Local Plant Diversity Research Articles

Monitoring Diversity Profiles of Forested Landscapes in the Mediterranean Spain: Their Contribution to Local and Regional Vascular Plant Diversity

Monitoring Diversity Profiles of Forested Landscapes in the Mediterranean Spain: Their Contribution to Local and Regional Vascular Plant Diversity

Camelid herding may homogenize Andean grassland plant communities

The current global decline in biodiversity is a matter of pressing concern, necessitating the conservation of diverse ecosystems across various spatial scales. Regions such as the tropical Andes face the imminent threat of biotic homogenization due to intensive livestock grazing, posing a significant risk to biodiversity. This study is focused on the sub-humid grasslands of northwestern Bolivia, within the the National Park Apolobamba. We surveyed a total of 105 plots distributed across seven sites, representing a natural gradient of grazing intensity. Within each site, the plots were organized into five clusters to explore the impact of environmental factors on plant diversity within and among communities. Our research reveals that local plant diversity, quantified by species richness and the inverse Simpson index, is predominantly shaped by soil pH. Notably, more acidic soil is associated with diminished diversity. Furthermore, our findings highlight that the dissimilarity in species composition among local communities may be linked to grazing intensity. This suggests that intensified grazing may have the potential to homogenize plant communities across the landscape. A concerning implication is the likelihood of communities becoming dominated by acquisitive species, leaving them more susceptible to the impacts of climate variability. The study underlines the necessity to analyze multiple facets of diversity for a comprehensive understanding of the environmental factors regulating and therefore to address potential drivers of diversity loss. To mitigate these threats, managers may consider adjusting livestock quantities and the spatial range used by grazers, aiming to sustain multiple aspects of plant diversity and prevent homogenization and degradation of grasslands in a changing world.

Contribution of homegardens in the conservation of local plant diversity in a Brazilian quilombo

Contribution of homegardens in the conservation of local plant diversity in a Brazilian quilombo

Phenological growth stages of Amaranthus palmeri according to the extended BBCH scale

AbstractAmaranthus palmeri S. Watson is a problematic weed that has been encountered almost all over the world because of its stronger adaptability, which causes huge economic losses and local plant diversity decline. As an invasive plant, A. palmeri has been found throughout China. We thus make a code system to describe the phenological growth process of A. palmeri according to the extended BBCH scale to better understand the phenological growth of this weed in China. The growth process of A. palmeri was divided into vegetative growth phases and reproductive growth phases. The vegetative growth phases are composed of seed germination (0), leaf development (1), formation of side shoots (2) and main stem elongation (3). Likewise, the reproductive growth phases include inflorescence emergence (5), blooming (6), fruit development (7), seed maturity (8) and senescence (9). Based on the extended BBCH scale, the first digit stands for the primary growth stages, and the third digit represents the secondary growth stages. In particular, the second digit defines the growth progress: the number 0, means the vegetative growth phases, and the number 1 stands for the reproductive growth phases. Owing to the fact that its seed can germinate multiple times within a year, a general illustration of the phenological development stages of A. palmeri germinating in different months was provided here to describe the growth dynamic characteristic at different times. These data are of great significance to develop effective strategies for weed control and management of A. palmeri.

Landscape heterogeneity correlates with bee and pollen diversity while size and specialization degree explain species-specific responses of wild bees to the environment

Access to adequate pollen sources in agricultural landscapes is critical for the nutrition and development of bees. The type and quantity of pollen available to bees and may be determined by local plant diversity, land-use intensity and landscape structure but different bee species likely respond differently to these parameters. Identifying community and specific responses is therefore imperative to understand pollinator population dynamics in agricultural landscapes. We sampled bees in 36 plots along a land-use gradient at 4 sites in Belgium and Germany over two years. We collected 1821 bees from 100 bee species and constructed a pollen foraging network with 36 common wild bee species based on pollen metabarcoding. We investigated differences in community responses and species-specific responses to environmental variables.Landscape heterogeneity positively correlated with bee species richness, diversity and functional richness, and significantly explained bee community composition per plot. Bee collected pollen diversity correlated with bee species diversity. Furthermore, landscape heterogeneity positively correlated with bee collected pollen diversity when pooling abundant bee species, while it did not correlate with pollen diversity of the most abundant generalists. Land-use intensity and local plant diversity had no significant effect on bee diversity. Larger bees showed negative responses to increasing land-use intensity and bees with more specialized diets showed positive correlations with landscape heterogeneity. Our study goes beyond mere floral diversity and provides new insight into the responses of wild bee communities to landscape structure and regional pollen availability, as well as the interplay between bee abundance and pollen foraging traits. Our results highlight the importance of determining species-specific nutritional needs and considering landscape level structure in pollinator conservation programs.

Between‐ versus within‐species variation in plant–soil feedback relates to different functional traits, but exudate variability is involved at both scales

Abstract Plant–soil feedback—feedback from plant‐induced changes in soil properties to plant fitness—is increasingly shown to drive the maintenance of local plant diversity at both interspecific and intraspecific levels. A robust understanding of the relationships between plant–soil feedback and functional plant traits, which would improve our ability to generalize plant–soil feedback results beyond specific study systems, is, however, still lacking. This is especially true at the intraspecific plant level. We assessed the relationship between plant–soil feedback and several functional traits in 13 co‐occurring grassland species, including 20 genotypes of the dominant grass, Festuca rubra. The traits encompassed various aspects of growth, root properties and root exudate variability. Combining these traits into principal gradients of functional trait variation, we also tested the potential for the conservation and collaboration gradients to explain variation in PSF. Between‐species plant–soil feedback variation was explained by differences in biomass production and exudate composition, as well as contrasting strategies along the collaboration gradient. Within‐species plant–soil feedback variation—that is between Festuca rubra genotypes—was associated with exudate variability, especially contrasting amounts of exuded phenols. Several traits had a significant effect on plant–soil feedback only via their interaction with exudate composition. Overall, PSF was associated with different traits at between‐species versus within‐species levels. Root exudate variability was, however, involved at both diversity levels. Our results put forth the role of root exudation patterns as an important driver of variation in plant–soil feedback. Better integration between research on plant–soil feedback and on root exudation would therefore improve our understanding of the processes—both ecological and evolutionary—supporting the maintenance of plant diversity within grassland communities. Read the free Plain Language Summary for this article on the Journal blog.

Uncovering the hidden: Leveraging sub-pixel spectral diversity to estimate plant diversity from space

Remotely sensed spectral diversity has emerged as a promising proxy for plant diversity. However, spectral diversity approaches relate image spectra to plant community diversity by only incorporating variation among adjacent pixels, considering each pixel as a homogeneous entity composed of one class, and disregarding the within-pixel variability. Although such approaches might work for remotely-sensed data with fine spatial resolution, they might not be viable solutions to estimate plant diversity using coarse-resolution data from forthcoming spaceborne imagers. To address the limitations associated with spectral diversity approaches, we proposed a novel approach, known as endmember diversity, for remote estimation of plant diversity through quantifying spectral diversity at the sub-pixel level and taking into account the within-pixel variability. The approach consisted of deriving the number and abundance of distinct spectral entities within each pixel via spectral unmixing. In doing so, we considered the spectral signature of each pixel as a mixture of distinct spectral entities, commonly known as endmembers. We then used the per-pixel endmembers and their abundance to calculate different spectral diversity metrics for every pixel. We assessed the performance of the endmember diversity approach at estimating plant taxonomic and phylogenetic diversity based on two experiments using a simulated spectral dataset and a real-world spaceborne DESIS (DLR Earth Sensing Imaging Spectrometer) dataset. In both experiments, we found significant associations between endmember diversity and in situ plant diversity. Additionally, our method applied to DESIS data outperformed a conventional spectral diversity metric based on the coefficient of variation when applied to 1-m airborne imaging spectroscopy data. Collectively, our results demonstrate the capability of forthcoming spaceborne imagers to monitor local plant diversity.

Invasion‐mediated mutualism disruption is evident across heterogeneous environmental conditions and varying invasion intensities

The impact of a biological invasion on native communities is expected to be uneven across invaded landscapes due to differences in local abiotic conditions, invader abundance, and traits and composition of the native community. One way to improve predictive ability about the impact of an invasive species given variable conditions is to exploit known mechanisms driving invasive species' success. Invasive plants frequently exhibit allelopathic traits, which can be directly toxic to plants or indirectly impact them via disruption of root symbionts, including mycorrhizal fungi. The indirect mechanism – mutualism disruption – is predicted to impact plants that rely on mycorrhizas but not affect non‐mycorrhizal plant species. To assess whether invader‐driven mutualism disruption explains observed changes in native plant communities, we analyzed long‐term (1998–2018) plant cover data from forest plots across the state of Illinois. We evaluated native plant communities experiencing a range of abundance of invasive allelopathic garlic mustard Alliaria petiolata and varying environmental conditions. Consistent with the mutualism disruption hypothesis, we showed that as garlic mustard abundance increased over time in 0.25 m2 sampling quadrats, the abundance of mycorrhizal plant species decreased, but non‐mycorrhizal plant species did not. Over space and time, garlic mustard abundance predicted plant abundances and diversity at the quadrat level, but this relationship was not present at a larger scale when quadrats were aggregated within sites. Garlic mustard's impact on the plant community was highly localized, yet it was as important as abiotic variables for predicting local plant diversity. We showed that garlic mustard abundance was a key predictor of patterns of plant diversity across invasion intensity and environmental heterogeneity in a way that is consistent with mutualism disruption. Our work indicates that the mutualism disruption hypothesis can provide generalizable predictions of the impacts of allelopathic invasive plants that are evident at a broad spatial scale.

Effects of photovoltaic power station construction on terrestrial ecosystems: A meta-analysis

The rapid increase in construction of solar photovoltaic power stations (SPPs) has motivated ecologists to understand how these stations affect terrestrial ecosystems. Comparing study sites, effects are often not consistent, and a more systematic assessment of this topic remains lacking. Here, we evaluated the effects of SPP construction on carbon emissions, edaphic variables, microclimatic factors and vegetation characteristics in a meta-analysis. We employed log response ratios (as effect sizes) to assess how control plots differed from those beneath solar photovoltaic panels. We found that SPP construction decreased the local air temperature and photosynthetically active radiation, while increasing air humidity, especially in grasslands. Furthermore, plant aboveground biomass and vegetation cover were also enhanced by SPP construction in grassland ecosystems. In farmland ecosystems, photovoltaic panel installation increased plant aboveground biomass, soil available phosphorus and soil pH, while reducing CO2 flux, plant species richness and vegetation cover in woodlands. Thus, while SPP construction had profound ecological impacts in terrestrial ecosystems, the direction and strength of these effects were largely dependent on ecosystem type. Most studies of SPP construction to date have focused on local microclimatic and plant diversity effects, but few studies have examined effects on ecosystem functions and services. Future assessments are needed of both the benefits and disbenefits of SPP construction across different ecosystems, to improve SPP site selection and adaptive management.

Factors and thresholds determining sediment delivery pathways between forest road and stream in mountainous watershed

Road erosion is a global environmental issue. The transport of eroded sediment from road to stream can devastatingly impact water quality. Research efforts to combat this issue have prioritized maintaining roads and preventing erosion. Little research has explored the fate of eroded road materials in their transport from road to stream. Therefore, taking the Xiangchagou watershed in the Dabie Mountains of China as a case, this study investigated how local geography determines the formation and thresholds of different delivery pathways (gullied, partially gullied, and diffuse pathways) for road-eroded sediment through runoff, based on the binary logistic regression analysis, random forest model, and the lowest point data fitting methods. It explored how these different pathways have variable impacts on local plant and soil communities. Our results showed that soil D50, bulk density, shrub-grass coverage, and local plant diversity varied significantly (p < 0.05) between different delivery pathways. In particular, soil bulk density and local plant diversity varied significantly (p < 0.05) among different position of these delivery pathways. Specifically, the diffuse pathways are characterized by lower soil bulk density, looser soil structure, and higher species diversity, likely explained by the deposition of sediment-loaded runoff. Gullied pathways, conversely, had significantly more compacted surface soil and lower local plant diversity, likely as a result of scouring by sediment-loaded runoff. Slope gradient of upslope catchment (Us), road segment (Rs), and lower hillslope (Ds) and effective contributing area (Eca), which determine the intensity and kinetic energy of sediment-loaded runoff, are the main external drivers that determine the occurrence of gullied pathways. By contrast, the soil median particle size, surface roughness, and shrub-grass cover of lower hillslope, which contribute to erosion resistance of hillslope, are the primary intrinsic drivers promoting development of pathways from partial to full gully. Furthermore, we found that the critical topographic thresholds for the initiation of the gully pathways and the continued development of gully from partial to complete gully pathways could be expressed as Ds = 0.35Eca−0.13 and Ds = 0.41Eca−0.17, respectively. These results are expected to provide basis for understanding the formation and development mechanism of sediment delivery pathways from road to stream.

Important plant areas (IPAs) in the Fergana Valley (Central Asia): The Bozbu-Too-Ungortepa massif

This paper discusses identifying Important Plant Areas (IPAs) in one of the most densely populated regions of Central Asia—the Fergana valley. The recognition of IPA sites is an attempt to introduce new ways of conserving local plant diversity with a high concentration of endemic species in Central Asia, where conservation methods of the former Soviet Union still prevail. The research revealed the current state and geography of many rare species and enriched the flora of Uzbekistan and Kyrgyzstan with several rare species. The second IPA is the transboundary territory of the Fergana valley, uniting the southern spurs of the Chatkal range and the Ungortepa-BozbuToo massif. We documented the distribution of 62 species in the IPAs under the sub-criteria of Plantlife International. Our study aimed at continuing studies on the IPAs in this region, addressing specific conservation challenges, such as conserving national endemics and endangered species that grow outside protected areas and GIS mapping of endemic species.

Multiple Site Dissimilarities of Herbaceous Species Due to Coal Fly Ash Dumping Based Soil Heavy Metal Toxication

The present study analyzes the determinants and patterns of the regional, local, and differential plant diversity of two different sites with similar climatic but varied edaphic factors. This research was undertaken to study the plant diversity and population structure as a consequence of variation in the soil quality between two biotopes: Guru Ghasidas Vishwavidyalaya in Koni (site-I) and National Thermal Power Corporation in Sipat (site-II). The soil of site-I was found to be fertile and showed rich vegetation. On the other hand, the soil of site II was found to be contaminated with heavy metals, which impacts the flora of the region. The ecology of both sites was studied, and their quantitative and qualitative aspects were compared and contrasted. The abundance, density, and richness of the plants in site II were fairly lower than in site-I, which was confirmed by utilizing Simpson's and Shannon's diversity indices. Many of the species collected from site II were heavy metal accumulators and could also serve as indicators of heavy metal toxicity.

Ethnomedicinal Plants Used By Local Inhabitants Of Kedarnath Valley, Garhwal Himalaya

Ethnobotany is the scientific discipline that studies the dynamic relationships between people and plants. The Indian Himalaya is a source of plant based indigenous medicinal knowledge based on local plant diversity. A rapid rural survey in more than 45 villages of Kedarnath valley of Rudraprayag district of Uttarakhand were conducted with altitudinal variation ranges from 1000 to 2500 masl. A total of 57 (19 trees, 6 shrubs, 4 climbers and 28 herbs) most highly effective medicinal plant species were recorded, that are used by local inhabitants for traditional local health care system. The local communities use these ethnobotanically important plants for curing fever, stomachache and gastric problem, cancer, diarrhea, dysentery, jaundice, diabetes, snake bite, tuberculosis, paralysis, rheumatic pain, liver ailments, asthma, cough, skin diseases, toothache, wounds and cuts etc. The present study provides valuable information about ethnomedicinal plants of Kedarnath Valley of Rudraprayag district of Uttarakhand.

Soil environmental DNA metabarcoding can quantify local plant diversity for biomonitoring across varied environments

Biomonitoring of plant communities is essential when evaluating outcomes of ecological restoration, but morphology‐based inventories can impede consistency across spatial and temporal scales. The Eden Project botanic garden (Cornwall, UK) offers an opportunity to test whether soil environmental DNA (eDNA) reflects plant species richness, community composition, and diversity. Furthermore, it enables the exploration of whether community complexity, environmental conditions, or sampling scale influence the similarity of soil eDNA‐derived results compared with those derived from classic botanical inventories. Survey plots were established encompassing a mixture of high‐ and low‐complexity plant assemblages, under either hot and humid or cool and dry conditions. Botanical inventories were conducted in quadrats up to 7 m around a soil eDNA sample plot. Soil samples were processed by metabarcoding of trnL p6 loop to determine plant eDNA identity and relative abundance. Differences in diversity and community composition were calculated before determining whether (1) inventory scale; (2) plant assembly complexity; (3) ambient conditions; (4) soil chemistry; (5) bulk root biomass and (6) soil respiration influenced the similarity of soil eDNA and botanical inventory methods. Inventory scale significantly determined the dissimilarity in both diversity and composition, with soil respiration, phosphorus, and C:N ratio also accounting for variation across sites. Our results demonstrate that soil eDNA metabarcoding is an effective approach for quantifying relative diversity in plant communities across broad habitat types and could be integrated into restoration monitoring strategies, but that its application requires an appropriate a priori knowledge of survey sites to best tailor soil eDNA survey implementation.

Characteristics and distribution of the &lt;i&gt;Opuntia&lt;/i&gt; (Cactaceae) representatives naturalized in Crimea

Background. Representatives of the Opuntia Mill. genus (Cactaceae), growing in natural habitats in South and North Americas, Mexico, Western India, and the Galapagos Islands, are widely used as ornamental, food and medicinal plants in different regions of the world. Many species have naturalized, and at least 27 species (or 14%) are invasive plants, thus posing a threat to local species and plant diversity. The largest numbers of naturalized species were observed in Spain, South Africa, and Australia. Studying the distribution of Opuntia Mill. representatives over Crimea is relevant because eight naturalized representatives of the genus have already been found in the region.Materials and methods. The information about Opuntia engelmannii Salm-Dyck var. lindheimeri (Engelm.) U. Guzman &amp; Mandujano), O. fragilis (Nutt.) Haw., O. humifusa (Raf.) Raf., O. macrorhiza Engelm., O. phaeacantha Engelm. f. rubra Späth., O. polyacantha Haw., O. tortispina Engelm. &amp; J.M. Bigelow, and O. tunoidea Gibbes is based on the research carried out in 2007–2021. Vegetation classification units were identified on the basis of geobotanical studies.Results. General characteristics and distribution of eight Opuntia representatives in natural and cultigenic areas are presented. It has been established that prickly pears were originally planted intentionally in Crimea, but later they spread in anthropogenically disturbed and seminatural biotopes, assigned to nine classes of vegetation (Quercetea pubescentis, Festuco­Brometea, Sedo­Scleranthetea, Koelerio­Corynephoretea, Artemisietea vulgaris, Asplenietea trichomanis, Cisto­Micromerietea julianae, Thero­Brachypodietea, and Pegano harmalae­Salsoletea vermiculatae). Opuntia humifusa and O. engelmannii var. lindheimeri have the widest distribution in Crimea. All species reproduce by seeds and vegetatively. The text is illustrated with photographs of the species and schematic maps of their distribution over the Crimean Peninsula.

δ13C in above-ground and below-ground organs of Spinulum annotinum (Lycopodiaceae)

• 12 C and 13 C isotope abundance in S. annotinum has been investigated for the first time. • δ 13 C value in S. annotinum is lower than that reported in other C 3 plants. • Different above- and below-ground S. annotinum organs have distinct δ 13 C values. • δ 13 C values of S. annotinum are connected with local plant diversity. Physiological processes in plants and plant–environment interactions can be analysed from the composition of stable carbon isotopes ( 13 C/ 12 C). This ratio can be indicated using the δ (delta) notation. Substantial evidence has been published in recent years demonstrating that post-photosynthetic fractionation occurs in plants and leads to differences in 13 C-enrichment in heterotrophic (as compared with autotrophic) organs. Yet our understanding of processes leading to 13 C divergence between leaves and heterotrophic tissues remains low. Large part of the isotope analysis is concerned with angiosperms, but not spore-bearing tracheophytes. In this study, we explored the 12 C and 13 C isotope distribution in above-ground and below-ground organs of an archaic lycophyte Spinulum annotinum (L.) A.Haines (interrupted clubmoss). The main objectives of this study were to determine the natural distribution of stable carbon isotopes in sporophytes of S. annotinum and to discuss possible causes for differences in δ 13 C. The study revealed that there are significant differences between δ 13 C in different S. annotinum organs. The δ 13 C values varied by about 2.4‰. The highest δ 13 C values were −30.0‰ in roots and the lowest were −32.4‰ in plagiotropic shoot leaves. The distance to a body of water had no significant effect on δ 13 C values in S. annotinum . Outgrowth size did not have a clear relationship with δ 13 C in S. annotinum . The Shannon Diversity Index was a significant predictor for δ 13 C values in S. annotinum . The uncovered δ 13 C and the relationship with abiotic habitat conditions and neighbouring plant species in the community provide a base for future lycophyte ecophysiology research.

Species‐specific DNA distribution in spruce–beech forest soil

AbstractEnvironmental DNA consists of species‐specific intracellular and extracellular fractions, whose content and information may not be similar in all environments. In forest soil, in particular, the biogeochemical fate of DNA originated by plant litter input has been extensively reviewed, but species‐specific persistence and distribution still await to be quantified. In the present work, based on the purification of extracellular and intracellular DNA fractions from forest soil samples representing 3 soil horizons at 36 randomized locations differing for stand composition (either beech‐ or spruce‐dominated, and mixed), followed by exDNA metabarcoding with the rbcL marker, we provide a clear picture of species‐specific plant DNA distribution, and explore plant community composition and diversity along the explored gradient and the soil profile. We did not find significant differences in intra‐ vs. extracellular total DNA distribution, with a progressive depletion with soil depth positively associated with soil organic C and N content and negatively associated with soil pH and mineral content. Species‐specific DNA distribution was horizontally dependent on beech and spruce basal area aboveground, while extracellular DNA showed peculiar species‐specific vertical patterns. Proportion of Fagus sylvatica DNA increased with depth in beech stand soil, and Picea abies DNA decreased in spruce stand soil, respectively, possibly linked to species‐specific differences in leaf litter decomposition dynamics and root litter contributions. Finally, our approach by metabarcoding provided a faithful, although incomplete, picture of the local plant diversity, suggesting that such technique could positively integrate traditional biodiversity inventory studies based on expert field assessments.

Microevolution of Pieris butterfly genes involved in host plant adaptation along a host plant community cline.

Herbivorous insects have evolved counteradaptations to overcome the chemical defences of their host plants. Several of these counteradaptations have been elucidated at the molecular level, in particular for insects specialized on cruciferous host plants. While the importance of these counteradaptations for host plant colonization is well established, little is known about their microevolutionary dynamics in the field. In particular, it is not known whether and how host plant diversity shapes diversity in insect counteradaptations. In this study, we examine patterns of host plant use and insect counteradaptation in three Pieris butterfly species across Japan. The larvae of these butterflies express nitrile-specifier protein (NSP) and its paralogue major allergen (MA) in their gut to overcome the highly diversified glucosinolate-myrosinase defence system of their cruciferous host plants. Pieris napi and Pieris melete colonize wild Brassicaceae whereas Pieris rapae typically uses cultivated Brassica as a host, regardless of the local composition of wild crucifers. As expected, NSP and MA diversity was independent of the local composition of wild Brassicaceae in P.rapae. In contrast, NSP diversity correlated with local host plant diversity in both species that preferred wild Brassicaceae. Both P.melete and P.napi revealed two distinct major NSP alleles, which shaped diversity among local populations, albeit with different evolutionary trajectories. In comparison, MA showed no indication for local adaptation. Altogether, MA appeared to be evolutionary more conserved than NSP, suggesting that both genes play different roles in diverting host plant chemical defence.

Pollination service delivery is complex: Urban garden crop yields are best explained by local canopy cover and garden scale plant species richness

Abstract Pollination is an important ecosystem service to agriculture, however, the factors influencing pollination in urban food gardens are poorly understood. We investigated how features within urban environments, including floral resources and canopy cover, impacted (a) flower visitation and seed production of a model plant (Brassica rapa) and (b) total yields of produce from urban gardens in Sydney, Australia. Floral visitation to model plants was dominated by a few common species, with honeybees responsible for 53.4% of visitation and native stingless bees and two hoverfly species accounting for another 37.1% of visitors; 28 other species were collectively responsible for less than 10% of visitation. While insect pollinators were abundant, the relationship between floral visitation and model plant reproductive output was weak and not always positive. The pollination success of model plants was only marginally impacted by environmental features, while pollinator visitation had a small negative impact. However, total crop yields across urban gardens were strongly influenced by local canopy cover and garden scale plant species richness. Synthesis and applications. The factors influencing pollination service delivery to urban gardens are complex; pollinator visitation, richness and/or floral resource availability may not always reflect positive, plant reproductive outcomes. Yields of garden crops, whether pollinator dependent or not, were more strongly influenced by surrounding environmental variables, including broad scale measures of canopy cover and local plant diversity, than pollination‐related metrics. This implies policies to support pollinator richness will likely differ to those supporting crop yields in urban gardens and will require assessment and management of external environmental factors.

Effects of landscape complexity and local management on bee pollinator diversity in apple orchards in Changping District, Beijing, China.

Pollinators provide important ecosystem services for crop production and food security. With the development of agricultural economy and the increasing intensity of land-use, a large number of natural or semi-natural habitats have been converted to croplands. Landscape homogenization and intensive management lead to the decline of wild bee diversity and threaten the sustainable agricultural production. In this study, we investigated the effects of landscape complexity (proportion of semi-natural habitats), local management practices (local flowering plant diversity and soil total nitrogen), and their interactions on diversity of bee pollinators in apple orchard in Changping District, Beijing. A total of 8642 bee individuals were captured, including 5125 honey bees and 3517 wild bees from 5 families, 14 genera, and 49 species. The optimal landscape scale for the response of bee diversity to landscape complexity and local management intensity was 500 m. Within 500 m radius of the site, the abundance of overall bees and wild bees significantly increased with increasing proportion of semi-natural habitats. The landscape complexity interacting with local flowering plant diversity significantly affected the richness of overall bee and wild bee. When the proportion of semi-natural habitats surrounding the apple orchards was low (≤29.9%), we found a positive effect of flowering plant diversity on the richness of overall bee and wild bee, whereas a reversed trend was found when the proportion of semi-natural habitats surrounding the apple orchards was high (>29.9%). In addition, the abundance of honey bees significantly increased with the increase of local flowering plant diversity and soil total nitrogen. The soil total nitrogen interacting with local flowering plant diversity significantly affected the honey bee abundance. At low levels of soil total nitrogen (≤1.9 g·kg-1), there was a positive effect of flowering plant diversity on honey bee abundance; whereas this trend was reversed at high levels of soil total nitrogen (>1.9 g·kg-1). Increasing the proportion of semi-natural habitats in agricultural landscape was beneficial to the increase of wild bee abundance, and flowering plant diversity could promote bee diversity but depending on landscape scale (proportion of semi-natural habitats) and local scale (nitrogen application). Therefore, multi-scale factors should be considered to develop conservation strategies to maintain the diversity of wild bees in agricultural landscape. Maintaining a higher proportion of cultivated land as much as possible is still a long-term requirement for production, while maintaining intermediate landscape complexity, increasing the diversity of flowering plants on the ground, and reducing the application of nitrogen fertilizer would be effective ways to promote the diversity of pollinating bees in apple orchards.