Higher Plant Species Richness Research Articles

Use of iron oxide nanoparticles for immobilizing phosphorus in-situ: Increase in soil reactive surface area and effect on soluble phosphorus

Phosphorus (P) immobilization has potential for reducing diffuse P losses from legacy P soils to surface waters and for regenerating low-nutrient ecosystems with a high plant species richness. Here, P immobilization with iron oxide sludge application was investigated in a field trial on a noncalcareous sandy soil. The sludge applied is a water treatment residual produced from raw groundwater by Fe(II) oxidation. Siliceous ferrihydrite (Fh) is the major Fe oxide type in the sludge. The reactive surface area assessed with an adapted probe ion method is 211–304 m2 g−1 for the Fe oxides in the sludge, equivalent to a spherical particle diameter of ~6–8 nm. This size is much larger than the primary Fh particle size (~2 nm) observed with transmission electron microscopy. This can be attributed to aggregation initiated by silicate adsorption. The surface area of the indigenous metal oxide particles in the field trial soils is much higher (~1100 m2 g−1), pointing to the presence of ultra-small oxide particles (2.3 ± 0.4 nm). The initial soil surface area was 5.4 m2 g−1 and increased linearly with sludge application up to a maximum of 12.9 m2 g−1 when 27 g Fe oxides per kg soil was added. In case of a lower addition (~10–15 g Fe oxides per kg soil), a 10-fold reduction in the phosphate (P-PO4) concentration in 0.01 M CaCl2 soil extracts to 0.3 µM was possible. The adapted probe ion method is a valuable tool for quantifying changes in the soil surface area when amending soil with Fe oxide-containing materials. This information is important for mechanistically predicting the reduction in the P-PO4 solubility when such materials are used for immobilizing P in legacy P soils with a low P-PO4 adsorption capacity but with a high surface loading.

The absence of keystone indigenous trees inhibits bird recovery up to a decade after invasive tree removal from riparian habitats

When invasive alien trees are removed, ecosystems are usually left to “self-repair”. Little is known about the extent of recovery or whether plant and animal taxa respond in a similar way. In most cases, the absence of a historical condition makes it difficult to measure restoration success and a flexible approach is usually followed using practical target communities. We explored these issues by sampling bird and plant assemblages after the removal of invasive trees, using a chronosequence (space-for-time substitution) approach. We used the Berg River, one of the most invaded riparian systems in the Cape Floristic Region of South Africa, as a case study. Study sites – cleared of Eucalyptus camaldulensis in 2005, 2007, 2008 and 2014 – were sampled in 2014 and compared to invaded and near-pristine areas. In total, 27 native plant species (four trees, six shrubs, seven forbs, four graminoids, four geophytes and two vines) and 26 alien plant species (four trees, three shrubs, twelve forbs and seven graminoids) from 50 genera and 31 families were recorded across all sites and years. Cleared sites had significantly more native plant species than invaded sites, but this was similar to near-pristine sites. Cleared sites had the highest plant species richness, driven by significantly more alien species, but canopy cover was significantly lower than in invaded or near-pristine sites. In total, 2049 birds from 52 species were recorded across all sites and years. A decade after clearing, bird species richness, abundance and community composition are different to near-pristine sites. This is due to the lower abundance and diversity of trees in cleared sites, which could be important as habitat or a food source for birds in an agricultural landscape. From a bird perspective, we support the approach of selectively clearing invasive trees over time to allow native trees to recover through succession. We highlight the importance of monitoring fauna to evaluate recovery after invasive alien plant clearing and to guide further management interventions.

Reduce health damage cost of greenhouse gas and ammonia emissions by assembling plant diversity in floating constructed wetlands treating wastewater

Abstract In wastewater treatment, to find a clean approach with low damage cost to human and ecosystem health has received increasing concerns. Constructed wetlands are regarded as a green treatment technology, but they are also important sources of greenhouse gas and ammonia emissions. However, the effects of optimizing plant community on the human and ecosystem health damage costs of multiple gas emissions are poorly understood. In this study, an experiment with 90 hydroponic microcosms that simulated floating constructed wetlands treating wastewater with a high concentration of ammonium was set to manipulate plant diversity to reduce health damage costs, which integrated the emissions of nitrous oxide, methane, and ammonia. Results showed that: (1) increasing plant species richness reduced the human and ecosystem health damage costs of the three gases; (2) the systems with Arundo donax had lower greenhouse gas emissions and ecosystem health damage costs, while the systems with Lythrum salicaria had lower ammonia emissions and human health damage costs than systems without the species; (3) the structural equation model indicated that the plant combinations with high biomass or high nitrate removal ability contributed to reducing health damage costs. This study suggests that manipulating high plant species richness and proper species is a clean approach in floating constructed wetlands for high ammonium wastewater treatment with low environmental costs.

Using contact networks and next-generation sequencing for wildlife epidemiology

Horizontal transmission of infectious diseases is strongly determined by the contact network between hosts [1] . Environmental and ecological variables that define the probability of contacts between individuals, such as food resource quality and quantity, have been largely neglected in models studying the dynamics and epidemiology of wildlife diseases. In this work, we used pollinators and their pathogens to study the role of contact networks in a natural multi-host pathogen community. In agricultural landscapes, wild flowers are the most important food resources of insect pollinators such as bees and flies. To boost yields of agricultural crops and ensure pollinator conservation, the UK Environmental Stewardship scheme prompted farmers to grow pollinator-friendly wild flower margins along their fields ( Fig. 1 ). Wild flower margins ( Fig. 1 ) have proven to be efficient to increase both density and diversity of bees in agricultural areas, and to increase pollination success of surrounding crops. As the rate of disease transmission should increase with host density, we hypothesize that the success of wild flower margins may generate hubs for pathogen exchange within the bee community. Several recent studies have illustrated the frequent transmission of infectious diseases between managed and wild bees, potentially via the shared use of flowers [2] . However, the environmental and ecological drivers of disease dynamics between pollinators remain uncharacterised [3] . To understand the role of flower density and diversity for bee disease transmission, we reconstructed high-resolution plant–insect visitor networks from flower visitation data collected in ten farms in Southern England (five farms participating in the scheme vs. five control farms), as well as a record of bee pollen collection to describe the resource bees were exploiting (pollen vs. nectar). When analysing the plant–pollinator networks, we found that flower density and diversity strongly define pollinator density and foraging behaviour, and influence the structure of indirect ‘contact networks’ among pollinators (via the use of flower species). Particularly, we found flower diversity to be positively correlated with the reduction of niche overlap between insect species. This response of insect pollinators suggest that wild flower margins with high plant species richness may reduce insect competition for resources, and potentially reduce the risk of inter-specific disease transmission by supporting diverse diet for insects exploiting different flowers. To test the effect of plant diversity on pathogen dynamics in bees, we sampled pollinators on these farms and characterized their virome by deep transcriptome sequencing. We are now combining these environmental data to virus discovery in order to reveal the impact of the agri-environmental scheme on viral dynamics. Ultimately, we aim to identify environmental (flower density, agricultural practices) and ecological factors (plant taxa, insect community assemblage) that significantly enhance the transmission of plant and pollinator viral diseases within our model to eventually improve agricultural practises and wildlife management.

Increased microbial growth, biomass, and turnover drive soil organic carbon accumulation at higher plant diversity.

Species‐rich plant communities have been shown to be more productive and to exhibit increased long‐term soil organic carbon (SOC) storage. Soil microorganisms are central to the conversion of plant organic matter into SOC, yet the relationship between plant diversity, soil microbial growth, turnover as well as carbon use efficiency (CUE) and SOC accumulation is unknown. As heterotrophic soil microbes are primarily carbon limited, it is important to understand how they respond to increased plant‐derived carbon inputs at higher plant species richness (PSR). We used the long‐term grassland biodiversity experiment in Jena, Germany, to examine how microbial physiology responds to changes in plant diversity and how this affects SOC content. The Jena Experiment considers different numbers of species (1–60), functional groups (1–4) as well as functional identity (small herbs, tall herbs, grasses, and legumes). We found that PSR accelerated microbial growth and turnover and increased microbial biomass and necromass. PSR also accelerated microbial respiration, but this effect was less strong than for microbial growth. In contrast, PSR did not affect microbial CUE or biomass‐specific respiration. Structural equation models revealed that PSR had direct positive effects on root biomass, and thereby on microbial growth and microbial biomass carbon. Finally, PSR increased SOC content via its positive influence on microbial biomass carbon. We suggest that PSR favors faster rates of microbial growth and turnover, likely due to greater plant productivity, resulting in higher amounts of microbial biomass and necromass that translate into the observed increase in SOC. We thus identify the microbial mechanism linking species‐rich plant communities to a carbon cycle process of importance to Earth's climate system.

Local representation of change and conservation of a Brazilian Caatinga refuge

A caatinga brasileira é uma das florestas tropicais secas mais ameaçadas do mundo, principalmente devido á fragmentação de habitats em função das pressões antrópicas. No entanto, as regiões montanhosas da Caatinga são consideradas refúgios de biodiversidade, com elevada riqueza de espécies vegetais, as quais são utilizadas para diversas finalidades por populações humanas locais. O presente estudo buscou identificar o conhecimento ecológico local das comunidades rurais no entorno de uma Serra na região semi-árida do Brasil, considerada um refúgio para a biodiversidade. O estudo foi realizado por meio de entrevistas semiestruturadas, com informantes-chave sendo selecionados pela técnica de amostragem de bola de neve. Segundo os informantes, a serra representa o resgate na memória de paisagens anteriores, ligadas à biodiversidade que ela contém e explicando a importância como fonte de recursos e influência nos regimes locais de chuvas. Para as populações locais, a conservação da biodiversidade da Caatinga representa mais do que apenas a preservação da fauna e flora, compreendendo também a permanência das funções dos ecossistemas para a manutenção de suas atividades.

Overwintering Anuran Niche Preferences in a Series of Interconnected Ponds in Northwestern Florida

This study identified variations in pond bank gradients and associated plant assemblages to better understand niche preferences of 3 species of overwintering anurans—Acris gryllus (Southern Cricket Frog), Lithobates grylio (Pig Frog), and Lithobates sphenocephalus (Southern Leopard Frog)—in northwest Florida (Escambia County). We selected 7 regions of 4 interconnected ponds in a coastal pine flatwoods wetland. We conducted visual and auditory surveys once every week for 10 weeks from 17 January to 24 March 2017. We categorized survey areas along pond shorelines by the plant assemblage composition and species richness, pond bank steepness, and sunlight exposure. We looked for correlations between each species and specific niche characteristics. None of the anuran species studied showed a preference for the amount of sunlight or the slope of the pond bank. However, plant species richness was positively correlated with Southern Cricket Frogs and negatively correlated with Pig Frogs; thus, there was a very strong negative correlation between Pig Frogs and Southern Cricket Frogs. Southern Cricket Frogs, the smallest frog species in this study, prefers high plant species richness, possibly for increased cover from predators, and avoids potential predators like Pig Frogs. Pig Frogs prefer lower species richness, relying on open water for escape. The Southern Leopard Frog showed no vegetation preferences, possibly because the species is more adaptable and has a variety of predator evasion methods. Wetland plant assemblages are an accurate reflection of life-history habits of anurans, particularly predator evasion tactics.

Comparison of plant and microbial communities between an artificial restoration and a natural restoration topsoil in coal mining subsidence area

Increased attention has been paid to the influences of coal mining subsidence on the ecological environment. The revegetation of former mining areas is critical to restore the ecological balance. The subsidence area in the Shendong mining area, located in the semiarid region of China, has been restored from 2003, using five different plant species. In July 2017, we compared the plant and microbial communities of artificial restoration areas (AR) and naturally regenerated areas (NR). Based on our results, restoration planting was somehow successful, but the sites did not reach a level similar to that prior to mining. Higher plant species richness, canopy coverage, and bacterial community diversity were observed in AR. However, these features have lower similarity compared with those in NR sites. Soil factors such as pH, moisture content, total carbon content, organic matter, nitrogen level, and bulk density have a greater impact on soil bacterial community structure and diversity. In the ecological restoration of mining areas, attention should be paid to the restoration of soil properties. This study provides a scientific basis for the successful ecological restoration or highly damaged mining areas.

Topsoil mixing or fertilization? Forest flora changes in the vicinity of badgers\u2019 (Meles meles L.) setts and latrines

AimsThe badgers may affect soil chemical properties and plant species composition in two ways: by digging burrows (topsoil mixing) and by using latrines (fertilized soils). Here is reported which kind of badgers’ activity plays a major role.MethodsSoil samples for pH, total N, NH4+, NO3− and data concerning plant species composition were collected on circular plots (N = 80) on burrow mounds, latrines and reference areas.ResultsBurrow mounds were characterized by higher pH and lower content of total N. The content of NH4+ − main component of manure, was higher in latrines than on mounds, whereas in the case of mounds, the content of NO3− was higher than in latrines. There was higher plant species richness on the burrow mounds than on the other plot types. Also plant species characterized with traits allowing them to settle on disturbed habitats were recorded at a higher number on burrow mounds. CCA analysis distinguished only one herbaceous plant aggregation associated with burrow mounds. The presence of latrines with high rate of nitrogen input did not affect plant species composition due to a low rate of soil mixing.ConclusionsSoil chemical properties and flora changes showed that badgers shape plant communities not by fertilization with excrements but, as a result of digging activity, by altering topsoil conditions.

Predatory arthropods in apple orchards across Europe: Responses to agricultural management, adjacent habitat, landscape composition and country

Local agri-environmental schemes, including hedgerows, flowering strips, organic management, and a landscape rich in semi-natural habitat patches, are assumed to enhance the presence of beneficial arthropods and their contribution to biological control in fruit crops. We studied the influence of local factors (orchard management and adjacent habitats) and of landscape composition on the abundance and community composition of predatory arthropods in apple orchards in three European countries. To elucidate how local and landscape factors influence natural enemy effectiveness in apple production systems, we calculated community energy use as a proxy for the communities’ predation potential based on biomass and metabolic rates of predatory arthropods. Predator communities were assessed by standardised beating samples taken from apple trees in 86 orchards in Germany, Spain and Sweden. Orchard management included integrated production (IP; i.e. the reduced and targeted application of synthetic agrochemicals), and organic management practices in all three countries. Predator communities differed between management types and countries. Several groups, including beetles (Coleoptera), predatory bugs (Heteroptera), flies (Diptera) and spiders (Araneae) benefited from organic management depending on country. Woody habitat and IP supported harvestmen (Opiliones). In both IP and organic orchards we detected aversive influences of a high-quality surrounding landscape on some predator groups: for example, high covers of woody habitat reduced earwig abundances in German orchards but enhanced their abundance in Sweden, and high natural plant species richness tended to reduce predatory bug abundance in Sweden and IP orchards in Spain. We conclude that predatory arthropod communities and influences of local and landscape factors are strongly shaped by orchard management, and that the influence of management differs between countries. Our results indicate that organic management improves the living conditions for effective predator communities.

Which spatial distribution model best predicts the occurrence of dominant species in semi-arid rangeland of northern Iran?

Rangelands with more than 8000 plant species occupy nearly 54.6% of the land area of Iran and thus are accounted for a rich plant genetic storage. Mazandaran province has 378,000 ha of rangelands with high plant species richness and diversity due to its climate conditions but plants distribution is at risk because of non-principle management, land use change and as a result changing environmental factors. Vegetation management strategies can be guided by models that predict plant species distribution based on governing environmental variables. This is especially useful for the dominant species that determine ecosystem processes. In fact, modelling algorithm in each SDM determines its suitability for different ecosystems. Our aim was to compare the predictive power of a number of SDMs and to evaluate the importance of a range of environmental variables as predictors in the context of semi-arid rangeland vegetation. The selected study area, the Sarkhas rangelands (northern Iran, 36°10′ 42˝ N - 51°19′ 11˝ E), covers approximately 4358.9 ha of Mazandaran province. The efficacy of four different modelling techniques as well as Ensemble model was evaluated to predict the distribution of five dominant forage plant species (Vicia villosa, Stachys lavandulifolia, Coronilla balansae, Sanguisorba minor and Alopecurus textilis). The used models included artificial neural network (ANN), boosted regression trees (BRT), classification and regression trees (CART), and random forest (RF). Ensemble, RF and CART had the highest area under curve. The AUC obtained for Vicia villosa, Stachys lavandulifolia, Coronilla balansae, Sanguisorba minor and Alopecurus textilis, were 0.90, 0.72, 0.76, 0.69 and 0.75 respectively. Ensemble model was the model that most consistently demonstrated high predictive power across species in the rangeland context investigated here. BRT exhibited the least predictive power. An importance analysis of variables showed that soil organic C according to the CART model (0.396) and K according to the RF model (0.396) were the most important environmental variables.

Wild food plants of Qakh district of Azerbaijan, the Southeastern Caucasus: diversity and distribution pattern along an elevation gradient

Environment can not exist without plants. Historically, plants have often been selected for different uses, as medicinal, food, ornamental and others. Plants are one of the main sources of food for life. Much of the food plants exist in nature as wild. Currently the depletion of natural resources is observed around the world. Considering these, it is important to study their location, resources and knowledge of their traditional use. Qakh is a historical district of the Azerbaijan, located in the north-west part of the country and on the south macroslope of the western part of the Great Caucasus. The region is one of the least studied areas of the country in terms of plant diversity. The checklist of wild food plants of the region has not been prepared, although the useful plants have been studied by a number of scientists. Generally, 323 wild food plants (vascular) were recorded in the region across 72 families and 211 genera, with by far the largest family being Asteraceae (35 plant species), followed by Rosaceae, Apiaceae, Fabaceae, Brassicaceae, Lamiaceae, Malvaceae and Polygonaceae. Total number of species include 29 tree species, 18 shrubs, 2 subshrubs, 1 climber, 69 annual, 27 biennial and 177 perennial herbs. It was recorded one endemic species of Azerbaijan (Rubus buschii Grossh. ex Sinkova), 35 endemics of Caucasus, and 25 species listed in the Red Book of the Republic of Azerbaijan. Most of the food plants are distributed in the northern and northeas-tern parts of the study area (263 species). The southern part has less numbers (55 species) than middle part (147 species) of the region. Besides, 52 species are found all over the area. In general, the high plant species richness in the area is found in lower and middle mountain zone between 600 m and 1700 m. Cluster analysis based on presence/absence of food plants of the area along an altitudinal gradient determinate two main cluster groups, where the first group consists of plants of the alpine zone and the second group combines the other zones.

A sharp floristic discontinuity revealed by the biogeographic regionalization of African savannas

AbstractAimIn tropical Africa, savannas cover huge areas, have high plant species richness and are considered as a major natural resource for most countries. There is, however, little information available on their floristics and biogeography at the continental scale, despite the importance of such information for our understanding of the drivers of species diversity at various scales and for effective conservation and management. Here, we collated and analysed floristic data from across the continent in order to propose a biogeographical regionalization for African savannas.LocationWe collated floristic information (specifically woody species lists) for 298 samples of savanna vegetation across Africa, extending from 18° N to 33° S and from 17° W to 48° E.TaxaWe focused on native woody species.MethodsWe used ordination and clustering to identify the floristic discontinuities and gradual transitions across African savannas. Floristic relationships, specificity and turnover, within and between floristic clusters, were analysed using a (dis‐)similarity‐based approach.ResultsWe identified eight floristic clusters across African savannas which in turn were grouped into two larger macro‐units. Ordinations at species and genus levels showed a clear differentiation in woody species composition between the North/West macro‐unit and the South/East macro‐unit. This floristic discontinuity matches to the High (i.e. N&W) and Low (S&E) division of Africa previously proposed by White () and which tracks climatic and topographical variation. In the N&W savannas, the floristic gradient determined by rainfall was partitioned into the Sudanian (drier) and Guinean (wetter) clusters. Within the highly heterogeneous S&E savannas and woodlands, six clusters were identified: Ugandan, Ethiopian, Mozambican, Zambezian, Namibian and South African.Main conclusionsThe proposed pan‐African classification of savannas and woodlands might assist the development of coordinated management and conservation policies.

ENDEMIC FLORA OF THE CARPATHIANS: THE IMPORTANCE OF DIGITALLY INTEGRATING SCIENTIFIC INFORMATION OF MAJOR CARPATHIAN REGION HERBARIA

The Carpathian Region is recognised as one of the most biodiverse regions of Europe, encompassing both a high global plant species richness and a high number of endemics. However, distribution data residing from old herbarium collections is often hard to access, although the information is relevant for a wider audience of researchers going beyond the single-country level. Here we aim to review the major role of herbarium collections in holding relevant information for the distribution of CR endemic plant taxa and the importance of herbarium digitization as both a more straightforward and non-invasive method of herbarium data visualization, investigation and data sharing within the CR and a tool for increasing the scientific knowledge in plant conservation strategies. We present an overview of the endemic taxa type specimen distribution among few selected major herbaria and the country-level spatial structure of endemic taxa specimens preserved in several of these herbaria in order to highlight the relevance of herbarium collections for researchers from other countries.

Plant diversity enhances the natural attenuation of polycyclic aromatic compounds (PAHs and oxygenated PAHs) in grassland soils

Increasing plant species richness stimulates microbial activity in soil, which might favor biodegradation of polycyclic aromatic compounds (PACs). To explore the relationship between plant community composition and PACs in grassland soils (Fluvisols exposed to an urban atmosphere), we determined the concentrations of 29 polycyclic aromatic hydrocarbons (PAHs) and 15 oxygenated PAHs (OPAHs) in topsoils of 80 plots of a grassland biodiversity experiment. The plots included different levels of plant species richness (1, 2, 4, 8, 16, 60 species) and 1–4 plant functional groups (grasses, small herbs, tall herbs, and legumes) in a randomized block design. The concentrations (ng g−1) of ∑29PAHs and ∑15OPAHs in the soils were 271–2407 and 57–329, respectively. Concentrations of 16 (out of 44) PACs and ∑29PAHs decreased significantly with increasing plant species richness, after accounting for the effects of block and initial soil organic C concentration (ANCOVA, p < 0.05). Microbial turnover as the mechanism underlying this relationship was supported by the findings that (i) the regression of the concentrations of PAH with >4 aromatic rings on plant species richness yielded slopes that were negatively correlated with their octanol-water partitioning coefficients, (ii) two OPAHs accumulated in soils with higher plant species richness, and (iii) higher plant species richness increased four OPAH/parent-PAH ratios. Accordingly, structural equation modeling indicated that the higher concentration of 1,2-acenaphthenequinone (a metabolite of acenaphthene) and the higher 1,2-acenaphthenequinone/acenaphthene and 1-indanone/fluorene ratios in plots with higher plant species richness were partly explained by higher soil microbial biomass on plots with higher plant species richness. We conclude that higher plant species richness can be used to enhance biodegradation of aged PACs in soil. We however caution that OPAHs (some of which are more toxic than their related PAHs) might accumulate in soils during such a plant-assisted remediation process.

Earwigs and woolly apple aphids in integrated and organic apple orchards: responses of a generalist predator and a pest prey to local and landscape factors

Organic management, connective woody habitats, and landscape complexity are supposed to enhance beneficial arthropods and biological pest control in agro-ecosystems. We studied earwigs (Dermaptera: Forficulidae) as generalist predators and aphids (Hemiptera: Aphididae) as key pests serving as earwig prey in a total of 58 commercial apple orchards differing in management (integrated production (IP) versus organic) in Germany and Spain. We focused on the effects of local agri-environmental structures, orchard management, and composition of the surrounding landscape on earwig populations and on tree infestation by the woolly apple aphid (WAA), Eriosoma lanigerum. Surprisingly, the common earwig, Forficula auricularia, did not benefit from organic management in either country, and we found even slightly higher earwig abundances in IP than in organic orchards in Germany. In Spain, we found a negative impact of IP compared to organic management on abundance of the earwig Forficula pubescens, whereas orchard management did not affect the abundance of F. auricularia. The presence of woody habitats adjacent to the orchard reduced the abundance of F. auricularia in IP but not in organic orchards in Germany. We did not study the effects of woody habitats in Spain, where these structures were very scarce. There was no effect of high plant species richness at the orchard boundary or compositional landscape heterogeneity on earwig abundance in either country. In Germany, WAA infestation was very low and driven by landscape characteristics rather than orchard management. In Spain, WAA infestation differed strongly between management types (higher in organic orchards). There were no strong, consistent correlations between earwig abundance and WAA infestation in either country. Our study shows that adjacent woody structures and orchard management may affect earwigs in perennial cropping systems. The consequences of orchard management, however, seem to strongly depend on earwig species. Our study suggests that woody elements may serve as sink habitats – potentially attracting earwigs by providing alternative prey and shelter – in IP (but not in organic) orchards.

Plant diversity decreases net global warming potential integrating multiple functions in microcosms of constructed wetlands

Abstract Constructed wetlands, which are designed ecosystems that consist of substrates, plants and microorganisms, have been used as an alternative clean technology to treat wastewater. However, greenhouse gas emission in constructed wetlands is still an accompanying problem. Finding a cleaner way to mitigate the net global warming potential while maintaining nitrogen removal efficiency has received increasing attention in recent years. High plant diversity has been found to increase nitrogen removal efficiency, but its effect on net global warming potential is not well understood. In this study, four species richness levels (1, 2, 3 and 4) were assembled in microcosms simulating constructed wetlands. The goal of this work is to explore the effects of plant diversity (species richness and identity) on the net global warming potential integrating multiple functions, including carbon sequestration in substrate, carbon dioxide emission mitigation by aboveground biomass converted to biofuel, and non-carbon dioxide (methane and nitrous oxide) emissions. Results showed that: (1) increasing species richness reduced the global warming potential based on carbon sequestration and carbon dioxide emission mitigation while increasing the global warming potential of non-carbon dioxide emissions of the microcosms; (2) increasing species richness mitigated the overall global warming potential due to the greater role of carbon sequestration and carbon dioxide emission mitigation; and (3) the presence of Rumex japonicus or Oenanthe javanica decreased the overall global warming potential of the microcosms. This study concluded that assembling communities with high plant species richness and several specific species instead of monocultures are more effective and cleaner for mitigating global warming potential while maintaining the efficiency of nitrogen removal.

Beyond green: Broad support for biodiversity in multicultural European cities

While urban growth contributes to the biodiversity crisis, biodiverse greenspaces within cities could support both human wellbeing and biodiversity conservation. Yet, urban greenspaces are under pressure due to the rapid densification of cities worldwide. Urban conservation policies thus need broad support, ideally from people with different sociocultural backgrounds. Whether urban residents prefer biodiverse over simply green spaces, however, largely remains an open question. We tested how diverse respondents (N = 3716) from five European cities valued three levels of biodiversity (plant species richness) in four ubiquitous greenspace types. Our field survey revealed that biodiversity matters: People largely prefer higher plant species richness in urban greenspaces (i.e., parks, wastelands, streetscapes) and agree that higher plant species richness allows for more liveable cities. Despite variation across European cities, positive valuations of high plant species richness prevailed among different sociocultural groups, including people of migrant background. The results of this study can thus support policies on a biodiversity-friendly development and management of urban greenspaces by highlighting social arguments for integrating biodiversity into urban development plans.

Remote sensing data to assess compositional and structural indicators in dry woodland

Integrating field-based and remotely sensed data has proven valuable for assessing on-the-ground diversity of plants across a range of spatial scales. Here we assessed whether remotely sensed data is a good indicator of vegetation composition and structure in dry, Prosopis flexuosa-dominated woodlands. Our objectives were (1) to quantify on-the-ground vegetation composition and structure using (A) field-based methods and (B) remotely sensed images and analysis techniques, and (2) to evaluate how well the data extracted from remotely sensed data estimate field-based measures of vegetation composition and structure. We selected 40 individuals of P. flexuosa in Ischigualasto Provincial Park (San Juan, Argentina) and its influence zone. Each individual was the center of a plot (1500-m2) where we recorded richness (compositional indicator) and abundance (structural indicator) of trees, shrubs and other plants (i.e. cacti, grasses and forbs). To assess woodland structure, we evaluated canopy area of each P. flexuosa and the proportion of adult P. flexuosa trees in a plot. In addition, we used Landsat 8 OLI to calculate SATVI (Soil Adjusted Total Vegetation Index) values from the pixel that corresponds with the center of each sample plot, and then estimated first- and second-order texture measures (in 3 × 3 and 5 × 5 moving window sizes). We fitted generalized linear models with different error distributions. Vegetation richness was significantly and directly related to range and entropy (3 × 3 and 5 × 5 windows). Both trees and shrubs, were related to SATVI values and first- and second-order means (3 × 3 and 5 × 5 windows). Moreover, shrub abundance was inversely related to range and entropy (5 × 5 window); and the “other plants” group was inversely related to first- and second-order means in the same window. Variance of the canopy area was directly related to range (5 × 5 window); however, proportion of adults was not related to remote sensing data. Our findings suggest satellite imagery-derived image texture is a valuable tool for management and conservation, and can indicate areas of high plant species richness and abundance of trees and shrubs and help differentiate areas of different canopy sizes in dry P. flexuosa-dominated woodlands of Argentina.

Effects of Inundation, Nutrient Availability and Plant Species Diversity on Fine Root Mass and Morphology Across a Saltmarsh Flooding Gradient.

Saltmarsh plants are exposed to multiple stresses including tidal inundation, salinity, wave action and sediment anoxia, which require specific root system adaptations to secure sufficient resource capture and firm anchorage in a temporary toxic environment. It is well known that many saltmarsh species develop large below-ground biomass (roots and rhizomes) but relations between fine roots, in particular, and the abiotic conditions in salt marshes are widely unknown. We studied fine root mass (<2 mm in diameter), fine root depth distribution and fine root morphology in three typical communities (Spartina anglica-dominated pioneer zone, Atriplex portulacoides-dominated lower marsh, Elytrigia atherica-dominated upper marsh) across elevational gradients in two tidal salt marshes of the German North Sea coast [a mostly sandy marsh on a barrier island (Spiekeroog), and a silty-clayey marsh on the mainland coast (Westerhever)]. Fine root mass in the 0–40 cm profile ranged between 750 and 2,500 g m−2 in all plots with maxima at both sites in the lower marsh with intermediate inundation frequency and highest plant species richness indicating an effect of biodiversity on fine root mass. Fine root mass and, even more, total fine root surface area (maximum 340 m2 m−2) were high compared to terrestrial grasslands, and were greater in the nutrient-poorer Spiekeroog marsh. Fine root density showed only a slight or no decrease toward 40 cm depth. We conclude that the standing fine root mass and morphology of these salt marshes is mainly under control of species identity and nutrient availability, but species richness is especially influential. The plants of the pioneer zone and lower marsh possess well adapted fine roots and large standing root masses despite the often water-saturated sediment.