Water quality parameters and tipping points of dragonfly diversity and abundance in fishponds

Fishponds are often enriched with nutrients in order to increase phytoplankton and zooplankton populations to support fish production. This eutrophication often leads to a global decrease of biodiversity. This biodiversity shift may be identified by a tipping point, the value of an environmental parameter above which a significant change of species richness and abundance occurs. A total of 110 eutrophic to highly eutrophic fishponds were studied in two areas in France to investigate parameters governing dragonfly species richness and species abundance by determining tipping points. Parameters investigated were chlorophyll a (CHL), water transparency, total N (TN), total P (TP), aquatic plant richness and coverage, adult dragonfly richness and abundance, and fish harvest. A high species richness of dragonflies was found in fishponds, with a total of 34 species, including six species of conservation concern. Dragonfly richness and abundance was shown to be negatively influenced by higher degrees of eutrophication. A high diversity of dragonflies occurred in the fishponds with CHL concentrations below 127 µg/l, water transparency above 67 cm, TN concentrations below 2.30 mg/l, and a fish harvest smaller than 253 kg/ha. A minimum of 5% of aquatic plant cover and the presence of a minimum 9 aquatic plant species seem to promote the richness and abundance of dragonflies. According to tipping points, 19 dragonfly species could be determined as indicator species for water quality in fishponds.     

Exploring the effect of soil management intensity on taxonomic and functional diversity of ants in Mediterranean olive groves

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Assessing the impacts of agricultural intensification on biodiversity: a British perspective

Agricultural intensification is best considered as the level of human appropriation of terrestrial net primary production. The global value is set to increase from 30%, increasing pressures on biodiversity. The pressures can be classified in terms of spatial scale, i.e. land cover, landscape management and crop management. Different lowland agricultural landscapes in Great Britain show differences among these pressures when habitat diversity and nutrient surplus are used as indicators. Eutrophication of plants was correlated to N surplus, and species richness of plants correlated with broad habitat diversity. Bird species diversity only correlated with habitat diversity when the diversity of different agricultural habitats was taken into account. The pressures of agricultural change may be reduced by minimizing loss of large habitats, minimizing permanent loss of agricultural land, maintaining habitat diversity in agricultural landscapes in order to provide ecosystem services, and minimizing pollution from nutrients and pesticides from the crops themselves. While these pressures could potentially be quantified using an internationally consistent set of indicators, their impacts would need to be assessed using a much larger number of locally applicable biodiversity indicators.     

Do hotspots fall within protected areas? A Geographic Approach to Planning analysis of regional freshwater biodiversity

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Management intensity at field and landscape levels affects the structure of generalist predator communities

Agricultural intensification is recognised as a major driver of biodiversity loss in human-modified landscapes. Several agro-environmental measures at different spatial scales have been suggested to mitigate the negative impact of intensification on biodiversity and ecosystem services. The effect of these measures on the functional structure of service-providing communities remains, however, largely unexplored. Using two distinct landscape designs, we examined how the management options of organic farming at the field scale and crop diversification at the landscape level affect the taxonomic and functional structure of generalist predator communities and how these effects vary along a landscape complexity gradient. Organic farming as well as landscapes with longer and more diversified crop rotations enhanced the activity-density of spiders and rove beetles, but not the species richness or evenness. Our results indicate that the two management options affected the functional composition of communities, as they primarily enhanced the activity-density of functionally similar species. The two management options increased the functional similarity between spider species in regards to hunting mode and habitat preference. Organic farming enhanced the functional similarity of rove beetles. Management options at field and landscape levels were generally more important predictors of community structure when compared to landscape complexity. Our study highlights the importance of considering the functional composition of generalist predators in order to understand how agro-environmental measures at various scales shape community assemblages and ecosystem functioning in agricultural landscapes.     

Factors affecting plant species richness in field boundaries in the Mediterranean region

Field boundaries are expected to support the maintenance of biodiversity in agroecosystems, since they provide the habitat for a range of plant species. However, plant diversity in field boundaries has decreased substantially in recent decades. This pattern is generally linked with the intensification of agricultural land use at field and landscape level. Therefore, we aimed to test the effect of farming management (field and boundary management), boundary structure (width and habitat assemblage considering the Mediterranean grassland element), and landscape heterogeneity on plant species richness of field boundaries. Plants were recorded along 30 field boundaries next to organic fields and 30 next to conventional fields located in 15 agrarian localities of NE Iberian Peninsula along a gradient of landscape complexity. A total of 517 plant species were identified in the 60 field boundaries. We recorded 162 species (31%) catalogued as rare, very rare or extremely rare in the flora of the Catalan Countries. Our results showed the importance of landscape heterogeneity, field management and habitat assemblage, since they were found to be the most influential variables for plant species richness; whereas boundary width and boundary management were seen to contribute less to explaining plant diversity. Accordingly, agri-environmental schemes should be designed to promote organic farming and maintain the structure of the landscape mosaic in order to benefit plant diversity in field boundaries in the Mediterranean region.     

What is the effect of climate change on marine fish biodiversity in an area of low connectivity,the Baltic Sea?

Aim Climate change could result in an increase in species richness because large‐scale biogeography suggests that more species could be gained from equatorial regions than may be lost pole‐ward. However, the colonization of newly available habitat may lag behind the rate dictated by climatic warming if there exists of a lack of connectivity between ‘donor’ and receiving areas. The objective of this study was to compare how regional warming affected the biodiversity of marine fish in areas that differed in their connectivity in the Baltic Sea. Location North‐east Atlantic, Kattegat and Baltic Sea. Methods The total species richness and the mean species richness from scientific surveys were related to changes in temperature and salinity. Changes in the extent of the distribution of individual fish species were related to the latitudinal distribution, salinity tolerance, maximum body size and exploitation status to assess to what extent climate change and fishing impacts could explain changes in species richness in the Baltic. Results Rising temperatures in the well‐connected Kattegat correlated to an increase in the species richness of fish, due to an increase in low‐latitude species. Unexpectedly, species richness in the poorly connected Baltic Sea also increased. However, the increase seems to be related to higher salinity rather than temperature and there was no influx of low‐latitude species. Main conclusions These results do not support the hypothesis that low‐connectivity areas are less likely to see increases in species richness in response to warming. This indicates that the effect of climate change on biodiversity may be more difficult to predict in areas of low connectivity than in well‐connected areas.     

Responses of tropical fruit bats to monoculture and polyculture farming in oil palm smallholdings

The oil palm industry is one of the main economic drivers in Southeast Asia. The industry has caused tropical deforestation on a massive scale in producing countries, and this forest conversion to oil palm agriculture has decimated the habitat of numerous native species. Monoculture and polyculture practices are two distinctive oil palm production systems. We hypothesize that polyculture farming hosts a greater diversity of species than monoculture farming. Habitat complexity in smallholdings is influenced by multiple farming practices (i.e. polyculture and monoculture). However, little is known about the effects of such farming practices in smallholdings on mammalian biodiversity, and particularly frugivorous bats. Our study aimed to find the best farming practice to reconcile oil palm production with biodiversity conservation. Mist-nets were used to trap frugivorous bats at 120 smallholdings in Peninsular Malaysia. We compared species richness and the abundance of frugivorous bats between monoculture and polyculture smallholdings. We investigated their relationships with vegetation structure characteristics. Our results revealed that species richness and abundance of frugivorous bats were significantly greater in polyculture smallholdings than monoculture smallholdings. We also found that 28.21% of the variation in species richness was explained by in situ habitat characteristics, including the number of dead standing oil palms and immature oil palms, non-grass cover, height of non-grass cover, and farming practices. The in situ habitat quality was closely associated with oil palm farming management. Commercial growers should implement polyculture rather than monoculture farming because polyculture farming has positive effects on the abundance and species richness of bats in oil palm production landscapes.     

Organic fields sustain weed metacommunity dynamics in farmland landscapes

Agro-ecosystems constitute essential habitat for many organisms. Agricultural intensification, however, has caused a strong decline of farmland biodiversity. Organic farming (OF) is often presented as a more biodiversity-friendly practice, but the generality of the beneficial effects of OF is debated as the effects appear often species- and context-dependent, and current research has highlighted the need to quantify the relative effects of local- and landscape-scale management on farmland biodiversity. Yet very few studies have investigated the landscape-level effects of OF; that is to say, how the biodiversity of a field is affected by the presence or density of organically farmed fields in the surrounding landscape. We addressed this issue using the metacommunity framework, with weed species richness in winter wheat within an intensively farmed landscape in France as model system. Controlling for the effects of local and landscape structure, we showed that OF leads to higher local weed diversity and that the presence of OF in the landscape is associated with higher local weed biodiversity also for conventionally farmed fields, and may reach a similar biodiversity level to organic fields in field margins. Based on these results, we derive indications for improving the sustainable management of farming systems.     

An Analysis of Fish Species Richness in Natural Lakes

There is a growing recognition of the need to conserve biodiversity that has been conceptualised in the Convention of Biological Diversity. Maintenance of fish species richness is particularly important, because habitat degradation in inland waters continues to accelerate on a global scale. Here we develop empirical models for predicting fish species richness in natural lakes in various geographical regions of the world. In tropical lakes where fish biodiversity is richer than in temperate lakes, fish species richness can be predicted by a few variables such as lake area and altitude. Low fish species richness in most temperate lakes might be due to the effect of glaciation on colonisation and speciation of fishes. In US, Canadian and northern European lakes, lake acidification is one of the important factors influencing fish species richness. Although limnological characteristics influence fish species richness in temperate lakes, lake area and altitude have greater predictive power. This is in contrast to fish species richness in rivers, which can be reliably predicted by basin area. In the power curves, which describe the relationship between fish species richness and habitat size in lakes and rivers, the exponent is always greater in tropical regions than in temperate regions. Because fish biodiversity is greater in the tropics threats to fish biodiversity through habitat degradation are greater than those in temperate inland waters.     

A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes

Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species richness, and whether impacts differ across spatial scales and landscape contexts. Using a global metadataset, we quantified the effects of organic farming and plant diversification on abundance, local diversity (communities within fields), and regional diversity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in‐field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in‐field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem service providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacommunities that may provide temporal and spatial stability of ecosystem service provisioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes.     

High Bee and Wasp Diversity in a Heterogeneous Tropical Farming System Compared to Protected Forest

It is a globally important challenge to meet increasing demands for resources and, at the same time, protect biodiversity and ecosystem services. Farming is usually regarded as a major threat to biodiversity due to its expansion into natural areas. We compared biodiversity of bees and wasps between heterogeneous small-scale farming areas and protected forest in northern coastal Belize, Central America. Malaise traps operated for three months during the transition from wet to dry season. Farming areas consisted of a mosaic of mixed crop types, open habitat, secondary forest, and agroforestry. Mean species richness per site (alpha diversity), as well as spatial and temporal community variation (beta diversity) of bees and wasps were equal or higher in farming areas compared to protected forest. The higher species richness and community variation in farmland was due to additional species that did not occur in the forest, whereas most species trapped in forest were also found in farming areas. The overall regional species richness (gamma diversity) increased by 70% with the inclusion of farming areas. Our results suggest that small-scale farming systems adjacent to protected forest may not only conserve, but even favour, biodiversity of some taxonomic groups. We can, however, not exclude possible declines of bee and wasp diversity in more intensified farmland or in landscapes completely covered by heterogeneous farming systems.     

Switching from monoculture to polyculture farming benefits birds in oil palm production landscapes: Evidence from mist netting data

Monoculture farming is pervasive in industrial oil palm agriculture, including those RSPO plantations certified as sustainably managed. This farming practice does not promote the maintenance of farmland biodiversity. However, little scientific attention has been given to polyculture farming in oil palm production landscapes. Polyculture farming is likely to increase the floristic diversity and stand structural complexity that underpins biodiversity. Mist nets were used to sample birds at 120 smallholdings in Peninsular Malaysia. At each site, 12 vegetation structure characteristics were measured. We compared bird species richness, abundance, and composition between monoculture and polyculture smallholdings and used predictive models to examine the effects of habitat quality on avian biodiversity. Bird species richness was significantly greater in polyculture than that of monoculture smallholdings. The number of fallen and standing, dead oil palms were also important positive predictors of species richness. Bird abundance was also strongly increased by standing and dead oil palms and decreased with oil palm stand height. Our results indicate that polyculture farming can improve bird species richness in oil palm production landscapes. In addition, key habitat variables that are closely associated with farming practices, such as the removal of dead trees, should and can be managed by oil palm growers in order to promote biodiversity. To increase the sustainability of oil palm agriculture, it is imperative that stakeholders modify the way oil palms are currently planted and managed. Our findings can guide policy makers and certification bodies to promote oil palm production landscapes that will function more sustainably and increase existing biodiversity of oil palm landscapes.     

Organic farming at local and landscape scales benefits plant diversity

Agri‐environment schemes (AES) have been suggested to counter negative effects of agricultural intensification and enhance farmland biodiversity, but evaluations have produced inconsistent results. We suggest that this is partly a consequence of scale‐dependence, i.e. that the consequence of organic farming will differ depending on the scale of uptake in a particular landscape. To test our hypothesis on diversity of forbs, we designed a landscape scale study using spatially explicit information about the Swedish AES for organic farming. The study system consisted of uncultivated field borders along paired fields (organic and conventional) in matched landscapes with either a high or a low proportion of organic faming, allowing separate tests of the effects of farming practice at the local and the landscape scale. The local effect of organic farming was consistently strong, with higher diversity in borders adjoining organic fields, most likely due to the lack of herbicide use on organically managed farmland. Thus, we show that not only the proportion of semi‐natural habitat is important for farmland biodiversity, but that also the management of cropland can influence the diversity in semi‐natural habitats. Furthermore, forb richness was also higher in borders situated in landscapes with a high proportion of organic land, irrespectively of local management, possibly as a result of dispersal of mainly annual plant species from the organically managed fields into the borders (mass effect). Our results demonstrate that farming practice at a local and a landscape scale independently can influence plant species richness, indicating that organic farming can influence diversity also at larger spatial scales and outside the organically managed land. Our study highlight the importance of studying multiple scales, including both local and landscape factors to provide a better understanding of biodiversity patterns.     

Plant biodiversity and vegetation structure in traditional cocoa forest gardens in southern Cameroon under different management

Floristic surveys were performed in 17 traditional cocoa forest gardens under different management regimes in the humid forest area of southern Cameroon, to assess the impact of intensification on plant biodiversity. This impact was evaluated by analyzing species richness, vegetation structure, carbon sequestration and above ground biomass. We hypothesize that: (a) plant (tree and herbs) species richness is negatively correlated to management intensity and (b) vegetational density predictably change with management intensity. Our results show that management as practiced in traditional cocoa forest gardens in southern Cameroon following a gradient of intensification from extensive cocoa forest gardens with high floristic diversity to intensive ones strongly impacts plant diversity, plant biomass and to some extend carbon storage with possible negative consequences on biodiversity. Great differences in species richness, species composition, and, for trees, diameter at breast height and basal area were evident among the five types of traditional cocoa forest garden systems investigated. In terms of plant species richness, we found a decreasing gradient of plant species numbers from extensive forest gardens to intensive ones. This study also highlights the importance of the Management Index for quantifying differences in the management; this index could be used to standardize certification procedures and assess conservation progress and success. Our findings support the idea that traditional cocoa forest gardens can help to protect many forest species, sustains smallholder production and offer more scope for conservation of biodiversity, at both species-level and landscape-level. Moreover, diverse traditional cocoa forest gardens may help in regulating pests and diseases and allow for efficient adaptation to changing socioeconomic conditions.     

Grassland management for meadow birds in the Netherlands is unfavourable to pollinators

Agricultural intensification and loss of semi-natural grassland have contributed to biodiversity decline, including pollinator species, in pastures around the world. To reverse the decline, agri-environmental schemes have been implemented, varying widely in effectiveness. In addition, many countries, including the Netherlands, have established nature reserves in which semi-natural grasslands are restored and are often managed for specific groups of species, e.g. meadow birds or plants. The effects of such measures on insect biodiversity are not well known but recent reports on the dramatic decline of insect biomass in nature reserves have put even more attention to the impact of land use and management on biodiversity. This study compares pollinator abundance and species richness in three common semi-natural grassland management types in the Netherlands: (1) hay meadows, (2) herb-rich grasslands and (3) meadow bird grasslands. Pollinator abundance and species richness were assessed in eleven study areas, each with all three management types present. Standardized transects, insect sampling within a standard 20 min time frame and plot-based flower surveys were used in spring and summer to assess the relationships between management regime, floral abundance and diversity and pollinator communities. The results show that meadow bird grasslands have lower pollinator abundance and diversity and a less unique pollinator assemblage than both other types. Moreover, flower abundance has a positive effect on pollinator abundance and flower diversity has a positive effect on pollinator species richness. These results indicate that meadow-bird grasslands are a comparatively unfavourable habitat for bees, hoverflies and butterflies, which may be explained by a lack of flowers as well as unsuitable mowing practices. Measures benefitting both insectivorous birds and flower-visiting insects, such as rotational mowing, could remediate this imbalance.     

Earthworms,spiders and bees as indicators of habitat quality and management in a low-input farming region—A whole farm approach

The benefits of low input farming on biodiversity and ecosystem services are already well-established, however most of these studies focus only on the focal field scales. We aimed to study whether these benefits exist at the whole farm scale, to find the main environmental driving effects on biodiversity at the whole farm scale in farms of different grassland grazing intensity, applying three well-known species diversity indicator groups of different ecological traits.Edaphic (earthworms), epigeic (spiders) and flying (bees) taxa were sampled in each identified habitat type within 18 low-input farms in Central Hungary, 2010. The number of habitat types, the number of grassland plots, the cumulative area of grasslands and habitat type had an effect on the species richness and abundance of spiders, while grassland grazing intensity influenced the species richness of bees. Both bees and spiders were sensitive to vegetation and weather conditions, resulting in more bees on flower-rich farms and those having higher temperature; and more spiders on farms with more heterogeneous vegetation structure and in low-wind areas. Relatively few earthworms were found in the whole study, and their abundance was not influenced by any of the farm composition and management variables.We conclude that local field management (grazing intensity of grassland patches) can have a farm scale effect, detectable on species diversity indicators that have high dispersal ability and strong connection to grasslands as important foraging sites (bees). However, other farmland biota (spiders) is also strongly determined by farmland composition and habitat diversity, therefore the maintenance of a mosaic within-farm habitat structure is strongly recommended. The application of earthworms as farmland composition or management indicators is strongly restricted because of their special needs of soil conditions.     

Local vs. landscape controls on diversity: a test using surface-dwelling soil macroinvertebrates of differing mobility

Aim A better understanding of the processes driving local species richness and of the scales at which they operate is crucial for conserving biodiversity in cultivated landscapes. Local species richness may be controlled by ecological processes acting at larger spatial scales. Very little is known about the effect of landscape variables on soil biota. The aim of our study was to partly fill this gap by relating the local variation of surface‐dwelling macroarthropod species richness to factors operating at the habitat scale (i.e. land use and habitat characteristics) and the landscape scale (i.e. composition of the surrounding matrix). Location An agricultural landscape with a low‐input farming system in Central Hesse, Germany. Methods We focused on five taxa significantly differing in mobility and ecological requirements: ants, ground beetles, rove beetles, woodlice, and millipedes. Animals were caught with pitfall traps in fields of different land use (arable land, grassland, fallow land) and different habitat conditions (insolation, soil humidity). Composition of the surrounding landscape was analysed within a radius of 250 m around the fields. Results Factors from both scales together explained a large amount of the local variation in species richness, but the explanatory strength of the factors differed significantly among taxa. Land use particularly affected ground beetles and woodlice, whereas ants and rove beetles were more strongly affected by habitat characteristics, namely by insolation and soil characteristics. Local species richness of diplopods depended almost entirely on the surrounding landscape. In general, the composition of the neighbouring landscape had a lower impact on the species richness of most soil macroarthropod taxa than did land use and habitat characteristics. Main conclusions We conclude that agri‐environment schemes for the conservation of biodiversity in cultivated landscapes have to secure management for both habitat quality and heterogeneous landscape mosaics.     

Adjacent woodlands rather than habitat connectivity influence grassland plant,carabid and bird assemblages in farmland landscapes

One response to biodiversity decline is the definition of ecological networks that extend beyond protected areas and promote connectivity in human-dominated landscapes. In farmland, landscape ecological research has focused more on wooded than open habitat networks. In our study, we assessed the influence of permanent grassland connectivity, described by grassland amount and spatial configuration, on grassland biodiversity. We selected permanent grasslands in livestock farming areas of north-western France, which were sampled for plants, carabids and birds. At two spatial scales we tested the effects of amount and configuration of grasslands, wooded habitats and crops on richness and abundance of total assemblages and species ecological groups. Grassland connectivity had no significant effects on total richness or abundance of any taxonomic group, regardless of habitat affinity or dispersal ability. The amount of wooded habitat and length of wooded edges at the 200 m scale positively influenced forest and generalist animal groups as well as grassland plant species, in particular animal-dispersed species. However, for animal groups such as open habitat carabids or farmland bird specialists, the same wooded habitats negatively influenced richness and abundance at the 500 m scale. The scale and direction of biodiversity responses to landscape context were therefore similar among taxonomic groups, but opposite for habitat affinity groups. We conclude that while grassland connectivity is unlikely to contribute positively to biodiversity, increasing or maintaining wooded elements near grasslands would be a worthwhile conservation goal. However, the requirements of open farmland animal species groups must be considered, for which such action may be deleterious.     

Bird assemblages in fragmented agricultural landscapes: the role of small brigalow remnants and adjoining land uses

Agricultural intensification typically leads to changes in bird diversity and community composition, with fewer species and foraging guilds present in more intensively managed parts of the landscape. In this study, we compare bird communities in small (2–32 ha) brigalow (Acacia harpophylla) remnants with those in adjacent uncultivated grassland, previously cultivated grassland and current cropland, to determine the contribution of different land uses to bird diversity in the agricultural landscape. Twenty remnant brigalow patches and adjacent agricultural (‘matrix’) areas in southern inland Queensland, Australia were sampled for bird composition and habitat characteristics. The richness, abundance and diversity of birds were all significantly higher in brigalow remnants than in the adjacent matrix of cropping and grassland. Within the matrix, species richness and diversity were higher in uncultivated grasslands than in current cultivation or previously cultivated grasslands. Forty-four percent of bird species were recorded only in brigalow remnants and 78% of species were recorded in brigalow and at least one other land management category. Despite high levels of landscape fragmentation and modification, small patches of remnant brigalow vegetation provide important habitat for a unique and diverse assemblage of native birds. The less intensively managed components of the agricultural matrix also support diverse bird assemblages and thus, may be important for local and regional biodiversity conservation.