Farshid S. Ahrestani

Ecosystem Services for 2020

The Convention on Biological Diversitys 2020 targets are an improvement over the 2010 target, but they could be strengthened. The vast majority of nations have fallen far short of the Convention on Biological Diversitys (CBDs) 2010 target: to reduce the rate of loss of biodiversity (1, 2). This prompted the CBD to develop a new plan of action, supported by 20 “SMART” (specific, measurable, ambitious, realistic, and time-bound) targets for 2020 (3, 4). As the 10th Conference of the Parties (COP) of the CBD meets in Nagoya, Japan, to negotiate both plan and targets, it is critical that targets also be grounded in the real interests that people have in benefits provided by biodiversity. To evaluate targets on this basis, we use the ecosystem services framework developed by the Millennium Ecosystem Assessment (MA) (5). This framework balances resource conservation and use according to how societies value consumptive (e.g., food and fuel) and nonconsumptive (e.g., health and aesthetics) services provided by ecosystems.

Ecosystem services, targets, and indicators for the conservation and sustainable use of biodiversity

After the collective failure to achieve the Convention on Biological Diversitys (CBDs) 2010 target to substantially reduce biodiversity losses, the CBD adopted a plan composed of five strategic goals and 20 “SMART” (Specific, Measurable, Ambitious, Realistic, and Time-bound) targets, to be achieved by 2020. Here, an interdisciplinary group of scientists from DIVERSITAS – an international program that focuses on biodiversity science – evaluates these targets and considers the implications of an ecosystem-services-based approach for their implementation. We describe the functional differences between the targets corresponding to distinct strategic goals and identify the interdependency between targets. We then discuss the implications for supporting research and target indicators, and make several specific suggestions for target implementation.

Connecting the green and brown worlds : allometric and stoichiometric predictability of above- and below-ground networks

Abstract We examine the potential of trait-based parameters of taxa for linking above- and below-ground ecological networks (hereafter ‘green’ and ‘brown’ worlds) to understand and predict community dynamics. This synthesis considers carbon, nitrogen and phosphorus-related traits, the abundance of component species and their size distribution across trophic levels under different forms of management. We have analysed existing and novel databases on plants, microbes and invertebrates that combine physico-chemical and biological information from (agro)ecosystems spanning the globe. We found (1) evidence that traits from above- and below-ground systems may be integrated in the same model and (2) a much greater than expected stoichiometric plasticity of plants and microbes which has implications for the entire food-web mass–abundance scaling. Nitrogen and phosphorus are primary basal resources (hence, drivers) and more retranslocation of P than of N from leaves will lead to higher N:P in the litter and soil organic matter. Thus, under nutrient-rich conditions, higher foliar concentrations of N and P are reflected by lower N:P in the brown litter, suggesting less P retranslocated than N. This apparent stoichiometric dichotomy between green and brown could result in shifts in threshold elemental ratios critical for ecosystem functioning. It has important implications for a general food-web model, given that resource C:N:P ratios are generally assumed to reflect environmental C:N:P ratios. We also provide the first evidence for large-scale allometric changes according to the stoichiometry of agroecosystems. Finally, we discuss insights that can be gained from integrating carbon and nitrogen isotope data into trait-based approaches, and address the origin of changes in Δ 13 C and Δ 15 N fractionation values in relation to consumer–resource body-mass ratios.

The importance of rare species: a trait-based assessment of rare species contributions to functional diversity and possible ecosystem function in tall-grass prairies

The majority of species in ecosystems are rare, but the ecosystem consequences of losing rare species are poorly known. To understand how rare species may influence ecosystem functioning, this study quantifies the contribution of species based on their relative level of rarity to community functional diversity using a trait-based approach. Given that rarity can be defined in several different ways, we use four different definitions of rarity: abundance (mean and maximum), geographic range, and habitat specificity. We find that rarer species contribute to functional diversity when rarity is defined by maximum abundance, geographic range, and habitat specificity. However, rarer species are functionally redundant when rarity is defined by mean abundance. Furthermore, when using abundance-weighted analyses, we find that rare species typically contribute significantly less to functional diversity than common species due to their low abundances. These results suggest that rare species have the potential to play an important role in ecosystem functioning, either by offering novel contributions to functional diversity or via functional redundancy depending on how rare species are defined. Yet, these contributions are likely to be greatest if the abundance of rare species increases due to environmental change. We argue that given the paucity of data on rare species, understanding the contribution of rare species to community functional diversity is an important first step to understanding the potential role of rare species in ecosystem functioning.

Towards a thesaurus of plant characteristics: an ecological contribution

Ecological research produces a tremendous amount of data, but the diversity in scales and topics covered and the ways in which studies are carried out result in large numbers of small, idiosyncratic data sets using heterogeneous terminologies. Such heterogeneity can be attributed, in part, to a lack of standards for acquiring, organizing and describing data. Here, we propose a terminological resource, a Thesaurus Of Plant characteristics (TOP), whose aim is to harmonize and formalize concepts for plant characteristics widely used in ecology. TOP concentrates on two types of plant characteristics: traits and environmental associations. It builds on previous initiatives for several aspects: (i) characteristics are designed following the entity-quality (EQ) model (a characteristic is modelled as the ‘Quality’ of an ‘Entity’ ) used in the context of Open Biological Ontologies; (ii) whenever possible, the Entities and Qualities are taken from existing terminology standards, mainly the Plant Ontology (PO) and Phenotypic Quality Ontology (PATO) ontologies; and (iii) whenever a characteristic already has a definition, if appropriate, it is reused and referenced. The development of TOP, which complies with semantic web principles, was carried out through the involvement of experts from both the ecology and the semantics research communities. Regular updates of TOP are planned, based on community feedback and involvement. TOP provides names, definitions, units, synonyms and related terms for about 850 plant characteristics. TOP is available online (www.top-thesaurus.org), and can be browsed using an alphabetical list of characteristics, a hierarchical tree of characteristics, a faceted and a free-text search, and through an Application Programming Interface. Synthesis. Harmonizing definitions of concepts, as proposed by TOP, forms the basis for better integration of data across heterogeneous data sets and terminologies, thereby increasing the potential for data reuse. It also allows enhanced scientific synthesis. TOP therefore has the potential to improve research and communication not only within the field of ecology, but also in related fields with interest in plant functioning and distribution.

The importance of observation versus process error in analyses of global ungulate populations

Population abundance data vary widely in quality and are rarely accurate. The two main components of error in such data are observation and process error. We used Bayesian state space models to estimate the observation and process error in time-series of 55 globally distributed populations of two species, Cervus elaphus (elk/red deer) and Rangifer tarandus (caribou/reindeer). We examined variation among populations and species in the magnitude of estimates of error components and density dependence using generalized linear models. Process error exceeded observation error in 75% of all populations, and on average, both components of error were greater in Rangifer than in Cervus populations. Observation error differed significantly across the different observation methods, and predation and time-series length differentially affected the error components. Comparing the Bayesian model results to traditional models that do not separate error components revealed the potential for misleading inferences about sources of variation in population dynamics.

Diet and habitat-niche relationships within an assemblage of large herbivores in a seasonal tropical forest

There is little understanding of how large mammalian herbivores in Asia partition habitat and forage resources, and vary their diet and habitat selection seasonally in order to coexist. We studied an assemblage of four large herbivores, chital (Axis axis), sambar (Cervus unicolor), gaur (Bos gaurus) and Asian elephant (Elephas maximus), in the seasonal tropical forests of Bandipur and Mudumalai, South India, and tested predictions regarding the species’ seasonal diet browse : graze ratios, habitat selection and habitat-niche preference and overlap. Field data collected for the study included the seasonal variation in grass quality, the seasonal variation in d13C in the species’ faeces and the seasonal variation in the species’ habitat selection and overlap using a grid-based survey. Results of the d13C analyses showed that the chital was more of a grazer in the wet season (-17.9‰to -21.6‰), but that it increased the proportion of browse in its diet in the dry season (-25.6‰ to -27.7‰); the gaur was a grazer for most of the year (-15.3‰to -18.6‰); the sambar preferred to browse throughout the year (-21.1‰to -30.4‰); and that the elephant was a mixed feeder (-14.2‰to -21.4‰). Elephant habitat-niche breadth was high (0.53 in wet and 0.54 in dry) and overlapped equally with that of the other species in both seasons (0.39–0.94). The gaur had the most restricted habitat-niche breadth in both seasons (0.25 in wet and 0.28 in dry), and it switched from the moist deciduous habitat in the dry season to the dry deciduous habitat in the wet season. These results offer the first insights into the seasonal variation in browse : graze diet ratios and the habitat-niche overlap amongst the common largest-bodied mammalian herbivore species found in South India.

Age and sex determination of gaur Bos gaurus (Bovidae)

Abstract One reason why the gaur Bos gaurus is a poorly understood species is because there are no reliable data to age and sex individuals. We studied captive gaur for two years in Mysore Zoo, India and Omaha Zoo, USA, and determined age-specific differences in morphological features and physical growth, by measuring shoulder height, of male and female gaur. We fitted von Bertalanffy growth functions to the shoulder height data and found maximum shoulder heights of 175 cm and 147 cm for males and females, respectively. This study ascertained for the first time that the greater the amount of white on the horns of a gaur, the older it is, and that the sexes can be distinguished based on horn shape and size differences. We found that gaur aged 15 months and below can be classified into three age classes, but are difficult to sex. The sex of gaur aged 15–36 months is best determined by a study of their horns. Adult gaur, greater than three years, are easy to sex, but are difficult to classify into single-year age classes and are reliably classified only into two age classes for females and three for males.

The ecology of large herbivores in South and Southeast Asia

The large herbivores of South and Southeast Asia: A prominent but neglected guild.- Evolutionary History of the Large Herbivores of South and Southeast Asia (Indomalayan Realm).- Species richness and size distribution of large herbivores in the Himalaya.- The ecology of large herbivore browsers and grazers in tropical Asia.- Frugivory and seed dispersal by large herbivores of Asia.- Behavioural ecology of a grassland antelope, the blackbuck Antilope cervicapra: linking habitat, ecology and behaviour.- Do large herbivores influence plant allocation to above- and below-ground compartments?.- Grazing and fire effects on community and ecosystem processes in a savanna grassland ecosystem.- Density and activity patterns of the globally significant large herbivore populations of Cambodias Eastern Plains Landscape.- Persistence of tropical Asian ungulates in the face of hunting and climate change.- The ecology of large herbivores of South and Southeast Asia: Synthesis and future directions.

The Ecology of Large Herbivores of South and Southeast Asia: Synthesis and Future Directions

The countries of South and Southeast Asia (SSEA) are home to a diverse array of large native herbivores, but the majority of these species are currently threatened with extinction. Ensuring the future survival of these species and the integrity of the ecological services they provide will require concerted management efforts, but these need to be built on a strong scientific foundation, which is currently lacking. In particular, there is an urgent need for research efforts to: (i) generate baseline data on the current status and distribution of large herbivores species in South and Southeast Asia, (ii) quantify vital rates of species and identify factors that regulate the population dynamics of different species across their ranges, (iii) understand the role of large herbivores in regulating community and ecosystem processes, and how their losses are likely to affect ecosystems, and (iv) characterize the ecological and socioeconomic drivers of human–herbivore conflicts to identify the most effective ways of reducing conflict and thereby sustain large herbivore populations across the landscape. The large herbivores of South and Southeast Asia also offer unlimited opportunities for addressing a diverse array of other basic, as well as applied, scientific questions ranging from evolution and behavior to disease dynamics and the responses of herbivore populations to changing climates. Besides establishing and sustaining research initiatives that will generate much-needed long-term scientific data on large herbivores, there is also an urgent need for greater cooperation between ecologists, sociologists, economists, politicians, land managers, and the public if we are to ensure the long-term survival of large herbivores in the region.