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opencc-zeroFeb 2022View details →

Removing understory vegetation in oil palm agroforestry reduces ground-foraging ant abundance but not species richness

Ants are known to provide valuable ecosystem services in agricultural landscapes, including oil palm plantations. Their communities are less diverse and more uneven in oil palm compared with forest, and this may increase their vulnerability to disturbance. This study quantifies ant communities in oil palm agroforestry and experimentally tests their robustness to a common-practice high-disturbance management intervention: removing understory vegetation. Fieldwork was based at the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Understory Vegetation Project in Sumatra, Indonesia, where three treatments varying in their degree of understory vegetation management were established in 2014: (1) widespread herbicide was applied removing all understory vegetation (Reduced); (2) herbicide was applied to the harvesting paths and circles, and other vegetation was allowed to grow (Normal – control); (3) no herbicide was applied (Enhanced). We measured ground-foraging ant communities before and after the treatments were implemented, using pitfall traps over 324 trap-nights (a trap-night is one trap set for one night). We investigated how ant abundance, species richness, species evenness, beta diversity, and community composition differed between the treatments. We found 3507 ants across 68 species or morphospecies. Seven of these were highly abundant and accounted for 78% of individuals. Post-treatment ant abundance was lower in the reduced treatment (mean per plot: 84) than in the normal (159) and enhanced (131) treatments, which did not differ from each other. Species richness, species evenness, beta diversity and community composition were not affected by the vegetation treatments. We recommend that oil palm growers maintain understory vegetation in oil palm plantations to support ground-foraging ants. Though not tested here, this may also improve ant-mediated ecosystem services, such as pest control, seed dispersal, nutrient redistribution, and the maintenance of soil health. This study demonstrates that enhancing habitat complexity through management practices can support biodiversity in monocrop landscapes.

opencc-zeroFeb 2022View details →

Mapping breeding bird species richness at management-relevant resolutions across the United States

Human activities alter ecosystems everywhere, causing rapid biodiversity loss and biotic homogenization. These losses necessitate coordinated conservation actions guided by biodiversity and species distribution spatial data that cover large areas yet have fine-enough resolution to be management-relevant (i.e., ≤ 5 km). However, most biodiversity products are too coarse for management or are only available for small areas. Furthermore, many maps generated for biodiversity assessment and conservation do not explicitly quantify the inherent tradeoff between resolution and accuracy when predicting biodiversity patterns. Our goals were to 1) generate predictive models of overall breeding bird species richness and species richness of different guilds based on nine functional or life history-based traits across the conterminous US at three resolutions (0.5, 2.5, and 5 km), and 2) quantify the tradeoff between resolution and accuracy, and hence relevance for management, of the resulting biodiversity maps. We summarized eighteen years of North American Breeding Bird Survey data (1992-2019) and modeled species richness using random forests, including 66 predictor variables (describing climate, vegetation, geomorphology, and anthropogenic conditions), 20 of which we newly derived. Among the three spatial resolutions, the percent variance explained ranged from 27% to 60% (median = 54%; mean = 57%) for overall species richness and 12% to 87% (median = 61%; mean = 58%) for our different guilds. Overall species richness and guild-specific species richness were best explained at 5-km resolution using approximately 24 predictor variables based on percent variance explained, symmetric mean absolute percentage error, and root mean squared error values. However, our 2.5-km resolution maps were almost as accurate and provided more spatially detailed information, which is why we recommend them for most management applications. Our results represent the first consistent, occurrence-based, and nationwide maps of breeding bird richness with a thorough accuracy assessment that are also spatially detailed enough to inform local management decisions. More broadly, our findings highlight the importance of explicitly considering tradeoffs between resolution and accuracy to create management-relevant biodiversity products for large areas.

opencc-zeroDec 2021View details →

Decreasing species richness and positive Rapoport effects of Crambidae (Lepidoptera) on Mount Taibai

The vertical gradient pattern of species richness has been studied intensively over the past decades. Among these, Rapoport's rule is one of the important hypotheses of the patterns of species richness and macroecology, asserting the latitude or altitude distributional width of animal and plant species gradually narrows from a high latitude or high altitude area to low latitude or low altitude areas. However, altitudinal distributions and Rapoport's rule have rarely been tested for Asian Lepidopterans. Pyraustinae and Spilomelinae (Lepidoptera: Crambidae) are widely distributed across the world's major geographic realms and some species pose serious economic problems. These crambids as model organisms are extremely diverse in temperate Asia including in Mount Taibai where is considered as an ideal area for studying the vertical distribution patterns of insect species and verifying the universality of Rapoport's rule from the perspective of spatial scale. Based on the investigation of altitudinal distribution data with identification by using both DNA barcoding and traditional classification of Pyraustinae and Spilomelinae, this paper determines the altitudinal gradient pattern for these two subfamilies on the north slope of Mount Taibai, and provides a test of the universality of Rapoport's rule in Lepidoptera by using four methods, including Stevens's method, Pagel's method, Rohde's method, and the cross-species method. Our results show that the abundance and α-diversity of Pyraustinae and Spilomelinae both decrease with rising altitude. By contrast, the species distribution ranges increase with rising altitude. Three of the four methods used to test Rapoport's rule yield positive results, while Rohde's results show a unimodal distribution model and do not support Rapoport's rule. This may be due to the Mid-Domain effect.

openMar 2022View details →

Data from: Forest hoverfly community collapse: abundance and species richness drop over four decades

To study abundance trends in hoverflies (Diptera: Syrphidae) in a Dutch forest, we monitored hoverflies over the course of 4 decades. Within the ‘Boeschoten’ forest the same permanent route of approximately 3 kilometres was inspected for the presence of hoverflies in the second half of the morning (10:00-13:00), for a duration of approximately 2 hours. The forest was included up to 30 meters from the route to obtain a complete inventory of the ecosystem; a complete list of all present hoverflies was aimed for each time. Monitoring was done only on sunny days, independent from temperature. All observed specimens have been counted and collected with an insect net, species and sex identified in the field, or preserved for identification later on (with e.g. Barendregt 1978; van der Goot 1981; Bot & van de Meutter 2019; Speight et al. 2020). While monitoring started in 1974, it was only from 1979 onwards that complete species lists were kept, and from 1982 onwards that the number of observed individuals per species was recorded. Boeschoten is an (extensively used) agricultural enclave within large mixed deciduous-coniferous forests in the center of The Netherlands, 40-50 m a.m.s., west of the village of Garderen (52º13'24"N, 5º40'31"E). The sandy soil is very dry and open water is only available in some small pools. The selected forest sections (ca. 20 ha) are partly dominated by Quercus for hundreds of years, partly former heathlands planted with Pinus and Pseudotsuga in the period 1900-1950. Locally, other tree species (Fagus, Larix) dominate; in the shrub layer Sorbus, Amelanchier, and Rhamnus are important. In the ground layer Vaccinium myrtillus dominates at many locations, next to some Rubus along paths. The forest did not change for at least 60 years in land use or management: only the trees matured further (no new planting) and in the ground layer the vegetation changed in some species after the period of intense acid rain around 1985, when Galium saxatile and Deschampsia flexuosa decreased and Rubus increased in abundance. In the surroundings of Boeschoten there are some smaller arable fields; 5 km to the south and west there is intensive livestock farming.  The file ‘counts.csv’ contains the counts per species per monitoring day. The file contains the following variables: date:                      date of monitoring (in the second half of the morning) Baccha.elongata and next 104 variables:                               number of observed individuals of a particular species per day of monitoring. Species lists were not complete in 1974-1978, hence the NAs when a species was not recorded in that period. Systematic counting started in 1982. Presence before 1982 is indicated with a ‘1’, meaning ‘at least 1’. observer:               initials of the person responsible for a day of monitoring. AB = Aat Barendregt, TZ = Theo Zeegers, WS = Wouter van Steenis. temp:                     mean temperature in degrees Celsius between 10:00 and 13:00 (i.e. during the general time of monitoring) on the day of monitoring, based on hourly data from KNMI weather station Deelen. sun:                       mean proportion of time with direct sunlight between 10:00 and 13:00 (i.e. during the general time of monitoring) at the day of monitoring, based on hourly data from KNMI weather station Deelen. precip:                   total amount of precipitation in millimeters between 10:00 and 13:00 (i.e. during the general time of monitoring) at the day of monitoring, based on hourly data from KNMI weather station Deelen. relhumid:               mean relative humidity (percentage) between 10:00 and 13:00 (i.e. during the general time of monitoring) at the day of monitoring, based on hourly data from KNMI weather station Deelen. T30d:                     mean temperature in degrees Celsius in the 30 days preceding the day of monitoring, based on daily data from KNMI weather station Deelen. S30d:                    mean proportion of time with direct sunlight in the 30 days preceding the day of monitoring, based on daily data from KNMI weather station Deelen. P30d:                    mean amount of precipitation (in millimeters) per day in the 30 days preceding the day of monitoring, based on daily data from KNMI weather station Deelen. Tapr:                     mean temperature in April of the year of monitoring, based on daily data from KNMI weather station Deelen. Sapr:                     mean proportion of time with direct sunlight in April of the year of monitoring, based on daily data from KNMI weather station Deelen. Papr:                     mean amount of precipitation (in millimeters) per day in April of the year of monitoring, based on daily data from KNMI weather station Deelen. seasonScore:        day-of-the-year-specific GAM prediction of the total abundance of hoverflies, rescaled between 0 and 1

opencc-zeroApr 2022View details →

Microbial community from species rich meadow supports plant specialists during meadow restoration

Soil properties and soil microbial communities can greatly affect plant communities, especially in disturbed ecosystems. However, their relative contribution to the final effect on plants has rarely been assessed. We manipulated the soil microbial community in microcosms by inoculating sterilized soils originating from preserved species-rich meadow and a restored meadow with a high and low diversity of microbial inoculum (manipulated by dilution of microbial community extract) from those soils in full factorial manner, yielding eight treatments (2 soil origins × 2 inoculum sources × 2 levels of inoculum diversity). In general, the biomass of plant meadow specialists (Filipendula vulgaris, Phleum phleoides, and Prunella grandiflora) was greater with the preserved meadow inoculum than with the restored meadow inoculum but tended to be greater in the restored meadow soil than in the preserved meadow soil. Two meadow generalists (Festuca rubra, and Centaurea jacea) were not significantly affected by soil origin, inoculum source, or inoculum diversity, but third generalist Plantago media produced greater biomass in the preserved meadow soil than in the restored meadow soil. Total aboveground biomass was not affected by the treatments, but total belowground biomass was greater with microbial inoculum from the preserved meadow than from the restored meadow, and this increase was greater in the restored meadow soil than in the preserved meadow soil. Our results indicate strong responses of the preserved meadow specialists to the soil microbial community, which may explain why they are rare in the meadows that were restored following agricultural use.

opencc-zeroApr 2022View details →

Richness, not evenness, of invasive plant species promotes invasion success into native plant communities via selection effects

Native plant communities are often invaded by multiple alien species. It is still unclear how increasing diversity of alien invasive species suppresses the growth of native species and thus contributes to invasion success. In the subtropical monsoon region of Southeast China, we experimentally created a native plant community with 18 herbaceous species. One week later, we let it be invaded by either zero (controls without invasion), one, two, four or eight alien plant species, with either high or low species evenness. After a four-month growth period we harvested the aboveground biomass of each species. We found that increasing invasive species richness significantly increased invasive plant biomass, the biomass of all invasive and native plant species within the community, and invasion success (the ratio of invasive plant biomass to the biomass of all native and invasive plants), but it did not significantly reduce native plant biomass. Experimentally manipulating invasive species evenness did not influence invasion success and did not show any differential suppression effects on native plants. One invasive species, Sesbania cannabina, became dominant in terms of plant biomass, irrespective of its proportion in the alien plant mixtures. Throughout this experiment, effects of invasive species richness on invasion success were mainly due to such selection effects among the invasive species. On the other hand, the unchanged biomass of native species under increasing invasive plant richness suggests the presence of at least partly complementary resource niches between invasive and native species.

opencc-zeroApr 2022View details →

Temporal stabilizing effects of species richness and seed arrangement on grassland biomass production

1. The extent to which individuals experience inter- and intraspecific interactions through their spatial arrangements within diverse plant communities, whether because of confounding effects of species richness, evenness, or direct changes in species patch sizes on their neighborhood relationships, could affect grassland biomass production and its stability at community scales. Elucidating the ways in which neighborhood effects and species richness contribute to such community responses has important implications for how practitioners establish grasslands to meet forage production and conservation goals. 2. We assessed the effects of altering plant species richness (3 levels: 2, 4, or 8 forage species per plot) and seed arrangements (4 levels: species mixed and seeded or seeded in 0.0625 m2, 0.25 m2, or 1.0 m2 single-species patches while maintaining plot-scale species evenness) on aboveground biomass production and its temporal stability in developing grasslands seeded with a suite of globally common forage species (three legumes, three cool-season grasses, two warm-season grasses). 3. Communities seeded with more species and those with their seeds arranged into smaller conspecific patches produced more biomass and were more temporally stable than those seeded with fewer species and larger conspecific patches. The effect of manipulating species arrangements is attributable to greater neighborhood scale interspecific interactions and stronger complementary effects. Furthermore, seeding species into conspecific patches resulted in communities that were 34% more productive, that were just as temporally stable, and that had similar diversity effects as those seeded with a species mixture, as is common in grassland reconstruction efforts. 4. Synthesis: In comparison with conventional mixed-seeding methods, seeding grasslands with high species richness and small, single-species patches may promote grassland reconstruction through increased biomass production, temporal stability, and complementarity effects. Our study highlights the importance of regulating intraspecific interactions within diverse communities for improving grassland biomass production and suggests that efforts to reevaluate methods used to establish forage and conservation grasslands could result in greater biomass production and stability in these systems.

opencc-zeroMay 2022View details →

Intra-annual species gain overrides species loss in determining species richness in a typical steppe ecosystem after a decade of nitrogen enrichment

Increasing deposition of atmospheric nitrogen (N) due to accelerated human activities is a threat to various ecosystems. However, there is a lack of long-term experimental evidence demonstrating the seasonal dynamics of plant species turnover that ultimately determine species richness in natural ecosystems under N enrichment. Moreover, the frequency of N addition also may affect species turnover in a community, but it is rarely studied. To assess the responses of a plant community to N addition, we manipulated the amounts (0-50 g N m-2 year-1) and frequency (2 vs. 12 times year-1) of N addition in an Inner Mongolian typical steppe ecosystem in northern China for 12 consecutive years (2008-2020). We measured species richness and density of plant in the growing seasons (May-September) from 2018 to 2020, starting 10 years after the initial N addition treatment. Both species gain and species loss decreased with increasing amounts of N addition, resulting in a lower plant species turnover rate and greater similarity in the community between two adjacent months throughout the growing season. Species loss and species gain increased modestly under high N addition frequency. Species gain was more important than species loss in determining species richness after a decade of N application. In addition, plant density increased at high N amounts, mainly driven by enhanced clonal growth of the dominant species, Leymus chinensis. Synthesis. Together, these results suggest that high levels of N deposition may suppress species richness due to aggravated soil chemical properties and may favor growth of a limited number of N-tolerant species compared to systems that experience low levels of N deposition. To conserve biodiversity and to facilitate restoration of degraded grassland ecosystems exposed to long-term N deposition, amelioration of the acidified soils induced by N deposition may be an important strategy to use.

opencc-zeroJul 2022View details →

Species richness and phylogenetic structure of 249 global islands

To study how the phylogenetic composition of native island floras influences naturalized alien species richness, we assembled a dataset of 249 global islands from the global inventory of floras and traits (GIFT, Weigelt et al., 2020) and the Global Naturalized Alien Flora database (GloNAF, van Kleunen et al. 2019). The dataset contains naturalized and native species number, island area (km²) geological information from these sources. Additionally, we calculated three phylogenetic community metrics (Faith's PD, MPD and MNTD) using a global seed plant phylogeny (Smith and Brown, 2018) with different source pools, unstandardized Faith's PD with global island species pool, global island and mainland species pool and without missing species added to the phylogeny (pd, pd.matched), standardized measures with global island species pool and missing species added into the phylogeny (pd.ses, mpd.ses, mntd.ses), standardized measures with global island and mainland species pool and missing species added into the phylogeny (pd.ses.all, mpd.ses.all, mntd.ses.all) and standardized measures with global island species pool and missing species added into the phylogeny (pd.ses.matched, mpd.ses.matched, mntd.ses.matched). We also included biogeographical and socio-economical variables for the islands: mean annual precipitation (mm) and temperature (°C) (Karger et al., 2017), distance to closest mainland in km (Weigelt and Kreft 2013 and Moser et al., 2018) and terrain ruggedness index (Riley et al., 1999, USGS 2011). Finally, we included gross domestic product and number of ports (World Port index 2019) and airports (Open Flights 2015).

opencc-zeroJul 2022View details →

Is species richness mediated by functional and genetic divergence? A global analysis in birds

Unravelling why species richness varies shows such dramatic spatial variation is an ongoing challenge. Common to many theories is that increasing species richness requires a compensatory trade-off on an axis of species' ecology. Spatial variation in species richness may also affect genetic diversity if large numbers of coexisting, related species result in smaller population sizes. Here, we test whether increasing species richness results in differential occupation of morphospace by the constituent species, or decreases species' genetic diversity. We test for two potential mechanisms of morphological accommodation: denser packing in ecomorphological space, and expansion of the space. We then test whether species differ in their nucleotide diversity depending on allopatry or sympatry with relatives, indicative of potential genetic consequences of coexistence that would reduce genetic diversity in sympatry. We ask these questions in a spatially explicit framework, using a global database of avian functional trait measurements in combination with >120,000 sequences downloaded from GenBank. We find that higher species richness within families is not systematically correlated with either packing in morphological space or overdispersion but, at the Class level, we find a general positive relationship between packing and species richness, but that packing is comparatively greater in tropical points relative to their species richness. We find limited evidence that geographical co-occurrence with closely related species or tropical distributions decreases nucleotide diversity of nuclear genes; however, this requires further analysis. Our results suggest that avian families can accumulate species regionally with minimal tradeoffs or cost, implying that external biotic factors do not limit species richness.

opencc-zeroAug 2022View details →

Seasonal species richness of birds on the world's islands and its geographical correlates

Migratory birds occur on islands during different seasons of the year, which results in seasonal variation in species richness. These patterns and their geographical correlates have not been examined. We used 20 years of bird observations on 690 islands to examine how seasonal species richness estimates vary as a function of island area, isolation, and latitude. Species richness was highest on islands within the mid-latitudes of the Northern Hemisphere during migration and on islands within tropical latitudes during the non-breeding season. Area defined positive, non-linear relationships with species richness across seasons, with the steepest slopes occurring with islands >1,100 km2. Distance to mainland defined negative, non-linear relationships with species richness across seasons, with the strongest slopes occurring with islands located >150 km from the mainland. Species-area relationships were weakest for the most remote islands and strongest for islands at intermediate distances to the mainland. Intermediate proximity to other islands was a poor predictor of species richness. Our findings emphasize the presence of seasonally dynamic relationships, the enhanced role of evolutionary processes on larger islands, the unique ecology of the world's most remote islands, and the importance of islands as stopover sites and wintering grounds for migratory bird species.

FIGURE 2 in Spatial distribution of species richness and endemism of Solanum (Solanaceae) in Mexico

FIGURE 2. Spatial distribution of species richness and endemism of Mexican Solanum by grid cell of 50 × 50 km. A) Species richness. B) Endemic's richness. C) Weighted Endemism. D) Corrected Weighted Endemism. The numbers inside the cells follow the text.

FIGURE 4 in Spatial distribution of species richness and endemism of Solanum (Solanaceae) in Mexico

FIGURE 4. Solanum species richness by vegetation type. A) Biogeographical provinces and vegetation types. B) Species richness distribution (first column), endemism (second column) and vegetation type endemics (third column). AS: Aquatic and subaquatic vegetation; CF: Cloud forest; G: Grassland; POF: Pine-oak forest; TF: Thorn forest; TDF: Tropical deciduous forest; TEF: Tropical evergreen forest; TSF: Tropical subdeciduous forest; XS: Xerophytic scrub.

FIGURE 3 in Spatial distribution of species richness and endemism of Solanum (Solanaceae) in Mexico

FIGURE 3. Solanum species richness by political division. The abbreviation of the Mexican states follows INEGI (2000).

FIGURE 1 in Spatial distribution of species richness and endemism of Solanum (Solanaceae) in Mexico

FIGURE 1. Species richness of Mexican Solanum by: A) Biogeographical region. B) Biogeographical province. BC: Baja Californian; BB: Balsas Basin; C: Californian; CH: Chiapas Highlands; CD: Chihuahuan Desert; PL: Pacific Lowlands; SMS: Sierra Madre del Sur; SMOc: Sierra Madre Occidental; SMOr: Sierra Madre Oriental; S: Sonoran; T: Tamaulipas; TVB: Transmexican Volcanic Belt; V: Veracruzan; Y: Yucatán Peninsula.

opencc-zeroSep 2022View details →

Data from: Plant species richness and sunlight exposure increase pollinator attraction to pollinator gardens

Evidence documenting the decline of insect populations is accumulating. Efforts have increased to mitigate pollinator losses by establishing gardens to support pollinator diversity. However, knowledge of the specific garden characteristics, landscape features and environmental factors that affect pollinator diversity and abundance is limited, particularly in biodiverse regions in North America. In order to better understand how garden characteristics affect pollinator attraction, we compared pollinator composition across 16 pollinator gardens in the Appalachian ecoregion in North America. We evaluated the effects of garden characteristics (e.g., plant richness, flower abundance, garden size, proportion of native species), landscape features (land-use type, distance to forest) and environmental factors (sunlight exposure) on pollinator richness, overall visitation rate and visitation rate by defined pollinator groups (i.e., solitary native bees, bumblebees, honeybees, lepidopterans and other insects). Solitary bees (i.e., native bees besides Bombus) were the most frequent visitors (61%). We found differences in pollinator species composition between urban and rural gardens. Moreover, plant richness had a positive effect on pollinator richness and an increase in flower abundance increased pollinator visitation rate. Flower abundance, plant richness and high sunlight exposure increased visitation rate of solitary bees. Visitation rate of solitary bees however, decreased with increasing proportion of native plants. Overall, our results indicate that garden characteristics, landscape and environmental factors all are important mediators of pollinator diversity and abundance. Solitary bees were most affected by garden (i.e., plant richness, number of flowers, proportion of native plants) and environmental factors (i.e., sunlight exposure). However, we also identified differential effects of garden and environmental factors across pollinator groups. We suggest that an integrated management approach that considers multiple garden and environmental characteristics could help improve the effectiveness of pollinator garden as a conservation tool and help preserve this key ecosystem service.

opencc-by-4.0Oct 2022View details →

Increasing landscape complexity enhances species richness of farmland arthropods, agri-environment schemes also abundance–A meta-analysis

Article dataset

opennotspecifiedSep 2017View details →

FIGURE 2. A in Patterns of species richness in two African-centered, aridity-adapted flightless weevil lineages (Coleoptera: Curculionoidea)

FIGURE 2. A simplified phylogeny depicting the relationships of basal Curculionidae following McKenna et al. (2009), with taxon ranks as in Leschen & Beutel (2014). Bold lines indicate African-centred lineages; all other lineages are globally widespread.

opennotspecifiedDec 2012View details →

Fig. 3 in Limited effects of dominant ants on assemblage species richness in three Amazon forests.

Fig. 3. The percentage of better-fit linear, asymptotic, and quadratic models applied to data from 1000 spatially-structured randomisations for each subsample, using baiting, pitfall trap, Winkler data, and for a subset of subordinate species that are more prone to interact with dominant ants. The subset of subordinate species used data from pitfall and Winkler sampling techniques combined. The subsamples were distributed along 225 m and spaced 25 m apart.