Dark diversity: shedding light on absent species

Ecological theory and nature conservation have traditionally relied solely on observed local diversity. In this review, we recommend including those species that are absent from an ecosystem but which belong to its species pool; that is, all species in the region that can potentially inhabit those particular ecological conditions. We call the set of absent species 'dark diversity'. Relating local and dark diversities enables biodiversity comparisons between regions, ecosystems and taxonomic groups, and the evaluation of the roles of local and regional processes in ecological communities. Dark diversity can also be used to counteract biodiversity loss and to estimate the restoration potential of ecosystems. We illustrate the dark diversity concept by globally mapping plant dark diversity and the local:dark diversity ratio.     

Biodiversity loss and the taxonomic bottleneck: emerging biodiversity science

Human domination of the Earth has resulted in dramatic changes to global and local patterns of biodiversity. Biodiversity is critical to human sustainability because it drives the ecosystem services that provide the core of our life-support system. As we, the human species, are the primary factor leading to the decline in biodiversity, we need detailed information about the biodiversity and species composition of specific locations in order to understand how different species contribute to ecosystem services and how humans can sustainably conserve and manage biodiversity. Taxonomy and ecology, two fundamental sciences that generate the knowledge about biodiversity, are associated with a number of limitations that prevent them from providing the information needed to fully understand the relevance of biodiversity in its entirety for human sustainability: (1) biodiversity conservation strategies that tend to be overly focused on research and policy on a global scale with little impact on local biodiversity; (2) the small knowledge base of extant global biodiversity; (3) a lack of much-needed site-specific data on the species composition of communities in human-dominated landscapes, which hinders ecosystem management and biodiversity conservation; (4) biodiversity studies with a lack of taxonomic precision; (5) a lack of taxonomic expertise and trained taxonomists; (6) a taxonomic bottleneck in biodiversity inventory and assessment; and (7) neglect of taxonomic resources and a lack of taxonomic service infrastructure for biodiversity science. These limitations are directly related to contemporary trends in research, conservation strategies, environmental stewardship, environmental education, sustainable development, and local site-specific conservation. Today’s biological knowledge is built on the known global biodiversity, which represents barely 20% of what is currently extant (commonly accepted estimate of 10 million species) on planet Earth. Much remains unexplored and unknown, particularly in hotspots regions of Africa, South Eastern Asia, and South and Central America, including many developing or underdeveloped countries, where localized biodiversity is scarcely studied or described. "Backyard biodiversity", defined as local biodiversity near human habitation, refers to the natural resources and capital for ecosystem services at the grassroots level, which urgently needs to be explored, documented, and conserved as it is the backbone of sustainable economic development in these countries. Beginning with early identification and documentation of local flora and fauna, taxonomy has documented global biodiversity and natural history based on the collection of "backyard biodiversity" specimens worldwide. However, this branch of science suffered a continuous decline in the latter half of the twentieth century, and has now reached a point of potential demise. At present there are very few professional taxonomists and trained local parataxonomists worldwide, while the need for, and demands on, taxonomic services by conservation and resource management communities are rapidly increasing. Systematic collections, the material basis of biodiversity information, have been neglected and abandoned, particularly at institutions of higher learning. Considering the rapid increase in the human population and urbanization, human sustainability requires new conceptual and practical approaches to refocusing and energizing the study of the biodiversity that is the core of natural resources for sustainable development and biotic capital for sustaining our life-support system. In this paper we aim to document and extrapolate the essence of biodiversity, discuss the state and nature of taxonomic demise, the trends of recent biodiversity studies, and suggest reasonable approaches to a biodiversity science to facilitate the expansion of global biodiversity knowledge and to create useful data on backyard biodiversity worldwide towards human sustainability.     

Nearctic earthworm fauna in the southern USA: biodiversity and effects on ecosystem processes

An important aspect of biodiversity is the relative importance of species in the functioning of ecosystems; this is particularly so for the soil biota which regulate organic matter and nutrient dynamics in soil. This paper explores some of the relationships between biodiversity and ecosystem processes, using the example of the nearctic earthworm fauna in the glacial refugium of the southern USA. Competitive exclusion of nearctic earthworm species by exotic species has been postulated but there is little direct evidence of it; habitat alteration is the likely cause of native species decline. Reduced earthworm diversity may or may not strongly affect certain ecosystem processes, but more diverse assemblages may more effectively exploit soil resources and influence a wider array of processes. Nearctic species may be better adapted than exotics to local conditions and thus more strongly influence ecosystem processes. Earthworm communities provide a clear case for the union of functional and taxonomic biodiversity studies, because of the recognized ecological strategies of many species. However, some nearctic taxa may deviate from these strategies. Earthworms utilize course woody debris in forests both as a refuge and a resource, while enhancing the decomposition of wood. Management strategies to maintain or increase biodiversity of soil biota should include residual wood on the forest floor. An important task for ecosystem management is to restore biodiversity in degraded ecosystems; introduction programmes and techniques such as periodic burning may increase the abundance and diversity of native earthworm species. Whole ecosystem conservation and management are probably the most practical ways to conserve biodiversity generally and may be the only ways to maintain soil biodiversity.     

Are indicator groups and cross-taxon congruence useful for predicting biodiversity in aquatic ecosystems?

Resources for biodiversity surveys and conservation planning are limited, and conservation biologists and environmental managers are thus striving to find suitable surrogates for mapping and predicting biodiversity. Among popular surrogates are indicator groups that could be used for predicting variation in the biodiversity of other taxonomic groups. Despite some success at large scales, surveys of multiple taxonomic groups across ecosystems have suggested that no single group can be used effectively to predict variation in the biodiversity of other taxonomic groups. This paper concentrates on indicator groups and cross-taxon congruence in species richness and assemblage composition patterns in inland aquatic ecosystems. As has been found in studies of terrestrial ecosystems, there is low utility for indicator groups in predicting the biodiversity of other taxa in aquatic ecosystems. Even when statistically highly significant correlations between taxonomic groups have been detected, these correlations have been too weak to provide reliable predictions of biodiversity among various taxonomic groups or biodiversity in general. Indicator groups and, more generally, cross-taxon congruence thus do not appear to be particularly relevant for conservation in the freshwater realm.     

Phylogenetic Patterns of Extinction Risk in the Eastern Arc Ecosystems,an African Biodiversity Hotspot

There is an urgent need to reduce drastically the rate at which biodiversity is declining worldwide. Phylogenetic methods are increasingly being recognised as providing a useful framework for predicting future losses, and guiding efforts for pre-emptive conservation actions. In this study, we used a reconstructed phylogenetic tree of angiosperm species of the Eastern Arc Mountains – an important African biodiversity hotspot – and described the distribution of extinction risk across taxonomic ranks and phylogeny. We provide evidence for both taxonomic and phylogenetic selectivity in extinction risk. However, we found that selectivity varies with IUCN extinction risk category. Vulnerable species are more closely related than expected by chance, whereas endangered and critically endangered species are not significantly clustered on the phylogeny. We suggest that the general observation for taxonomic and phylogenetic selectivity (i.e. phylogenetic signal, the tendency of closely related species to share similar traits) in extinction risks is therefore largely driven by vulnerable species, and not necessarily the most highly threatened. We also used information on altitudinal distribution and climate to generate a predictive model of at-risk species richness, and found that greater threatened species richness is found at higher altitude, allowing for more informed conservation decision making. Our results indicate that evolutionary history can help predict plant susceptibility to extinction threats in the hyper-diverse but woefully-understudied Eastern Arc Mountains, and illustrate the contribution of phylogenetic approaches in conserving African floristic biodiversity where detailed ecological and evolutionary data are often lacking.     

Poor historical data drive conservation complacency: The case of mammal decline in south‐eastern Australian forests

Forested ecosystems of south‐eastern Australia now differ physically, compositionally and functionally from their condition prior to European settlement. Understanding these changes, and how native species and entire ecosystems have responded, is crucial for biodiversity conservation and ecosystem management. Here I argue that a combination of limited historical information and a knowledge base biased towards modern ecological studies has resulted in a distorted perception of ecosystem condition, hindering the instigation of effective biodiversity conservation measures. This argument is based on recently obtained information about changes to the non‐volant mammal community, which reveals relatively recent but underreported ecological changes, including major declines in species distribution and abundance, shifts in niche utilization and associated disruption of ecosystem functions. Ultimately, many mammal species are being denied the capacity to function to the extent they did historically. Following this re‐assessment, it is evident that current forest management does not adequately address contemporary conservation dilemmas posed by detrimental ecosystem changes. This is especially salient when most of the factors responsible for causing changes to the mammal community are still active and include forest management and utilization activities. Therefore, additional conservation measures are essential to meet forest stewardship and biodiversity conservation obligations. For the health, functionality and sustainability of forested ecosystems, native mammal species must be capable of functioning to their ecological potential and occupy their original niche. This will be facilitated by the suppression of threatening processes (primarily exotic species), ensuring ecologically sensitive fire regimes and the reintroduction/translocation of missing species. The recovery or restoration of forest functionality based on mammal conservation should have wide‐scale benefits for biodiversity conservation.     

Rapid assessment of invertebrate biodiversity on rocky shores: where there’s a whelk there’s a way

The lack of species inventory data for most marine habitats currently hampers the objective management of marine biodiversity. There is thus a clear need to find reliable indicator taxa that can be targeted in marine conservation studies, providing cost-effective data for planning and monitoring. Using the rocky shores of the Solitary Islands Marine Park, NSW, Australia, as a model, I evaluated macroinvertebrates and determined which taxa (i) best reflected ecological patterns of the broader intertidal community; and (ii) were able to accurately predict species richness of assemblages at the headland scale. Both molluscs and crustaceans showed high levels of correlation with overall species richness. However, molluscs, and in particular prosobranchs, most closely reflected patterns in the community data and provided the most accurate predictions of species richness at the scale of the headland. The potential time savings of using molluscs in rapid assessments are considerable and relate to reductions in field time (by up to 40%) as well as the reduced need to invest time developing extensive taxonomic knowledge of other invertebrate groups. Molluscs are widespread and easily sampled, with stable taxonomy and well-known ecology relative to other marine invertebrate taxa. Their use as surrogates of biodiversity shows great potential for future marine conservation studies.     

Designing criteria suites to identify discrete and networked sites of high value across manifestations of biodiversity

Suites of criteria specifying ecological, biological, social, economic, and governance properties enable the systematic identification of sites and networks of high biodiversity value, and can support balancing ecological and socioeconomic objectives of biodiversity conservation in terrestrial and marine spatial planning. We describe designs of suites of ecological, governance and socioeconomic criteria to comprehensively cover manifestations of biodiversity, from genotypes to biomes; compensate for taxonomic and spatial gaps in available datasets; balance biases resulting from conventionally-employed narrow criteria suites focusing on rare, endemic and threatened species; plan for climate change effects on biodiversity; and optimize the ecological and administrative networking of sites. Representativeness, replication, ecological connectivity, size, and refugia are identified as minimum ecological properties of site networks. Through inclusion of a criterion for phylogenetic distinctiveness, criteria suites identify sites important for maintaining evolutionary processes. Criteria for focal species are needed to overcome data gaps and address limitations in knowledge of factors responsible for maintaining ecosystem integrity.     

Changing conservation strategies in Europe: a framework integrating ecosystem services and dynamics

Protecting species and their habitats through the designation and management of protected areas is central to present biodiversity conservation efforts in Europe. Recent awareness of the importance of ecosystem dynamics in changing environments and of human needs for the sustainable provision of ecosystem services expose potential weaknesses in current European conservation management strategies and policy. Here we examine these issues in the light of information gained from reviews, workshops, interviews and discussions undertaken within the RUBICODE project. We present a new conceptual framework that joins conventional biodiversity conservation with new requirements. The framework links cultural and aesthetic values applied in a static environment to the demands of dynamic ecosystems and societal needs within social–ecological systems in a changing Europe. We employ this framework to propose innovative ways in which ecosystem service provision may be used to add value to traditional conservation approaches by supporting and complementing present European biodiversity conservation strategy and policy while remaining within the guidelines of the Convention on Biological Diversity.     

Conservation biogeography in North-east India: hierarchical analysis of cross-taxon distributional congruence

Distributional similarity (congruence) between phylogenetically independent taxonomic groups has important biogeographical as well as conservation implications. When multiple groups show congruence, one or two of them can be used as surrogates of diversity in others; thus, simplifying some of the challenges of area prioritization for conservation action. Here we test for congruence in complementarity between amphibians, reptiles and birds across seven tropical rainforest sites in the Eastern Himalaya and Indo-Burma global biodiversity hotspots. The results show that while frogs and lizards are strongly congruent with each other, birds as a whole do not show congruence with either of them. However, certain bird subgroups delineated on the basis of broad ecological niche and life history attributes are significantly congruent with both frogs and lizards. Multiple Mantel regression between environmental variable and species distribution dissimilarity matrices indicate that along with differential response to between-site ecological differences, inherent life-history characteristics shared by certain groups contributes to observed patterns of congruence. Our analyses indicate that examining biologically distinct subsets of larger groups can improve the resolution of congruence analyses. This approach can refine area-prioritization initiatives by revealing fine-scale discordances between otherwise concordant groups, and vice versa. Given that monetary resources do not always allow inclusion of multiple groups in biodiversity inventorying efforts, performing such analyses also makes economic sense because it can provide better resolution even with single-group data. In the context of conservation in North-east India, the results highlight the biogeographical complexity of the region, and also point at future priorities for biodiversity inventorying and conservation prioritization, both in terms of areas as well as taxonomic groups.     

中国生物多样性就地保护成效与展望

生物多样性就地保护是指通过开展自然保护地体系的建立与管理, 结合自然保护地以外其他有效的基于区域的保护措施(other effective area-based conservation measures, OECMs), 从而实现物种种群及其栖息地的保护与恢复以及保障和提升生态系统服务的目标。就地保护是实现2020年全球生物多样性保护目标最为重要的措施之一。本文从自然保护地数量与面积、代表性、有效性, 以及其他生物多样性就地保护措施等方面, 整理和综述了国内外近年来的相关报道。总体来看, 我国基本建立了具有中国特色的生物多样性就地保护与管理体系, 实施了各项生物多样性保护恢复措施, 取得了一系列重大进展。自然保护地的面积和数量均呈现上升趋势, 已覆盖陆域国土面积的18%, 对一些重要生态系统及重点保护物种的保护取得了一定成效。正在建设的10处国家公园体制试点提升了部分重点物种的保护连通性。自然保护区总体管理状况相对较好, 保护了90%以上的哺乳动物和97%的兰科植物。此外, 其他有效的基于区域的保护措施亦为生物多样性就地保护贡献了民间力量。在此基础上, 本文对照《中国生物多样性保护战略与行动计划(2011-2030年)》中对“加强生物多样性就地保护”的各项要求, 分析总结了当前我国生物多样性就地保护仍然存在的问题与不足, 具体表现在以下几个方面: 自然保护地整体保护能力仍有待提升; 生物多样性保护优先区域仍然存在保护空缺; 自然保护区管理质量有待提升; 缺乏公共协商机制; 自然保护地以外的其他就地保护工作仍在探索阶段等。在此基础上, 对将来我国生物多样性就地保护提出了进一步建议与展望: (1)制定更为具体和量化的生物多样性就地保护目标; (2)加大力度减少物种受威胁程度, 特别是受关注较少的物种; (3)以保障和提升生态系统服务为目标, 提升生态系统保护修复的系统性与整体性; (4)加强自然保护地以外的生物多样性就地保护; (5)完善长期监测体系, 为生物多样性就地保护成效评估提供数据支撑。本文可为“2020年后全球生物多样性框架”特别是就地保护目标的制定与实施提供参考。     

Conservation and restoration of plant–animal mutualisms on oceanic islands

Islands harbour much of the world's threatened biodiversity. Recent work has highlighted how it is not species diversity per se but rather the interactions between organisms that breathes life into ecosystems. Thus, the real challenge to preserving and restoring biodiversity on islands is not to only focus on species themselves, but more importantly on maintaining and restoring the integrity of interactions between the species. Here we argue that mutualistic plant–animal interactions play a pivotal role with regards to conservation and restoration on islands. Furthermore, these interactions are ideally suited for inter-island comparisons due to ecological and evolutionary similarities across geographical and taxonomical boundaries. The similarities include highly generalised mutualistic systems, the evolution and readjustment of plant reproductive traits, and a disharmony in taxonomic groups of mutualists, compared to continental ecosystems. We highlight past and present threats to island plant–animal mutualisms, as well as the challenges and opportunities inherent to these interactions. In particular, we (1) argue that mutualistic networks provide an ideal approach to collect information and advance our knowledge on the systems, (2) suggest the use of interactions as biodiversity monitoring and assessment tools, (3) highlight the differences and similarities between pollination and seed dispersal interactions in the context of restoration, and (4) briefly discuss the ambiguous role of alien invasive species in the management of mutualistic interactions. Finally, we highlight how a recently proposed but controversial restoration strategy, rewilding, can be gainfully applied to and further advanced in island settings.     

Melting barriers to faunal exchange across ocean basins

Accelerated loss of sea ice in the Arctic is opening routes connecting the Atlantic and Pacific Oceans for longer periods each year. These changes may increase the ease and frequency with which marine birds and mammals move between the Pacific and Atlantic Ocean basins. Indeed, recent observations of birds and mammals suggest these movements have intensified in recent decades. Reconnection of the Pacific and Atlantic Ocean basins will present both challenges to marine ecosystem conservation and an unprecedented opportunity to examine the ecological and evolutionary consequences of interoceanic faunal exchange in real time. To understand these changes and implement effective conservation of marine ecosystems, we need to further develop modeling efforts to predict the rate of dispersal and consequences of faunal exchange. These predictions can be tested by closely monitoring wildlife dispersal through the Arctic Ocean and using modern methods to explore the ecological and evolutionary consequences of these movements.     

关于中国淡水生态系统生物多样性监测与管理的探讨

China is one of the countries in the world with therichest species biodiversityinfreshwater ecosystem.How-ever,duetothe rapid economic growthandthe continuingincrease of human disturbances and destructions of aquatichabitats,the biodiversity of freshwater ecosystemsis dras-tically declining.Waterbodies become more and more“deserted”of sensitive species.Water areas are reduced,fragmentized,and changed in their hydrodynamics(i.e.damming),causing changes in sedimentation and otherchanges.Forinstance,the area o...     

Putting bryophyte communities in the map: A case study on prioritizing monitoring of human pressure in riverscapes

Freshwater ecosystems support biological communities with high species richness and conservation interest. However, these ecosystems are highly altered by human intervention and threatened worldwide, making them a priority in conservation planning and biodiversity monitoring. Bryophytes, including several conservation-interest taxa, are recognized indicators of ecological status in freshwaters. We aimed to develop a framework for designing monitoring networks to detect trends in aquatic and semi-aquatic bryophyte communities, prioritizing high-conservation interest communities in different contexts of human pressure (specifically, resulting from the intersection of two criteria: (i) protection status and (ii) presence of a potential impact area).The framework consists of three steps: (1) Spatial modelling of biodiversity; (2) Spatial conservation prioritization; and (3) Model-assisted monitoring network design. Community-level modelling was used to model the distribution of the main bryophyte assemblages in the study area. A conservation prioritization software was utilized to identify areas with high conservation value. The monitoring network was designed using stratified random sampling and unequal-probability sampling techniques to target high conservation value sites distributed across different contexts of human pressure.We have identified four distinct community types, each characterized both by a small group of common and dominant species, and by small group of rarer, conservation-interest species. This typification of four species assemblages occurring in the study area, also highlighted those with potentially higher conservation-interest. The most valuable areas for the conservation of aquatic and semi-aquatic bryophyte communities coincide with specific environmental zones: mountainous areas in Lusitania, large watercourses in the Mediterranean North and some locations in the Mediterranean Mountains. Finally, we obtained a potential monitoring network consisting of 64 monitoring points, unequally distributed across different contexts of human pressure, privileging locations with higher conservation value.The framework presented here illustrates the potential of combining biodiversity modelling, spatial conservation prioritization and monitoring design in the development of monitoring networks. Namely, this framework allowed us to counter data deficiencies, to identify high priority areas to monitor and to design a monitoring network considering different scenarios of human pressure at a regional scale.This framework can also be valuable for conservation efforts as an approach to monitoring conservation-interest biodiversity features in anthropogenically modified riverscapes, which present different degrees of human pressure and the cumulative effects of these different impact elements. Moreover, this approach allows for the comprehensive monitoring of biodiversity values important for management at the national and regional levels. In addition, this framework is one of the first efforts in the development of monitoring networks that target aquatic and semi-aquatic bryophyte communities, a long-neglected plant group of high ecological and conservation importance in freshwater ecosystems.     

Conserving the functional and phylogenetic trees of life of European tetrapods

Protected areas (PAs) are pivotal tools for biodiversity conservation on the Earth. Europe has had an extensive protection system since Natura 2000 areas were created in parallel with traditional parks and reserves. However, the extent to which this system covers not only taxonomic diversity but also other biodiversity facets, such as evolutionary history and functional diversity, has never been evaluated. Using high-resolution distribution data of all European tetrapods together with dated molecular phylogenies and detailed trait information, we first tested whether the existing European protection system effectively covers all species and in particular, those with the highest evolutionary or functional distinctiveness. We then tested the ability of PAs to protect the entire tetrapod phylogenetic and functional trees of life by mapping species'' target achievements along the internal branches of these two trees. We found that the current system is adequately representative in terms of the evolutionary history of amphibians while it fails for the rest. However, the most functionally distinct species were better represented than they would be under random conservation efforts. These results imply better protection of the tetrapod functional tree of life, which could help to ensure long-term functioning of the ecosystem, potentially at the expense of conserving evolutionary history.     

Biodiversity and China's new Great Wall

Coastal armouring and the reclamation of intertidal areas through the use of seawalls and other artificial structures has been practiced for thousands of years, but its recent expansion in China and elsewhere in Asia has been unprecedented in its rate and intensity. One result has been the recent loss of nearly two‐thirds of tidal flats in the Yellow Sea, a globally unique ecosystem of high ecological value. The severe effects on biodiversity of the recent large‐scale coastal land claim activities in China are well documented, yet some recent studies have emphasized the ecological opportunities provided by such artificial coastal infrastructure in China, in some cases suggesting that the ecological impacts of coastal infrastructure should be reconsidered due to benefits to some rocky shore species in a changing climate. This is cause for concern because, while studying the “new ecology” arising from coastal modification is useful, broad conclusions around the ecological role or conservation gains from seawall construction without adequate contextualization underplays the ecological consequences of large‐scale coastal land claim, and could potentially undermine efforts to achieve biodiversity conservation. Here, we clarify the characteristics of seawall construction in China and summarize the environmental damage and some broadscale impacts caused by this type of infrastructure expansion on the endangered Yellow Sea tidal flats ecosystem. We also highlight the urgent need for all coastal development plans to consider how coastal wetlands and ecosystem functionality can be maximally retained within the development precinct.     

Aquatic biodiversity assessment for the lazy

The world is covered in DNA. In any ecosystem, extracellular DNA fragments can be found that once formed the genomes of a variety of micro‐ and macroorganisms. A few years ago, it was proposed to use this environmental DNA (eDNA) as a source of information on local vertebrate biodiversity (Ficetola et al. 2008 ; Taberlet et al. 2012 ). This idea offered an elegant solution to take up the gauntlet of rapidly increasing monitoring needs. Coupled with barcoding efforts, it promised to be cost‐efficient in many respects, for example man‐hours and taxonomic expertise. Ecologists and conservation biologists with an interest in aquatic ecosystems have enthusiastically adopted and pioneered this new method, producing dozens of eDNA studies. Most of these studies have, however, focused on a single or a few aquatic species. In this issue of Molecular Ecology, Valentini et al. ( 2016 ) move the field a step further by demonstrating that metabarcoding approaches – which simultaneously target large groups of organisms such as amphibians or fish – can match and sometimes even outperform other inventory methods.     

A conceptual framework for urban ecological restoration and rehabilitation

Urban greenspace has gained considerable attention during the last decades because of its relevance to wildlife conservation, human welfare, and climate change adaptation. Biodiversity loss and ecosystem degradation worldwide require the formation of new concepts of ecological restoration and rehabilitation aimed at improving ecosystem functions, services, and biodiversity conservation in cities. Although relict sites of natural and semi-natural ecosystems can be found in urban areas, environmental conditions and species composition of most urban ecosystems are highly modified, inducing the development of novel and hybrid ecosystems. A consequence of this ecological novelty is the lack of (semi-) natural reference systems available for defining restoration targets and assessing restoration success in urban areas. This hampers the implementation of ecological restoration in cities. In consideration of these challenges, we present a new conceptual framework that provides guidance and support for urban ecological restoration and rehabilitation by formulating restoration targets for different levels of ecological novelty (i.e., historic, hybrid, and novel ecosystems). To facilitate the restoration and rehabilitation of novel urban ecosystems, we recommend using established species-rich and well-functioning urban ecosystems as reference. Such urban reference systems are likely to be present in many cities. Highlighting their value in comparison to degraded ecosystems can stimulate and guide restoration initiatives. As urban restoration approaches must consider local history and site conditions, as well as citizens’ needs, it may also be advisable to focus the restoration of strongly altered urban ecosystems on selected ecosystem functions, services and/or biodiversity values. Ecosystem restoration and rehabilitation in cities can be either relatively inexpensive or costly, but even expensive measures can pay off when they effectively improve ecosystem services such as climate change mitigation or recreation. Successful re‐shaping and re-thinking of urban greenspace by involving citizens and other stakeholders will help to make our cities more sustainable in the future.     

Annelids, arthropods or molluscs are suitable as surrogate taxa for selecting conservation reserves in estuaries

The urgent need to conserve aquatic biodiversity and the lack of spatial data on biodiversity has motivated conservation planners and researchers to search for more readily obtainable information that could be used as proxies or surrogates. The surrogate taxon approach shows promise in some aquatic environments (e.g. intertidal) but not others (e.g. coral reefs, temperate rocky reefs). Estuaries are transitional environments at the land–sea junction with a unique biodiversity, but are the most threatened of aquatic environments because of high levels of human use. The comparatively small numbers of conservation reserves means that estuarine biodiversity is poorly protected. Selecting additional conservation reserves within estuaries would be facilitated by the identification of a suitable surrogate that could be used in conservation planning. In one estuary in Southeast Australia, we evaluated separately the effectiveness of annelids, arthropods, and molluscs as surrogates for predicting the species richness, abundance, assemblage variation, and summed irreplaceability of other species and for coincidentally representing other species in networks of conservation reserves selected for each surrogate. Spatial patterns in the species richness and assemblage variation (but not summed irreplaceability) of each surrogate were significantly correlated with the spatial patterns of other species. The total abundance of annelids and the total abundance of arthropods were each significantly correlated with the total abundances of other species. Networks of conservation reserves selected to represent each surrogate performed significantly better than random selection in representing other species. The greatest number of non-surrogate species was coincidentally included in reserves selected for the group of mollusc species. We conclude that annelids and arthropods are effective surrogate taxa for identifying spatial variation in several measures of conservation value (species richness, abundance, assemblage variation) in estuaries. We also conclude that spatial data on annelids, arthropods or molluscs can be used to select networks of conservation reserves in estuaries. The demonstrated effectiveness of these surrogates should facilitate future conservation planning within estuaries.