Munemitsu Akasaka

Global legume diversity assessment : concepts, key indicators, and strategies

While many plant species are considered threatened under anthropogenic pressure, it remains uncertain how rapidly we are losing plant species diversity. To fill this gap, we propose a Global Legume Diversity Assessment (GLDA) as the first step of a global plant diversity assessment. Here we describe the concept of GLDA and its feasibility by reviewing relevant approaches and data availability. We conclude that Fabaceae is a good proxy for overall angiosperm diversity in many habitats and that much relevant data for GLDA are available. As indicators of states, we propose comparison of species richness with phylogenetic and functional diversity to obtain an integrated picture of diversity. As indicators of trends, species loss rate and extinction risks should be assessed. Specimen records and plot data provide key resources for assessing legume diversity at a global scale, and distribution modeling based on these records provide key methods for assessing states and trends of legume diversity. GLDA has started in Asia, and we call for a truly global legume diversity assessment by wider geographic collabora- tions among various scientists.

Hydrologic connection between ponds positively affects macrophyte α and γ diversity but negatively affects β diversity

Connections between habitat patches can positively influence the number of species in respective patches, providing a basis for preferentially conserving interconnected patches. However, from a regional perspective, it is not known whether conserving multiple sets of interconnected habitat patches would include more species (i.e., show higher γ diversity) than conserving multiple, unconnected, solitary patches. We studied aquatic macrophytes in 15 sets of unidirectionally interconnected ponds and 19 unconnected ponds and also tested whether α and β diversity, expressed as the number of species and dissimilarity in species composition, respectively, differed between connected and unconnected ponds. We found that γ diversity was higher in connected ponds than in unconnected ponds, even after controlling for surface area. This resulted from a higher α diversity in connected ponds, despite lower β diversity. These results suggest that connections between habitat patches positively influence diversity at both ...

Effects of pond draining on biodiversity and water quality of farm ponds.

Farm ponds have high conservation value because they contribute significantly to regional biodiversity and ecosystem services. In Japan pond draining is a traditional management method that is widely believed to improve water quality and eradicate invasive fish. In addition, fishing by means of pond draining has significant cultural value for local people, serving as a social event. However, there is a widespread belief that pond draining reduces freshwater biodiversity through the extirpation of aquatic animals, but scientific evaluation of the effectiveness of pond draining is lacking. We conducted a large-scale field study to evaluate the effects of pond draining on invasive animal control, water quality, and aquatic biodiversity relative to different pond-management practices, pond physicochemistry, and surrounding land use. The results of boosted regression-tree models and analyses of similarity showed that pond draining had little effect on invasive fish control, water quality, or aquatic biodiversity. Draining even facilitated the colonization of farm ponds by invasive red swamp crayfish (Procambarus clarkii), which in turn may have detrimental effects on the biodiversity and water quality of farm ponds. Our results highlight the need for reconsidering current pond management and developing management plans with respect to multifunctionality of such ponds. Efectos del Drenado de Estanques sobre la Biodiversidad y la Calidad del Agua en Estanques de Cultivo.

The role of roads and urban area in occurrence of an ornamental invasive weed: a case of Rudbeckia laciniata L

Road density and proportion of urban area are considered to be useful indicators of invasion risk from non-native plants. However, the mechanisms behind the relationship between these indicators and establishment of non-native species have rarely been addressed explicitly. To identify these mechanisms, we used a species distribution model (MaxEnt) for an invasive ornamental weed Rudbeckia laciniata using road density and proportion of urban area as explanatory variables, along with soil moisture and solar radiation. Overall model performance is relatively high (AUC = 0.91). Road density explained most R. laciniata occurrence, followed by the proportion of urban area. The occurrence probability of R. laciniata increased monotonically with road density, but the rates of increase constantly fell. The occurrence probability also increased with urban area when the proportion of urban area was small, but started to decrease when the proportion of urban area reached 0.2. Our results suggest that both road density and proportion of urban area are important factors in determining R. laciniata establishment but work differently.

Combined burning and mowing for restoration of abandoned semi‐natural grasslands

Questions Does reintroducing grassland management aid in the recovery of vegetation with high grassland species diversity in abandoned semi-natural grasslands? How do management tools and local topographic factors influence the magnitude of recovery? Do effective restoration tools and sites differ depending on measurement indices (community- and species-level responses)? Location Semi-natural grasslands surrounding Mt. Aso, Kumamoto Prefecture, Japan. Methods We conducted vegetation surveys in grassland sites with two land-use forms (continuously managed/restored after abandonment) and two management types (burning only/burning and mowing). We assessed restoration success by examining plant species composition using the similarity index. We also examined the community-level (i.e. species richness) and species-level (i.e. species occurrence) responses to land-use form, management type and local topographic factors (elevation and slope aspect). Results Reintroduction of grassland management can recover the plant species composition of restored sites. Combined burning and mowing management was a principal determinant of the species richness and occurrence of most grassland species. A north-facing slope was a clear topographic determinant of higher species richness. However, we also found that the presence of some of the grasslands endangered species (i.e. Achillea alpina subsp. subcartilaginea, Artemisia stolonifera and Viola orientalis) was limited in continuously managed sites and that the response to topographic factors was species-specific. Conclusions The reintroduction of combined burning and mowing management in various topographic areas is essential for both plant diversity recovery and local endangered species conservation for the restoration of abandoned semi-natural grasslands. Our results also suggest that selecting restoration sites on northern slopes can enhance the recovery of plant species diversity.

Development of a National Land-Use/Cover Dataset to Estimate Biodiversity and Ecosystem Services

Land-use/cover data are essential to estimate biodiversity and ecosystem services. Although many data and maps have been produced in Japan, there is significant variation in their characteristics, such as publication year, spatial resolution, and land-use/cover classification categories because the purposes of the data and maps differ (e.g., resource inventory). Unfortunately, little attention has so far been paid to biodiversity and ecosystem services, which require preparation of new land-use/cover data. First, we searched existing public national data in Japan published by government sectors and researchers and evaluated their characteristics. Second, we briefly reviewed user needs (e.g., temporal coverage, spatial resolution, and classification categories) to estimate biodiversity and ecosystem services. We then integrated the information, and we present herein a procedure to prepare a new national land-use/cover dataset from existing datasets to bridge the gaps between data producers and users by determining the temporal coverage needed to reveal historic change, determining the spatial resolution suitable for estimation, and setting classification categories needed for estimation. The resultant land-use/cover data could contribute significantly to research and management related to conservation of biodiversity and provision of ecosystem services.

Classification of roadside weeds along two highways in different climatic zones according to ecomorphological traits.

Abstract Growth of vegetation in curbside cracks causes deterioration of asphalt and curbs, reducing road longevity and safety capabilities. Road managers spend a considerable amount of time and money on roadside vegetation management every year. The vegetation in curbside cracks in these study regions is managed approximately once a year by mowing and road sweeping using street-sweeper trucks. Nevertheless, ideal management practices of roadside vegetation have not yet been established partly due to insufficient knowledge of the ecological strategies of plants invading roadsides, especially curbside cracks. Although establishment of plants in the cracks might be restricted due to severe anthropogenic road disturbances, the cracks could be habitats for species with specific ecological traits. The objective of this study was to clarify the floristic and functional characteristics of roadside weeds, particularly species invading curbside cracks, to provide information for effective road management. The species composition of plants invading the cracks was surveyed along Route 3 (southern Japan) and Route 4 (eastern Japan) in different climatic zones, based on 108 floristic inventories. We compared species occurrence and composition to characterize the dominant ecomorphological traits of the species. In total, 163 species occurred in curbside cracks along both routes. Species composition of vegetation in curbside cracks was more variable between the routes than between land-use types. Of the 54 species, more than 5% occurred in all plots, and only three had differences in occurrence among land-use types. Ecomorphological trait composition patterns of the species were similar across land-use types. From these results, we found that regardless of differences in species composition among regions, climatic conditions, and surrounding land-use type, there were some dominant ecomorphological traits of roadside vegetation with plants in curbside cracks, such as ephemeral monophytes that are barochorous or anemochorous. By contrast, rhizomatous perennials, which cause greater deterioration of asphalt than ephemeral monophytes, were rare along the cracks. Although vegetation composition and structure generally depend on land-use types and disturbance regimes, linear landscape elements such as curbsides might be habitats for plants adapted to road disturbances. Roadside vegetation management, such as mowing and road sweeping once a year, seems sufficient to restrict establishment of rhizomatous perennials around Japan.

Water depletion drives plant succession in farm ponds and overrides a legacy of continuous anthropogenic disturbance

Questions Abandonment of anthropogenic ecosystems threatens biodiversity in rural areas globally. Successional responses in anthropogenic ecosystems have been shown to differ from those in natural ecosystems because of the legacy of continuous management activities. However, few studies have focused on successional changes in anthropogenic freshwater ecosystems following abandonment. Focusing on two drivers (water depletion and cessation of anthropogenic disturbance), we tested whether water depletion plays a larger role than years since abandonment in determining the both plant functional diversity and composition in farm ponds. Location Awaji Island, western Japan. Methods We investigated flora at 200 farm ponds, which had experienced long-term continuous anthropogenic disturbance. We interviewed 100 managers of the surveyed ponds and local farmers to identify the ponds’ management status. To capture community processes during succession, we focused on functional richness and functional trait composition. We assessed the relative contribution of the two successional drivers in determining functional richness by adopting a linear model. We classified the survey ponds into five groups based on the two successional drivers and performed PERMANOVA to test differences in functional composition among the groups. Results Water depletion played a larger role than elapsed time since cessation of anthropogenic disturbance in determining functional richness. Functional composition of water-depleted ponds significantly differed from that of managed ponds, regardless of years since abandonment. Conclusions Our results indicate that water depletion has a larger effect on successional changes in ponds than cessation of anthropogenic disturbance; that is, water depletion drives succession and overrides the legacy of continuous anthropogenic disturbance. The results suggest that, in freshwater ecosystems, the functional change in a community is greater in the transition from macrophytes to terrestrial plants than it is in the transition from stress-tolerant species to competitive species.

Calling-Site Preferences of Three Co-occurring Endangered Frog Species on Amami-Oshima Island

Abstract Hotspots of amphibian species diversity typically occur in limited geographical ranges, and critically endangered habitats often contain a large number of endemic amphibian species. In such regions, it is prudent to engage conservation strategies for multiple amphibian species simultaneously. To correctly identify suitable habitats for multiple species, species interactions should be considered in species distribution models. In this study, we adopted a joint species distribution model to determine the abiotic and biotic factors that affect calling-site choice in three endangered co-occurring frog species on Amami-Oshima Island, and examined whether they co-occur more than expected after considering the overlapping preferences in environmental variables. Occurrences of Babina subaspera, Odorrana splendida, and O. amamiensis were assessed by monitoring mating calls using automatic digital voice recorders at 67 sites in 12 streams and explained by 8 environmental variables: water flow volume, temperature, pH, electrical conductivity, ammonium (NH4+-N) concentration, elevation, slope, and forest stand age. The flow volume was negatively associated with occurrences in B. subaspera and O. splendida, but not O. amamiensis. Odorrana splendida occurred more frequently at higher elevations. Babina subaspera and O. splendida showed positive environmental correlations, indicating that they preferred similar environmental conditions, while exhibiting no negative relationships with each other. Our results indicated that B. subaspera and O. splendida do not avoid each other despite potential competition during the tadpole stage. Our results demonstrated that conserving preferable areas for O. splendida would also benefit B. subaspera with no negative species interactions, but not O. amamiensis. Considering species interactions in species distribution models will help us take more effective measures in the conservation of multiple species.

Landscape- and Local-Scale Actions Are Essential to Conserve Regional Macrophyte Biodiversity

Regional-scale pond diversity is supported by high variation in community composition. To effectively and efficiently conserve pond regional diversity, it is essential to recognize the community types in a focal region and the scales of the factors influencing the occurrence of respective community types. Based on a flora survey and GIS analysis of 367 ponds in western Japan, we developed a multinomial regression model that describes the relationship between aquatic macrophyte community type (based on cluster analysis) and five environmental factors that differ in the spatial scale at which they operate (i.e., landscape or local scale) and origin (i.e., natural or anthropogenic). A change in topographic configuration resulted in a transition of the community types with high species richness. Increasing urban and agricultural area around ponds resulted in a decrease in species-rich community occurrence; an increase in urban area increased the probability of a pond having no macrophytes, whereas that of paddy field increased the probability of a pond having only a few macrophytes. Pond surface area and proportion of artificial embankment significantly defined the pond community: greater embankment proportions increased the probability of ponds having few or no macrophytes. Our results suggest that conserving regional pond biodiversity will require actions not only at a local scale but also at a sufficiently large spatial scale to cover the full gradient of topographic configurations that influence the macrophyte species composition in ponds.