Questioning the ecosystem services argument for biodiversity conservation

One of the central justifications for the conservation of biodiversity is the notion that species diversity is essential for the maintenance of ecosystem services. However, an important observation overlooked by proponents of this argument is that most ecosystem services are provided not by whole ecosystems, but by any group of species that fulfils certain basic functional criteria. Distinguishing between services that are resilient in response to species decline, and those that are not, is a far less challenging task than identifying the precise influence on ecosystem functioning of rare species. Conservationists have been almost unanimous in their failure to acknowledge this distinction between resilient and sensitive ecosystem services. Not only does this threaten the credibility of conservation science, but also increases the likelihood that natural area management becomes hijacked by the demand that ecosystem service provision be made the dominant management criteria.     

Forest biodiversity,ecosystem functioning and the provision of ecosystem services

Forests are critical habitats for biodiversity and they are also essential for the provision of a wide range of ecosystem services that are important to human well-being. There is increasing evidence that biodiversity contributes to forest ecosystem functioning and the provision of ecosystem services. Here we provide a review of forest ecosystem services including biomass production, habitat provisioning services, pollination, seed dispersal, resistance to wind storms, fire regulation and mitigation, pest regulation of native and invading insects, carbon sequestration, and cultural ecosystem services, in relation to forest type, structure and diversity. We also consider relationships between forest biodiversity and multifunctionality, and trade-offs among ecosystem services. We compare the concepts of ecosystem processes, functions and services to clarify their definitions. Our review of published studies indicates a lack of empirical studies that establish quantitative and causal relationships between forest biodiversity and many important ecosystem services. The literature is highly skewed; studies on provisioning of nutrition and energy, and on cultural services, delivered by mixed-species forests are under-represented. Planted forests offer ample opportunity for optimising their composition and diversity because replanting after harvesting is a recurring process. Planting mixed-species forests should be given more consideration as they are likely to provide a wider range of ecosystem services within the forest and for adjacent land uses. This review also serves as the introduction to this special issue of Biodiversity and Conservation on various aspects of forest biodiversity and ecosystem services.     

Phytodiversity of temperate permanent grasslands: ecosystem services for agriculture and livestock management for diversity conservation

Plant diversity has been reported to increase productivity. Farming practices aiming at conserving or increasing plant diversity are, however, usually less profitable than conventional ones. In this review, we aim to find reasons for this discrepancy, discuss ecosystem services of grassland phytodiversity that are useful for farmers, and ways of livestock management most beneficial for diversity. Under agricultural conditions, a clear effect of species richness on a site’s primary or secondary production has not yet been demonstrated. Reasons could be that species numbers in permanent grassland are above the threshold of five species found effective in experimental plots or that the conditions are more in equilibrium with management than in weeded experimental plots. Other diversity effects on production stability, nutrient and water retention or product quality might convince farmers to increase diversity. However, these should be tested in agricultural situations, as most research has again been carried out in experimental plots. To enhance phytodiversity, grazing has been found superior over mowing, as selective grazing, treading and excreta deposition increase the heterogeneity of a sward and thus the niches available. Especially rotational grazing with intermediate intensity may be advantageous for phytodiversity. However, complex interactions between environmental conditions, sward composition, management and livestock behaviour make it difficult to forecast grazing effects. Thus, ecological and agricultural researchers should cooperate more, e.g. either in interdisciplinary projects or by hiring researchers from the respective other profession and thus diversifying research groups, in order to integrate agricultural management into biodiversity research and biodiversity measurements into agricultural research to advance our understanding of how to make conservation and enhancement of grassland phytodiversity both feasible and sustainable.     

Marine biodiversity and ecosystem services: an elusive link

Efforts to test the hypothesised positive link between ecosystem services and functions and biodiversity are increasing in order to forecast the consequences of the present erosion of biodiversity on ecosystem functions and to provide an additional basis for the conservation of biodiversity. These efforts have been, however, modest in marine ecosystems. An examination of seagrass communities, which are simple assemblages with a limited membership of about 50 species worldwide and <12 species in any one community, provides, however, strong evidence for the existence of such positive link between species richness and ecosystem functions. Ecosystem functions are, however, dependent on the particular membership of the community, rather that its number, for the functions are species-specific properties. Yet evidence, is provided, that an increasing species richness should be, on average, linked to an increase in the functional repertoire present in the community, will lead to a more efficient use of resources and a greater capacity to ensure the sustainability of ecosystem functions under disturbance or ecosystem change. Closer examination indicates that the functional variability of mixed-species seagrass assemblages is correlated to the variability in species size, whereas species of similar size tend to show similar functional capacities and, therefore, a greater degree of functional redundancy. In addition, the demonstration of positive interactions in seagrass communities, which are also dependent on the presence of engineering species in the community that facilitate the growth of other species, provides increasing grounds to expect an enhanced functional performance of mixed communities over that expected from a simple additive contribution of the community members. Multispecific communities also hold, within the functional repertoire they contain, many unrealised functional potentials that may prove instrumental to ensure the sustainability of ecosystem functions in the presence of disturbance or a changing environment. The arguments offered, illustrated for the comparatively simple seagrass communities, provide strong reasons to expect a strong — if difficult to test experimentally — positive relationship between species diversity and the functions of marine ecosystems and, thereby, the services they yield to humanity.     

Restoration of ecosystem services and biodiversity: conflicts and opportunities

Ecological restoration is becoming regarded as a major strategy for increasing the provision of ecosystem services as well as reversing biodiversity losses. Here, we show that restoration projects can be effective in enhancing both, but that conflicts can arise, especially if single services are targeted in isolation. Furthermore, recovery of biodiversity and services can be slow and incomplete. Despite this uncertainty, new methods of ecosystem service valuation are suggesting that the economic benefits of restoration can outweigh costs. Payment for Ecosystem Service schemes could therefore provide incentives for restoration, but require development to ensure biodiversity and multiple services are enhanced and the needs of different stakeholders are met. Such approaches must be implemented widely if new global restoration targets are to be achieved.     

Ecosystem services and biodiversity conservation: concepts and a glossary

The RUBICODE project draws on expertise from a range of disciplines to develop and integrate frameworks for assessing the impacts of environmental change on ecosystem service provision, and for rationalising biodiversity conservation in that light. With such diverse expertise and concepts involved, interested parties will not be familiar with all the key terminology. This paper defines the terms as used within the project and, where useful, discusses some reasoning behind the definitions. Terms are grouped by concept rather than being listed alphabetically.     

Avian conservation practices strengthen ecosystem services in California vineyards

Insectivorous Western Bluebirds (Sialia mexicana) occupy vineyard nest boxes established by California winegrape growers who want to encourage avian conservation. Experimentally, the provision of available nest sites serves as an alternative to exclosure methods for isolating the potential ecosystem services provided by foraging birds. We compared the abundance and species richness of avian foragers and removal rates of sentinel prey in treatments with songbird nest boxes and controls without nest boxes. The average species richness of avian insectivores increased by over 50 percent compared to controls. Insectivorous bird density nearly quadrupled, primarily due to a tenfold increase in Western Bluebird abundance. In contrast, there was no significant difference in the abundance of omnivorous or granivorous bird species some of which opportunistically forage on grapes. In a sentinel prey experiment, 2.4 times more live beet armyworms (Spodoptera exigua) were removed in the nest box treatment than in the control. As an estimate of the maximum foraging services provided by insectivorous birds, we found that larval removal rates measured immediately below occupied boxes averaged 3.5 times greater than in the control. Consequently the presence of Western Bluebirds in vineyard nest boxes strengthened ecosystem services to winegrape growers, illustrating a benefit of agroecological conservation practices. Predator addition and sentinel prey experiments lack some disadvantages of predator exclusion experiments and were robust methodologies for detecting ecosystem services.     

Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from Hatfield Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and fluctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in fish and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between different insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems     

Parasites, biodiversity and ecosystem stability

The influence of parasites in ecosystems, especially on biodiversity, is discussed. Various examples illustrate the role that parasites play in the outcome of interspecific competition, in the success of invading species, and in the separation of emerging species. Parasites can be stabilizers or destabilizers, depending on factors such as susceptibility of hosts and size of the ecosystem. Parasites play a major role each time something disturbs living beings at the populational and/or specific level, as they do at the individual level.     

Assessing conservation biology priorities through the development of biodiversity indicators.

Biodiversity erosion is now a recognized phenomenon within the scientific community, and it is understood that there is an urgent need for action to relieve this loss. However, no consensus exists on how to go about achieving this goal. This is due to two kinds of problems: namely, that there are many different reasons which can motivate conservation attempts and hence they can lead to different priorities, sometimes in direct contrast with one another; and that of the complexity of the natural world which we have to operate in. Regarding the latter, several authors have lamented a severe lack of theoretical support for many conservation decisions. We briefly review some of the criteria that are commonly adopted in conservation, and indicate some of their problems; we then introduce a new theoretical framework based on the use of a series of biological indicators, many of which have already been proposed in the past but never fully explained and/or adopted. In addition, we propose two indices for one of these potential indicators, i.e. evolutionary potential. We conclude with an appeal for a greater collaboration between conservation scientists and evolutionary biologists, in order to encompass evolutionary evidence in the decision-making process. In doing so, we hope to increase the chances of successful conservation efforts.     

生态系统及其服务保护评估:指标与方法

生态系统及其服务的保护日益成为保护生态学研究的前沿和热点领域.本文对国际上生态系统保护和生态系统服务评估的最新概念和方法进展进行综述,主要包括生态系统保护状况及濒危或保护优先等级确定的指标、标准,以及生态系统服务评估和保护的主要方法(包括参数法、模型法和定量指标法),并结合中国生态保护研究的进展和需求,明确了急需解决的问题:1)提出适合中国国情的生态系统保护评估的指标、标准和方法;2)发展生态系统服务评估的定量化方法;3)确定生态系统和生态功能保护需求及其空间优化布局;4)生态系统及其服务保护的政策和激励机制.这些问题的解决将会为生态文明建设提供重要保障.     

Aquatic biodiversity in forests: a weak link in ecosystem services resilience

The diversity of aquatic ecosystems is being quickly reduced on many continents, warranting a closer examination of the consequences for ecological integrity and ecosystem services. Here we describe intermediate and final ecosystem services derived from aquatic biodiversity in forests. We include a summary of the factors framing the assembly of aquatic biodiversity in forests in natural systems and how they change with a variety of natural disturbances and human-derived stressors. We consider forested aquatic ecosystems as a multi-state portfolio, with diverse assemblages and life-history strategies occurring at local scales as a consequence of a mosaic of habitat conditions and past disturbances and stressors. Maintaining this multi-state portfolio of assemblages requires a broad perspective of ecosystem structure, various functions, services, and management implications relative to contemporary stressors. Because aquatic biodiversity provides multiple ecosystem services to forests, activities that compromise aquatic ecosystems and biodiversity could be an issue for maintaining forest ecosystem integrity. We illustrate these concepts with examples of aquatic biodiversity and ecosystem services in forests of northwestern North America, also known as Northeast Pacific Rim. Encouraging management planning at broad as well as local spatial scales to recognize multi-state ecosystem management goals has promise for maintaining valuable ecosystem services. Ultimately, integration of information from socio-ecological ecosystems will be needed to maintain ecosystem services derived directly and indirectly from forest aquatic biota.     

Alien plants as mediators of ecosystem services and disservices in urban systems: a global review

Urban areas have unique assemblages of species which are governed by novel ecological processes. People living in these environments have specific needs and demands in terms of ecosystem services (ES). Urban ecosystems are transformed in many ways by human activities and their floras comprise a high proportion of alien plant species, many of which were intentionally introduced to provide, augment or restore ES. Urban environments also have novel disturbance regimes and provide colonization sites for the establishment, dispersal and proliferation of alien plant species; such conditions often generate biological invasions which may cause marked changes to ES. We review the roles that alien plants play in providing urban ES and ecosystem disservices (EDS) globally. We identify the main ES and EDS associated with alien plants, and highlight the key species involved. A literature search revealed 335 papers, representing studies in 58 cities or urban areas in 27 countries. These studies recorded 337 alien plant species, contributing to 39 different ES and 27 EDS–310 species were recorded as contributing to ES and 53 species to EDS. A small number of alien plant taxa were frequently recorded as providing multiple ES in many urban ecosystems; the 10 most recorded species accounted for 21% of the ES recorded. Some of these species also result in significant EDS; three species accounted for 30% of the EDS recorded. Cultural services (notably aesthetics) are the most reported ES provided by alien plants in urban areas of developed countries, while provisioning services (notably food production) are most reported in developing countries. The most commonly studied EDS provided by alien plants is the impact on human health (notably allergic reactions). Eighty percent of studies on alien plants and ES and EDS have been done in developed countries. To elucidate the full range of effects of alien plants, more work is needed in developing countries. Urban planners and managers need to be mindful of both the positive and negative impacts of alien plant species to maximise the provision of ES.     

Terrestrial birds as indicators of agricultural-induced changes and associated loss in conservation value of Mediterranean wetlands

During the last decades, agricultural intensification has modified the hydrology of Mediterranean wetlands, as has occurred in the Mar Menor coastal lagoon (SE Spain). Salt-steppe dominated wetlands, characteristic of transitional areas surrounding this lagoon and rich in biodiversity values, are threatened by changes in their water regime originated by land-use changes in the watershed. Traditional dryland cultures have also been replaced by irrigated ones. We assess the direct and indirect changes induced by agriculture on a terrestrial vertebrate community (steppe birds) especially sensitive to these ecosystem changes. This is made on the basis of several surveys of terrestrial birds (excluding aerial feeders and raptors) carried out between 1984 and 2008 in a representative wetland of the lagoon's continental margin (Marina del Carmolí). The changes in this bird assemblage reflect the hydrological modifications induced by agriculture at the watershed scale, which have significant effects on the relative representation of wetland habitats. Bird metrics and indices (species abundance, taxonomic composition, conservation value) describe these community changes as the combination of early declines in some species and families, and transient or late increases in other. In the long term, the family Alaudidae (and particularly species like Melanocorypha calandra) have lost importance to the benefit of Turdidae and Fringillidae. The area of salt-steppe explains a large part of the variation in the abundance of Alaudidae, while most variation of Turdidae and Fringillidae respond to the area of saltmarsh. Some Alaudidae seem to take advantage of the intermediate stages of saltmarsh expansion (Calandrella rufescens), or from the marginal irrigated crops fringing the wetland (Calandrella brachydactyla) that could compensate the loss of original agricultural habitats. Habitat changes in the wetland have occurred in three differentiated stages, and modify the steppe bird community towards a more heterogeneous assemblage including scrubland and palustrine species. Among three indices of ornithological value, only that based on the EU Bird's Directive Annex I species was negatively affected, but since the wetland has been designated a Specially Protected Area under this regulation, this represents a management failure. There exists some chance, however, to manage peripheral cropland in favour of biodiversity. The importance of monitoring in conservation evaluation and management is also stressed, since the terrestrial bird community of this wetland has not been regularly surveyed. In fact, its evaluation against the Bird's Directive criteria was made in a period of quick departure from the original, good ecological state of the wetland.     

Biodiversity and biodiversity conservation in Yunnan, China

Yunnan, an inland province at a low latitude and high elevation, lying between 21°09–29°15 N and 97°32–106°12 E in southwestern China, has a vast territory with diversified and unique nature resources. There are more than 18000 high plant species (51.6% of China's total) and 1836 vertebrate species (54.8% of China's total) living in Yunnan on a land area of 39.4 × 10⁴km², i.e., only 4.1% of China's total. Among 15000 seed plants found in Yunnan there are 151 rare and endangered plant species (42.6% of China's protected plants). Out of 335 China priority protected wild animals, Yunnan has 243 species, accounting for 72.5% of China's total, 15% of which are species endemic to Yunnan. However, Yunnan's biodiversity is faced with the menace of excessive exploitation of resources and changes in environmental conditions caused by the activities of an expanding human population. This paper discusses the background, the composition, and the structure of Yunnan's biodiversity. Its biodiversity fragility and the threatened situation are also discussed. Suggestions and recommendations on the strategy and actions of Yunnan biodiversity conservation and sustainable development are proposed.     

陕西省生态系统服务价值评估及时空差异

基于土地利用变更调查数据,运用中国陆地生态系统服务价值当量表,分析了2001-2006年陕西省生态系统服务价值变化与不同尺度上的差异,探讨了耕地占补平衡和退耕还林工程对生态系统服务价值的影响,并分析了其生态系统服务价值动态.结果表明:研究期间,陕西省生态系统服务价值整体呈增加趋势,其中,林地生态系统服务价值量占全省总价值量的比例达76.5％,林地生态系统服务价值增加量占全省增加总量的97.5％,生态系统服务价值降低的地类有耕地、草地和未利用地,耕地生态系统服务价值降低量占全省总降低量的81.7％.研究期内不同地市生态系统服务价值均有不同程度的增加,延安市的增加量最大,其次是榆林市,杨凌区最低.陕西省生态系统服务价值增加最明显的地区为黄土高原地区,其增加量占全省生态系统服务价值总增加量的61.2％,秦巴山地次之,关中平原地区最低.陕西省耕地占补平衡力度相对较大,其2001-2006年耕地生态系统服务价值呈增加趋势.退耕还林工程使黄土高原区生态系统服务价值增加最多,关中平原区增加最少.