辽西半干旱区几种人工林生态系统涵养水源功能研究

从森林生态系统树冠截留降雨、枯落物持水及土壤蓄水3个层次对辽西半干旱区5种人工林生态系统的涵养水源功能进行了定量研究．结果表明,各人工林生态系统树冠对降雨的平均截留率为14．58％～37．19％,依次为沙棘林>油松沙棘混交林>杨树沙棘混交林>油松纯林>杨树纯林;枯落物层厚度为1．6～4．1cm,枯落物贮量为1890．4～6425．2kg·hm^-2,枯落物层厚度和贮量均为沙棘林>油松沙棘混交林>杨树沙棘混交林>油松纯林>杨树纯林,枯落物最大持水量取决于枯落物贮量及其最大持水率,枯落物最大持水量为5957．7～19332．9kg·hm^-2,依次为沙棘林>油松沙棘混交林>杨树沙棘混交林>油松纯林>杨树纯林;各人工林生态系统0～40cm土壤层非毛管蓄水量为23．70～37．85mm,依次为沙棘林>杨树沙棘混交林>油松沙棘混交林>杨树纯林>油松纯林．在5种人工林生态系统中,沙棘林的涵养水源功能最好,混交林较油松和杨树纯林有更好的涵养水源功能．     

Soil organic matter and litter chemistry response to experimental N deposition in northern temperate deciduous forest ecosystems

The effects of atmospheric nitrogen (N) deposition on organic matter decomposition vary with the biochemical characteristics of plant litter. At the ecosystem‐scale, net effects are difficult to predict because various soil organic matter (SOM) fractions may respond differentially. We investigated the relationship between SOM chemistry and microbial activity in three northern deciduous forest ecosystems that have been subjected to experimental N addition for 2 years. Extractable dissolved organic carbon (DOC), DOC aromaticity, C : N ratio, and functional group distribution, measured by Fourier transform infrared spectra (FTIR), were analyzed for litter and SOM. The largest biochemical changes were found in the sugar maple–basswood (SMBW) and black oak–white oak (BOWO) ecosystems. SMBW litter from the N addition treatment had less aromaticity, higher C : N ratios, and lower saturated carbon, lower carbonyl carbon, and higher carboxylates than controls; BOWO litter showed opposite trends, except for carbonyl and carboxylate contents. Litter from the sugar maple–red oak (SMRO) ecosystem had a lower C : N ratio, but no change in DOC aromaticity. For SOM, the C : N ratio increased with N addition in SMBW and SMRO ecosystems, but decreased in BOWO; N addition did not affect the aromaticity of DOC extracted from mineral soil. All ecosystems showed increases in extractable DOC from both litter and soil in response to N treatment. The biochemical changes are consistent with the divergent microbial responses observed in these systems. Extracellular oxidative enzyme activity has declined in the BOWO and SMRO ecosystems while activity in the SMBW ecosystem, particularly in the litter horizon, has increased. In all systems, enzyme activities associated with the hydrolysis and oxidation of polysaccharides have increased. At the ecosystem scale, the biochemical characteristics of the dominant litter appear to modulate the effects of N deposition on organic matter dynamics.     

Soil organic matter molecular composition with long-term detrital alterations is controlled by site-specific forest properties

Forest ecosystems are important global soil carbon (C) reservoirs, but their capacity to sequester C is susceptible to climate change factors that alter the quantity and quality of C inputs. To better understand forest soil C responses to altered C inputs, we integrated three molecular composition published data sets of soil organic matter (SOM) and soil microbial communities for mineral soils after 20 years of detrital input and removal treatments in two deciduous forests: Bousson Forest (BF), Harvard Forest (HF), and a coniferous forest: H.J. Andrews Forest (HJA). Soil C turnover times were estimated from radiocarbon measurements and compared with the molecular-level data (based on nuclear magnetic resonance and specific analysis of plant- and microbial-derived compounds) to better understand how ecosystem properties control soil C biogeochemistry and dynamics. Doubled aboveground litter additions did not increase soil C for any of the forests studied likely due to long-term soil priming. The degree of SOM decomposition was higher for bacteria-dominated sites with higher nitrogen (N) availability while lower for the N-poor coniferous forest. Litter exclusions significantly decreased soil C, increased SOM decomposition state, and led to the adaptation of the microbial communities to changes in available substrates. Finally, although aboveground litter determined soil C dynamics and its molecular composition in the coniferous forest (HJA), belowground litter appeared to be more influential in broadleaf deciduous forests (BH and HF). This synthesis demonstrates that inherent ecosystem properties regulate how soil C dynamics change with litter manipulations at the molecular-level. Across the forests studied, 20 years of litter additions did not enhance soil C content, whereas litter reductions negatively impacted soil C concentrations. These results indicate that soil C biogeochemistry at these temperate forests is highly sensitive to changes in litter deposition, which are a product of environmental change drivers.     

顺德产业生态系统能值动态分析

虽然当前的产业生态学研究多集中于生产线、企业和产业生态园尺度,但城市无疑是产业系统基本组合单元,城市区域尺度的产业生态学研究是产业生态学研究尺度上推的必经阶段。我国产业生态系统及城市化进程的空间分布不均,以顺德等为代表的东南沿海市(县)产业生态系统的发展历程对中西部地区有拉动和借鉴的双重作用。以能值理论方法为基础,结合环境经济学和区域经济学方法,从系统开放性、本土性、闭路循环性和经济性4个方面,投入和产出端2个角度,对顺德市产业生态系统改革开放22a的发展动态进行分析研究。结果发现,22a系统能值总用量增加15.65倍,能值密度增加16.31倍,人均能值使用强度增加9.70倍,外部不可更新资源用量增加16.32倍。能值废弃率在20世纪80年代不断上升而在90年代迅速下降,但环境负载率则表现为无规律的波动状态。20世纪90年代,系统能值出口率上升至1978年的4.10倍,但能值交换率小于1。结果表明,改革开放22a,顺德产业生态系统自组织能力明显提高,土地资源利用率不断提高,但系统对周边负熵资源,尤其是不可更新资源的依赖性不断提高,人力资源生产力水平提高相对较慢。20世纪90年代污染物处理产业发展迅速,但在系统资料消耗端的绿色化方面则无显明进展。系统对不可更新资源的利用效率不高,产出商品在市场交换中处于表面繁荣背景下的生态经济不利地位。系统已到了向知识密集型发展道路转变的拐点域。能值理论方法与环境经济学和区域经济学分析的整合可以满足产业生态系统分析评价要求,针对产业生态系统特点,进行多尺度、多方面联立评价,实现系统发展现状、动态与动因的整合分析,对产业生态系统优化点的发现与优化方向的确定有直接的意义。     

互花米草群落功率最大化倾向

植物新种进入新区域后,通过扰动或搅局,改变生态系统的结构,形成有特色的自组 织生态系统,趋向新条件下的功率最大化.本文应用能值分析的方法,分别对苏北互花米草 生态系统和光滩生态系统进行能值分析和系统评估.结果表明：互花米草生态系统每年能值 产出比光滩生态系统高1.52E+18 sej.能值密度是光滩的4.72倍,基础能值产出率约为光滩生态系统的5倍.互花米草生态系统能更有效地利用能量,增加系统内部的 能值贮存,实现系统内部的功率最大化.互花米草入侵某区域滩涂后,通过自组织促使整个互花米草生态系统趋于功率最大化,充分发挥生态服务功能,但由于其繁殖扩散过快,导致种群爆发,产生了一系列负面效应,如抑制本土物种、侵占航道、危害贝类养殖等.     

The origin of soil organic matter controls its composition and bioreactivity across a mesic boreal forest latitudinal gradient

Warmer climates have been associated with reduced bioreactivity of soil organic matter (SOM) typically attributed to increased diagenesis; the combined biological and physiochemical transformation of SOM. In addition, cross‐site studies have indicated that ecosystem regime shifts, associated with long‐term climate warming, can affect SOM properties through changes in vegetation and plant litter production thereby altering the composition of soil inputs. The relative importance of these two controls, diagenesis and inputs, on SOM properties as ecosystems experience climate warming, however, remains poorly understood. To address this issue we characterized the elemental, chemical (nuclear magnetic resonance spectroscopy and total hydrolysable amino acids analysis), and isotopic composition of plant litter and SOM across a well‐constrained mesic boreal forest latitudinal transect in Atlantic Canada. Results across forest sites within each of three climate regions indicated that (1) climate history and diagenesis affect distinct parameters of SOM chemistry, (2) increases in SOM bioreactivity with latitude were associated with elevated proportions of carbohydrates relative to plant waxes and lignin, and (3) despite the common forest type across regions, differences in SOM chemistry by climate region were associated with chemically distinct litter inputs and not different degrees of diagenesis. The observed climate effects on vascular plant litter chemistry, however, explained only part of the regional differences in SOM chemistry, most notably the higher protein content of SOM from warmer regions. Greater proportions of lignin and aliphatic compounds and smaller proportions of carbohydrates in warmer sites' soils were explained by the higher proportion of vascular plant relative to moss litter in the warmer relative to cooler forests. These results indicate that climate change induced decreases in the proportion of moss inputs not only impacts SOM chemistry but also increases the resistance of SOM to decomposition, thus significantly altering SOM cycling in these boreal forest soils.     

Emergy and eco-exergy evaluation of four forest restoration modes in southeast China

Four different forest restoration modes (Acacia mangium plantation, mixed-native species plantation, conifer plantation and Eucalyptus plantation) were evaluated using Energy System Theory and the emergy synthesis method. In addition, the eco-exergies of the four forest restoration modes were calculated, and combined with emergy and empower density to explore the restoration and self-organization efficiencies of these modes. The results showed that the two plantations of exotic species, especially the Acacia mangium plantation, were best for biomass accumulation and soil improvement, whereas the two plantations of native species, especially the mixed-native plantation, were more efficient in capturing the available natural resources. Transformity is an important emergy index for the evaluation of system efficiency, because it takes both input and output into account. In subtropical plantations, trees mainly contribute to eco-exergy, whereas herbs and shrubs mainly contribute to specific eco-exergy. The c-value Paradox does exist in conifer species in this study, and it could affect the eco-exergy evaluation. The joint use of eco-exergy and emergy analysis is helpful in comparing both different and similar kinds of ecosystems.     

Soil Organic Matter Dynamics Along a Vertical Vegetation Gradient in the Gongga Mountain on the Tibetan Plateau

Our knowledge about soil organic matter (SOM) dynamics is limited although this is an important issue in the study of responses of ecosystems to global climate changes. Twelve sampling plots were set up every 200 m from 1 700 to 3 900 m along the vertical vegetation gradient along the east slope of Gongga Mountain. Samples were taken from all 12 plots for SOM content measurement, although only 5 of the 12 plots were subjected to radiocarbon measurements. A radiocarbon isotope method and a time-dependent model were used to quantify the SOM dynamics and SOM turnover rates along the vertical vegetation gradient. The results showed that the SOM turnover rate decreased and turnover time increased with soil depth for all vegetation types. The litter layer turnover rates presented a clear trend along the gradient. The litter layer turnover rates decreased with an increase in elevation, except that the litter layer turnover rate of mixed forest was higher than that of evergreen forest. Climatic factors, such as temperature and precipitation, were the main factors influencing the surface soil carbon dynamics. The turnover rates of the subsoil (including the A, B, and C horizons in the soil profiles) along the vertical gradient had no clear trends. The SOM of subalpine shrub and meadow turned over more slowly than that of the forest types in almost all soil horizons. The characteristic of short roots distributing in the upper part of the soil profile leads to different SOM dynamics of shrub and meadow compared with the forest types. Coniferous and mixed forests were susceptible to carbon loss from the young carbon pool, but their long and big roots resulted in high △^14C values of the deep soil profiles and increased the input of young carbon to the deep soil. In evergreen forest, the carbon cumulative ability from the B horizon to the C horizon was weak. The different vegetation types, together with their different modes of nutrient and carbon intake, may be the mechanism conditioning the subsoil organic matter dynamics.     

Soil Organic Matter Dynamics Along a Vertical Vegetation Gradient in the Gongga Mountain on the Tibetan Plateau

Our knowledge about soil organic matter (SOM) dynamics is limited although this is an important issue in the study of responses of ecosystems to global climate changes. Twelve sampling plots were set up every 200 m from 1 700 to 3 900 m along the vertical vegetation gradient along the east slope of Gongga Mountain. Samples were taken from all 12 plots for SOM content measurement, although only 5 of the 12plots were subjected to radiocarbon measurements. A radiocarbon isotope method and a time-dependent model were used to quantify the SOM dynamics and SOM turnover rates along the vertical vegetation gradient. The results showed that the SOM turnover rate decreased and turnover time increased with soil depth for all vegetation types. The litter layer turnover rates presented a clear trend along the gradient. The litter layer turnover rates decreased with an increase in elevation, except that the litter layer turnover rate of mixed forest was higher than that of evergreen forest. Climatic factors, such as temperature and precipitation,were the main factors influencing the surface soil carbon dynamics. The turnover rates of the subsoil (including the A, B, and C horizons in the soil profiles) along the vertical gradient had no clear trends. The SOM of subalpine shrub and meadow turned over more slowly than that of the forest types in almost all soil horizons. The characteristic of short roots distributing in the upper part of the soil profile leads to different SOM dynamics of shrub and meadow compared with the forest types. Coniferous and mixed forests were susceptible to carbon loss from the young carbon pool, but their long and big roots resulted in high △14C values of the deep soil profiles and increased the input of young carbon to the deep soil. In evergreen forest,the carbon cumulative ability from the B horizon to the C horizon was weak. The different vegetation types,together with their different modes of nutrient and carbon intake, may be the mechanism conditioning the subsoil organic matter dynamics.     

Modeling analysis of primary controls on net ecosystem productivity of seven boreal and temperate coniferous forests across a continental transect

Process‐based models are effective tools to synthesize and/or extrapolate measured carbon (C) exchanges from individual sites to large scales. In this study, we used a C‐ and nitrogen (N)‐cycle coupled ecosystem model named CN‐CLASS (Carbon Nitrogen‐Canadian Land Surface Scheme) to study the role of primary climatic controls and site‐specific C stocks on the net ecosystem productivity (NEP) of seven intermediate‐aged to mature coniferous forest sites across an east–west continental transect in Canada. The model was parameterized using a common set of parameters, except for two used in empirical canopy conductance–assimilation, and leaf area–sapwood relationships, and then validated using observed eddy covariance flux data. Leaf Rubisco‐N dynamics that are associated with soil–plant N cycling, and depend on canopy temperature, enabled the model to simulate site‐specific gross ecosystem productivity (GEP) reasonably well for all seven sites. Overall GEP simulations had relatively smaller differences compared with observations vs. ecosystem respiration (RE), which was the sum of many plant and soil components with larger variability and/or uncertainty associated with them. Both observed and simulated data showed that, on an annual basis, boreal forest sites were either carbon‐neutral or a weak C sink, ranging from 30 to 180 g C m^?2 yr^?1; while temperate forests were either a medium or strong C sink, ranging from 150 to 500 g C m^?2 yr^?1, depending on forest age and climatic regime. Model sensitivity tests illustrated that air temperature, among climate variables, and aboveground biomass, among major C stocks, were dominant factors impacting annual NEP. Vegetation biomass effects on annual GEP, RE and NEP showed similar patterns of variability at four boreal and three temperate forests. Air temperature showed different impacts on GEP and RE, and the response varied considerably from site to site. Higher solar radiation enhanced GEP, while precipitation differences had a minor effect. Magnitude of forest litter content and soil organic matter (SOM) affected RE. SOM also affected GEP, but only at low levels of SOM, because of low N mineralization that limited soil nutrient (N) availability. The results of this study will help to evaluate the impact of future climatic changes and/or forest C stock variations on C uptake and loss in forest ecosystems growing in diverse environments.     

Biomass, Litter, and Soil Respiration Along a Precipitation Gradient in Southern Great Plains, USA

Knowledge of how ecosystem carbon (C) processes respond to variations in precipitation is crucial for assessing impacts of climate change on terrestrial ecosystems. In this study, we examined variations of shoot and root biomass, standing and surface litter, soil respiration, and soil C content along a natural precipitation gradient from 430 to 1200 mm in the southern Great Plains, USA. Our results show that shoot biomass and soil respiration increased linearly with mean annual precipitation (MAP), whereas root biomass and soil C content remained relatively constant along the precipitation gradient. Consequently, the root/shoot ratio linearly decreased with MAP. However, patterns of standing, surface, and total litter mass followed quadratic relationships with MAP along the gradient, likely resulting from counterbalance between litter production and decomposition. Those linear/quadratic equations describing variations of ecosystem C processes with precipitation could be useful for model development, parameterization, and validation at landscape and regional scales to improve predictions of C dynamics in grasslands in response to climate change. Our results indicated that precipitation is an important driver in shaping ecosystem functioning as reflected in vegetation production, litter mass, and soil respiration in grassland ecosystems.     

Production of Total Potentially Soluble Organic C, N, and P Across an Ecosystem Chronosequence: Root versus Leaf Litter

Dissolved organic matter (DOM) plays several important roles in forest ecosystem development, undergoing chemical, physical and/or biological reactions that affect ecosystem nutrient retention. Very few studies have focused on gross rates of DOM production, and we know of no study that has directly measured DOM production from root litter. Our objectives were to quantify major sources of total potentially water-soluble organic matter (DOM_tps) production, with an emphasis on production from root litter, to quantify and compare total potentially soluble organic C, N, and P (DOC_tps, DON_tps, and DOP_tps) production, and to quantify changes in their production during forest primary succession and ecosystem development at the Mt. Shasta Mudflows ecosystem chronosequence. To do so, we exhaustively extracted freshly senesced root and leaf and other aboveground litter for DOC_tps, DON_tps, and DOP_tps by vegetation category, and we calculated DOM_tps production (g m⁻² y⁻¹) at the ecosystem level using data for annual production of fine root and aboveground litter. DOM production from throughfall was calculated by measuring throughfall volume and concentration over 2 years. Results showed that DOM_tps production from root litter was a very important source of DOM_tps in the Mount Shasta mudflow ecosystems, in some cases comparable to production from leaf litter for DON_tps and larger than production from leaf litter for DOP_tps. Total DOC_tps and DON_tps production from all sources increased early in succession from the 77- to the 255-year-old ecosystem. However, total DOP_tps production across the ecosystem chronosequence showed a unique pattern. Generally, the relative importance of root litter for total fine detrital DOC_tps and DON_tps production increased significantly during ecosystem development. Furthermore, DOC_tps and DON_tps production were predominantly driven by changes in biomass production during ecosystem development, whereas changes in litter solubility due to changes in species composition had a smaller effect. We suggest that DOM_tps production from root litter may be an important source of organic matter for the accumulation of SOM during forest ecosystem development. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Shauna M. Uselman, Robert G. Qualls, and Juliane Lilienfein conceived of or designed the study and performed research. SMU analyzed data and wrote the article. SMU and RGQ contributed new methods or models.     

尖峰岭热带山地雨林生态系统碳平衡的初步研究

报道了我国海南岛目前保存面积较大,林分的组成和结构复杂的热带山地雨林生态系统的Ｃ素库和群落的ＣＯ２排放动态,通过在尖峰岭林区进行为期３ａ的研究,结果表明,热带山地雨林的碳素库主要有３个方面,即森林生物量中的Ｃ为２３４．３０５６ｔ／ｈｍ＾２,森林凋落的现存是中的Ｃ为２．９８ｔ／ｈｍ＾２以及土壤层中的Ｃ为１０４．６９６ｔ／ｈｍ＾２,合计为３４１．９８１６ｔ／ｈｍ＾２,森林生态系统中的ＣＯ２平衡的基本动     

全球气候变暖对凋落物分解的影响

凋落物分解作为生态系统核心过程,参与生态系统碳的周转与循环,影响生态系统碳的收支平衡,调控生态系统对全球气候变暖的反馈结果。全球气候变暖通过环境因素、凋落物数量和质量以及分解者3个方面,直接或间接地作用于凋落物分解过程,并进一步影响土壤养分周转和碳库动态。气候变暖可通过升高温度和改变实际蒸散量等环境因素直接作用于凋落物分解。气候变暖可引起植物物种短期内碳、氮和木质素等化学性质的改变以及群落中物种组成的长期变化从而改变凋落物质量。在凋落物分解过程中,土壤分解者亚系统作为主要生命组分(土壤动物和微生物)彼此相互作用、相互协调共同参与调节凋落物的分解过程。凋落物分解可以通过改变土壤微生物量、微生物活动和群落结构来加快微生物养分的固定或矿化,以形成新的养分利用模式来改变土壤有机质从而对气候变化做出响应。未来凋落物分解的研究方向应基于大尺度跨区域分解实验和长期实验,关注多个因子交互影响下,分解过程中碳、氮养分释放、地上/地下凋落物分解生物学过程与联系、分解者亚系统营养级联效应等方面。     

Parasites boost productivity: effects of mistletoe on litterfall dynamics in a temperate Australian forest

The importance of litter in regulating ecosystem processes has long been recognised, with a growing appreciation of the differential contribution of various functional plant groups. Despite the ubiquity of mistletoes in terrestrial ecosystems and their prominence in ecological studies, they are one group that have been overlooked in litter research. This study evaluated the litter contribution from a hemiparasitic mistletoe, Amyema miquelii (Lehm. ex Miq.) Tiegh., in an open eucalypt forest (Eucalyptus blakelyi, E. dwyeri and E. dealbata), at three scales; the forest stand, single trees and individual mistletoes. Litter from mistletoes significantly increased overall litterfall by up to 189%, the amount of mistletoe litter being proportional to the mistletoe biomass in the canopy. The high litter input was due to a much higher rate of mistletoe leaf turnover than that of host trees; the host litterfall and rate of leaf turnover was not significantly affected by mistletoe presence. The additional litter from mistletoes also affected the spatial and temporal distribution of litterfall due to the patchy distribution of mistletoes and their prolonged period of high litterfall. Associated with these changes in litterfall was an increase in ground litter mass and plant productivity, which reflects similar findings with root-parasitic plants. These findings represent novel mechanisms underlying the role of mistletoes as keystone resources and provide further evidence of the importance of parasites in affecting trophic dynamics.     

季节性雪被变化对森林凋落物分解及土壤氮动态的影响

全球气候变化引发的雪被格局变化将深刻影响植被的凋落物分解、陆地生态系统的土壤养分循环等过程.森林是陆地生态系统的主体,在全球生物地球化学循环中起着不可替代的作用.本研究综述了季节性雪被变化对森林凋落物分解及土壤氮动态的影响.全球气候变化情景下季节性雪被表现出因地域而异的增加或减少的变化格局,一方面通过改变环境温湿度、凋落物质量、分解者动态等直接影响分解过程,另一方面通过改变森林群落结构、植被物候、土壤养分等间接地作用于凋落物分解.同时,季节性雪被通过影响氮富集作用、雪被下土壤温湿度、冻融循环、森林群落、雪下动物和微生物等相关因子而改变森林土壤氮循环.本领域未来应开展的研究是: 1) 全面考虑全球气候变化情景下季节性雪被格局的变异性,开展不同季节性雪被格局变化的模拟研究;2) 开展季节性雪被融雪水淋溶作用对森林凋落物分解和土壤氮动态的影响研究;3) 阐明不同生态系统和气候带中季节性雪被格局变化对森林凋落物分解过程和土壤氮动态的驱动机制研究;4) 量化季节性雪被变化对森林凋落物分解和土壤氮动态在雪被覆盖期的瞬时影响和无雪期的延续影响,为阐明和模型预测陆地生态系统生物地球化学循环对全球气候变化的响应提供理论基础和数据支持.     

Effects of eutrophication and exotic crayfish on health status of two Spanish lakes: a joint application of ecological indicators

Lake Sentiz and Lake Chozas are two small water bodies in the Province of León (NW Spain). The former is mesotrophic and the latter went from oligotrophic to turbid in 1997, due to introduction of an invasive allochthonous crayfish Procambarus clarkii (Rodríguez et al., 2003, Rodríguez et al., 2005, Marchi et al., 2011a, Marchi et al., 2011b). We set out to study health status of the two ecosystems by the joint use of different but correlated ecological indicators, supplementing the values obtained by monitoring campaigns. We examine three scenarios: (1) Lake Sentiz, (2) Lake Chozas before and (3) Lake Chozas after the biological invasion. We evaluate eco-exergy, emergy and eco-exergy–empower ratio, three holistic ecological indicators based on the thermodynamics of far-from-equilibrium systems. When structural changes take place in ecosystems it is recommended to apply holistic thermodynamic indicators as presented in Jørgensen et al., 2010a, Jørgensen et al., 2010b. We propose their joint application for a complete overview of the monetary value of natural capital, because they provide information added to statistical analysis and direct measurement. The aim is to determine which of these indicators best represents the effects of eutrophication and perturbations caused by alien species in the two freshwater systems. The eco-exergy–empower ratio gives the best results, since it clearly indicates lake efficiency in transforming direct and indirect solar energy inputs into organization. The eco-exergy (work capacity) results are used to estimate ecosystem services and quantify the economic value of lake natural capital. Calculation of ecosystem services on an eco-exergy basis provides good indications of monetary gains or losses possible in perturbed systems, including eutrophic or invaded ecosystems. This is not surprising, because work capacities include all possible services offered by ecosystems, not only the services actually used by humans. Eco-exergy and the eco-exergy–empower ratio can be guidelines for the calculation of ecosystem services, although they give only a partial indication of the environmental costs and benefits of a given level of information. The present results suggest political and economic considerations and solutions, and are a useful example for organisations involved in environmental management of pollution and biological invasions by exotic species.     

Establishing and validating individual-based carbon budget model FORCCHN of forest ecosystems in China

According to the principles of plant physiology, forest ecology and soil environment, the individual-based carbon budget model of forest ecosystems in China was established. The model process included two timesteps: the primary daily process comprises photosynthesis, plant respiration, allocation and litter production, and soil respiration and transfer; the primary annual process consists of allocation between stands, increase of tree height and breast diameter, and production of large amount of litter fall. Through validating net primary productiviry (NPP) and net ecosystem productivity (NEP) at the plot level and at the country level, it was demonsteated that the model can well simulate carbon budget of forest ecosystems in China, so it can also simulate dynamics of carbon budget of forest ecosystems in the past and in the future.     

Complementarity of ecological goal functions

This paper summarizes, in the framework of network environ analysis, a set of analyses of energy-matter flow and storage in steady-state systems. The network perspective is used to codify and unify ten ecological orientors or extremal principles: maximum power (Lotka), maximum storage (J?rgensen-Mejer), maximum empower and emergy (Odum), maximum ascendency (Ulanowicz), maximum dissipation (Schneider-Kay), maximum cycling (Morowitz), maximum residence time (Cheslak-Lamarra), minimum specific dissipation (Onsager, Prigogine), and minimum empower to exergy ratio (Bastianoni-Marchettini). We show that, seen in this framework, these seemingly disparate extrema are all mutually consistent, suggesting a common pattern for ecosystem development. This pattern unfolds in the network organization of systems.     

森林生态系统碳循环动态仿真系统的设计

模型方法是森林碳循环研究的有力工具.在Simulink环境下设计开发了通用的森林生态系统碳循环动态仿真系统FORCASS,从仿真系统的模式框架、设计方案和开发过程方面进行综合分析表明,FORCASS具有可行性.该仿真系统具有如下特点：1）将森林生态系统划分为植被碳库、枯落物碳库、土壤碳库和动物碳库4个分室,考虑了众多碳流转移项,具有较高的机理性和解释性;2）仿真系统基于过程,以植被器官生物量碳储量Richards生长方程为驱动项,带入差分方程组进行计算,可操作性高,能够实现林龄变化下的植被净第一性生产力（NPP）、净生态系统生产力（NEP）等多种输出;3）仿真系统基于通用的碳循环模式框架建立,可扩展性能良好.