was Liaoning Province; while Hunan Province was the smallest beneficiary between the 9th Five-year Plan.     

漓江流域生态系统服务价值最大化的土地利用结构优化

土地利用结构优化是促进生态系统可持续发展的重中之重,而生态管理的最终目标是优化生态系统服务,使生态系统提供的服务达到最大化。选择典型生态脆弱区漓江流域为研究区,将整个生态系统服务价值的最大化作为研究目标,首先结合野外实验和五期Landsat高分遥感影像获取基础数据,对研究区1998-2018年各项生态系统服务价值进行估算,然后结合灰色线性模型对2018-2028年价值进行预测,借助Lingo软件提出生态效益最大化的土地结构优化方案,进而对优化前后研究区生态系统服务价值进行比较与分析。结果表明：（1）近20年间研究区主要土地利用类型一直以林地与耕地为主,所占比例保持在整个流域的95%。水域与耕地面积逐年减少,林地、建设用地及未利用地面积持续增加。此外,未利用地面积发生的变化最为显著,增加了近30倍,主要由林地与耕地转变而来。（2）研究区生态系统服务价值总体约减少了19.55×10⁶元,呈现先上升后下降趋势,并将长期处于下降趋势,至2028年时流域生态系统服务价值将减少至8067.43×10⁶元。在流域整体生态系统中,林地价值最高,在历年约占流域总价值的86%,其次是水域及耕地,分别占比8%、6%。（3）对研究区进行优化后,漓江流域总生态系统服务价值增长了2%,其中主要来源于林地与水域面积的增加,提高了生态系统调节服务的供给能力,耕地、建设用地面积略微增加,未利用地面积显著减少,基本与2008年水平持平。本研究通过优化喀斯特地区关键生态系统服务价值,为该区域生态管理提供科学支撑。     

Impacts of Urbanization on Ecosystem Goods and Services in the U.S. Corn Belt

In this study, three cities located in the U.S. Corn Belt are evaluated for impacts of past (1992–2001) and projected (2001–2030) urban expansion on ecosystem goods and services, with a specific focus on changes in energy balance, hydrology, and productivity. Scenarios for high-, medium- and low-density urban areas are simulated using a dynamic agro-ecosystem model (Agro-IBIS), by incorporating new parameterizations for impervious surfaces and turf grass. Moderate Resolution Imaging Spectroradiometer (MODIS) 500-m albedo data and remote sensing-derived 30-m resolution maps from the U.S. National Land Cover Database are used as model input to simulate biogeochemical, thermodynamic, and hydrological cycles for a range of land-cover types in each region. The results show that the expanding urban areas have a significant impact on each city’s capacity to regulate climate and flooding. High-density urban areas, for instance, have soil surface temperatures up to 6°C higher than soils within natural and managed ecosystems. Expansion of turf grass in residential areas could require an additional 8–105 million m³ of water use annually, which increases runoff by 15–48% and reduces the capacity to respond/adapt to flooding. Finally, the analysis shows that net primary productivity (NPP) decreases as expected due to the removal of cropland, forests, and grasslands in favor of development, but increased urban turf grass provides an annual offset of 40–210 g C m⁻². Urban expansion through 2030 is estimated to lower total annual crop production by 8.1, 8.6, and 16.7% for the Madison, Peoria, and Indianapolis regions, respectively. Given current projections for city growth to exceed 2–3% per year in the north-central U.S., urban expansion across a nine-state region in the Corn Belt could potentially take an additional 210,000–310,000 ha of farmland out of production annually at a time when demand for food, fuel, and fiber is increasing. Because conversion of cropland to urban uses is nearly always unidirectional, any changes to ecosystem goods and services due to urbanization are likely to be permanent and irreversible.     

基于生态足迹的大型水电工程建设生态补偿标准评价模型——以三峡工程为例

生态足迹作为重要的生态环境指标,已被广泛应用于可持续性分析中,但在生态补偿领域应用的较少。运用生态足迹思想,构建了6类大型水电工程建设的生态供给足迹与生态需求足迹模型,以此为基础,确立了大型水电工程建设的生态补偿标准评价模型;并进行了三峡工程案例研究。结果表明:(1)三峡工程建设6项正面影响的生态供给足迹为949.96×104hm2/a,换算成总经济价值为619.18×108元/a;三峡工程建设9项负面影响的生态需求足迹为188.98×104hm2/a,换算成总经济损失为123.18×108元/a。(2)发电产品、调蓄洪水和发电环境效益是三峡工程的主要正面影响,三者经济价值占总经济价值的95.06%;水库泥沙淤积和水库淹没是三峡工程的主要负面影响,两者经济损失占总经济损失的85.56%。(3)三峡工程建设的生态补偿标准为123.18×108元/a,水电开发业主、中央政府和地方政府是主要的生态补偿主体,两者承担了95.06%的生态补偿标准额度;河流生态系统和移民是主要的生态补偿对象,两者获得了91.39%的生态补偿额度。通过对比分析发现,构建的模型在三峡工程案例中得到了很好的验证。     

A trait-based approach to species’ roles in stream ecosystems: climate change,community structure,and material cycling

The sustained decline in habitat quality and community integrity highlights the importance of understanding how communities and environmental variation interactively contribute to ecosystem services. We performed a laboratory experiment manipulating effects of acclimation temperature (5, 15, 25, and 35°C) on resource acquisition, assimilation and subsequent ecosystem services provided by eight freshwater mussel species. Our results suggest that although freshwater mussels are broadly categorized as filter feeders, there are distinct nested functional guilds (thermally tolerant and sensitive) associated with their thermal performance. At 35°C, thermally tolerant species have increased resource assimilation and higher rates of contributed ecosystem services (nutrient excretion, benthic–pelagic coupling). Conversely, thermally sensitive species have decreased assimilation rates and display an array of functional responses including increased/decreased benthic–pelagic coupling and nutrient excretion. Although thermally sensitive species may be in poorer physiological condition at warmer temperatures, their physiological responses can have positive effects on ecosystem services. We extrapolated these results to real mussel beds varying in species composition to address how shifts in community composition coupled with climate change may shift their contributed ecological services. Comparative field data indicate that two co-existing, abundant species with opposing thermal performance (Actinonaias ligamentina, Amblema plicata) differentially dominate community biomass. Additionally, communities varying in the relative proportion of these species differentially influence the magnitude (benthic–pelagic coupling) and quality (N:P excretion) of ecosystem services. As species are increasingly threatened by climate change, greater emphasis should be placed on understanding the contribution of physiological stress to the integrity and functioning of ecosystems. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

污染足迹及其在区域水污染压力评估中的应用——以太湖流域上游湖州市为例

传统生态足迹理论虽然在可持续发展评价等方面得到了广泛的应用,但却仍然无法全面衡量人类活动对生态系统造成的各种影响。其无法全面评估人类活动的根源在于,土地功能排他性假设限制了其对利用生态系统非生物生产性产品和服务的人类活动的衡量。为了摆脱传统生态足迹理论的局限性,建议承认土地功能多样性的客观事实,将生态足迹构建于多种生态系统服务功能之上。针对传统生态足迹对定义中废弃物吸纳的考虑不足,提出了基于污染物吸纳功能的生态足迹,即污染足迹。污染足迹不是对传统生态足迹中能源足迹的简单置换,而是能够囊括人类活动产生的大部分污染物,并可以根据不同的污染物类别或类型进一步细化的足迹类型。构建了太湖流域有机物、氮和磷污染足迹模型,并利用该模型对流域上游湖州市的水污染压力进行了综合评估。结果表明:(1)2007年湖州市污染足迹为39948.73 hm²,东部平原地区污染足迹较大,西部丘陵地区污染足迹相对较小;(2)湖州市人类活动排放的氮磷污染物对水域空间的生态占用已经远远超过了有机污染物;(3)2007年湖州市污染承载力为20896.00 hm²,污染赤字为19052.73 hm²,人类排污活动俨然超出了当地水域的承载能力;(4)2007年湖州市污染压力指数为1.91,当地水环境总体上处于轻度接近中度污染压力;(5)湖州市水污染压力较大的地区,区域内人类活动的维持建立在区域水环境质量恶化或污染物向下游输移的基础之上。     

南方丘陵山地生态系统服务与农村社区协同发展模式研究——以广东乐昌市8个乡村为例

生态系统服务是保障农村经济可持续发展和生态环境健康的重要基础,农村社区作为乡村社会经济的基本构成单位以及小尺度复合生态系统,其经济活动将直接扰动自然生态系统服务。南方丘陵山地是我国重要的生态屏障带,生态保护的意义重大。以该地带重要生态功能区的广东乐昌市的8个地形地貌相似、但发展存有较大差异的乡村为研究对象,利用遥感影像和实地调查数据,综合分析各村土地利用及经济发展状况;基于国际通用生态系统服务分类标准和评估方法,构建乡村生态系统服务指标体系,对各村生态系统服务进行价值评估,并探讨生态系统服务与农村社区协同发展的典型模式。研究表明：（1）从生态服务功能总价值来看,浆源村最高,为16585.173万元/a,前村次之,为13152.621万元/a,车头园村最低,为1611.611万元/a;单位面积生态系统服务价值量总体呈相似的格局,但局部略有差异。前村、上丛村较高,分别为8.739万元hm^-2 a^-1、8.080万元hm^-2 a^-1。（2）土地利用以及经济发展方式的差异,影响了生态系统服务的保持、维护及利用,各村农户经济收入与从生态系统服务获得的福利,以及乡村生态系统服务价值与经济发展水平呈现不均衡的特征。（3）基于发展基础、生态条件等,适度发展乡村特色种植和生态旅游等低影响经济发展模式,有利于降低对生态系统服务,尤其是调节、支持类等功能的影响,并促进生态系统服务非商业价值向商业价值转变,提升乡村经济发展水平。研究结果以期为维护重点生态功能区的生态安全,优化乡村经济结构与发展模式,推进生态服务功能提升及农村社区协同发展提供参考。     

鹤岗矿区生态系统服务价值

生态系统服务与人类福祉有着密切的关系。采用修正后的单位面积生态系统价值当量因子的方法,对鹤岗矿区不同沉陷时期（1993、2000、2013年）9种类型生态系统服务价值进行核算。结果表明：①1993、2000和2013年鹤岗矿区生态系统的总服务价值量分别为2219.21、1025.15和3531.95万元。就生态系统而言,耕地的平均服务价值最高,占平均总价值的189.35%;其次是林地和水域,分别占平均总价值的46.50%和26.83%。②就生态系统服务类别而言,支持功能服务价值最高,平均价值量占平均总价值量的186.67%,其次是调节服务,占45.34%,文化服务占5.73%,供给服务占-137.74%。③1993-2013年,鹤岗矿区生态系统服务价值自西向东递增,这与采煤方向和开采程度差异有关。这种分布趋势主要受由采矿活动引起的土地利用类型、面积及质量变化的影响。④与无考虑空间异质性因素情况相比,1993、2000年鹤岗矿区生态系统服务总价值分别减少了152.96和580.12万元,2013年增加了781.63万元。随煤炭开采,1993-2013年鹤岗矿区采煤沉陷地自然生态环境状况呈现一个由下降到好转的过程。     

黄土高原生态工程对关键生态系统服务时空变化的影响——以延河流域为例

黄土高原地区生态工程的实施,使其生态环境得到显著改善,提高了生态系统服务能力。现有的研究成果中,生态工程对生态系统服务影响的定量评价比较匮乏。以延河流域为例,采用RUSLE模型和InVEST模型对生态系统服务进行评价,通过构建模型识别出不同时期的生态工程区,探究生态工程对生态系统服务的定量影响,为下一步生态工程的实施提供科学的指导和依据。结果表明：(1)2000—2018年,延河流域土壤保持服务和产水服务均呈波动增长趋势,但二者的变化并不同步。(2)4个时期内,能产生生态效应的生态工程区面积呈波动增长趋势,从854 km²增加到1343 km²,在整个流域均有分布,不同时期的重点分布区不同。(3)生态工程增强了区域的土壤保持能力和产水能力,土壤保持服务增强区面积从477.5 km²增加到1140.6 km²,保持的土壤总量从2.1×10⁷ t增加到5.6×10⁷ t;产水服务增强区面积从139.1 km²增加到485.5 km     

δ<Superscript>15</Superscript>N constraints on long-term nitrogen balances in temperate forests

Biogeochemical theory emphasizes nitrogen (N) limitation and the many factors that can restrict N accumulation in temperate forests, yet lacks a working model of conditions that can promote naturally high N accumulation. We used a dynamic simulation model of ecosystem N and δ¹⁵N to evaluate which combination of N input and loss pathways could produce a range of high ecosystem N contents characteristic of forests in the Oregon Coast Range. Total ecosystem N at nine study sites ranged from 8,788 to 22,667 kg ha⁻¹ and carbon (C) ranged from 188 to 460 Mg ha⁻¹, with highest values near the coast. Ecosystem δ¹⁵N displayed a curvilinear relationship with ecosystem N content, and largely reflected mineral soil, which accounted for 96–98% of total ecosystem N. Model simulations of ecosystem N balances parameterized with field rates of N leaching required long-term average N inputs that exceed atmospheric deposition and asymbiotic and epiphytic N₂-fixation, and that were consistent with cycles of post-fire N₂-fixation by early-successional red alder. Soil water δ¹⁵NO₃ ⁻ patterns suggested a shift in relative N losses from denitrification to nitrate leaching as N accumulated, and simulations identified nitrate leaching as the primary N loss pathway that constrains maximum N accumulation. Whereas current theory emphasizes constraints on biological N₂-fixation and disturbance-mediated N losses as factors that limit N accumulation in temperate forests, our results suggest that wildfire can foster substantial long-term N accumulation in ecosystems that are colonized by symbiotic N₂-fixing vegetation.     

Coarse woody debris mass and nutrients in forest ecosystems of Korea

Coarse woody debris (CWD) is an essential component of forests. However, quantification of both the mass and nutrient content of CWD within a given environment tends to be a fairly labor-intensive proposition that requires long-term studies to be conducted for viable data to be obtained. As a result, various aspects of CWD in forest ecosystems remain somewhat poorly understood. In this review, we have compiled all available estimates of CWD mass and nutrients from both coniferous and deciduous forests in Korea. The CWD mass data varied substantially by forest type, age, location, and sampling time, ranging from 1.5 to 24.5 Mg ha⁻¹, and for the amount (kg ha⁻¹) of nutrients in the CWD, ranging from 3.5 to 23.6 for nitrogen (N), 0.8 to 4.7 for phosphorus (P), 3.9 to 13.3 for potassium (K), 25.9 to 30.9 for calcium (Ca), 1.4 to 4.2 for magnesium (Mg), and 0.1 to 0.6 for sodium (Na). The mass of CWD transferred from live trees to the forest floor ranged between 0.1 and 4.9 Mg ha⁻¹ year⁻¹, and these values were roughly equivalent to 26–42% of the annual litterfall inputs (2.5–10.8 Mg ha⁻¹ year⁻¹) for mixed Quercus spp. forests within the relevant region. Annual nutrients inputs (kg ha⁻¹ year⁻¹) through CWD decomposition were 0.7–1.6 for N, 0.04–0.3 for P, 0.3–1.0 for K, 1.7–3.1 for Ca, and 0.1–0.3 for Mg. Consequently, these results revealed that the ecological value of CWD for C and nutrient cycling was relatively insignificant. However, only a limited number of studies have been conducted on CWD in different coniferous or mixed deciduous forests in the region. As a direct result of this paucity of data, further long-term studies on CWD mass and nutrients in a variety of forest types are required in order to be able to evaluate accurately the ecological value of CWD on biodiversity and physical properties in Korean forest ecosystems.     

Spatial Resilience of Coral Reefs

There have been several earlier studies that addressed the influence of natural disturbance regimes on coral reefs. Humans alter natural disturbance regimes, introduce new stressors, and modify background conditions of reefs. We focus on how coral reef ecosystems relate to disturbance in an increasingly human-dominated environment. The concept of ecosystem resilience—that is, the capacity of complex systems with multiple stable states to absorb disturbance, reorganize, and adapt to change—is central in this context. Instead of focusing on the recovery of certain species and populations within disturbed sites of individual reefs, we address spatial resilience—that is, the dynamic capacity of a reef matrix to reorganize and maintain ecosystem function following disturbance. The interplay between disturbance and ecosystem resilience is highlighted. We begin the identification of spatial sources of resilience in dynamic seascapes and exemplify and discuss the relation between “ecological memory” (biological legacies, mobile link species, and support areas) and functional diversity for seascape resilience. Managing for resilience in dynamic seascapes not only enhances the likelihood of conserving coral reefs, it also provides insurance to society by sustaining essential ecosystem services. Received 25 February 2000; accepted 31 January 2001.