Grassland Cover Research Articles

Рекреационные изменения компонентов лесных экосистем на примере объекта культурного наследия «Беломорские петроглифы» (Республика Карелия)

Recreation digression of forest ecosystems in the heritage site “White Sea Petroglyphs” was studied for the first time. This site is a compact system of rock outcrops partially cleared of forest vegetation, which bear Neolithic rock carvings (petroglyphs), and are linked together by walking trails. Patterns have been identified in the transformation of soils, plant cover components (tree stand, tree seedlings, understory and living ground cover), as well as fine roots (within 3 mm in diameter) of woody species under the recreation impact. Trampling was found to deform and destroy the top soil horizons, entailing a significant loss of the forest floor thickness and organic matter stores. Overall, the flora of the area is quite well preserved; 95–100 % of which is represented by native species. The living ground cover is noticeably damaged in the most actively used sites (fragments of trails and vista points). They feature a poor species composition, shrinking of the herb-dwarf shrub and moss-lichen cover, and a low percent cover of grassland and ruderal species. Easily accessible and actively visited sites have no or reducing amounts of tree seedlings, the tree stand is damaged and forest regeneration is hampered – the number of viable seedlings is minimal (100 pcs/ha). The mass of roots below 3 mm in diameter in heavily trampled trails showed a reduction of up to 74 %, while the root saturation in less affected trails slightly increased. Recreation transformations of the plant communities have not resulted in a loss of their resilience so far. The recreational digression in the studied sites was classified into stages I–III (weakly disturbed – strongly disturbed). Function zoning of the area should be modified using recreation-tolerant communities more intensively in order to reduce recreation impact. The most damaged areas, which are losing their stability, should be excluded from active use by modification of walking trails and building additional boardwalks.

Impact of climate, soil properties and grassland cover on soil water repellency

Numerous soil water repellency (SWR) studies have investigated the possible causes of this temporal phenomenon, yet there remains a lack of knowledge on the order of importance of the main driving forces of SWR in the context of changing environmental conditions under grassland ecosystems. To study the separate and combined effects of soil texture, climate, and grassland cover type on inducing or altering SWR, four sites from different climatic and soil regions were selected: Ciavolo (CI, IT), Csólyospálos (CSP, HU), Pwllpeiran (PW, UK), Sekule (SE, SK). The investigated parameters were the extent (determined by repellency indices RI, RIc and RIm) and persistence (determined by water drop penetration time (WDPT) and water repellency cessation time, WRCT) of SWR, as well as field water (Sw) and ethanol (Se) sorptivity, water sorptivity of hydrophobic soil state (Swh) water sorptivity of nearly wettable soil state (Sww) and field hydraulic conductivity (K). Our findings showed an area of land has a greater likelihood of being water repellent if it has a sandy soil texture and/or a high frequency of prolonged drought events. Water infiltration was positively correlated with all the sorptivities (r = 0.32–0.88), but was mostly negatively correlated with RI (r = – 0.54 at CI), WDPT (r = – 0.47 at CI) and WRCT (r = – 0.58 at CI). The importance of natural and synanthropized vegetation covers with regards to SWR was not coherent; moving to regions having coarser texture or moving to drier climatic zones led to higher risk of SWR conditions. Climate change has been predicted to lead to more frequent extreme weather events and prolonged dry periods across Europe, which will most likely increase the extent of SWR-affected areas and increase the role of SWR in water management of grassland ecosystems. Therefore, there is a need to determine SWR risk zones to prevent decreases in soil moisture content, soil fertility, carbon and nitrogen sink potentials, as well as biomass production of the related agro-ecosystems.

Event-based hydrology and sedimentation in paired watersheds under commercial eucalyptus and grasslands in the Brazilian Pampa biome

Ecological and hydrological impacts are expected when watersheds are under commercial eucalyptus. In this study we evaluated event-based hydrology and sedimentation in paired watersheds under commercial eucalyptus and grasslands cover. Flow, suspended sediment concentration, and sediment production were measured and simulated with the Limburg Soil Erosion Model (LISEM) in paired hydrographic watersheds located in southern Brazil; one occupied with 7-years old Eucalyptus saligna plantation (forest watershed-FW; 0.83 km2) and another Pampa biome with native and exotic grasses used for beef cattle production (grassland watershed-GW; 1.10 km2). The effect of rainfall on hydrological and sedimentological variables was more evident in GW compared with FW. The shape of the hydrograph was steepest in GW, with rapid, marked increase and decrease in flow during rainfall. The parameters changed for model calibration in FW and GW were soil saturated hydraulic conductivity, initial soil moisture, and Manning roughness coefficient, whereby the statistical performance was classified as good (NSE> 0.75). Fourteen events different from those used in the calibration process were validated for FW and GW, with NSE index classified as “good” and “very good” for hydrology. Our study shows limitations of LISEM in calibrating and validating the sediment yield for individual events due to the spatial variability of factors controlling soil erosion. The validated modeling results of this study may be applied in simulating soil and crop scenarios in watersheds cultivated with commercial forest and grassland for grazing.

Disentangling Drought and Grazing Effects on Soil Carbon Stocks and CO2 Fluxes in a Semi-Arid African Savanna

Grasslands cover ca. 30% of the global land surface and provide critical ecosystem services. Among them, carbon storage is one of the most important. However, grasslands are increasingly threatened by drought and overgrazing which might negatively affect soil carbon stocks. Despite this threat, there is a dearth of information on how drought and grazing jointly impact soil carbon stocks and CO2 fluxes in dryland grasslands. With the aid of a large field experiment, we studied the combined effects of a five-year extreme drought and moderate grazing on soil carbon stocks, CO2 fluxes and soil chemical properties. Extreme drought was induced by reducing ambient rainfall by 66% using large rainout shelters. We found CO2 fluxes to strongly respond to the five-year experimental drought. Extreme drought reduced CO2 emission rates by 32% compared to ambient conditions. CO2 fluxes averaged 5.7 mg m-2min-1 under drought compared to 8.3 mg m-2 min-1 under ambient conditions. CO2 fluxes were however not influenced by grazing. At the end of the growth period, grazed plots under ambient rainfall had released 16.3 tons of CO2 ha-1 which was 58% higher than observed on grazed plots subjected to severe drought. Soil carbon stocks were higher under drought conditions due to slower decomposition rates. Drought resulted in increased concentrations of primary macronutrients (N, P, and K), micronutrients (Zn and Mn) and pH in the top 30 cm of the soil relative to ambient conditions. The results also showed that grazing reduced the concentration of N and P in the topsoil compared to the ungrazed plots. This study provided insights on the soil carbon storage, CO2 emission rates and nutrient dynamics in a semi-arid dryland grassland as influenced by both drought and grazing. Our study also revealed that long-term extreme drought may be favourable in terms of preserving the existing soil carbon stocks through reduced CO2 release. This finding is critical for understanding future soil carbon dynamics in dryland grasslands in the face of climate change.

Roadsides provide refuge for orchids: characteristic of the surrounding landscape.

Seminatural habitats are declining throughout the world; thus, the role of small anthropogenic habitats in the preservation of plants is becoming increasingly appreciated. Here, we surveyed the orchid flora of roadside verges in five Central European countries (Austria, Hungary, Romania, Slovakia, and Slovenia) and tested how the surrounding landscape matrix affects the overall number of species and individuals, and also different functional groups of orchids. We found more than 2,000 individuals of 27 orchid species during our surveys. According to our results, the increasing coverage of agricultural and urban areas negatively affects both the number of orchid species and individuals on roadsides. Our study further suggests that differences in the surrounding habitats affect which species are found on roadsides, since the increasing coverage of grasslands or forested areas around orchid occurrences had a significant positive effect on the number of grassland or forest‐dwelling species and individuals, respectively. Most variance in orchid numerosity and diversity was explained by the cover of the suitable habitat types of the respective taxa in the surrounding landscape of the sampling points. This highlights the importance of roadsides acting as refugia for numerous species and valuable plant communities as well as in supporting biodiversity in general.

Grassland-to-crop conversion in agricultural landscapes has lasting impact on the trait diversity of bees

ContextGlobal pollinator decline has motivated much research to understand the underlying mechanisms. Among the multiple pressures threatening pollinators, habitat loss has been suggested as a key-contributing factor. While habitat destruction is often associated with immediate negative impacts, pollinators can also exhibit delayed responses over time.ObjectivesWe used a trait-based approach to investigate how past and current land use at both local and landscape levels impact plant and wild bee communities in grasslands through a functional lens.MethodsWe measured flower and bee morphological traits that mediate plant–bee trophic linkage in 66 grasslands. Using an extensive database of 20 years of land-use records, we tested the legacy effects of the landscape-level conversion of grassland to crop on flower and bee trait diversity.ResultsLand-use history was a strong driver of flower and bee trait diversity in grasslands. Particularly, bee trait diversity was lower in landscapes where much of the land was converted from grassland to crop long ago. Bee trait diversity was also strongly driven by plant trait diversity computed with flower traits. However, this relationship was not observed in landscapes with a long history of grassland-to-crop conversion. The effects of land-use history on bee communities were as strong as those of current land use, such as grassland or mass-flowering crop cover in the landscape.ConclusionsHabitat loss that occurred long ago in agricultural landscapes alters the relationship between plants and bees over time. The retention of permanent grassland sanctuaries within intensive agricultural landscapes can offset bee decline.

Habitat and weather conditions influence reproductive rates of suburban and rural Red‐shouldered Hawks Buteo lineatus

Both habitat and weather can strongly influence reproductive rates of birds. We measured reproductive rates of suburban and rural Red‐shouldered Hawks Buteo lineatus in southern Ohio, USA, from 1997 to 2016, and then tested how weather conditions and habitat in the areas surrounding the nest‐sites were related to two measures of reproductive rate. Reproductive rates of Red‐shouldered Hawks did not differ between the suburban and rural study areas, and were relatively stable from year to year. Suburban Red‐shouldered Hawks produced 2736 young in 1773 nesting attempts (i.e. nest with eggs) at 302 territories (1.54 young per nesting attempt), and rural‐nesting Hawks produced 996 young in 640 nesting attempts at 108 territories (1.56 young per nesting attempt). Annual nesting success averaged 58.9 ± 1.1% for suburban birds and 58.9 ± 2.1% for rural birds. Several factors influenced Red‐shouldered Hawk reproductive rates, measured as either the number of young per nesting attempt or the percentage of nesting attempts that were successful. Higher air temperatures during May (the nestling period) and increasing amounts of coniferous forest were associated with higher reproductive rates, whereas increasing April air temperatures and increasing amount of grassland cover had the opposite effect. Land cover variables associated with suburban landscapes, such as the amount of residential development, did not influence the number of young per nesting attempt or nesting success, suggesting that Red‐shouldered Hawks are welladapted to human‐dominated landscapes in southern Ohio. Our study also illustrates the value of long‐term datasets for improving our understanding of factors that affect raptors’ demographic parameters.

Compound-specific isotope analysis with nested sampling approach detects spatial and temporal variability in the sources of suspended sediments in a Scottish mesoscale catchment

Intensification of land use is a primary cause of increased suspended sediment load in freshwater systems, hence land-use-specific sediment source tracing is necessary to inform sustainable land and water management. Here we tested the application of compound-specific isotope analysis (CSIA) of vegetation biomarkers to fingerprint suspended sediment sources from the mesoscale agricultural Tarland catchment (74 km2) in NE Scotland. Our aim was to test a parsimonious nested sampling approach from a headwater sub-catchment to apportion suspended sediment sources across headwater to catchment-wide scales. Compound-specific carbon isotopic signatures (δ13C) of long-chain fatty acids (LCFAs) from source soils were able to successfully distinguish between forest, heather moorland, permanent grassland, and arable land cover. Permanent grassland was a prominent source of sediment at both headwater and catchment scales, with an annual average contribution of 79% and 56%, respectively, indicating grazing pressure and runoff via preferential pathways. Increased sediment input from arable land at the catchment scale (40%) compared to the headwater sub-catchment (18%) indicated land use intensification in lowland areas. Forest and heather moorland contributed marginally to suspended sediments (~2%), despite covering 43% area of the catchment area. Temporal variability of sediment sources observed over fourteen months (May 2017 – June 2018) showed a higher relative contribution from arable land during summer and autumn and a higher contribution from permanent grassland during winter and spring, likely linked to seasonality of rainfall and agronomic activities.These results demonstrate a successful use of δ13C values of LCFAs to quantify land-use-specific suspended sediment sources. Comparison of two suspended sediment techniques showed usefulness of time-integrated mass samplers for representative and cost-effective sampling. We recommend that future nested sampling designs should include spatially distributed source soil tracer characterization covering the whole catchment area to reduce the uncertainty in sediment source attribution from headwaters to the catchment outlet.

Postglacial evolution of forest and grassland in southeastern Gobi (Northern China)

Increasing afforestation efforts are made in the southeastern Gobi in the Inner Mongolia Autonomous Region of China, where tree and grass coexist. However, afforestation that does not consider climate carrying capacity and afforestation at the cost of grassland reduction have caused more and more drawbacks, although forests are of global significance for preventing dust storm emission. Reconstructions of historical forest and grassland cover, forest-grassland interactions, and drivers are urgently required to test the predictions of ecosystem models that support afforestation. Based on a robust reconstruction method applied to a 19,000-year long pollen sequence from northern China, we show that tree cover peaked during the early Holocene (30.7 ± 12.3%) and gradually declined to 13.2 ± 4.3% during the last two centuries. Temperature, precipitation, and fire drove the postglacial evolution of tree and grass cover, and forest may suppress grassland when tree cover is higher than 13.8%. Our study suggests that a cautious approach should be taken regarding the risks posed by afforestation efforts in the southeastern Gobi.

Interaction of climate change and nitrogen deposition on subalpine pastures

AbstractAimsNitrogen (N) deposition causes compositional shifts in subalpine grassland, which can threaten their high plant species diversity. The effects of the interaction of N deposition and climate change are unknown. What are the independent and joint effects of N deposition, warming and water stress on plant functional group cover in subalpine grassland? Do these results apply to the main grassland types of this region typical of base‐poor and ‐rich soils? What vegetation changes can we expect with the current N critical load limits in a warmer future?LocationCentral Alps, southeast Switzerland.MethodsA fully‐factorial three‐way transplant experiment was established, with a water treatment and three‐level N addition (+0, +3, +15 kg N·ha−1·year−1) along an elevation gradient representing temperature changes of −1.4 to +3.0°C. In all, 216 monoliths, sourced from six summer pastures and with vegetation typical of base‐poor and base‐rich soils, were grown in the experimental site for five years. The cover of functional groups (grasses, sedges, forbs and legumes) was estimated annually.ResultsNitrogen addition increased sedge cover only at cooler sites. Grass cover was higher at warmer compared to cooler sites, but the watering treatment reversed this pattern. N addition increased grass cover at warmer sites. Legumes showed a unimodal temperature response with maximum cover at +0.7 to +1.8°C. Further warming decreased their cover and also that of forbs. Watering increased the cover of the latter two functional groups at warmer sites especially.ConclusionsIn subalpine grassland, the stimulating effect of increased N on sedge cover is dampened by increased temperatures in both grassland types. Within the current critical N load limits, however, a distinct compositional change — increased grass cover — is expected in a warmer climate. Forb and legume cover decreases with temperature increases greater than 2°C, attributable to both water deficit and temperature.

Ecological Risk Assessment Based on Land Cover Changes: A Case of Zanzibar (Tanzania)

Land use and land cover (LULC) under improper land management is a major challenge in sub-Saharan Africa and has drastically affected ecological security. Addressing environmental impacts related to this challenge requires efficient planning strategies based on the measured information of land use patterns. This study assessed the ecological risk index (ERI) of Zanzibar based on LULC. A random forest classifier was used to classify three Landsat images of Zanzibar for the years 2003, 2009, and 2018. Then, a land change model was employed to simulate the LULC changes for 2027 under a business-as-usual (BAU), conservation, and extreme scenarios. Results showed that the built-up areas and farmland of Zanzibar Island have increased constantly, while the natural grassland and forest cover have decreased. The forest, agricultural, and grassland were highly fragmented into several small patches. The ERI of Zanzibar Island increased at a constant rate and, if the current trend continues, this index will increase by up to 8.9% in 2027 under an extreme scenario. If a conservation scenario is adopted, the ERI will increase by 4.6% whereas if a BAU policy is followed, this value will increase by 6.2%. This study provides authorities with useful information to understand better the ecological processes and LULC dynamics and prevent unmanaged growth and haphazard development of informal housing and infrastructure.

Agricultural intensification is causing rapid habitat change in the Tonle Sap Floodplain, Cambodia

The Tonle Sap Lake and Floodplain (TSLF) supports many globally threatened species and its fishery has sustained Cambodia’s people for millennia. The rate of habitat loss has accelerated in recent years due to political and economic conditions, and a warming climate and El Nino events that created opportunities for people to burn scrubland at an elevated rate. Here, we use a point-based landcover assessment method to document the impacts of local-scale drivers, in particular agricultural intensification, on habitat trends between 1993 and 2018. The areal extent of scrubland and grassland in the TSLF declined from ~ 74% in 1993 to ~ 52% in 2018, as a result of intensification and expansion of rice cultivation. During that time period, grassland cover declined from ~ 3160 to ~ 519 km2, whilst between 2008 and 2018, scrubland cover declined from ~ 8660 to ~ 6776 km2. Habitat loss has had catastrophic implications for grassland-dependant species, such as Bengal Florican, and, we estimate that habitat changes in the TSLF may have caused carbon stocks to decline by 12% while fish productivity is also likely to have dropped, with significant implications for food security. To put this habitat loss in context, losses over the past 10 years have been nearly twice as large as published predictions of the amount likely to be lost between 2010 and 2040 due to hydropower. We suggest that the expansion and intensification of rice cultivation is the greatest current threat to habitats in the TSLF and deserves greater attention from policy makers and practitioners.

Assessment of endemic northern swamp deer (Rucervus duvaucelii duvaucelii) distribution and identification of priority conservation areas through modeling and field surveys across north India

Recent declines in large herbivores have led to significant conservation efforts globally. However, the niche-specific megaherbivores residing outside protected areas face more imminent extinction threats. Swamp deer, the obligate grassland-dwelling endemic cervid is the most extinction-prone megaherbivore in the Indian subcontinent. Limited information on distribution and habitat status pose significant conservation and management challenges for the remaining fragmented populations in north, north-east and central India. To this end, we combined exhaustive field surveys and Maximum Entropy (MaxEnt) modeling to generate the most detailed distribution map for the northern swamp deer subspecies. We used primary data from more than 6000 km2 field surveys and eight ecologically relevant covariates for model predictions. Grassland cover, annual mean temperature and distance from water were the major factors that predicted the species distribution. Models predicted swamp deer distribution in only ~3% of the entire landscape, covering both protected (~1.4%) as well as non-protected (~1.6%) areas. Our validation surveys in some of these predicted areas confirmed swamp deer presence and indicated ~85% model accuracy. Finally, we identified four ‘‘Priority Conservation Areas’’ still retaining adequate grassland habitat and species presence that require immediate attention to ensure landscape-level population connectivity. These results highlight the importance of the marginalized grassland ecosystems of northern India that still retain high biodiversity. We suggest a swamp deer-centric conservation approach to protect these human-dominated habitats and emphasize in generating such information for other endemic, habitat-specialist species across the globe.

Wetland Ecosystem Service Dynamics in the Yellow River Estuary under Natural and Anthropogenic Stress in the Past 35 Years

Assessing long-term dynamics of ecosystem service is critical for sustainable restoration and management of estuarine wetlands. We analyzed ecosystem services dynamics from 1980 to 2015 and their natural and anthropogenic drivers in the Yellow River Delta National Nature Reserve, which consists of the old and current Yellow River estuaries. Our results showed that biodiversity conservation, carbon storage, and water purification services in the old Yellow River estuary were improved gradually, but water yield decreased during the study period. Ecosystem services in the current Yellow River estuary changed sharply during 1980–1990, but fluctuated since 1990. The warming climate in the past 35 years negatively affected water yield and enhanced carbon storage in the old Yellow River estuary. Marshland was critical for improving ecosystem services in the old Yellow River estuary, and medium cover grassland provided suitable habitats for water birds in the current Yellow River estuary. Furthermore, the release of freshwater from the Yellow River into estuarine wetlands enhanced the provision of ecosystem services. In comparison with biodiversity conservation, water purification, and carbon storage services, water supply service responded differently to ecological restoration. Better tradeoffs should be identified to ensure effective provision of desired ecosystem services during ecological restoration.

Köppen’s climate classification projections for the Iberian Peninsula

Projections of Köppen-Geiger climate classifications under future climate change for the Iberian Peninsula are investigated using a 7-ensemble mean of regional climate models obtained from EURO-CORDEX. Maps with predicted future scenarios for temperature, precipitation and Köppen-Geiger classification are analyzed for RCP4.5 and RCP8.5 in Iberia. Widespread statistically significant shifts in temperature, precipitation and climate regimes are projected in the 2041-2070 period, with greater shifts occurring under RCP8.5. An overall increase in temperature and a decrease in precipitation in the south-southeast is predicted. Of the two climate types, dry (B) and temperate (C), the dominant one was C in 86% of Iberia for 1961-1990, predicted to decrease by 8.0% by 2041-2070 under RCP4.5 (9.5% under RCP8.5). The hot-summer Mediterranean climate (CSa) will progressively replace CSb (warm-summer climate) in the northwestern half of Iberia until 2070. This shift, depicted by the SSIM index, is particularly noticeable in Portugal, with the projected establishment of the CSa climate by 2041-2070. The predicted retreat of humid subtropical (Cfa) and temperate oceanic (Cfb) areas in the northeast towards the Pyrenees region is noteworthy, as is the increase of desert (BW) and semi-desert (BS) climates (7.8 and 9%) in the southeast (between Granada and Valencia). Climate types BSh and BWh (hot semi-desert and hot desert, respectively), non-existent in the 1961-1990 period, are projected to represent 2.8% of the territory in 2041-2070 under RCP4.5 (5% under RCP8.5). The statistically significant projected changes hint at the disappearance of some vegetation species in certain regions of Iberia, with an expected increase in steppe, bush, grassland and wasteland vegetation cover, typical of dry climates in the southeast.

Changes in grassland cover and in its spatial heterogeneity indicate degradation on the Qinghai-Tibetan Plateau

Arid grassland ecosystems undergo degradation because of increasing environmental and human pressures. Degraded grasslands show vegetation cover reduction and soil-patch development, leading to grassland fragmentation and changes in spatial heterogeneity. Understanding grassland degradation that involves soil-patch development remains a challenge over large areas with limited accessibility such as the Qinghai-Tibetan Plateau. We hypothesized that vegetation cover, its spatial heterogeneity and changes thereof over time retrieved from satellite data can indicate grassland development and degradation levels. To test the hypothesis, we studied these indicators from 2000 to 2016 and related them to previously described degradation levels on the eastern Qinghai-Tibetan Plateau (QTP) in 2004. We further use these indicators to map the new grassland development and degradation levels in 2016.We found that lower vegetation cover does not always indicate a more severe degradation; instead, higher spatial heterogeneity is a better correlate of degradation. Combined temporal changes in grassland cover and its spatial heterogeneity are related to the literature-defined degradation levels. We found that grassland areas on the eastern QTP have moved into new degradation stages from 2000 to 2016 using changes in grassland cover and its spatial heterogeneity as indicators. The normalized difference vegetation index (NDVI) as a proxy for grassland cover declined over time in the literature-defined degraded areas but increased in the desert areas from 2000 to 2016. Spatial heterogeneity generally increased across different degradation levels from 2000 to 2016; however, this increase was less pronounced in severely degraded and slightly deserted areas. Our newly defined degradation levels in 2016 included degradation, desertification, and improving levels. Across our study area, 63% of all areas were classified as degraded and 2% were at risk of desertification. The remaining areas (35%) classified as improving and re-growing occurred in higher-elevation or previously severely degraded grassland. Our study demonstrates that a combination of changes in grassland cover and in its spatial heterogeneity can indicate grassland degradation levels and serve as an early-warning signal for desertification threats.

Spatially Explicit Reconstruction of Anthropogenic Grassland Cover Change in China from 1700 to 2000

Long-term anthropogenic land use and land cover changes (LULCCs) are regarded as an important component of past global change. The past 300 years have witnessed dramatic changes in LULCC in China, and this has resulted in the large-scale conversion of natural vegetation to agricultural landscapes. Studies of past LULCC in China have mainly focused on cropland and forest; however, estimates of grassland cover remain rare due to the scarcity of grassland-related historical documents. Based on a qualitative analysis of trends in grassland cover in China and their driving forces, we devised different reconstruction methods for grassland cover in eastern and western China and then developed a 10 km database of grassland cover in China for the past 300 years. The grassland area in western China decreased from 295.54 × 106 ha in 1700 to 269.78 × 106 ha in 2000 due to the increase in population and cropland, especially in northeastern China (Heilongjiang, Jilin, and Liaoning), Gan-Ning, and Xinjiang. In eastern China, grassland is degraded secondary vegetation characterized by shrub grassland and meadow grassland, which is scattered in the hills and mountains; its area increased from 7.30 × 106 ha in 1700 to 16.43 × 106 ha in 1950 due to the increase in the degraded land caused by deforestation.

Incidencia del fuego en un gradiente altitudinal de las sierras del centro de la Argentina

Fil: Arganaraz, Juan Pablo. Comision Nacional de Actividades Espaciales. Instituto de Altos Estudios Espaciales Mario Gulich; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba; Argentina

Landscape composition and configuration have scale-dependent effects on agricultural pest suppression

Increasing landscape heterogeneity (composition and configuration) can enhance natural enemy populations and support pest suppression in agricultural landscapes. Using a network-based data mining approach, we examined independent gradients of landscape composition and configuration at six spatial scales that were associated with pest suppression services measured at 32 sites in Michigan and Wisconsin, USA. We compared the relative effects of landscape composition and configuration across scales with those of local crop type (corn or grassland). We found that multiple gradients of configurational heterogeneity were independent of composition and strongly associated with pest suppression, with different configuration metrics being predictive of pest suppression depending on the spatial scales and regions considered. Landscapes that were more configurationally heterogeneous at smaller spatial scales consistently supported higher pest suppression. In Michigan, pest suppression increased in landscapes with high edge contrast between annual crops and surrounding habitats and high edge density of grassland within 250−500 m radii. In Wisconsin, pest suppression increased with large core area of grassland and high field density within a 250 m radius. The main compositional effect we found was a positive relationship between grassland cover and pest suppression occurring at larger spatial scales (1000−1500 m) and occurring in Wisconsin but not in Michigan. Our findings demonstrate that effects of landscape composition and configuration on pest suppression differ across spatial scales and vary regionally. The network-based data mining techniques used here could be useful for disentangling intercorrelated landscape metrics in a variety of other contexts in landscape ecology.

Confronting an individual-based simulation model with empirical community patterns of grasslands.

Grasslands contribute to global biogeochemical cycles and can host a high number of plant species. Both–species dynamics and biogeochemical fluxes–are influenced by abiotic and biotic environmental factors, management and natural disturbances. In order to understand and project grassland dynamics under global change, vegetation models which explicitly capture all relevant processes and drivers are required. However, the parameterization of such models is often challenging. Here, we report on testing an individual- and process-based model for simulating the dynamics and structure of a grassland experiment in temperate Europe. We parameterized the model for three species and confront simulated grassland dynamics with empirical observations of their monocultures and one two-species mixture. The model reproduces general trends of vegetation patterns (vegetation cover and height, aboveground biomass and leaf area index) for the monocultures and two-species community. For example, the model simulates well an average annual grassland cover of 70% in the species mixture (observed cover of 77%), but also shows mismatches with specific observation values (e.g. for aboveground biomass). By a sensitivity analysis of the applied inverse model parameterization method, we demonstrate that multiple vegetation attributes are important for a successful parameterization while leaf area index revealed to be of highest relevance. Results of our study pinpoint to the need of improved grassland measurements (esp. of temporally higher resolution) in close combination with advanced modelling approaches.