scholarly journals Optimizing Species Richness in Mosaic Landscapes: A Probabilistic Model of Species-Area Relationships

2021 ◽  
Vol 2 ◽  
Author(s):  
Ola Olsson ◽  
Mark V. Brady ◽  
Martin Stjernman ◽  
Henrik G. Smith
Keyword(s):  
Species Richness ◽  
Biodiversity Conservation ◽  
Optimal Allocation ◽  
Optimal Solution ◽  
Average Density ◽  
Agricultural Landscapes ◽  
Natural Habitats ◽  
Total Size ◽  
Α Diversity ◽  
Species Area

Most landscapes are comprised of multiple habitat types differing in the biodiversity they contain. This is certainly true for human modified landscapes, which are often a mix of habitats managed with different intensity, semi-natural habitats and even pristine habitats. To understand fundamental questions of how the composition of such landscapes affects biodiversity conservation, and to evaluate biodiversity consequences of policies that affect the composition of landscapes, there is a need for models able to translate information on biodiversity from individual habitats to landscape-wide predictions. However, this is complicated by species richness not being additive. We constructed a model to help analyze and solve this problem based on two simple assumptions. Firstly, that a habitat can be characterized by the biological community inhabiting it; i.e., which species occur and at what densities. Secondly, that the probability of a species occurring in a particular unit of land is dictated by its average density in the associated habitats, its spatial aggregation, and the size of the land unit. This model leads to a multidimensional species-area relation (one dimension per habitat). If the goal is to maximize species diversity at the landscape scale (γ-diversity), within a fixed area or under a limited budget, the model can be used to find the optimal allocation of the different habitats. In general, the optimal solution depends on the total size of the species pool of the different habitats, but also their similarity (β-diversity). If habitats are complementary (high β), a mix is usually preferred, even if one habitat is poorer (lower α diversity in one habitat). The model lends itself to economic analyses of biodiversity problems, without the need to monetarize biodiversity value, i.e., cost-effectiveness analysis. Land prices and management costs will affect the solution, such that the model can be used to estimate the number of species gained in relation to expenditure on each habitat. We illustrate the utility of the model by applying it to agricultural landscapes in southern Sweden and demonstrate how empirical monitoring data can be used to find the best habitat allocation for biodiversity conservation within and between landscapes.

scholarly journals Family graveyards form underappreciated local plant diversity hotspots in China's agricultural landscapes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cheng Gong ◽  
Liangtao Li ◽  
Jan C. Axmarcher ◽  
Zhenrong Yu ◽  
Yunhui Liu
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Natural Habitat ◽  
Plant Species Richness ◽  
Agricultural Landscapes ◽  
Natural Habitats ◽  
Landscape Features ◽  
Habitat Islands ◽  
Local Plant ◽  
Ecological Functioning

AbstractIn the intensively farmed, homogenous agricultural landscape of the North China Plain, family graveyards form distinct cultural landscape features. In addition to their cultural value, these graveyards represent semi-natural habitat islands whose potential roles in biodiversity conservation and ecological functioning has remained poorly understood. In this study, we investigated plant species richness on 199 family graveyards of different ages and sizes. In accordance with biogeography theory, both overall and insect-pollinated plant species richness increased with area and age of graveyards. Even small graveyards show a strong potential for conserving local plant richness, and a mosaic of both large and small family graveyards could play an important role in the conservation of farmland biodiversity and related ecosystem functions. The launch of agri-environmental measures that conserve and create semi-natural habitats, in turn benefitting agricultural biodiversity and ecological functioning, has proven difficult in China due to the shortage of dispensable arable land. Given the great value of family graveyards as semi-natural habitats reflected in our study, we propose to focus preliminary efforts on conserving these landscape features as existing, widespread and culturally important semi-natural habitat islands. This would represent an effective, complementary policy to a subsequent re-establishment of other semi-natural habitats for the conservation of biodiversity and ecological functioning in agricultural landscapes.

Holy or Not, Israel is a Palaearctic Biodiversity Hotspot

2011 ◽  
Vol 57 (3) ◽  
pp. 207-211
Author(s):  
Yoni Gavish
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Grid Cell ◽  
Biodiversity Hotspot ◽  
Statistical Prediction ◽  
Β Diversity ◽  
Α Diversity ◽  
Species Area ◽  
Prediction Limits ◽  
Global Biodiversity

In their rebuttal to my comment, Roll et al. (2011) defend their original conclusion, by questioning the theoretical framework on which I based my analysis. They stress the importance of the statistical prediction limits and the treatment of latitudinal location as a covariate. They also add an additional grid-cell-based analysis. Here, I claim that even if provincial species-area relationships (SPAR) are not parallel, they are still different. While relying on Roll et al.'s (2011) analyses, I show that for each taxon there is at least one other provincial SPAR that lies considerably above the Palaearctic SPAR, making Palaearctic countries less favorable to be identified as a global biodiversity hotspot. I further claim that prediction limits should not be used to answer the question in focus and that adding latitude as a covariate does not alter the results. Finally, I address the grid-cell analyses of Roll et al. (2011), claiming that Israel's diversity lies mainly in the species turnover between cells (i.e., β diversity) and not on the average species richness within cells (α diversity). Therefore I hold on to my former conclusion that at least for three taxa—birds, mammals, and reptiles—Israel is indeed a Palaearctic provincial hotspot.

Contribution of the Cerrado as Habitat for Sunflower Pollinating Bees

Sociobiology ◽  
2020 ◽  
Vol 67 (2) ◽  
pp. 281
Author(s):  
Mayra Layra Santos Almeida ◽  
Gabriel Santos Carvalho ◽  
Júlia Rodrigues Novais ◽  
Danielle Storck Tonon ◽  
Márcio Luiz Oliveira ◽  
...  
Keyword(s):  
Species Richness ◽  
Food Source ◽  
Seed Mass ◽  
Agricultural Landscapes ◽  
Natural Habitats ◽  
Mato Grosso ◽  
Sunflower Crop ◽  
Bee Diversity ◽  
Floral Visitors ◽  
Pan Traps

Agricultural landscapes sometimes include natural habitats which can support the ecosystem by enhancing the pollination of crops, thus boosting the productivity. This research was conducted between May and July 2017, in the municipality of Tangará da Serra, Mato Grosso, Brazil, to assess the Cerrado from the perspective of it being a crucial habitat to sustain the sunflower-pollinating bees (Helianthus annuus L.). The bees were sampled using entomological nets and pan traps, in specifically marked out plots (20 m x 150 m), in the Cerrado, and in a sunflower crop, at different distances from the Cerrado border. The assessment was done in terms of the composion and species richness, abundance of individuals and the mass (g) of the sunflower chapters exposed and isolated from the floral visitors. While species richness showed no differences between the Cerrado and sunflower crop, a difference was observed for abundance, with more numbers of individuals in the sunflower crop, most likely because of the food source supply. In the sunflower crop, the bee diversity decreased proportionally as the distance from the border increased. The seed mass of the sunfl ower chapters was significantly higher in the flowers open to visitors than in those of the isolated chapters open for visitation. From the results, it was evident that the bees presente in the Cerrado visit the sunflower crop to gather pollen and nectar, and thus assist in cross-pollinating them and raising the productivity.

scholarly journals Drivers of vascular plant species area relationships in British broadleaved woodlands and their effects on the species area curve

2020 ◽  
Author(s):  
Petra Guy ◽  
Simon Smart ◽  
Colin Prentice
Keyword(s):  
Organic Matter ◽  
Species Richness ◽  
Soil Organic Matter ◽  
Plant Species ◽  
Habitat Heterogeneity ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Riparian Zones ◽  
Natural Habitats ◽  
Species Area

SummaryThe loss of plant biodiversity in Great Britain is a major concern, with a fifth of species endangered or vulnerable according to the latest IUCN Red List. The Government’s 25 Year Plan for the environment aims to halt this loss and build new habitats, including new woodlands. To ensure that biodiversity loss is halted in existing woodlands and gain is maximised in new ones, we need to better understand which drivers have been most influential in controlling biodiversity. Here we focus on vascular plant species’ richness.Previous attempts to explain plant species richness have mainly focussed on alpha diversity in a consistent, fixed unit area. Here, we additionally undertake a novel analysis of the effects of environmental heterogeneity and abiotic factors on species-area relationships derived from 16 randomly placed quadrats in each of 103 semi-natural, broad-leaved woodlands across Britain. Species-area relationships were examined at two scales (4m2 to 200m2 and 200m2 to 3200m2) to explore the relationship between the drivers of species richness and the exponent z, of the canonical species-area curve, S = cAz. We also explore the use of a new metric ζr, based on zeta diversity to quantify heterogeneity. Zeta diversity quantifies the number of species shared between multiple combinations of plots.Habitat heterogeneity increased species richness, as did the proximity of the woodlands to surrounding natural habitats. Higher levels of soil organic matter and the progression of woodlands to later successional stages, decreased species richness. Richness was also seen to have a unimodal response to soil acidity with a peak around pH 6. At the smaller scale, heterogeneity elements in the woodland such as riparian zones or coppicing led to an increase in the value of the exponent of the species area curve. At the larger scale, species turnover led to an increase in the exponent of the curves while succession led to a decrease. At both scales, soil organic matter content had a negative effect. ζr was found to be a significant and important variable and to affect both species richness and the slope of the species accumulation curves at larger scales.SynthesisHabitat heterogeneity measures included the presence of coppicing, open areas such as rides and riparian zones and the difference between species assemblages in different plots in the woodland. Results suggest that to maximize vascular plant diversity, woodlands should be managed for heterogeneity. In addition, the increase in richness with exposure to surrounding natural habitats suggests that woodlands benefit from being embedded in more benign habitats and further, that land management surrounding woodlands has a clear role to play in supporting biodiversity within woodlands. This is an area were Agri-environment schemes have an important role.

scholarly journals Linking pollinator occurrence in field margins to pollinator visitation to a mass-flowering crop

2021 ◽  
Vol 28 ◽  
pp. 153-166
Author(s):  
Marjaana Toivonen ◽  
Irina Herzon ◽  
Jenni Toikkanen ◽  
Mikko Kuussaari
Keyword(s):  
Species Richness ◽  
Landscape Heterogeneity ◽  
Agricultural Landscapes ◽  
Field Margins ◽  
Natural Habitats ◽  
Pollination Services ◽  
Pollinator Visitation ◽  
Mass Flowering ◽  
Pollinator Abundance ◽  
Management Approaches

Uncultivated field margins are important refugia for pollinating insects in agricultural landscapes. However, the spill-over of pollination services from field margins to adjacent crops is poorly understood. This study (i) examined the effects of landscape heterogeneity on pollinator occurrence in permanent field margins and pollinator visitation to adjacent mass-flowering turnip rape (Brassica rapa ssp. oleifera) in boreal agricultural landscapes, and (ii) tested whether pollinator abundance and species richness in field margins predict abundance and species richness of crop visitors. Pollinators visiting the crop were more affected by landscape heterogeneity than pollinators in adjacent margins. Species richness, total abundance, and the abundance of syrphid flies visiting the crop increased with increasing landscape heterogeneity, whereas, in field margins, landscape heterogeneity had little effect on pollinators. In field-dominated homogeneous landscapes, wild pollinators rarely visited the crop even if they occurred in adjacent margins, whereas in heterogeneous landscapes, differences between the two habitats were smaller. Total pollinator abundance and species richness in field margins were poor predictors of pollinator visitation to adjacent crop. However, high abundances of honeybees and bumblebees in margins were related to high numbers of crop visitors from these taxa. Our results suggest that, while uncultivated field margins help pollinators persist in boreal agricultural landscapes, they do not always result in enhanced pollinator visitation to the adjacent crop. More studies quantifying pollination service delivery from semi-natural habitats to crops in different landscape settings will help develop management approaches to support crop pollination. 

scholarly journals Organic farming expansion drives natural enemy abundance not diversity in agricultural landscapes

2019 ◽  
Author(s):  
Lucile Muneret ◽  
Arthur Auriol ◽  
Olivier Bonnard ◽  
Sylvie Richart-Cervera ◽  
Denis Thiéry ◽  
...  
Keyword(s):  
Biodiversity Conservation ◽  
Organic Farming ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Farming Systems ◽  
Crop Productivity ◽  
Agricultural Landscapes ◽  
List Type ◽  
Natural Habitats ◽  
Ecological Intensification

AbstractOrganic farming is seen as a prototype of ecological intensification able to conciliate crop productivity and biodiversity conservation in agricultural landscapes. However, how natural enemies, an important functional group supporting pest control services, respond to organic farming at different scales and in different landscape contexts remain unclear.Using a hierarchical design within a vineyard-dominated region located in southwestern France, we examine the independent effects of organic farming and semi-natural habitats at the local and landscape scales on natural enemies.We show that the proportion of organic farming is a stronger driver of species abundance than the proportion of semi-natural habitats and is an important facet of landscape heterogeneity shaping natural enemy assemblages. Although our study highlight a strong taxonomic group-dependency about the effect of organic farming, organic farming benefits to dominant species while rare species occur at the same frequency in the two farming systems.Independently of farming systems, enhancing field age, reducing crop productivity, soil tillage intensity and pesticide use are key management options to increase natural enemy biodiversity.Synthesis and Applications. Our study indicates that policies promoting the expansion of organic farming will benefit more to ecological intensification strategies seeking to enhance ecosystem services than to biodiversity conservation.

scholarly journals Pollinator enhancement in agriculture: comparing sown flower strips, hedges and sown hedge herb layers in apple orchards

2021 ◽  
Author(s):  
Vivien von Königslöw ◽  
Felix Fornoff ◽  
Alexandra-Maria Klein
Keyword(s):  
Species Richness ◽  
Agricultural Landscapes ◽  
Floral Resources ◽  
Apple Orchards ◽  
Wild Bees ◽  
Natural Habitats ◽  
Flower Visitation ◽  
Wild Bee ◽  
Pollinator Community ◽  
Main Driver

AbstractIn intensive agricultural landscapes semi-natural habitats for pollinators are often limited, although willingness to establish pollinator habitat is increasing among farmers. A common pollinator enhancement measure is to provide flower strips, but existent or improved hedgerows might be more effective. In this study, we compare the effectiveness of three pollinator enhancement measures at edges of conventional apple orchards: (i) perennial flower strips, (ii) existent hedgerows, and (iii) existent hedgerows complemented with a sown herb layer. We used orchard edges without any enhancement as control. The study took place over three consecutive years in Southern Germany. Wild bee abundance and species richness were highest in flower strips followed by improved hedges. Hoverflies were also most abundant in flower strips, but not more species rich than at control sites. Wild bee but not hoverfly community composition differed between control and enhancement sites. The overall pollinator community included only few threatened or specialized species. Flower abundance was the main driver for wild bee diversity, whereas hoverflies were largely unaffected by floral resources. Pollinator enhancement had neither an effect on the abundance or species richness within the orchards nor on apple flower visitation. Perennial flower strips seem most effective to enhance wild bees in intensive agricultural landscapes. Additionally, flower-rich hedgerows should be promoted to complement flower strips by extending the flowering period and to increase connectivity of pollinator habitat in agricultural landscapes.

scholarly journals Ecological impacts of tropical forest fragmentation: how consistent are patterns in species richness and nestedness?

2011 ◽  
Vol 366 (1582) ◽  
pp. 3265-3276 ◽  
Author(s):  
Jane K. Hill ◽  
Michael A. Gray ◽  
Chey Vun Khen ◽  
Suzan Benedick ◽  
Noel Tawatao ◽  
...  
Keyword(s):  
Species Richness ◽  
Tropical Forest ◽  
Forest Fragmentation ◽  
Species Turnover ◽  
Meta Analysis ◽  
Agricultural Landscapes ◽  
Ecological Impacts ◽  
Sequential Loss ◽  
Forest Remnants ◽  
Species Area

Large areas of tropical forest now exist as remnants scattered across agricultural landscapes, and so understanding the impacts of forest fragmentation is important for biodiversity conservation. We examined species richness and nestedness among tropical forest remnants in birds (meta-analysis of published studies) and insects (field data for fruit-feeding Lepidoptera (butterflies and moths) and ants). Species–area relationships were evident in all four taxa, and avian and insect assemblages in remnants typically were nested subsets of those in larger areas. Avian carnivores and nectarivores and predatory ants were more nested than other guilds, implying that the sequential loss of species was more predictable in these groups, and that fragmentation alters the trophic organization of communities. For butterflies, the ordering of fragments to achieve maximum nestedness was by fragment area, suggesting that differences among fragments were driven mainly by extinction. In contrast for moths, maximum nestedness was achieved by ordering species by wing length; species with longer wings (implying better dispersal) were more likely to occur at all sites, including low diversity sites, suggesting that differences among fragments were driven more strongly by colonization. Although all four taxa exhibited high levels of nestedness, patterns of species turnover were also idiosyncratic, and thus even species-poor sites contributed to landscape-scale biodiversity, particularly for insects.

scholarly journals Climatic, Regional Land-Use Intensity, Landscape, and Local Variables Predicting Best the Occurrence and Distribution of Bee Community Diversity in Various Farmland Habitats in Uganda

2013 ◽  
Vol 2013 ◽  
pp. 1-38 ◽  
Author(s):  
M. B. Théodore Munyuli
Keyword(s):  
Land Use ◽  
Species Richness ◽  
Agricultural Landscapes ◽  
Floral Resources ◽  
Percent Cover ◽  
Land Use Intensity ◽  
Natural Habitats ◽  
Services Delivery ◽  
Bee Community ◽  
Species Richness And Abundance

This study was conducted in 2006 in central Uganda to provide baseline data on relationships between bee community variables and local, climatic, landscape and regional drivers affecting bee community abundance and diversity in agricultural landscapes. Bee abundance and species richness increased significantly () with increase in percent cover of semi-natural habitats and the abundance of wild and cultivated floral resources in the landscape. There were strong linear declines () in bee species richness and abundance with cultivation intensity. Bee species richness declined very steeply with forest distance. Bee species richness and abundance were negatively affected by land-use intensity (). Bee species richness and abundance were strongly negatively correlated () with increase in mean annual temperatures in the previous years than in current years indicating potential vulnerability of local bee species to future climate changes. The percent cover of semi-natural habitats and natural in the farmland predicted best the occurrence and distribution in central Uganda. It is therefore recommended to policy-makers and to farmers to invest in the protection of forest fragments (and related semi-natural habitats) acting as buffer in the mitigation of negative effects of climate change on bee biodiversity and pollination services delivery.

scholarly journals Predation on Drosophila suzukii within Hedges in the Agricultural Landscape

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 305
Author(s):  
Alexandra Siffert ◽  
Fabian Cahenzli ◽  
Patrik Kehrli ◽  
Claudia Daniel ◽  
Virginie Dekumbis ◽  
...  
Keyword(s):  
Agricultural Landscape ◽  
Vital Role ◽  
Agricultural Landscapes ◽  
Gut Content ◽  
Drosophila Suzukii ◽  
Natural Habitats ◽  
Host Fruit ◽  
Molecular Gut Content Analysis ◽  
Wild Fruits ◽  
Diverse Community

The invasive Drosophila suzukii feeds and reproduces on various cultivated and wild fruits and moves between agricultural and semi-natural habitats. Hedges in agricultural landscapes play a vital role in the population development of D. suzukii, but also harbor a diverse community of natural enemies. We investigated predation by repeatedly exposing cohorts of D. suzukii pupae between June and October in dry and humid hedges at five different locations in Switzerland. We sampled predator communities and analyzed their gut content for the presence of D. suzukii DNA based on the COI marker. On average, 44% of the exposed pupae were predated. Predation was higher in dry than humid hedges, but did not differ significantly between pupae exposed on the ground or on branches and among sampling periods. Earwigs, spiders, and ants were the dominant predators. Predator communities did not vary significantly between hedge types or sampling periods. DNA of D. suzukii was detected in 3.4% of the earwigs, 1.8% of the spiders, and in one predatory bug (1.6%). While the molecular gut content analysis detected only a small proportion of predators that had fed on D. suzukii, overall predation seemed sufficient to reduce D. suzukii populations, in particular in hedges that provide few host fruit resources.

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