Species-rich Habitats Research Articles

Měkkýši přírodních památek V Krátkých a Lom Rasová v CHKO Bílé Karpaty [Molluscs of the V Krátkých and Lom Rasová Nature Monuments in the White Carpathians PLA

The V Krátkých Nature Monument (NM) comprises of landscape mosaic of meadows, groves, spring fen and wetland while the Lom Rasová NM is a former sandstone quarry with open and forested areas. Both are situated near Vápenice village in the White Carpathians. In total, 44 species (40 terrestrial gastropods, 3 aquatic snails and 1 bivalve) were found in V Krátkých NM. Three species are listed in the Red List of Threatened Species: Daudebardia brevipes (VU), Lehmannia carpatica (NT) and Bythinella austriaca (NT). Most diversity consists of forest species, followed by eurytopic and hygrophilous species. The spring fen is the most species-rich habitat, as hygrophilous, eurytopic and forest species are present. To retain the favourable conservation status, extensive kettle grazing or mowing of the fen and meadows is suggested while the groves should remain in a non-intervention regime with possible subtle intrusion of broadleaved trees. In the Lom Rasová NM, 18 terrestrial gastropod species were recorded (aquatic malacofauna was not surveyed). All species are common and widespread, and their composition is a mixture of predominantly forest, euryvalent and open-country taxa. To support gastropod diversity, the broadleaved groves should remain in a non-intervention regime, while deciduous trees should be replaced with broadleaved species and overall habitat diversity should be supported.

Two decades of dune slack restoration in North Wales: diversity, community and habitat specialists

Humid dunes slacks are a highly threatened habitat, listed as vulnerable in the EU habitat red list. Accelerated successional processes in dune systems have resulted in the loss and degradation of ideal conditions for specialist dune slack species, hence the need for conservation management. We investigated the restoration of a dune slack in North Wales, UK, where vegetation and soil removal to 10 cm depth was undertaken to reinstate nutrient‐poor, open and damp conditions. We assessed the outcomes of the management for dune slack communities over the 18 years since restoration. We also assessed the differences between restored and unrestored areas of dune slacks. The dunes were restored in the winter of 2004/2005, after which we conducted vegetation surveys in fixed quadrats for most years in the restored and adjacent, un‐restored dune slacks. Species diversity and plant community composition changes over time were assessed using Shannon's index, multivariate analysis and indicator species analysis. Comparisons between the restored and unrestored areas of the dune slacks were also made. Ellenberg indicator values (EIVs) were examined to identify potential environmental drivers of post management successional changes. After 18 years the restored dune slacks developed a species‐rich and diverse community. compared to the unrestored slacks. The establishment of species occurred rapidly in the first three years, followed by continued but slower increases in species richness and diversity. This is due to the addition of new species without losses of established species. EIVs show no significant difference over time suggesting the restored areas are still at an early stage of succession. Distinct stages of community change since restoration are characterised by different indicator species. Plants are likely to be largely recruited from an existing seed bank. Restoration by turf removal may be suitable for other low nutrient, species rich habitats dependent upon fluctuating groundwater levels.

Ant diversity along elevational gradients in the European Alps: insights for conservation under a changing climate

Due to particular vulnerabilities and environmental constraints, Alpine faunas are exposed to significant threats from climate change. However, baseline diversity and distribution data to monitor the trends of key arthropod groups are often scarce. Ants are highly diversified and key ecological actors across terrestrial ecosystems, including mountain ranges. We investigated ant diversity and distribution in the Southern European Alps to provide detailed data over wide elevational gradients and make a first assessment of potential vulnerabilities in the face of global warming. We detected 40 species from 700 to over 2600 m asl, with progressively less diversity corresponding to higher elevations and lower temperatures. Maximum temperature was weakly related to ant diversity as compared to mean and minimum temperature. In shaping ant diversity, the highest elevation species had wide elevation ranges, consistent with Rapoport’s rule. We documented a fauna characterized by cold-adapted genera, species with wide geographic distributions and presumably high dispersal capabilities, no dietary specializations, and a high frequency of social parasitism. Concerning Bergmann’s rule, average ant species size was not larger in the coldest environments. Red wood ants, characterized by much more populous colonies as compared to the other ant species, had the highest number of ant individuals to be found at intermediate elevations and in woodland habitats. On the other hand, grasslands and shrublands proved to be the most species-rich habitats. Our data lay the groundwork for further investigation on elevational shifts and provide context for the discussion of key aspects of the management and conservation of European alpine ants.Implications for insect conservationThe cold climate of the European Alps has so far protected its ant fauna from the incursion of alien competitors as compared to what is observed in the Mediterranean region. The scarcity of species with restricted distribution ranges or high-elevation specialists, as well as diet specialists, may grant ants of the European Alps more resilience to climate change as compared to other Alpine arthropod groups. On the other hand, many species are highly interconnected by social parasitism relationships that may be vulnerable to ecological cascade effects. While forest habitats host red wood ants, which are often protected for their important ecological role, the importance of grassland must not be overlooked as they support the highest ant species richness.

Current Water Management of Small Lotic Waterbodies in the Context of Nature Conservation in Germany

Small lotic waterbodies are abundant and species rich habitats, offering refuges and microhabitats to protected species of the European Union Habitats Directive. Highly impacted by water management actions, it is essential to reveal the current status and challenges of water management. The present study aims to identify relevant issues by conducting a survey concerning water management authorities. Authorities were selected according to their involvement in the management of small lotic waterbodies within the actual range of a threatened species, Coenagrion mercuriale (Odonata), which is highly dependent on water management actions and protected by the Habitats Directive. The survey involved three sets of questionnaires, (1) socio-demographic (personal) questions (2) specific questions about water management and (3) questions on the biological background. Out of 181 selected authorities, 75 participated in the survey. The results showed that though nature conservation interests are partially considered, they represented a minor factor in water management decision-making. In addition, knowledge exchange is insufficient between involved stakeholders from policy, management practice and science, which was especially reflected in the case of equipment use and accruing material. The reconciliation of both, water management and nature conservation interests, can contribute to enhance the conservation status of key protected species of small lotic waterbodies under the Habitats Directive.

Floral resources used by bees in urban areas: the case of Geneva, Switzerland

It is now largely recognized that pollinators are threatened in agricultural habitats. Cities are thus seen as potential refuges for pollinators, if suitable green spaces are available, because they present favorable abiotic conditions for many pollinator species. However, data on resources used by bees in urban habitats are scarce. Moreover, promoting indigenous meadows in urban green spaces could help pollinator’s survival. In this study, Apis mellifera was taken as a model to investigate potential difference in plant diversity used in agricultural and urban habitat. Pollen loads were sampled in 15 hives in both habitat types, using pollen traps. Then, the attractiveness of a melliferous meadow on wild bees was tested. To that end, a new seed mix (BF) including 35 indigenous plants producing nectar and/or pollen harvested by bees was developed and its attractiveness was compared to a seed mix widely used in Geneva (PFG). For most of the season, quantity and diversity of the pollen sampled was not significantly different between agricultural and urban habitats. Nevertheless, honey bees used different species in both habitats, probably because different plant communities are present. Sixty-one wild bee species were observed foraging in the new BF seed mix compared to only 47 species in the PFG. Likewise, more plants species were used in the BF seed mix than in the PFG. These results show that urban zones can be interesting for pollinators because they display diverse and abundant plant communities. Additionally, it shows that urban parks are species rich habitats, and that pollinator communities respond immediately to additional resources when available.

Determinants of chironomid species richness in mid-European temperate rivers – Environmental factors, regional influences, diversity, and seasons

Multiscale determinants of riverine chironomid species richness were assessed in seven rivers in Central Poland, an area representative of the European temperate climatic zone. The impact of environmental factors, seasonality, as well as the concepts of gamma diversity, i.e. habitat species richness (HSR), alpha diversity, i.e. local species richness (LSR), and the relationships between these, i.e. beta diversity, were studied.One site in each river was defined as a habitat and monthly LSR time series data were obtained at each site over a full annual cycle for analysis. No strong trend in the time series was detected. The autocorrelation function (ACF) indicated that the time series were uncorrelated white noise.A stepwise forward regression model with no HSR indicated that depth, Substrate Index (SI), velocity and dissolved oxygen were significant factors of LSR values in the studied area, explaining together with summer (as a dummy variable) 67.01% of LSR variance (R2adj = 0.66). Seasonality was noticeable in the impact of summer on increase in species richness. When HSR was included in a similar model then it explained, together with benthic particulate organic matter (BPOM), SI, depth, and velocity, 70.90% of variability in LSR variance (R2adj = 0.69), HSR alone accounting for 58.95% in LSR variance (R2adj = 0.59).In both the annual cycle and in given seasons, HSR strongly positively correlated with the minimum, maximum, and mean LSR values, and there was no saturation of the rivers by chironomid species, i.e. other chironomid species were still able to inhabit the rivers beside the present ones. HSR did not correlate with beta diversity when measured by two widely used setwise beta diversity indices, or by three pairwise beta diversity indices. The exception was in autumn, where one setwise and two pairwise beta diversity measures correlated with both alpha and gamma diversity measures, which suggests a greater stability of larval chironomid assemblages in that season. This larval stability was not associated with greater stability of environmental factors in autumn, hence the stability seems to be related to undisclosed biotic mechanisms.Seasonality was also a strong factor in predicting the exchange of species. Turnover index between seasons ranged from 0.133 (spring vs summer) to 0.261 (autumn vs winter) and UPGMA clustering determined least chironomid similarity between winter and other seasons.

Positive long-term effects of year-round horse grazing in orchid-rich dry calcareous grasslands–Results of a 12-year study

IntroductionDry calcareous grasslands are among the most species-rich habitats worldwide but strongly endangered by abandonment causing a severe decline of characteristic species such as orchids. To counteract further degradation, economically sustainable restoration tools such as megaherbivore grazing, that aim to substitute extinct wild grazers, should be considered. However, the long-term effects on target species of dry grasslands, and in particular for orchid populations, is still unclear.MethodsTo contribute to this knowledge gap, we applied vegetation surveys (5 m × 5 m), as well as large-scale census-based orchid observation and mapping of habitat structures (50 m × 50 m) in a year-round grazing scheme of a Natura 2000 site in Central Germany over 12 years. The horses and their grazing activity were observed via GPS telemetry. We fitted linear mixed models to evaluate whether Ophrys apifera density was affected by horse feeding frequency, habitat structure variables (bare soil patches, woody plant cover), grassland type or years.ResultsA The main results were that the target dry calcareous grassland vegetation significantly increased in species numbers and cover. The total abundance of O. apifera increased from 1,237 (2013) and 1,893 (2018), to 4,652 (2021) individuals. Ophrys apifera density was positively affected by horse feeding frequency as well as grazing-induced enhanced bare soil patches but underlying mechanisms varied between the three classified grassland types.DiscussionOur results indicate that low-intensity year-round horse grazing as a relatively new restoration tool in dry calcareous grasslands has the potential to enhance floristic biodiversity in general, and particularly O. apifera density in the long run. Furthermore, we showed that highvalue xeric grasslands with outstanding orchid abundances can be integrated into the year-round grazing system and that there is no need of fencing off such sections.

Invasion history and distribution of the aquatic alien Elodea canadensis (Hydrocharitaceae) in Turkey

Submerged macrophyte Elodea canadensis Michx. is a non-native species to Turkey where it was first recorded in 1982. In this study, we aim to provide the current distribution of E. canadensis in Turkey with notes on its invasion history and ecology. We performed field studies to measure the physical and chemical parameters of the invaded lakes. Our study is based on new field works, herbarium specimen examination and literature survey. As a result of our findings, E. canadensis has invaded 15 wetlands in eight water basins of Turkey. Eleven of the invaded wetlands, including the largest freshwater lake of Turkey have protection forms ranging from national parks, nature parks to nationally/locally protected areas. Type of the wetlands are also diverse, like drainage canals, ancient pools, karstic, crater, tectonic and alluvial set lakes with trophic status from oligotrophic to eutrophic. Physico-chemical parameters measured in seven invaded wetlands are as follow: Water temperature between 15.5 and 22.3 °C, pH between 7.1 and 8.6, dissolved oxygen as 3.7–8,8 mg l-1, electrical conductivity as 230–610 µS cm-1, salinity between 0.1 and 0.29 ppt, and ammonium as 0.25–0.74 mg l-1. The altitude range of the colonized wetlands is between sea level and 2100 m a.s.l. Elodea canadensis forms single species stands in many sites, but we could totally record 22 accompanying macrophyte taxa in species rich habitats. Here we present the most comprehensive distribution and ecology data for E. canadensis in Turkey which could be used for further research and management to understand its future spread and effect on native vegetation.

Ground-nesting bees prefer bare ground areas on calcareous grasslands

Although most of the wild bee species are ground-nesting, little is known about their nesting requirements and the conservation measures to promote ground-nesting bees. Calcareous grasslands are one of the most species-rich habitats in Central Europe and therefore essential for protecting bee diversity. The management practices of calcareous grasslands are so far often focused on plant populations, but in order to support declining insect populations, additional measures have to be considered for nature conservation. As wild bees depend on the availability of nesting sites, we studied the effects of locally increased bare ground availability on ground-nesting bees on four large and four small calcareous grasslands in Central Germany. Vegetation cover of 24 experimental plots (1 m²) was removed. The number of bee nests as well as the presence of bees on these plots (here: nesting activity) were compared to 24 control plots during six sampling runs. Results showed that the number of bee nests on experimental plots was fourteen times higher compared to control plots, positively related to the surrounding flower cover and higher on steeper slopes, independent of grassland area. Moreover, the observed nesting activity on experimental plots was 2.5 times higher compared to the control and positively related to the currently prevailing soil surface temperature. Bee abundance quantified during transect walks increased on grasslands with a generally higher bare ground availability and a higher flower cover. In conclusion, our study emphasizes the need to consider the availability of nesting resources to promote the vast majority of wild bees, which are ground-nesting. They benefited from bare ground availability as well as adjacent floral resources, and experimental removal of the vegetation cover appeared to be a major, so far underestimated conservation practice. • Ground-nesting bees prefer artificially created vegetation free patches on calcareous grasslands. • The abundance of (ground-nesting) bees is enhanced by a higher bare ground availability. • Nearby floral resources and steeper slopes increase the nest number of ground-nesting bees. • Higher soil temperatures increased the nesting activity of ground nesting bees. • Habitat size has no influence on bee abundance, the proportion of ground-nesting bees or colonization.

Initial assemblage characteristics determine the functional dynamics of flower-strip plant communities.

In agroecosystems, species‐rich habitats, such as linear field margins and flower strips, are beneficial to the overall biodiversity and contribute to pest control. Their effects are thought to be mediated by plant species composition and diversity. However, the management of plant communities with targeted levels of functional diversity has been little investigated. In an open field landscape, we compared the effects of the sown species richness (9, 14, and 29 species) and functional diversity (high vs. low) of eight different seed mixtures, sown in flower strips, on the 4‐year temporal dynamics of their functional diversity. There was a good agreement between the expected and realized species richness and functional diversity at the start of the experiment. All plant assemblages progressively lost species over time, but this decline was lower for assemblages sown with a high initial functional diversity, in which species evenness was maintained at higher levels. Species‐rich assemblages had a higher degree of functional redundancy, and their functional diversity remained higher over time than less rich assemblages. A possible explanation for this is that functional redundancy would have enabled the compensation for the loss of species by functionally equivalent species. The realized functional diversity of the sown species also limited the establishment of spontaneous species, perhaps due to a higher degree of niche occupancy. This study provides useful insight into the creation of functionally diversified plant communities. A high level of initial species and functional diversity is required to guarantee a greater temporal persistence of the communities.

Does regional species diversity resist biotic invasions?

The role of regional species diversity in large-scale species invasions has been largely controversial. On the one hand, it has been proposed that diversity may facilitate invasion (“diversity begets diversity”) because regions with higher diversity may indicate favorable conditions for many more species. On the other hand, high diversity may indicate high levels of niche occupation, thus making it more difficult for new species to invade. In the past, invasion biologists have evaluated how regional native and exotic richness are related. Here, we test whether the range size of exotic species may be constrained by regional native richness using plant data from three continental regions in the Northern Hemisphere, i.e., Europe, Eastern Asia, and North America. We found that regional native plant diversity is inversely related to the range size of exotic species. This result may be due to stronger species interactions such as competition in species-rich habitats that limit the establishment and spread of exotic species.

Effects of experimental rewilding on butterflies, bumblebees and grasshoppers

Grassland ecosystems are species-rich habitats that are rapidly declining globally posing serious concerns for biodiversity conservation. This situation is particularly relevant in agricultural areas in Europe. As traditional management practices and livestock grazing regimes ceased, rewilding could be a potential avenue to tackle current biodiversity declines. To test this hypothesis, we set up a 3-year experiment where 12 horses were introduced in three 10-hectare enclosure replicates (four horses per enclosure). Horses were kept without supplementary feeding to mimic ecosystem functions of wild horses. We applied Generalized Linear Mixed Effects Models and a backward stepwise model selection procedure to elucidate factors that modulate insect richness induced by grazing. Our results show that plant species richness, the proportion of flowers and plant height play a significant role for butterfly and bumblebee richness, while the opposite effect was detected for grasshoppers. However, the effect on grasshoppers was counterbalanced by increased grasshopper species richness in habitats adjacent to horse latrines.Implications for insect conservationRewilding with horses may offset current biodiversity declines by maintaining important functional links between plants and pollinators in grassland ecosystems. Horse grazing can however have different effects on diverse functional groups of insects. Application of integrative landscape scale approaches may be needed to elucidate the effects of rewilding for certain functional groups such as grasshoppers. With current biodiversity declines, up-scaling rewilding research and practice might be crucial to mitigate the pervasive effects on insects as their services and functions are critical for our existence.

Exploration of the response of soil properties and plant species composition to centuries-old traditional meadow irrigation

Abstract Only targeted and sustainable management will preserve extensively managed grasslands, one of Europe’s most species-rich habitats. Traditionally, largely abandoned irrigation might prove a sustainable management strategy, but the understanding of the interactions among irrigation, soil properties and plant species are low for a generally humid ecoregion. We aimed at advancing our understanding of plant ecology by disentangling plant community responses to traditional lowland meadow irrigation from traditionally low fertilization rates. We studied plant composition and diversity jointly with the underlying links to soil properties (Corg, total N, water holding capacity and mesofaunal activity) and soil nutrients (Nmin, P, K, Mg and B). In a field study, we compared 13 long-term traditionally irrigated and 13 non-irrigated (17 fertilized and 9 non-fertilized) meadows. We surveyed plant diversity, composition and soil nutrients as well as soil properties for 1 year assuming low annual variation. Irrigation and fertilization led to differences in soil properties and soil nutrients without impact on sheer plant species diversity but on plant species composition. Finer grain sizes due to siltation increased water holding capacity and nutrient storage. Hence, resource-acquisitive graminoid species had advantages in irrigated meadows. Thus, irrigation is not only a mean to preserve biodiversity of extensively used meadows of Central Europe but may prove a tool to differentiate between plant functional traits.

A Treasure of Bioactive Compounds from the Deep Sea.

The deep-sea environment is a unique, challenging extreme habitat where species have had to adapt to the absence of light, low levels of oxygen, high pressure and little food. In order to survive such harsh conditions, these organisms have evolved different biochemical and physiological features that often have no other equivalent in terrestrial habitats. Recent analyses have highlighted how the deep sea is one of the most diverse and species-rich habitats on the planet but less explored compared to more accessible sites. Because of their adaptation to this extreme environment, deep-sea species have the potential to produce novel secondary metabolites with potent biological activities. Recent advances in sampling and novel techniques in microorganism culturing and chemical isolation have promoted the discovery of bioactive agents from deep-sea organisms. However, reports of natural products derived from deep-sea species are still scarce, probably because of the difficulty in accessing deep-sea samples, sampling costs and the difficulty in culturing deep-sea organisms. In this review, we give an overview of the potential treasure represented by metabolites produced by deep marine species and their bioactivities for the treatment and prevention of various human pathologies.

Environmental determinants of avian species richness in forests in a highly urbanized subtropical city: The effects of spatial scale and open space feature

Numerous avian studies have emphasized the importance of natural/semi-natural elements, especially green spaces to conserve avian diversity in a city. However, little is known about environmental factors associated with avian diversity in a densely populated and highly urbanized subtropical city where large scale of conservation management is not feasible. Using Macao as a case city, we investigated the relationship between environmental features and species richness of urban birds in forests at multiple scales. We analyzed point count data of birds collected at eight transects in five forests in Macao during 2007–2009. We divided survey periods into three seasons and considered them as temporal replicates. We calculated percent cover of each of two environmental features, i.e., open water (waterbody) and open green vegetation at three scales: 50 m, 250 m, and 500 m buffer areas surrounding transect. Rarefaction was used to estimate total richness (richness of all species) and richness of each guild (open habitat, shrub, and forest species). Total richness, open habitat species richness and forest species richness were affected by environmental features within the 250 m buffer area, whereas shrub species richness was not related with any scale. Percent cover of open water influenced positively open habitat and forest species richness and consequently total richness. Percent cover of open green vegetation had a positive effect on open habitat species richness but negative on forest species richness. These patterns were somewhat associated with vegetation features of forests. Our study indicates that even in highly developed small city, the relationship between environmental features and avian species richness can be influenced by spatial scale(s) at which these features are measured as well as species’ habitat preference. It also suggests that open features, especially open water could be an important factor affecting bird diversity in forests in urban areas.

Impacts of soil disturbance on plant diversity in a dry grassland

Dry grasslands are not only amongst the most species-rich habitats in Europe but also amongst the most threatened. Threats include habitat destruction as well as modification to the historic disturbance regime under which native plants have evolved (e.g. too high or too low levels of disturbance). The aim of this study is to examine the effects of soil disturbance intensity on species composition and diversity in a dry grassland in Mols Bjerge National Park in Denmark. We recorded vascular plant species inside and just outside patches of bare sand and at the transition between bare sand and dense vegetation outside the patches. We found that species richness was highest in the dense vegetation, intermediate in the transition zone and lowest in bare sand areas. However, an analysis of plant traits showed that the number of small annual species was highest in the transition zone. High abundance of small annual species may therefore indicate intermediate disturbance regimes. Moreover, literature indicates that many threatened species are adapted to such habitats, which suggests that dry grasslands should be managed to maintain areas with intermediate disturbance intensities to improve conditions for many threatened species. High abundance of small annual species thus indicates that favourable management has been achieved.

Minor Treatments Can Play a Significant Role in Preserving Natural Habitats and Protected Species on the Shore of a Central European Lake

Semi-natural grasslands were previously established through traditional land use and maintained by active management, but their extension nowadays is declining rapidly, particularly in areas that also have tourism potential. In parallel, the conservation value of the remaining areas is increasing. The shore of Lake Balaton is a particularly good example, as Lake Balaton is an area highly affected by tourism, yet there have been valuable habitats able to survive and provide refuge for many vulnerable, protected species. Fortunately, we have reliable information about the vegetation of the area from two decades ago. Comparing these data with our recent surveys we investigated the changes in habitats and the distribution of protected plant species in connection with the active conservation treatments such as grazing or cutting. Our results show that in areas where treatments are still ongoing, protected plant species are more likely to survive, or even other species can appear, which is in clear contrast with conditions experienced in abandoned areas, where at least seven protected species have disappeared. According to our results, minor, but appropriately chosen and well-executed management interventions, can help in the long-term maintenance of species-rich habitats and improving the conservation status of threatened species.

Ecological correlates of chimpanzee (Pan troglodytes schweinfurthii) density in Mahale Mountains National Park, Tanzania.

Understanding the ecological factors that drive animal density patterns in time and space is key to devising effective conservation strategies. In Tanzania, most chimpanzees (~75%) live outside national parks where human activities threaten their habitat's integrity and connectivity. Mahale Mountains National Park (MMNP), therefore, is a critical area for chimpanzees (Pan troglodytes schweinfurthii) in the region due to its location and protective status. Yet, despite its importance and long history of chimpanzee research (>50 years), a park-wide census of the species has never been conducted. The park is categorized as a savanna-woodland mosaic, interspersed with riparian forest, wooded grassland, and bamboo thicket. This heterogeneous landscape offers an excellent opportunity to assess the ecological characteristics associated with chimpanzee density, a topic still disputed, which could improve conservation plans that protect crucial chimpanzee habitat outside the park. We examined the influence of fine-scale vegetative characteristics and topographical features on chimpanzee nest density, modeling nest counts using hierarchical distance sampling. We counted 335 nests in forest and woodland habitats across 102 transects in 13 survey sites. Nests were disproportionately found more in or near evergreen forests, on steep slopes, and in feeding tree species. We calculated chimpanzee density in MMNP to be 0.23 ind/km2, although density varied substantially among sites (0.09-3.43 ind/km2). Density was associated with factors related to the availability of food and nesting trees, with topographic heterogeneity and the total basal area of feeding tree species identified as significant positive predictors. Species-rich habitats and floristic diversity likely play a principal role in shaping chimpanzee density within a predominately open landscape with low food abundance. Our results provide valuable baseline data for future monitoring efforts in MMNP and enhance our understanding of this endangered species' density and distribution across Tanzania.

Green Vegetation Cover Dynamics in a Heterogeneous Grassland: Spectral Unmixing of Landsat Time Series from 1999 to 2014

The ability to quantify green vegetation across space and over time is useful for studying grassland health and function and improving our understanding of the impact of land use and climate change on grasslands. Directly measuring the fraction of green vegetation cover is labor-intensive and thus only practical on relatively smaller experimental sites. Remote sensing vegetation indices, as a commonly-used method for large-area vegetation mapping, were found to produce inconsistent accuracies when mapping green vegetation in semi-arid grasslands, largely due to mixed pixels including both photosynthetic and non-photosynthetic material. The spectral mixture approach has the potential to map the fraction of green vegetation cover in a heterogeneous landscape, thanks to its ability to decompose a spectral signal from a mixed pixel into a set of fractional abundances. In this study, a time series of fractional green vegetation cover (FGVC) from 1999 to 2014 is estimated using the spectral mixture approach for a semi-arid mixed grassland, which represents a typical threatened, species-rich habitat in Central Canada. The shape of pixel clouds in each of the Landsat images is used to identify three major image endmembers (green vegetation, bare soil/litter, and water/shadow) for automated image spectral unmixing. The FGVC derived through the spectral mixture approach correlates highly with field observations (R2 = 0.86). Change in the FGVC over the study period was also mapped, and green vegetation in badlands and uplands is found to experience a slight increase, while vegetation in riparian zone shows a decrease. Only a small portion of the study area is undergoing significant changes, which is likely attributable to climate variability, bison reintroduction, and wildfire. The results of this study suggest that the automated spectral unmixing approach is promising, and the time series of medium-resolution images is capable of identifying changes in green vegetation cover in semi-arid grasslands. Further research should investigate driving forces for areas undergoing significant changes.

Richness of Primary Producers and Consumer Abundance Mediate Epiphyte Loads in a Tropical Seagrass System

Consumer communities play an important role in maintaining ecosystem structure and function. In seagrass systems, algal regulation by mesograzers provides a critical maintenance function which promotes seagrass productivity. Consumer communities also represent a key link in trophic energy transfer and buffer negative effects to seagrasses associated with eutrophication. Such interactions are well documented in the literature regarding temperate systems, however, it is not clear if the same relationships exist in tropical systems. This study aimed to identify if the invertebrate communities within a tropical, multispecies seagrass meadow moderated epiphyte abundance under natural conditions by comparing algal abundance across two sites at Green Island, Australia. At each site, paired plots were established where invertebrate assemblages were perturbed via insecticide manipulation and compared to unmanipulated plots. An 89% increase in epiphyte abundance was seen after six weeks of experimental invertebrate reductions within the system. Using generalised linear mixed-effect models and path analysis, we found that the abundance of invertebrates was negatively correlated with epiphyte load on seagrass leaves. Habitat species richness was seen to be positively correlated with invertebrate abundance. These findings mirrored those of temperate systems, suggesting this mechanism operates similarly across latitudinal gradients.