A General Stochastic Model for the Prediction of Biodiversity Losses Based on Habitat Conversion

Summary 1. Biotic homogenization (BH), a dominant process shaping the response of natural communities to human disturbance, reflects both the expansion of exotic species at large scales and other mechanisms that often operate at smaller scales. 2. Here, we examined the relationship between BH in plant communities and spatio-temporal landscape disturbance (habitat fragmentation and surrounding habitat conversion) at a local scale (1 km²), using data from a standardized monitoring programme in France. We quantified BH using both a spatial partitioning of taxonomic diversity and the average habitat specialization of communities, which informs on functional BH. 3. We observed a positive relationship between local taxonomic diversity and landscape fragmentation or instability. This increase in local taxonomic diversity was, however, paralleled by a decrease in average community specialization in more fragmented landscapes and in more unstable landscapes around forest sites. The decrease in average community specialization suggests that landscape disturbance causes functional BH, but there was limited evidence for concurrent taxonomic BH. 4. Synthesis. Our results show that landscape disturbance is partly responsible for functional BH at small scales via the extirpation of specialist species, with possible consequences for ecosystem functioning. However, this change in community composition is not systematically associated with taxonomic BH. This has direct relevance in designing biodiversity indicators: metrics incorporating species sensitivity to disturbance (such as species specialization to habitat) appear much more reliable than taxonomic diversity for documenting the response of communities to disturbance.

Approximately 3.4% of the predicted total number of species on Earth is plants. Plants and their communities are an indispensable part of the Earth's biosphere as plants not only affect ecosystem functioning, but also provide essential ecosystem services for the benefit of humans. However, plants face many threats and current extinction rates have been estimated to be 100–1000 times higher than those of the prehuman era. The five most important drivers of plant extinction are: (1) habitat loss and fragmentation, (2) introduction of exotic species, (3) climate change, (4) overexploitation and (5) pollution. For conservation plans to be effective, four essential steps are needed to maintain viable plant populations in the long term. These include assessment of the biological status of a species, diagnosis of the causes of decline, prescription of management strategies that will counterbalance the decline, and implementation of management practices and further monitoring. Key Concepts: Approximately 17% of all known species on Earth are plant species, that is, approximately 215 600 species have been recorded. The tropical Andes, Mesoamerica and the Caribbean contain the highest plant diversity and therefore can be considered as the world's most important plant biodiversity hotspots. Increasing evidence that plant species diversity positively correlates with the efficiency of many ecosystem functions and services provides conservationists with strong scientific arguments for biodiversity conservation. Rare species are an important part of recent evidence‐based approaches to biodiversity analysis, prioritisation and conservation. Current rates of plant species extinction are estimated to be 100–1000 times higher than those of the prehuman era. One in five plant species is currently threatened with extinction. There are five major anthropogenic drivers of plant species loss: (1) habitat loss and fragmentation, (2) introduction of exotic species, (3) climate change, (4) overexploitation and (5) pollution. Each attempt to protect endangered plant species from going extinct should consist of four different steps: assessment, diagnosis, prescription and prognosis. Minimal Viable Population (MVP) size has been estimated at c . 5000 individuals. Although still an important concept, MVP sizes should not be considered as a magic number. A biodiversity audit consists of a methodology that aims at adopting the most efficient and feasible management interventions within a particular area, using quantitative data on all species present and considering the benefits and drawbacks for all stakeholders involved. An efficient plant conservation strategy should create: space for plants; improve environmental quality for plants, both in the designated areas for conservation and in the surrounding landscape matrix; develop a specific plant species conservation policy (including an in situ and possibly an ex situ component) and enlarge the social basis for plant conservation through education, information and participation.

Four Commentaries on the Pope’s Message on Climate Change and Income Inequality. IV. Pope Francis’ Encyclical Letter Laudato Si’, Global Environmental Risks, and the Future of Humanity.

A key measure of humanity's global impact is by how much it has increased species extinction rates. Familiar statements are that these are 100-1000 times pre-human or background extinction levels. Estimating recent rates is straightforward, but establishing a background rate for comparison is not. Previous researchers chose an approximate benchmark of 1 extinction per million species per year (E/MSY). We explored disparate lines of evidence that suggest a substantially lower estimate. Fossil data yield direct estimates of extinction rates, but they are temporally coarse, mostly limited to marine hard-bodied taxa, and generally involve genera not species. Based on these data, typical background loss is 0.01 genera per million genera per year. Molecular phylogenies are available for more taxa and ecosystems, but it is debated whether they can be used to estimate separately speciation and extinction rates. We selected data to address known concerns and used them to determine median extinction estimates from statistical distributions of probable values for terrestrial plants and animals. We then created simulations to explore effects of violating model assumptions. Finally, we compiled estimates of diversification-the difference between speciation and extinction rates for different taxa. Median estimates of extinction rates ranged from 0.023 to 0.135 E/MSY. Simulation results suggested over- and under-estimation of extinction from individual phylogenies partially canceled each other out when large sets of phylogenies were analyzed. There was no evidence for recent and widespread pre-human overall declines in diversity. This implies that average extinction rates are less than average diversification rates. Median diversification rates were 0.05-0.2 new species per million species per year. On the basis of these results, we concluded that typical rates of background extinction may be closer to 0.1 E/MSY. Thus, current extinction rates are 1,000 times higher than natural background rates of extinction and future rates are likely to be 10,000 times higher.

To Achieve Big Wins for Terrestrial Conservation, Prioritize Protection of Ecoregions Closest to Meeting Targets

What determines plant species diversity in Central Africa?

Biodiversity conservation, plant growth and spatial distribution of plant species are the central issues in contemporary community ecology. Ephemeral stream may influence soil properties, which in turn may determine biodiversity and function of an ecosystem in alluvial fan of arid desert region. Ephemeral stream is one of the most common natural disturbances, yet the effects of the ephemeral stream on plant communities in terms of species diversity and plant species distribution remain poorly studied. In this study, the information of species distribution, ephemeral stream beds (‘washes’), and the characteristics of plant growth, i.e. height, crown area, were interpreted at different heights using the images of low altitude unmanned aerial vehicle (UAV). After that, soil properties such as soil texture (sand, silt and clay), soil water content, pH, soil organic matter, soil electric conductivity, soil bulk density and the percentage of gravel content, and their relationships with UAV data were assessed in order to explore the influences of ephemeral stream on species diversity, plant growth characteristics and species distribution in an alluvial fan of arid desert region. The results showed that deep-rooted plants were only distributed in washes whereas shallow-rooted plants were distributed in both washes and the outside of washes (‘non-washes’). Species richness was significantly higher in washes than that in non-washes whereas the opposite pattern was true for abundance. Soil properties, plant height and crown area were higher in washes than that in non-washes. Plant height, crown area and the total number of individual plants increased with increasing wash width and per unit length of stream flow. This study highlights that the coupling factors of ephemeral stream, such as soil erosion, particle transport and sedimentation, can dramatically cause changes in soil properties and total number of individual plants, and hence, can influence species diversity, plant growth characteristics and spatial distribution of plant species in an alluvial fan of arid desert regions.

The abundance of birds, reptiles and frogs was recorded at 370 quadrats and the abundance of mammals and the basal area of woody plants was recorded at these and a further 10 quadrats in Stage I11 of Kakadu National Park. Patterns in the distribution of these species were related to two environmental mapping schemes. The more specific and localised of these was a 1 : 100 000 habitat map for Kakadu National Park, established by Schodde et al. (1987), based on environmental attributes considered to be significant for the distribution of wildlife species: floristics, vegetation structure, substrate and landscape position. The more generalised scheme was that of Wilson et a[. (1991), which mapped vegetation communities at a 1:1 000 000 scale across the Northern Territory. The distributions of assemblages of plant, all vertebrate, bird and reptile species were strongly associated with the distributions of both Schodde habitats and Wilson vegetation units. The associations were less good, but still highly significant, for distributions of native mammal and frog assemblages. Patterns in the similarity of species composition between the different habitats or vegetation units varied between different animal and plant groups. Similarity in vertebrate species composition was high between most sandstone habitats. Floristic similarity was high between woodland habitats on different substrates. Melaleuca open forests were distinct from other vegetation units in their composition of bird, frog, reptile and plant species. Mammal species composition divided the vegetation units into an upland rocky group and a lowland group. The distribution and abundance of most individual animal species were significantly related to the habitat or floristic unit divisions. This association was clearer for species recorded from at least 20 quadrats than for those recorded from 6-19 quadrats. For the latter group of species, association was more apparent with the Schodde habitat scheme than with the Wilson vegetation classification. The proportion of native mammals that showed significant associations with either classification was smaller than that for birds and reptites. The generally significant associations between distributions of individual species and the mapping of defined habitats suggests that the Schodde scheme offers a useful template for predicting species distributions within Stage 111 of Kakadu. However, the restriction of this habitat mapping to the Kakadu area renders this scheme inapplicable for the prediction of distributions beyond Kakadu, and therefore handicaps the assessment of the wildlife value of Kakadu National Park in a regional context. The Wilson vegetation map can be used to extrapolate distributions beyond Kakadu, but because that ~lassification scheme includes many vegetation units that were not sampled within the Kakadu area the predicted distribution in this case will be very incomplete.

Assessment of minimum stream corridor width for biological conservation: Species richness and distribution along mid-order streams in Vermont, USA

Refreshing Approaches

Biodiversity is the very basis of human survival and economic well-being, and encompasses all life forms, ecosystems and ecological processes. The current estimates of the total number of species on earth vary from 5 to more than 100 million, with a more conservative figure of 13.6 million species. Of these, only 1.78 million species have yet been described and awarded scientific names. Thus, our knowledge of diversity is remarkably incomplete. Biodiversity at any point in time is the balance between the rates of speciation and extinction. Biodiversity is not uniformly distributed on the earth and shows prominent latitudinal and altitudinal gradients. At least five major mass extinctions have occurred in the past at geologic-time boundaries. Studies indicate that we have entered into the sixth phase of mass extinctions. In all ecosystem types, terrestrial, freshwater and marine, species populations are declining. The current rates of species extinction are 100–1000 times higher than the background rate of 10−7 species/species year inferred from fossil record. It is now in the order of 1,000 species per decade per million species. Today we seem to be losing two to five species per hour from tropical forests alone. This amounts to a loss of 16 m populations/year or 1,800 populations/h. Major drivers for changes of biodiversity in future, in decreasing rank of their impact are land use change, climate change, N deposition, biotic exchange and atmospheric loading of CO2. Accuracy of estimates of the total number of resident species and current rates of extinction remains undetermined, and the impact of species deletions on ecosystem function and stability is still a subject of debate among ecologists. There are two basic, often complementary strategies for biodiversity conservation. The in situ strategy emphasizes the protection of ecosystems for the conservation of overall diversity of genes, populations, species, communities and the ecological processes which are crucial for ecosystem services. Establishment of networks of protected areas are effective in this regard as these have the possibility to conserve primary forests and red-listed ecosystems. The concept of biodiversity banking could induce public participation. Establishment of the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services, an independent, international science panel (like IPCC) would help coordinate and highlight research on pressing topics, conduct periodic assessments on regional as well as global scales and provide predictions.

Effective monitoring of the current status of species distributions and predicting future distributions are very important for conservation practices at the ecosystem and species levels. The human population, land use, and climate are important factors that influence the distributions of species. Even though future simulations have many uncertainties, such studies can provide a means of obtaining species distributions, range shifts, and food production and help mitigation and adaptation planning. Here, we simulate the population, land use/land cover and species distributions in the Eastern Ghats, India. A MaxEnt species distribution model was used to simulate the potential habitats of a group of endemic (28 species found in this region) and rare, endangered, and threatened (RET) (22 species found in this region) plant species on the basis of IPCC AR5 scenarios developed for 2050 and 2070. Simulations of populations in 2050 indicate that they will increase at a rate of 1.12% relative to the base year, 2011. These increases in population create a demand for more land for settlement and food productions. Land use land cover (LULC) simulations show an increase in built-up land from 3665.00km2 in 2015 to 3989.56km2 by 2050. There is a minor increase of 0.04% in the area under agriculture in 2050 compared with 2015. On the other hand, the habitat simulations show that the combined effects of climate and land use change have a greater influence on the decline of potential distributions of species. Climate change and the prevailing rate of LULC change will reduce the extents of the habitats of endemic and RET species (~ 60% and ~ 40%, respectively). The Eastern Ghats have become extensively fragmented due to human activities and have become a hotspot of endemic and RET species loss. Climate and LULC change will enhance the species loss and ecosystem services.

Summary 1. A large proportion of the world's land surface is extensively managed for livestock production. In areas where livestock systems are becoming more intensive, a major challenge is to predict those plant species likely to decline, persist or increase as a result of agricultural intensification. 2. Most analyses develop inferences for frequent or abundant species, or rely on intensive studies of single species. A promising approach is to identify plant traits related to disturbance to enable inference to be made about changes in plant community composition. We used a Bayesian hierarchical model to analyse the response to agricultural intensification of 494 plant species of pastures and woodlands in southern Australia, and to identify how simple species' traits (life form, growth form and species origin) influence those responses. 3. The probability of occurrence of most species declined along the two intensification gradients, grazing intensity and soil phosphorous concentration, although the occurrence of a greater proportion of species was negatively correlated with soil phosphorous. Responses could be broadly predicted from both plant origin and plant traits, in particular growth form. 4. Native perennial geophytes, ferns and shrubs were most negatively affected by both gradients, while exotic annual grasses and forbs were more tolerant. Along the phosphorous gradient, 24 of the 30 most negatively affected plant species were native geophytes. Mean within-group responses masked considerable within- and between-species variation, particularly for the exotic species group which included species that responded both negatively and positively to intensification. 5. Synthesis and applications. The hierarchical model described here provides a powerful method for estimating individual plant responses and identifying how species' traits influence those responses. Plant species native to southern Australia are sensitive to grazing and phosphorous apparently due to a shared evolutionary history of low grazing intensity and low phosphorous soils. Invading exotic plants have faced strongly contrasting ecological filters, leading to a greater diversity of responses. Where grazing systems have been most intense, a small suite of exotics dominate. Maintaining native and functional plant diversity will necessitate limits being placed on intensive livestock management systems.

Global climate is rapidly changing and while many studies have investigated the potential impacts of this on the distribution of montane plant species and communities, few have focused on those with oceanic montane affinities. In Europe, highly sensitive bryophyte species reach their optimum occurrence, highest diversity and abundance in the north-west hyperoceanic regions, while a number of montane vascular plant species occur here at the edge of their range. This study evaluates the potential impact of climate change on the distribution of these species and assesses the implications for EU Habitats Directive-protected oceanic montane plant communities. We applied an ensemble of species distribution modelling techniques, using atlas data of 30 vascular plant and bryophyte species, to calculate range changes under projected future climate change. The future effectiveness of the protected area network to conserve these species was evaluated using gap analysis. We found that the majority of these montane species are projected to lose suitable climate space, primarily at lower altitudes, or that areas of suitable climate will principally shift northwards. In particular, rare oceanic montane bryophytes have poor dispersal capacity and are likely to be especially vulnerable to contractions in their current climate space. Significantly different projected range change responses were found between 1) oceanic montane bryophytes and vascular plants; 2) species belonging to different montane plant communities; 3) species categorised according to different biomes and eastern limit classifications. The inclusion of topographical variables in addition to climate, significantly improved the statistical and spatial performance of models. The current protected area network is projected to become less effective, especially for specialised arctic-montane species, posing a challenge to conserving oceanic montane plant communities. Conservation management plans need significantly greater focus on potential climate change impacts, including models with higher-resolution species distribution and environmental data, to aid these communities' long-term survival.

Most textbooks on measuring terrestrial vegetation have focused on the characteristics of biomass, cover, and the density or frequency of dominant life forms (trees, shrubs, grasses, and forbs), or on classifying, differentiating, or evaluating and monitoring dominant plant communities based on a few common species. Sampling designs for measuring species richness and diversity, patterns of plant diversity, species-environment relationships, and species distributions have received less attention. There are compelling, urgent reasons for plant ecologists to do a far better job measuring plant diversity in this new century. Rapidly invading plant species from other countries are affecting rangeland condition and wildlife habitat, placing more plant species on threatened and endangered species lists, and increasing wildfire fuel loads. Attention has shifted from the classification of plant communities to accurately mapping rare plant assemblages and species of management concern to afford them better protection. More ecologists, wildlife biologists, and local and regional planners recognize the value in understanding patterns, dynamics, and interactions of rare and common plant species and habitats to better manage grazing, fire, invasive plant species, forest practices, and restoration activities. Thus, revised and new sampling approaches, designs, and field techniques for measuring plant diversity are needed to assess critical emerging issues facing land managers. This book offers alternatives to the approaches, designs, and techniques of the past that were chiefly designed for dominant species and other purposes. The author focuses on field techniques that move beyond classifying, mapping, and measuring plant diversity for relatively homogeneous communities. This book complements methods for measuring the biomass and cover of dominant plant species. Most species are sparse, rare, and patchily distributed. It empowers the reader to take an experimental approach in the science of plant diversity to better understand the distributions of common and rare species, native and non-native species, and long-lived and short-lived species.