Semi-natural Grasslands Research Articles

Spatial heterogeneity ensures long-term stability in vegetation and Fritillaria meleagris flowering in Uppsala Kungsäng, a semi-natural meadow.

Semi-natural grasslands are becoming increasingly rare, and their vegetation may be affected by environmental changes and altered management. At Kungsängen Nature Reserve, a wet to mesic semi-natural meadow near Uppsala, Sweden, we analysed long-term changes in the vegetation using data from 1940, 1982, 1995 and 2016. We also analysed the spatial and temporal dynamics in the Fritillaria meleagris population based on countings of flowering individuals in 1938, 1981-1988 and 2016-2021. Between 1940 and 1982 the wet part of the meadow became wetter, which led to an increased cover of Carex acuta and pushed the main area of flowering of F. meleagris up towards the mesic part. Annual variation in the flowering propensity of F. meleagris (in May) was affected by temperature and precipitation in the phenological phases of growth and bud initiation (June in the previous year), shoot development (September in the previous year) and initiation of flowering (March-April). However, the response to weather was in opposite directions in the wet and mesic parts of the meadow, and the flowering population showed large year-to-year variation but no long-term trend. Variation in management (poorly documented) led to changes in different parts of the meadow, but the overall composition of the vegetation, species richness and diversity changed little after 1982. Species richness and species composition of the meadow vegetation, and the long-term stability of the F. meleagris population are maintained by the variation in wetness, highlighting the importance of spatial heterogeneity as an insurance against biodiversity loss in semi-natural grasslands and nature reserves generally.

Retaining natural vegetation to safeguard biodiversity and humanity.

Global efforts to deliver internationally agreed goals to reduce carbon emissions, halt biodiversity loss, and retain essential ecosystem services have been poorly integrated. These goals rely in part on preserving natural (e.g., native, largely unmodified) and seminatural (e.g., low intensity or sustainable human use) forests, woodlands, and grasslands. To show how to unify these goals, we empirically derived spatially explicit, quantitative, area-based targets for the retention of natural and seminatural (e.g., native) terrestrial vegetation worldwide. We used a 250-m-resolution map of natural and seminatural vegetation cover and, from this, selected areas identified under different international agreements as being important for achieving global biodiversity, carbon, soil, and water targets. At least 67 million km2 of Earth's terrestrial vegetation (∼79% of the area of vegetation remaining) required retention to contribute to biodiversity, climate, soil, and freshwater conservation objectives under 4 United Nations' resolutions. This equates to retaining natural and seminatural vegetation across at least 50% of the total terrestrial (excluding Antarctica) surface of Earth. Retention efforts could contribute to multiple goals simultaneously, especially where natural and seminatural vegetation can be managed to achieve cobenefits for biodiversity, carbon storage, and ecosystem service provision. Such management can and should co-occur and be driven by people who live in and rely on places where natural and sustainably managed vegetation remains in situ and must be complemented by restoration and appropriate management of more human-modified environments if global goals are to be realized.

Local and landscape environmental heterogeneity drive ant community structure in temperate seminatural upland grasslands.

Environmental heterogeneity is an important driver of ecological communities. Here, we assessed the effects of local and landscape spatial environmental heterogeneity on ant community structure in temperate seminatural upland grasslands of Central Germany. We surveyed 33 grassland sites representing a gradient in elevation and landscape composition. Local environmental heterogeneity was measured in terms of variability of temperature and moisture within and between grasslands sites. Grassland management type (pasture vs. meadows) was additionally included as a local environmental heterogeneity measure. The complexity of habitat types in the surroundings of grassland sites was used as a measure of landscape environmental heterogeneity. As descriptors of ant community structure, we considered species composition in terms of nest density, community evenness, and functional response traits. We found that extensively grazed pastures and within-site heterogeneity in soil moisture at local scale, and a high diversity of land cover types at the landscape scale affected ant species composition by promoting higher nest densities of some species. Ant community evenness was high in wetter grasslands with low within-site variability in soil moisture and surrounded by a less diverse landscape. Fourth-corner models revealed that ant community structure response to environmental heterogeneity was mediated mainly by worker size, colony size, and life history traits related with colony reproduction and foundation. We discuss how within-site local variability in soil moisture and low-intensity grazing promote ant species densities and highlight the role of habitat temperature and humidity affecting community evenness. We hypothesize that a higher diversity of land cover types in a forest-dominated landscape buffers less favorable environmental conditions for ant species establishment and dispersal between grasslands. We conclude that spatial environmental heterogeneity at local and landscape scale plays an important role as deterministic force in filtering ant species and, along with neutral processes (e.g., stochastic colonization), in shaping ant community structure in temperate seminatural upland grasslands.

How is plant biodiversity inside grassland type related to economic and ecosystem services: An Estonian case study

Biodiversity is globally recognised as a cornerstone of healthy ecosystems and extensive management is assumed to increase biodiversity in all grassland habitats. Often, the maintenance of these semi-natural grasslands via mowing or grazing is financially subsidized and different ecosystem benefits are associated with the plant biodiversity value. These assumptions are usually made after comparing different ecosystems or management options. However, less information is available about the relations between plant biodiversity and ecosystem services in practice. Hence, we studied the impact of biodiversity on the fodder quantity and quality in two different semi-natural grassland habitats. We also checked if the species more commonly found in sites with higher biodiversity are more endangered in comparison to the rest of the species and if they have special site requirements in terms of Ellenberg indicator values. The soil of Estonian calcareous grasslands had higher pH as well as organic matter and Nitrogen content than the soil of Estonian mesic grasslands (habitat 6270). However, the average annual biomass production in the first ones was significantly smaller most probably due to water shortage. No clear relation between site productivity and plant species number was detected in either habitat. The average species number in both studied habitats was almost similar, but the median species amount in mesic grasslands was more than 13% higher than that in calcareous grasslands. Crude protein along with starch & sugar content in the calcareous grassland biomass tended to be lower than in mesic grasslands. In the last habitat, the content of these two components favoured both for fodder and biogas purposes tended to be lower in sites with more species. Positive correlations were found between species number and biomass detergent fibre contents, which is why it must be inferred that plant biodiversity does not improve grassland biomass quality. We detected several species of the Near Threatened category from the IUCN red list, but none of these appeared in our list of species that grew with higher probability in grasslands with higher plant biodiversity. According to principal component analyses, these listed species are less common, less nutrient demanding and more salt tolerant than the rest of the plant species found in calcareous grasslands and more common than the rest in mesic grasslands species. We conclude that high site biodiversity does not guarantee any larger income for the typical bioeconomy products, so other potential economic services should be included to the farm’s budget.

Forage nutritive value shows synergies with plant diversity in a wide range of semi-natural grassland habitats

This paper aims in assessing the relationship between grassland plant diversity and agronomic value, which represents a major challenge to reconcile nature conservation and agricultural use of semi-natural grassland habitats. The effects of plant diversity and functional traits were studied on forage nutritive value and early standing biomass in a wide set of semi-natural temperate grassland habitats. Plant communities were described by their species and functional diversity, community-weighted means (CWM) of plant functional traits, and the relative cover of main plant functional types (graminoids, forbs, and legumes). Species richness was found to be negatively associated with early standing biomass and average mineral content. Community evenness, for both species and plant functional types, was positively correlated with digestibility, crude protein content, and average mineral content but negatively with early standing biomass. Early standing biomass was found to increase with increasing graminoid cover and to decrease with increasing forb cover. Forage nutritive value improved with higher legume cover, higher specific leaf area CWM and lower leaf dry matter content CWM, while these functional community characteristics were not found to impact early standing biomass. Our results highlight that a better forage nutritive value can be obtained with a higher plant species evenness in permanent grassland habitats. Furthermore, in grasslands with an even distribution of plant functional types, forage nutritive value may be improved with no loss in early standing biomass.

“The ASO grassland-restoration project”, to maintain and restore the ASO semi-natural grassland using local certified plants

“The ASO grassland-restoration project”, to maintain and restore the ASO semi-natural grassland using local certified plants

Creation of semi-natural grassland on rooftop

Creation of semi-natural grassland on rooftop

Contrasting Response of Mountain Plant-Pollinator Network to Fragmented Semi-Natural Grasslands

The majority of the world’s plants rely on animal pollinators for reproduction, making pollination a key ecosystem service for the maintenance of natural and cultivated plant communities. Mutual interactions between plants and pollinators, also called “plant-pollinator networks”, are becoming increasingly vulnerable due to the intensification of anthropogenic land use and climate change. Thus, due to the rapid decline of semi-natural grasslands in the Northern Apennines (Italy), we aimed at understanding how the fragmentation of these habitats, the spatial distribution, and the amount of semi- and natural areas surrounding them, could affect species diversity and plant-pollinator networks. Specifically, in the Northern Apennines, we monitored semi-natural grasslands belonging to the EU habitat type 6510 to evaluate the effect of fragmentation on plant and pollinator richness and on the plant-pollinator network. We carried out generalized linear models considering three taxonomical and six network descriptors as response variables and the combinations of grasslands size and isolation, as well as 10 other factors describing landscape composition as explanatory variables. We found a well-structured plant-pollinator network, characterized by a high diversity of both plants and pollinators, with mutual relations marginally specialized, highly affected by habitat fragmentation and the land use of surrounding grasslands. Moreover, large and neighboring patches increased pollinator richness and improved the overall network structure while the occurrence of meadows and shrubs around fragmented patches was important to ensure the continuity of floristic resources. Finally, extensive croplands and agricultural settlements significantly reduced plant and pollinator diversity, favoring generalist (probably invasive) species, which however increased the strength and stability of the network.

Structurally rich dry grasslands – Potential stepping stones for bats in open farmland

Agricultural intensification has caused decrease and fragmentation of European semi-natural dry grasslands. While a high biodiversity value of dry grasslands is acknowledged for plants and insects, locally and on landscape level, their relevance for mobile species, such as bats, is unknown. Here we investigate the use of dry grassland fragments by bats in an agriculturally intensified region in Germany and evaluate local and landscape factors influencing bat activity and assemblages. Specifically, we predicted that a combination of local dry grassland structural richness and landscape features as well as their interactions affect bat activity and foraging above dry grasslands. We also expected that these features influence compositions of local bat assemblages. We repeatedly sampled at 12 dry grassland plots with acoustic monitoring and assessed activity and foraging of bat species/sonotypes, which we grouped into guilds known for foraging in open land, at vegetation edges and in narrow spaces. We determined structural richness of the dry grassland plots in field and derived landscape features from digital landscape data. A relatively high proportion of bat species/sonotypes used dry grasslands regularly. The edge space foragers responded positively to higher local structural richness. Their dry grassland use increased when surrounding forests and woody features were less available, but they foraged more on dry grasslands closer to water bodies. Narrow space bat activity on dry grasslands decreased with less landscape connectivity. Open and narrow space foragers responded to local structural richness only in landscape context. For all bat guilds we found increased use of structurally richer dry grasslands when there was more open farmland in the surroundings. This was also the case for edge space foragers, when landscapes were more homogeneous. Lastly, with increasing structural richness, bat assemblages were more dominated by edge space foragers. We show the importance of European dry grassland fragments for the highly mobile group of bats under certain local structural and landscape compositional conditions. Our results underline the value of heterogeneous dry grassland fragments as potential stepping stones in intensively used farmland areas and contribute to evidence based decision making in dry grassland management and bat conservation.

Long-term success of floodplain meadow restoration on species-poor grassland

Restoration of floodplain meadows remains a challenge, as many degraded sites suffer from seed limitation. The transfer of seed-containing plant material from species-rich donor sites is a widely used method to restore semi-natural grasslands. However, most studies on the success of such restoration projects comprise limited time frames. As factors determining restoration success may only become evident after many years, long-term observations are crucial. We re-investigated 20 restored grassland sites in the floodplain of the Northern Upper Rhine 13–16 years after plant material transfer with different soil preparation treatments. To this end, we carried out vegetation surveys on 254 permanent plots and studied the potential influence of soil preparation, soil nutrients, and hydrology on plant species composition, diversity, and transfer of target species. Since sustainable agricultural use is important to ensure the long-term stability of restored semi-natural grasslands, we further investigated biomass productivity and feeding value. While most target species increased in frequency or remained stable over time, we found no positive long-term effect of soil preparation on vegetation development and target species establishment. Instead, increased biomass yield and flooding frequency led to reduced restoration success, while higher soil C/N ratios had a positive effect. Overall, restoration measures did not affect the agricultural value of the restored grasslands, which had higher dry matter biomass yields compared with the donor sites. Our results indicate that the positive effect of soil preparation on the number and cover of target species, which is regularly reported in short-term studies, diminishes over time, and other factors such as site conditions become increasingly important. Furthermore, additional plant material transfer or manual seeding may be necessary to support target species establishment. Concerning agricultural usability, the integration of restored floodplain meadows in farming systems is possible and can ensure long-term management and thus stability of these ecosystems. Our study shows that long-term monitoring of restoration projects is necessary, as factors determining restoration success may only become evident in the long-term.

Long-term effects of environmental alterations in protected grasslands – Land-use history determines changes in plant species composition

Nutrient-poor, semi-natural grasslands are among the most species-rich ecosystems across Europe. However, due to the transition from pre-industrial farming to modern agriculture, the extent of such grasslands has greatly decreased and the remaining patches have often suffered from habitat deterioration. Here, we analysed the effects of land-use and climate change as well as of nitrogen deposition on plant communities of dry (sand) (n = 118) and wet grasslands (n = 30) in a protected area, representative for the NE German young moraine landscape. Our study revealed that over a time period of 25 years, plant species composition in protected grasslands has changed considerably. Overall, plant species richness increased in both dry and wet grasslands from 1994 to 2019. The number of threatened species, however, decreased in dry but increased in wet grasslands. Land-use history was identified as the major driver of changes in species composition within the studied semi-natural grasslands. In wet grasslands, after >30 years of abandonment prior to the first survey, species-rich communities such as the Molinietalia have successfully been restored through the re-introduction of continuous, low-intensity management (mostly mowing once in late summer) shortly before the first survey. This has led to an increase of often threatened, light-demanding species of nutrient-poor wet grasslands. In dry grasslands, however, changes in vegetation were often contrary to those in wet grasslands; for example dry grasslands exhibited an increase in the nitrogen indicator value while it decreased in wet grasslands. Overall, open, nutrient-poor dry grasslands rich in stress-tolerant and often threatened species have been replaced by dense, more mesophytic grasslands with competitive generalists and some ruderal annuals. These successional changes were caused in particular by (i) an increase in abandonment on the least productive soils, (ii) undergrazing in permanent pastures and (iii) an insufficient time period since the re-introduction of grazing combined with a too low grazing pressure in new pastures on more productive soils. Nitrogen deposition was a further driver, especially on more acidic, dry soils. Additionally, grassland ruderalization was favoured by cropping of some plots and climate change since warm winters and severe summer droughts have led to an increase of annual ruderal species.

Plant Gall Diversity in Burned Semi-natural Grasslands in Japan

We surveyed woody plants, including oaks and chestnuts (Quercus L. and Castanea Mill.), and recorded the inhabiting galls induced by oak gall wasps (Hymenoptera: Cynipidae: Cynipini) at seven Japanese semi-natural grassland sites maintained by traditional regular burning with two of the seven abandoned grassland areas. Woody plants were established in all burned and abandoned grasslands. Oak species were found at four of the seven sites. In total, 15 types of cynipid galls were recorded at all four sites where oak species were found. However, the occurrence of species was site-specific for host trees and cynipid galls. Although a few ecological studies of oak gall wasps inhabiting grassland environments, which have rapidly decreased in recent decades, have been conducted, this study suggests that semi-natural grasslands may be potential habitats for oak gall wasps and their host trees, and we provide a checklist of oak gall wasps with host oak records in semi-natural grasslands throughout Japan.

Site dependence of local variations in taxonomic and functional diversity of plant communities in semi-natural dry grasslands

Site dependence of local variations in taxonomic and functional diversity of plant communities in semi-natural dry grasslands

Interaction of Management and Spontaneous Succession Suppresses the Impact of Harmful Native Dominant Species in a 20-Year-Long Experiment

Our study focused on the compositional changes of Pannonian semi-natural dry grasslands. The preservation of these valuable habitats requires regular management. Our mowing experiment aimed to study the suppression of the native dominant Calamagrostis epigejos L. Roth in mid-successional grasslands. Mowing was applied twice a year in eight permanent plots. The vegetation was sampled annually from 2001 to 2021. The impacts of mowing were tested using repeated–measures analysis of variance (ANOVA). After 10 years, the cover of C. epigejos in the mown plots decreased significantly, from an initial average cover of 56.6 to 5.6%. In 20 years, it declined to 1.3%. Surprisingly, in the control plots, it decreased also from 63.7 to 6.9%. Species richness was affected by mowing: significant differences between mown and control plots were detected from the eighth year of our experiment. However, species richness steadily increased in both treatment types from 15 to 36 in the mown plots and 18 to 25 in the control plots, indicating a combined effect of vegetation succession and treatment. Our results suggest that long-term in situ experiments and comprehensive botanical studies are necessary to provide a basis for multi-objective management and reliable utilization of grasslands.

Elevated Ozone Negatively Affects the Community Characteristics and Productivity of Subtropical Grassland in India

Tropospheric ozone (O 3 ) is found to be a severe threat to agriculture and natural vegetation. The present study was conducted to investigate the structural and functional changes in an intact seminatural grassland community when exposed to elevated O 3 (EO 3 ; ambient + 20 parts per billion) compared to ambient O 3 (AO 3 ) for 3 years using open-top chambers. Parameters such as species richness (SR), evenness ( E ), Shannon index ( H ′), β-diversity (BD), concentration of dominance (Cd), similarity index (SI), biomass in canopy layers, and community productivity were evaluated. Species like Cynodon dactylon , Dichanthium annulatum , Parthenium hysterophorus , Digitaria sanguinalis , Cyperus killinga , Oplismenus burmannii , and Commelina benghalensis showed higher importance value index (IVI), whereas Trifolium resupinatum , Desmodium triflorum , Melilotus officinalis , Oxalis corniculata , Eleusine indica , Cyperus rotundus , Malvestrum coromandelianum , and Lindernia anagallis showed lower IVI under EO 3 treatment compared to AO 3 . EO 3 enhanced BD and Cd, whereas SR, E , and H ′ in the community reduced. Biomass accumulation reduced maximally in top layer compared to bottom and middle canopy layers in both forbs and grasses fraction under EO 3 treatment. Higher reduction in total biomass compared to aboveground biomass indicates less carbon allocation toward root system. The results of the present study clearly indicates that 3 years of exposure at EO 3 level caused deleterious impact on grassland community by increasing O 3 -tolerant and decreasing sensitive species, thus resulting in a shift in species composition and community productivity.

Explore variations of DOM components in different landcover areas of riparian zone by EEM-PARAFAC and partial least squares structural equation model

Dissolved organic matter (DOM) plays key roles in species-distribution of contaminants and the biogeochemical cycle of carbon in ecosystems. Riparian zone is the representative of water-land ecotone and controls the DOM exchange between water and land. However, the variance of DOM in different landcover areas of an urban river riparian zone is unknown. In this study, fluorescence excitation-emission matrix (EEM) spectroscopy coupled with parallel factor analysis (PARAFAC) and partial least squares structural equation model (PLS-SEM) was applied to character dissolved organic matter (DOM) fractions in four types of landcover riparian areas (natural forest, artificial forest, semi-natural grassland, and cropland) of Puhe River and trace latent factors. Soil samples were collected at 0–20 cm, 20–40 cm, 40–60 cm, and 60–80 cm. The results showed that soil DOM components and humification varied between forests with grassland and cropland samples, and soil humification was obviously higher in the forest samples than that in the grassland and cropland samples. In the natural and artificial forest soils, the humic/fulvic-like were the dominant fractions of DOM, whose variations were smaller than the protein-like with soil depths. However, the tyrosine-like was the representative component in the grassland and cropland soils, whose variation was smaller than the humus substances. According to the PLS-SEM, the DOM components and humification were affected by soil physiochemical properties and DOM sources. The humification in the forest soils had a positive correlation with tryptophan-like, which derived from blended source of the autochthonous and terrigenous. Nevertheless, a positive correlation was observed between humification and humus substances, which could derive from microbial degradation of tyrosine-like, in the grassland and cropland soils. Moreover, the soil physiochemical properties were negatively related to DOM components in all soil samples, which could affect indirectly soil humification. Therefore, EEM combined with PARAFAC and PLS-SEM might be an effective method to investigate DOM fractions and trace the latent factors in different landcover areas of the riparian zone.

Hosszú távú kaszálás hatása a vegetációra és a biomassza összetételére a Nyugat-Cserhát pannon száraz gyepeiben

This study is focusing on the vegetation of seminatural dry grasslands. Those loess grasslands are valuable with large biodiversity; however their long-term preservation requires regular conservation management. The report demonstrates the results of mowing experiment, designed to suppress the spread of unpalatable grass species, Calamagrostis epigeios. The study site is located in mid-successional loss grasslands, in the Western-Cserhát, near Rád, northern Hungary.
 The study aims to the investigate the followings: Can the unpalatable Calamagrostis epigejos be suppressed by mowing? Are there possibilities to increase the diversity of sward by this? The study aims, to measure potential value-increasing effect of mowing, and to determine the carrying capacity in the aspect of grassland management.
 In 2001, Camagrostis epigeios was the species with the highest coverage rate according to the both treatment types, with an average cover value of 63%. However, as a result of mowing, a significant difference was detected in the amount of litter and legumes species as well. The number of species showed a slight increase in both types of treatment, from 15 to 37 in the mowed plots, but also from 18 to 27 in the control plots. We concluded that mowing twice a year was beneficial to modify botanical composition of a grassland. In a way it was suited well for agricultural usage, in particular grazing which can replace the expensive and time-consuming scythe. It is also a suitable management measure for controlling the native invader species as a Calamagrostis epigeios, and can significantly increase the proportion of species with higher forage values.
 Mowing has significantly increased the density of Calamagrostis epigeios, the species richness, and the diversity in the course of secondary succession. Therefore, mowing twice a year proved to be a successful management measure for controlling Calamagrostis epigeios, and for obtaining a sward composition. The treatment was effective in restoring grassland composition, although the achievement and maintenance of favourable conservation status for the grassland habitat require long-term management planning and regular treatment. According to the objectives, mowing not only promotes the control of the invasive species, but also the economic utilization of the area.

Short-Term Effects and Vegetation Response after a Megafire in a Mediterranean Area

In Mediterranean-climate areas, wildfires have an important ecological role, selecting organisms, influencing species composition and structure of vegetation, and shaping landscapes. However, the increase in frequency and severity of fires can cause, among others, progressive vegetation degradation, biodiversity, and ecosystem services loss. Under the climate change scenario, the frequency and severity of wildfires are expected to increase, especially in the Mediterranean Basin, recognized as among the most affected by the intensification of droughts and heat waves in the future. Therefore, from the perspective of adaptation, it is important not only to assess the sudden effects after a fire but also to investigate the ecological changes and vegetation response over time. In this framework, this study investigates the effects and the short-term vegetation response in an area struck by a megafire. The vegetation response one year after a fire has been assessed in semi-natural grasslands, shrublands, and woodlands at the landscape scale through spectral indices, and at the field scale through floristic and vegetation surveys. Our results showed that after a severe wildfire, although some areas did not exhibit vegetation regrowth, the response of natural vegetation was notable after one year. In the study area, the most resilient vegetation type was semi-natural grasslands, suggesting that this type of vegetation can be crucial for landscape recovery. The other vegetation types showed different response patterns that also prefigure possible changes in species composition and loss of plant diversity over the medium term. This study highlights the value of combining remote sensing spectral analyses and detailed floristic and vegetation surveys for understanding the direction of the early stages of post-fire vegetation dynamics.

Invasion of natural grasslands by exotic trees increases flood risks in mountainous landscapes in South India

Invasive trees in catchments around the world are a source of concern due to their hydrological and ecological impacts. A large number of studies have focused on their impact on dry-season stream discharge due to enhanced transpiration. The impact of invasive trees on stream discharge and flood risk during extreme rain events, which are becoming more frequent due to climate change, has not been addressed adequately. We examined the influence of land-cover, canopy cover, and other catchment morphological characteristics on stream discharges in hilly catchments during light, heavy, and extreme rain events. Three years of rainfall-runoff observations, between January 2014 and December 2016, were collected in eleven neighbouring mountainous catchments in Nilgiris, South India. Each catchment had a distinct land cover, namely shola forests, montane grasslands, and catchments invaded by wattle (Acacia mearnsii). Hourly rain intensities between the percentiles 25–90, 90–95 and over 95 were categorised as light, heavy and extreme respectively, and were used to study hourly peak stream discharge responses. We compared discharge between native grassland catchments and grassland catchments invaded by wattle. Discharge rates were corrected for the catchment area. We found that land cover and canopy-cover influenced the hydrologic response to extreme rain events. Regression models with flood event as the response variable suggested an increase in rainfall-runoff response with an increase in canopy cover. The maximum hourly discharge observed in the reference grassland catchment (0.00098 mm s−1) was lower than the maximum discharge observed in low density (0.00529 mm s−1) and high density (0.00497 mm s−1) wattle catchments. At higher discharges, the flood magnitude in wattle invaded catchments was much greater than that in the grassland catchment for a given flood frequency – indicating a higher risk of severe flooding in wattle-dominated catchments. We attribute the enhanced flood discharges to the effects of spreading wattle roots on the enhancement of rapid, shallow sub-surface flows in invaded catchments. Catchments dominated by shallow sub-surface flows are known to have reduced water retention times in response to high rain intensities. Antecedent moisture conditions and drainage density were other factors that influenced the local rainfall-runoff relationships. In the Western Ghats and other parts of India grasslands have been planted with exotic woody trees, and some have become invasive. Our study indicates that replacing grasslands with woody plants at landscape scales, could affect hydrological processes and could increase flood risks during the monsoon, especially in mountainous regions. Management of invaded catchments by regulation of wattle and restoration of semi-natural grassland, combined with the installation of early warning systems in these impacted areas will help reduce flood risk during extreme rain under climate change.

Could green infrastructure supplement ecosystem service provision from semi-natural grasslands?

Ancient semi-natural grasslands in Europe are important for ecosystem service (ES) provision. Often, the surrounding matrix contains ‘Grassland Green Infrastructure’ (GGI) that contain grassland species which have the potential to supplement grassland ES provision across the landscape. Here we investigate the potential for GGI to deliver a set of complementary ES, driven by plant composition.We surveyed 36 landscapes across three European countries comprising core grasslands and their surrounding GGI. We calculated community-level values of plant species characteristics to provide indicators for four ES: nature conservation value, pollination, carbon storage and aesthetic appeal.Inferred ES delivery for GGI was substantially lower than in core grasslands for conservation, pollination and aesthetic appeal indicators, but not for carbon storage. These differences were driven by the GGI having 17% fewer plant species, and compositional differences, with 61% of species unique to the core grasslands. In addition, connectivity to the core, the amount of GGI and inferred seed dispersal distances by livestock, were strongly positively correlated with conservation value, pollination and aesthetic indicators. All ES indicators showed similar responses to the GGI spatial structure and distance to the core, suggesting robust effects of these drivers on ES. We projected that improved landscape-wide delivery of nature conservation value and pollination could be achieved through targeted GGI management. Reductions in the distances seeds would need to disperse, more GGI, along with a diversification of the GGI elements, were predicted to enhance service credits.We conclude that for vegetation-related ES, species surveys can be employed to assess potential ES delivery. Creating and enhancing GGI is a useful landscape management strategy to supplement the ES delivered by ancient grasslands.