Assessing significant harm to terrestrial ecosystems from contaminated land

Abstract. Terrestrial ecosystem risk assessment remains in its infancy by comparison with the aquatic discipline, yet it is advancing quickly in response to increasing concerns surrounding soil quality and the sustainable use of soil. Several international frameworks have been developed during the last decade to aid decision-makers as the need for scientifically derived tools for determining ecological risk from land contamination has been recognized. From the regulatory viewpoint, the priority is establishing what to protect in order to prevent ecological harm. This is a complex issue requiring clear objectives in a risk assessment context. The most important factor in assessing ecological harm is whether or not ecosystem function is altered as a result of land contamination and, if it is, judging the significance. A consensus is developing that ecological risk assessment should aim to protect populations rather than individuals. This paper critically reviews recent developments in risk assessment for terrestrial ecosystems and land contamination in the UK, with emphasis on deriving a measure of ecological harm to assess ecosystem function. We seek to further justify the use of earthworms as a favoured indicator species for protecting ecological function. Guidance on how to measure harm in relation to ecological function is, however, still lacking.     

1981-2010年内蒙古沙漠化演变对区域生态系统服务价值的影响

土地沙漠化是生态系统服务价值变化的重要影响因素,文章基于NDVI等多源数据与GIS、敏感性分析方法,分析了1981—2010年内蒙古地区沙漠化演变对区域生态系统服务价值的影响。结果表明:（1）1981—2010年,内蒙古地区沙漠化面积净增加6.92万km²,但总体沙漠化程度有所改善。沙漠化逆转区域主要集中于内蒙古西南部的鄂尔多斯与阿拉善,而沙漠化发展区域主要发生在中北部的科尔沁和浑善达克。（2）生态系统服务总价值减少671.57亿元;沙漠化演变对生态系统服务价值具有中度线性相关关系,其造成生态系统服务价值损失比例为23.7%。（3）沙漠化演变对沙区生态系统服务价值变化的影响具有空间异质性,在鄂尔多斯、浑善达克等地表现为促进作用,在土默特、内蒙后山等表现为反向作用。（4）各沙区生态系统服务价值对沙漠化演变敏感度差异明显;科尔沁、河套平原等地敏感性指数高于50,而呼伦贝尔、内蒙后山等则小于1。该结果可为内蒙古自治区的科学土地规划、生态保护及可持续发展提供重要参考。     

Diversity and dynamics of eco-units in the biological reserves of the Fontainebleau Forest (France): Contribution of soil biology to a functional approach

Beech integral biological reserves of the Fontainebleau forest (France) display varied site conditions due to geomorphological heterogeneity and to interactions between biological components of the ecosystem. Taking examples in shifts observed in plant communities following gap opening, the authors show that, as Oldeman viewed it, tree-fall gaps seem to be the driving force in sylvigenesis as well as a source of spatial biodiversity. Studies carried out on macromorphological features of humus profiles and on the behaviour of soil invertebrate communities (Lumbricidae and Nematoda) pointed out two key aspects of forest functioning. First, the renewal of the forest ecosystem is linked to the dynamics of humus forms and of soil animal functional groups, featuring the regeneration of trees. Second, tree-fall gaps are places where the forest ecosystem is destabilized and thereafter may renew itself or on the contrary may evolve towards another ecosystem, showing either a co-adaptation between the sylvigenetic and the edaphic cycle, or a discordance between these two cycles. These two aspects (co-adaptation and discordance), important from the point of view of fundamental ecology and forest management, suggest a need for further field research.

Résumé

La hêtraie des réserves biologiques intégrales de la forêt de Fontainebleau offre des situations naturelles variées en fonction de l'hétérogénéité géomorphologique et des interactions entre les composantes biologiques de l'écosystème. Prenant comme exemple l'évolution des associations végétales au sein des clairières, les auteurs montrent que, selon la conception d'Oldeman, le chablis apparaît comme l'élément moteur de la sylvigénèse et un facteur important de biodiversit é spatiale. Des études portant sur la caractérisation macromorphologique des profils d'humus et le comportement des peuplements d 'invertébrés du sol (Lumbricidae, Nematoda) mettent en avant deux points importants pour le fonctionnement de l'écosysteme forestier. Premièrement, le renouvellement de l'écosystème est associé à la dynamique des humus et des groupes fonctionnels de la pédofaune, façonnant ainsi la niche de régénération. Deuxièmement, les clairières apparaissent comme une zone de rupture de l'écosystème forestier pouvant lui permettre, soit de se renouveler, soit d'évoluer vers un autre écosystème, montrant ainsi soit une co-adaptation entre le cycle sylvigénétique et le cycle édaphique, soit une discordance entre ces deux cycles. Cette approche fonctionnelle par le biais de la biologie des sols suggère une réflexion touchant autant l'écologie fondamentale que la gestion forestière.     

重建生态系统有机碳贮量的时空变异

In global change research, changes of soil organic carbon (SOC) reservoirs in tropical and subtropical regions are still unknown. The temporal-spatial variability of SOC stocks was determined in a basin of over 579 km² in subtropical China from 1981 to 2002. ArcGIS8.l software was utilized for spatial analysis of semivariance, ordinary kriging (OK), and probability kriging (PK). Grid and hierarchical approaches were employed for the sampling scenario in 2002 with 106 Global Position System (GPS) established spots sampled. Bulk topsoil samples (0-30 cm) were collected at three random sites on each spot. The SOC content for 1981 came from the SOC map of the Second National Soil Survey. Geostatistical results of the nugget to sill ratio (0.215-0.640) in the rehabilitating ecosystem indicated a moderate spatial dependence for SOC on this large scale. The range of SOC changed from 2.04 km in 1981 to 7.15 km in 2002. The mean topsoil SOC increased by 4.6% from 10.63 g kg^-1 (1981) to 11.12 g kg^-1 (2002). However, during this 21-year period 25.2% of the total basin area experienced a decrease in SOC. Also, the probability kriging results showed that the geometric mean probabilities of SOC ≤ 6.0 g kg^-1, ≤ 11.0 g kg^-1 and > 15.0 g kg^-1 were 0.188, 0.534 and 0.378, respectively in 2002, comparing to 0.234, 0.416 and 0.234 in that order in 1981, respectively. The SOC storage in the topsoil increased by 17.0% during this time with the main increase occurring in forests and cultivated land, which amounted to 82.5% and 17.0% of the total increase, respectively.     

The impact of ecotourism on livelihood and natural resource management in Eselenkei,Amboseli Ecosystem,Kenya

This paper presents the impact of ecotourism on livelihood and natural resource management in the periphery of Amboseli Biosphere Reserve in Kenya. Ecotourism initiatives that have been introduced by Porini Ecotourism, a private investor, are benefiting Eselenkei Group Ranch in terms of income, improved infrastructure, employment opportunities and exposure. Over US$5000 is received annually as land rent, gate fee and bed charges. Twenty‐six Maasai men are employed for the upkeep of project facilities. The community's capacity to facilitate resource‐related conflicts has improved following support from development institutions. An expanding livelihood base is reducing local vulnerability to disaster and people–wildlife conflicts. The numbers of resident wildlife species in the conservation area have increased due to regeneration of woody species and reduced frequency of livestock. Despite the achievements, ecotourism is threatened by cultivation. The latter is jeopardizing conservation efforts, as the area frequented by wildlife is being lost and people–wildlife conflicts intensified. Another dilemma is that the Eselenkei community is not effectively participating in ecotourism a situation that is associated with inadequate management and negotiation skills in the group ranch committee. The latter requires leadership and microenterprise management skills if earnings from ecotourism are to be effectively invested in alternative sources of livelihood, to reduce current and potential conflicts. There is also need to build the community's capacity for the promotion of activities that compliment ecotourism. Frequent breakdown of community boreholes lead to dependence on the conservation area for water during prolonged drought, intensifying conflicts between livestock and wildlife.

1 Referring to low‐impact nature‐based tourism packages that benefit local communities and the national government while helping to conserve the resource base (Kenya Wildlife Service (KWS), unpublished report, 2001).

Copyright © 2002 John Wiley & Sons, Ltd.     

土地利用变化对长江上游生态系统服务价值的影响

该文以典型生态脆弱带——长江上游地区1980、1990和2000年的土地利用动态数据为基础,参照中国陆地生态系统单位面积服务价值表,结合敏感度分析,探讨了土地利用变化及其对生态系统服务价值的影响。结果表明,1980－1990年研究区林地、草地和湿地面积都有不同程度增长,生态系统服务价值呈增加趋势;但在1990－2000年间,建设用地、耕地和未利用地面积大幅度增加,且大多来源于林地和草地等地类的转化或退化,使得整个研究期间内各项生态系统服务功能都出现不同程度的衰退。生态系统服务价值也从1980年的11 119.16亿元减少到2000年的11 077.85亿元,净减少值为41.31亿元。该区域快速城市化和以经济利益为目的的发展模式给生态系统服务功能和可持续发展带来巨大压力,这种生态环境急剧退化的趋势必须引起高度重视并进行有效控制。     

1990-2014年长江中游经济带生态系统服务价值时空变化特征

基于1990-2014年长江中游经济带土地利用变化过程,参照"中国生态系统单位面积生态系统服务价值当量表",采用Costanza的计算模型估算生态系统服务价值并分析其时空变化特征。结果表明:1990-2014年间,长江中游经济带生态系统服务价值增加113.84亿元,年均增长0.016%,总体呈"山区 > 丘陵区 > 平原区"的空间分布格局,上升区集中于江汉平原南部及洞庭湖平原西部,下降区主要沿"石首市-渝水区-九江县"分布;从不同功能价值来看,区域供给、支持服务功能价值分别下降28.08亿元,35.55亿元,调节、文化服务价值分别上升156.90亿元,20.57亿元,供给、支持和文化服务价值均呈山区高、平原低的分布格局,调节服务价值高值、低值区均集中于平原区,4种生态功能价值主要沿"石首市-渝水区-九江县"下降,调节、文化服务价值在江汉平原南部及洞庭湖平原西部上升,支持服务价值在江汉平原西南部上升,供给服务价值无上升集中区。     

人工管理措施改善了我国西部高寒沙化草甸土壤水分和碳、氮、磷含量

Regeneration of degraded grassland ecosystems is a significant issue in restoration ecology globally. To understand the effects of artificial management measures on alpine meadows, we surveyed topsoil properties including moisture, organic carbon (SOC), nitrogen (N), and phosphorus (P) contents five years after fencing and fencing + reseeding management practices in a sandy meadow in the eastern Qinghai-Tibetan Plateau, northwestern China. Both the fencing and fencing + reseeding management practices significantly increased soil moisture storage, SOC, total N, available N, total P, and available P, as compared to the unmanaged control. Fencing plus reseeding was more effective than fencing alone for improving soil C, N, and P contents. These suggested that rehabilitation by reseeding and fencing generally had favorable effects on the soil properties in degraded sandy alpine meadows, and was an effective approach for restoration of degraded meadow ecosystems of the Qinghai-Tibetan Plateau.     

Assessing net ecosystem carbon exchange of U.S. terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations

More accurate projections of future carbon dioxide concentrations in the atmosphere and associated climate change depend on improved scientific understanding of the terrestrial carbon cycle. Despite the consensus that U.S. terrestrial ecosystems provide a carbon sink, the size, distribution, and interannual variability of this sink remain uncertain. Here we report a terrestrial carbon sink in the conterminous U.S. at 0.63 pg C yr⁻¹ with the majority of the sink in regions dominated by evergreen and deciduous forests and savannas. This estimate is based on our continuous estimates of net ecosystem carbon exchange (NEE) with high spatial (1 km) and temporal (8-day) resolutions derived from NEE measurements from eddy covariance flux towers and wall-to-wall satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the U.S. terrestrial ecosystems could offset a maximum of 40% of the fossil-fuel carbon emissions. Our results show that the U.S. terrestrial carbon sink varied between 0.51 and 0.70  pg C yr⁻¹ over the period 2001-2006. The dominant sources of interannual variation of the carbon sink included extreme climate events and disturbances. Droughts in 2002 and 2006 reduced the U.S. carbon sink by ∼20% relative to a normal year. Disturbances including wildfires and hurricanes reduced carbon uptake or resulted in carbon release at regional scales. Our results provide an alternative, independent, and novel constraint to the U.S. terrestrial carbon sink.     

Assessing turnover of microbial biomass phosphorus: Combination of an isotopic dilution method with a mass balance model

Microbial biomass phosphorus (P) can play an important role in P cycling and availability to plants by acting as a source (remineralization) or sink (immobilization) of phosphate ions (iP). To assess the role of the microbial P pools, both the dynamics (i.e. the turnover) and the size of the microbial P pools were studied in forest soils. Combining an isotopic dilution method with a modelling approach, we showed the existence of two pools of microbial P with different dynamics and therefore of different importance in soil P availability and cycling. In particular, we showed that the largest pool of microbial P (80%) had a fast turnover (nine days). Microbial P increased with an increase in soil organic matter and represented up to 53% of total P in contrasting forest soils. By combining these results with the turnover times of microbial P obtained in the modelling study, we evaluated that 8.5-17.3 kg P ha⁻¹ of microbial P could turn over in a few days. This suggests that microbial biomass P is a potentially significant source of available iP, and that micro-organisms can play a major role in P cycling in the forest studied here. However, microbial biomass can also be in competition with the trees since most of the remineralized P could be immobilized again in the microbial turnover.