Wooded Grassland Research Articles

Assessment of Methods for Land Surface Temperature Retrieval from Landsat-5 TM Images Applicable to Multiscale Tree-Grass Ecosystem Modeling

Land Surface Temperature (LST) is one of the key inputs for Soil-Vegetation-Atmosphere transfer modeling in terrestrial ecosystems. In the frame of BIOSPEC (Linking spectral information at different spatial scales with biophysical parameters of Mediterranean vegetation in the context of global change) and FLUXPEC (Monitoring changes in water and carbon fluxes from remote and proximal sensing in Mediterranean “dehesa” ecosystem) projects LST retrieved from Landsat data is required to integrate ground-based observations of energy, water, and carbon fluxes with multi-scale remotely-sensed data and assess water and carbon balance in ecologically fragile heterogeneous ecosystem of Mediterranean wooded grassland (dehesa). Thus, three methods based on the Radiative Transfer Equation were used to extract LST from a series of 2009–2011 Landsat-5 TM images to assess the applicability for temperature input generation to a Landsat-MODIS LST integration. When compared to surface temperatures simulated using MODerate resolution atmospheric TRANsmission 5 (MODTRAN 5) with atmospheric profiles inputs (LSTref), values from Single-Channel (SC) algorithm are the closest (root-mean-square deviation (RMSD) = 0.50 °C); procedure based on the online Radiative Transfer Equation Atmospheric Correction Parameters Calculator (RTE-ACPC) shows RMSD = 0.85 °C; Mono-Window algorithm (MW) presents the highest RMSD (2.34 °C) with systematical LST underestimation (bias = 1.81 °C). Differences between Landsat-retrieved LST and MODIS LST are in the range of 2 to 4 °C and can be explained mainly by differences in observation geometry, emissivity, and time mismatch between Landsat and MODIS overpasses. There is a seasonal bias in Landsat-MODIS LST differences due to greater variations in surface emissivity and thermal contrasts between landcover components.

Contrasting long‐term records of biomass burning in wet and dry savannas of equatorial East Africa

Rainfall controls fire in tropical savanna ecosystems through impacting both the amount and flammability of plant biomass, and consequently, predicted changes in tropical precipitation over the next century are likely to have contrasting effects on the fire regimes of wet and dry savannas. We reconstructed the long-term dynamics of biomass burning in equatorial East Africa, using fossil charcoal particles from two well-dated lake-sediment records in western Uganda and central Kenya. We compared these high-resolution (5 years/sample) time series of biomass burning, spanning the last 3800 and 1200 years, with independent data on past hydroclimatic variability and vegetation dynamics. In western Uganda, a rapid (<100 years) and permanent increase in burning occurred around 2170 years ago, when climatic drying replaced semideciduous forest by wooded grassland. At the century time scale, biomass burning was inversely related to moisture balance for much of the next two millennia until ca. 1750 ad, when burning increased strongly despite regional climate becoming wetter. A sustained decrease in burning since the mid20th century reflects the intensified modern-day landscape conversion into cropland and plantations. In contrast, in semiarid central Kenya, biomass burning peaked at intermediate moisture-balance levels, whereas it was lower both during the wettest and driest multidecadal periods of the last 1200 years. Here, burning steadily increased since the mid20th century, presumably due to more frequent deliberate ignitions for bush clearing and cattle ranching. Both the observed historical trends and regional contrasts in biomass burning are consistent with spatial variability in fire regimes across the African savanna biome today. They demonstrate the strong dependence of East African fire regimes on both climatic moisture balance and vegetation, and the extent to which this dependence is now being overridden by anthropogenic activity.

Water utilization of Pinus sylvestris var. mongolica in a sparse wood grassland in the semiarid sandy region of Northeast China

Key message Mongolian pine in a sparse wood grassland stand maintains a relatively stable state under the current water conditions by varying its water use sources at a constant water use efficiency.

Development of secondary woodland decreases epiphyte metapopulation sizes in wooded grasslands

Abandoned management of wooded grasslands leads to development of secondary woodland. We investigated how this development affects the colonization–extinction dynamics and persistence of epiphytic lichens associated with old trees. We modelled colonization probability based on observed colonizations (turnover data) during four years of two old-oak-associated lichens on 1236 oaks. Persistence was assessed by projections of future dynamics. We also used the turnover models to validate models fitted to snapshot data (from one point in time). Epiphyte colonization probabilities were lower on trees in closed than in open conditions, and the probabilities increased with increasing connectivity to surrounding occupied trees. The additional four study species had too few colonizations to be modelled, and thus, very low colonization rates. Local extinctions occurred only deterministically through patch destruction processes. In projections of future metapopulation dynamics, when assuming that all trees were in closed conditions, the metapopulations decreased slowly; new equilibria had not been reached after 200years. In contrast, when assuming open conditions for all trees, to test for effects of clearing vegetation around oaks in closed conditions, the metapopulations increased comparatively fast. The turnover models and the snapshot models, gave similar projections of metapopulation sizes, when assuming that the present level of secondary woodland remained constant over time. Development of secondary woodland in wooded grassland has negative impacts on epiphyte metapopulations. However, the slow metapopulation declines suggest that restoration will be successful. High priority should be given to resumed grazing and clearing vegetation around old trees, in particular close to dispersal sources.

Variation in soil C and microbial functions across tree canopy projection and open grassland microenvironments

Mixtures of grasslands and perennial woody crops or vineyards represent a major source of potential carbon storage or release. Understanding the spatial variability of soil properties in these ecosystems is important in determining soil constraints related to the management of soil resources. The aims of the study were 1) to explore the spatial variability associated to the trees for soil C storage and its components and reactivity; and 2) to assess the similarities between microenvironments in terms of microbial functional diversity. Eight microenvironments characterized by different long-term soil management practices and different positions with respect to woody plant canopy soil vertical projections were selected in a Mediterranean agropastoral system. Four management types were considered: pasture, hay crop, grass-covered vineyard, and tilled vineyard. Soil organic C, microbial biomass, and respiration were measured to assess C storage and dynamics, while functional diversity was determined by means of soil enzyme activities. The results showed that the microenvironmental variation of soil organic C and functional microbial diversity generated by the tree canopies in the wooded grassland can be very relevant for an accurate assessment of soil organic C content and its dynamics. The same was not applicable to vineyards, where the spatial variation of both soil organic C and functional diversity was negligible, independently of the soil management practices. These results suggest that in such systems the microscale spatial variability generated by the trees is worth of further investigation for improving our understanding of the long-term management effects on soil C dynamics.

Using partial volumes to estimate available browse biomass in Southern African semi-arid savannas

Aims With the increase of game farming in woody areas, as well as the pressing need to assess the spatial distribution of carbon, the quantification of available browse biomass has become an important subject to refine. We aimed to (1) calculate tree canopy volume (CVol) for varying tree canopy shapes and for strata within those shapes to cater for different herbivore browse heights, (2) develop a relation to estimate available browse of deciduous (micro- and mesophyllous) and evergreen (macrophyllous) semi-arid savanna tree species using our calculated CVols, and (3) demonstrate the application of the use of partial volumes and the resultant regression models in the determination of available browse biomass for browsing game species. Location Four key savanna tree species were sampled in the open wooded grassland areas of three game reserves in northeastern KwaZulu-Natal, South Africa: Bonamanzi Game Park, Mun-Ya-Wana Private Game Reserve and Pongola Game Reserve. Methods Tree CVol determination involved calculation of partial volumes, using the integration of a series of circles, allowing a wider range of tree shapes to be included. Non-linear regression was used to investigate the relation between available browse biomass of deciduous microphyllous Acacia nilotica, evergreen macrophyllous Euclea divinorum and Gymnosporia senegalensis and deciduous mesophyllous Spirostachys africana and their respective calculated partial CVols. Results Exponential non-linear regression of the natural logarithm of CVol data provided an accurate and precise description of the tree CVol–available browse biomass relation. Significant relations were obtained over a 2-yr period (2003–2004) for species–site models and general species models. The incorporation of tree foliage densities in available browse biomass estimation further improved model accuracy and precision. Conclusion The general models provided an objective means of determining the browsing capacity of a tree population. In addition, estimation of carbon sequestration could be related to the model output, particularly when changes over time are recorded. Regular measurement of available browse comprises a useful monitoring tool to evaluate impact of animals on trees and shrubs.

Stable isotope analyses of tooth enamel carbonate of large herbivores from the Tugen Hills deposits: Palaeoenvironmental context of the earliest Kenyan hominids

Understanding shifts in past climatic and environmental conditions are crucial for throwing light on human evolution. Available reconstructions of the palaeoecology of faunal and floral assemblages indicate that the earliest Kenyan hominids, including Orrorin tugenensis, are associated with forest landscapes. In this study, we present stable isotope data of tooth enamel carbonate of large herbivores associated with these hominids in order further to evaluate their environmental context. Fossil teeth were sampled in the Lukeino Formation (6.1–5.7 Ma, Late Miocene) and the Mabaget Formation (5.3–4.5 Ma, Early Pliocene) at the foot of the Tugen Hills (Great Rift Valley). Despite chemical changes in fossil enamel, preservation of the palaeoenvironmental signals is supported by the difference in δ18O between hippos and terrestrial fauna. Moreover, the giraffid specimen from the Mabaget Formation exhibits one of the highest δ18O values, as expected for a drought-tolerant animal. The δ13C of large herbivores indicates that the earliest Kenyan hominids inhabited a mixed C3–C4 environment as did Ardipithecus (Ethiopia) and Sahelanthropus (Chad), two early putative hominids. The Tugen Hills might have been a wooded grassland with patches of woodland. There is no record of closed-canopy forest at the time of deposition. We emphasize differences in food habits among herbivore groups. Deinotheres, nearly all elephantids and the giraffid individual had a C3 diet which reflected browsing behaviour. The intake of C4 plants prevailed for equids and gomphotheres and was consistent with grazing habits. Most hippos and suids were mixed C3–C4 feeders and consequently were generalist herbivores. Bovids and rhinos had a diet ranging from C3 to C4 plants. Variations in δ13C and δ18O among faunal assemblages suggest changes in local climate and vegetation. Moister conditions likely occurred in the Early Pliocene and the latest Miocene (ca. 5.7 Ma) than before. The C3 plant biomass would have increased in the latest Miocene. There were probably denser stands of trees within the depositional environment during the Early Pliocene than in the Late Miocene, which is consistent with palaeontological studies.

Assessment Impacts of Weather and Land Use/Land Cover (LULC) Change on Urban Vegetation Net Primary Productivity (NPP): A Case Study in Guangzhou, China

Net primary productivity (NPP) can indicate vegetation ecosystem services ability and reflect variation response to climate change and human activities. This study applied MODIS-1 km NPP products to investigate the NPP variation from 2001 to 2006, a fast urban expansion and adjustment period in Guangzhou, China, and quantify the impacts of weather and land use/land cover (LULC) changes, respectively. The results showed that the NPP mean value increased at a rate of 11.6 g∙C∙m−2∙yr−1 during the initial three years and decreased at an accelerated rate of 31.0 g∙C∙m−2∙yr−1 during the final three years, resulting in a total NPP loss of approximately 167 × 106 g∙C. The spatiotemporal of NPP varied obviously in the central area, suburb and exurb of Guangzhou driven by three patterns of weather and LULC changes. By the interactive effects and the weather variation dominated effects, NPP of most areas changed slightly with dynamic index less than 5% of NPP mean value in the central area and the suburb. The LULC change dominated effects caused obvious NPP reduction, by more than 15% of the NPP mean value, which occurred in some areas of the suburb and extended to the exurb with the outward urban sprawl. Importantly, conversion from wood grassland, shrublands and even forests to croplands occupied by urban landscapes proved to be a main process in the conversion from high-NPP coverage to low-NPP coverage, thereby leading to the rapid degradation of urban carbon stock capacity in urban fringe areas. It is helpful for government to monitor urban ecological health and safety and make relevant policies.

Biodiversity composition reflects the history of ancient semi-natural woodland and forest habitats—Compilation of an indicator complex for restoration practice

For centuries, Fennoscandian wooded meadows and woodland pastures (Habitats Directive habitat types *6530 and 9070 respectively) covered large areas of Northern Europe. In the Twentieth Century, abandonment-driven encroachment has led to the wooded grasslands changing into what may be considered as old-growth deciduous forests. The present paper examined whether the present stand structure and the composition of three contrasting functional groups (herbaceous layer vascular plants, epiphytic bryophytes, and earthworms) could serve as indicators of the historic origin of the forest patches, i.e. to what extent changes in ecological conditions in overgrown woodlands have shifted towards broad-leaved forests with ancient trees. Indicators were tested for the objective of restoration planning of habitat quality, i.e. whether semi-open woodlands could be restored or if it would be more appropriate to preserve them as broad-leaved forests. The study was carried out by comparing the composition of ancient forest cores, forest edges and overgrown wooded grasslands. The land use history of sample sites was examined from historical topographical maps and aerial photos.The results showed that as long as 60 years after abandonment, parts of the studied forests still retained some light-demanding plant species characteristic of historical wooded grasslands. The composition of earthworm communities was similar in all of the studied historical forest groups. Only some of the stand structure characteristics and epiphytic mosses indicated that there were differences between ancient forest cores and overgrown wooded grasslands. We conclude that the combination of various functional indicators should be used in the evaluation of successional woodlands for habitat restoration.

Impacts of Tree Rows on Grassland Birds and Potential Nest Predators: A Removal Experiment

Globally, grasslands and the wildlife that inhabit them are widely imperiled. Encroachment by shrubs and trees has widely impacted grasslands in the past 150 years. In North America, most grassland birds avoid nesting near woody vegetation. Because woody vegetation fragments grasslands and potential nest predator diversity and abundance is often greater along wooded edge and grassland transitions, we measured the impacts of removing rows of trees and shrubs that intersected grasslands on potential nest predators and the three most abundant grassland bird species (Henslow’s sparrow [Ammodramus henslowii], Eastern meadowlark [Sturnella magna], and bobolink [Dolichonyx oryzivorus]) at sites in Wisconsin, U.S.A. We monitored 3 control and 3 treatment sites, for 1 yr prior to and 3 yr after tree row removal at the treatment sites. Grassland bird densities increased (2–4 times for bobolink and Henslow’s sparrow) and nesting densities increased (all 3 species) in the removal areas compared to control areas. After removals, Henslow’s sparrows nested within ≤50 m of the treatment area, where they did not occur when tree rows were present. Most dramatically, activity by woodland-associated predators nearly ceased (nine-fold decrease for raccoon [Procyon lotor]) at the removals and grassland predators increased (up to 27 times activity for thirteen-lined ground squirrel [Ictidomys tridecemlineatus]). Nest success did not increase, likely reflecting the increase in grassland predators. However, more nests were attempted by all 3 species (175 versus 116) and the number of successful nests for bobolinks and Henslow’s sparrows increased. Because of gains in habitat, increased use by birds, greater production of young, and the effective removal of woodland-associated predators, tree row removal, where appropriate based on the predator community, can be a beneficial management action for conserving grassland birds and improving fragmented and degraded grassland ecosystems.

GIS를 활용한 부산지역의 해안·강변지역 열섬특성 분석

주거, 상업, 공공시설용지 등의 토지개발은 시외지역에 비하여 도심지역의 온도가 상승하는 원인이 되어왔다. 따라서 본 연구에서는 강변지역과 해안지역을 중심으로 연구지역을 선정하여 토지이용 및 기후변화에 따른 온도변화를 분석하였고, 또한 지형적 특징과 온도변화와의 상관관계를 알아보았다. 2003년에 비해 2007년 기온은 1.80℃ 증가하였고, 풍속은 0.24m/s 감소하였다. 또한 시가화 지역은 3.27% 증가하였고, 산림지역은 2.54% 감소하였다. 상관관계를 비교 분석한 결과 강변지역은 초지와 나지가, 해안지역은 산림과 초지에서 지형인자와 기후인자간의 상관성이 비교적 높게 나타났다. 이러한 연구결과는 지역 특성에 따라 열섬현상 문제에 대한 방안을 제시, 예측 등의 기초자료로 활용될 것으로 기대된다.

Effects of changes in management on resistance and resilience in three grassland communities

AbstractQuestionDiversification of grassland management is recommended as a tool for conservation of different taxonomic groups living in those habitats. How resistant and resilient are species‐rich grasslands in terms of plant species richness and vegetation composition to short‐term, small‐scale perturbations caused by changes in management practice?LocationBílé Karpaty Mountains, SE Czech Republic.MethodsThe experiment included the effect of six management regimes (mowing in June; mowing in September; mowing in June and September; mowing in June and high stubble left; no management; mowing in June and mulching). It was conducted in species‐rich wooded grasslands in the White Carpathians Mts., Czech Republic, represented by three types of plant community: a Bromus erectus community (with high species richness and low productivity), a Molinia arundinacea community (with high species richness and high productivity), and a Calamagrostis epigejos community (with low species richness and high productivity). After 3 yr, resistance was assessed, and traditional management (mowing once each year in June) was resumed; resilience was evaluated after three more years.ResultsWhile the species‐rich, unproductive Bromus community was relatively resistant to less intensive management in terms of species richness, and therefore its resilience could not be assessed, it changed substantially in terms of vegetation composition (maximum dissimilarity between control and abandoned plots was 63%). The more productive Molinia and Calamagrostis communities lost up to 37% of species due to abandonment, but not as a consequence of other changes management regimes. After the traditional management was resumed, resilience was higher in the Calamagrostis community than in the Molinia community. Vegetation composition was not affected by treatments.ConclusionsThe results show that short‐term abandonment causes loss of plant diversity in productive grasslands but not in less productive, species‐rich grasslands in the short term. Other relaxed management regimes (e.g. high stubble and delayed mowing) were comparable with the control and can be used for a short time to increase diversity of management without an effect on plant species richness. However, further research is needed to assess the effects of these management practices when they are applied repeatedly or over the long term.

Association between avian assemblages and mountain bushveld communities along a single mountain slope in the Usuthu Gorge, South Africa

The study investigated the bird species diversity associated with vegetation communities found on a single mountain slope in the Usuthu Gorge Community Conservation Area, northern KwaZulu-Natal. Thirteen sample sites were surveyed on a monthly basis for 12 months. Over this period, 279 birds and 55 species were recorded, of which the Dark-capped Bulbul Pycnonotus tricolor was the most abundant. The Rattling Cisticola Cisticola chiniana was the indicator species in the highest community, Open Bushveld, which is characterised by grassland and bush patches. The White-bellied Sunbird Cinnyris talatala was an indicator in the second-lowest community, Dense Bushveld–Woodland, which is characterised by steep slopes and thickets. In Wooded Grassland, located between the above two communities, the highest beta diversity (species turnover) was recorded and this outcome was probably caused by large areas covered by rocks that compelled woodland birds to move through this community. Contrary to expectation, the gamma diversity per vegetation community increased with elevation from 18 to 33 species in Dense Bushveld–Woodland, Wooded Grassland and Open Bushveld. A future study should measure bird species diversity on larger elevational gradients, i.e. slopes from 500 to 3 000 m above sea level, which also include more distinct vegetation communities.

Isotopic ecology of fossil fauna from Olduvai Gorge at ca 1.8 Ma, compared with modern fauna

Light stable isotope ratios (δ13C and δ18O) of tooth enamel have been widely used to determine the diets and water sources of fossil fauna. The carbon isotope ratios indicate whether the plants at the base of the food web used C3 or C4 photosynthetic pathways, while the oxygen isotope ratios indicate the composition of the local rainfall and whether the animals drank water or obtained it from plants. The contrasting diets of two early hominin species – Homo habilis and Paranthropus boisei – of ca 1.8 Ma (million years ago) in Tanzania were determined by means of stable carbon isotope analysis of their tooth enamel in a previous study. The diets of two specimens of P. boisei, from Olduvai and Peninj, proved to be particularly unusual, because 80% of their carbon was derived from C4 plants. It was suggested that their diet consisted primarily of plants, with particular emphasis on papyrus, a C4sedge. The dominance of C4 plants in the diet of P. boisei is a finding supported in another study of 22 specimens from Kenya. The isotopic ecology and diets of fossil fauna that were present at the same time as the two fossil hominin species are described here, in order to provide a fuller understanding of their contrasting diets and of the moisture sources of their water intake. This information was then compared with the isotopic composition of modern fauna from the same region of Tanzania. The carbon isotope ratios for both fossil and modern specimens show that the habitats in which these faunal populations lived were quite similar – grassland or wooded grassland. They had enough bushes and trees to support a few species of browsers, but most of the animals were grazers or mixed feeders. The oxygen isotope ratios of the fossil and modern fauna were, however, very different, suggesting strongly that the source of moisture for the rain in the Olduvai region has changed during the past 1.8 million years.

Long-term land-use and landscape dynamics in Budalen, central Norway

Humans have used resources in mountain landscapes for thousands of years, but the intensity and continuity of different land uses and the corresponding landscape changes are not well understood. This study examined long-term interactions between land use and landscapes in Budalen, central Norway, by using a multidisciplinary approach. Palaeoecological investigations at three sites in a north-south transect along the length of the valley indicate mowing and livestock grazing from AD 1500 to 1600. No clear signs of human-induced vegetation shifts are indicated at earlier time stages at the two southern sites. No archaeological findings support land use prior to AD 1500. Written sources give evidence for haymaking at AD 1600 and a more intense land use with summer farming followed in the eighteenth century. Land-use impact had a longer continuity at the northernmost site where furnaces for iron production and other human artefacts are dated as early as 180 BC–AD 25. These archaeological findings closely correspond to an opening of the woodland. We conclude that the intensity, diversity and continuity of land use decreased with increasing distance from permanent settlements in the lowland. The wooded grasslands probably dominated the Budalen valley also before humans started to use the land.

Dietary and paleoenvironmental reconstruction using stable isotopes of herbivore tooth enamel from middle Pliocene Dikika, Ethiopia: Implication for Australopithecus afarensis habitat and food resources

Carbon and oxygen isotopes of mammalian tooth enamel were used to reconstruct paleoenvironments of Australopithecus afarensis from the middle Pliocene locality of Dikika, Ethiopia. Isotopic analyses were conducted on 210 mammalian herbivore teeth from 15 different taxa collected from the Basal Member (∼3.8–3.42 Ma) and Sidi Hakoma Member (3.42–3.24 Ma) of the Hadar Formation. The isotopic analyses aim specifically at reconstructing shifts in the relative abundance of C4 grasses in mammalian diets, and more generally at paleoclimate factors such as aridity and seasonality, as well as habitat structure. Carbon isotopic data suggest a wide range of foraging strategies, characterized by mixed C3/C4 to C4-dominated diets in wooded grasslands to open woodlands. Weighted average C4 dietary proportions range between 60% and 86% in the Basal Member and 49% and 74% in the Sidi Hakoma Member. Paleoclimatic conditions based on the reconstructed mean annual water deficit from the δ18Oenamel values indicate a wetter climate as compared to either the early Pliocene or the Pleistocene nearby. The middle Pliocene habitat structure at Dikika could be as diverse as open grassland and wooded grassland, and woodland to forest in the Sidi Hakoma Member while wooded grassland, woodland to grassland are evident in the Basal Member. All habitats except closed woodland and forest are persistent through both members; however, the relative proportion of individual habitats changed through time. These changes could have put the fauna in competition for preferred habitats and food resources, which could have forced migration, adaptation to other resources and/or extinction. Thus, the existence of A. afarensis throughout the middle Pliocene indicates either this species might have adapted to a wide range of habitats, or its preferred habitat was not affected by the observed environmental changes.

Isotopic evidence for an early shift to C₄ resources by Pliocene hominins in Chad.

Foods derived from C(4) plants were important in the dietary ecology of early Pleistocene hominins in southern and eastern Africa, but the origins and geographic variability of this relationship remain unknown. Carbon isotope data show that Australopithecus bahrelghazali individuals from Koro Toro in Chad are significantly enriched in (13)C, indicating a dependence on C(4) resources. As these sites are over 3 million years in age, the results extend the pattern of C(4) dependence seen in Paranthropus boisei in East Africa by more than 1.5 million years. The Koro Toro hominin fossils were found in argillaceous sandstone levels along with abundant grazing and aquatic faunal elements that, in combination, indicate the presence of open to wooded grasslands and stream channels associated with a greatly enlarged Lake Chad. In such an environment, the most abundant C(4) plant resources available to A. bahrelghazali were grasses and sedges, neither of which is usually considered as standard great ape fare. The results suggest an early and fundamental shift in hominin dietary ecology that facilitated the exploitation of new habitats.

Soil carbon stocks and soil solution chemistry in Quercus ilex stands in Mainland Spain

The quantification of terrestrial carbon pools is important for the modeling of carbon fluxes in forest ecosystems. As a contribution to the understanding of the factors that influence the carbon sequestration capacity of Mediterranean forest soils, the present study focuses on the quantification of the superficial soil carbon stocks in evergreen oak stands (Quercus ilex L.) representative of its distribution area in Mainland Spain and to analyze the influence of site factors (climate and topography) and the soil chemical properties in the topsoil carbon storage capacity. For that purpose, 103 Quercus ilex stands were studied grouped in four main formations: 40 wooded grassland ecosystems with scattered oak trees (dehesas), 14 open Holm oak stands, 28 mixed Holm oak forests and 21 dense Holm oak forests. The soil organic carbon stocks (SOCS) in the upper organo-mineral soil layer ranged between 1.4–15.6 kg m−2 and total soil carbon stocks (TSCS) between 1.4–17.9 kg m−2. Tree density was a significant factor for SOC storage in the soil. The wooded grassland dehesas presented the minimum superficial SOC stocks (3.6 kg m−2), while dense Holm oak forests reached the maximum average values (7.6 kg m−2). Maximum SOCS (>10 kg m−2) were measured in the mixed and dense Holm oak forests over soils with calcareous substrates. Summer mean temperature (R = −0.46; P < 0.001) was the climatic variable that most influenced the SOCS. Soil properties had stronger positive correlations with SOCS than site factors: nitrogen concentrations (R = 0.70; P < 0.001), clay content (R = 0.62; P < 0.001), soluble calcium (R = 0.60; P < 0.001) and magnesium (R = 0.42; P < 0.001). Climatic and topographic variables together explained 30 % of the SOCS variability. An increase up to 63 % was obtained by including soil variables. Under Mediterranean climate conditions, the soil properties that enhance the organic matter protection achieve a notable relevance. The soil carbon storage is favored by large organic matter inputs, high soil clay contents, a calcium-saturated soil matrix and reduced summer aridity.

Scenarios of changes in the spatial pattern of land use in China

Land use changes affect many aspects of Earth System functioning, for example in impacting global carbon cycle, contributing to climate change, or increasing soil erosion. The simulation of land use change is important in environmental impact assessment and land use planning. We assessed the land use scenarios of China in the next 100 years based on the SMLC (surface modelling of land cover change) model and Dyna-CLUE (dynamic conversion of land use and its effects) model. Three SRES scenarios were evaluated: Global Economy (A1FI): lean government, strong globalization; Continental Markets (A2a): lean government, regional culture and economic development; Regional communities (B2a): much government intervention, regional cultural and economic development. Ten land cover types were simulated, which are cultivated land, woodland, grassland, built-up land, water area, wetland, nival area, desert, bare rock and desertification land. The SMLC model was used to calculate changes in area for each land use types in the future at country level while the spatially explicit land use model Dyna-CLUE was used to simulate land use pattern at 2 km2 resolution based on the country level areas demands for each land cover type. The results show that the cultivated land would decrease in all of the three scenarios, while in the A2a scenario, the cultivated land would decrease with the lowest rate because of the high population growth, high level of market protection and low agricultural efficiency; in the B2a scenario, it would decrease with the highest rate caused by the decreased population numbers and increased crop productivity. The nival area would decrease with the highest rate in the A1FI scenario since the rapid introduce of new technology and the energy system is fossil intensive, which would discharge more greenhouse gas than other two scenarios. The area of natural ecosystems such as wood land, grassland, water area and wet land would increase significantly in the B2a scenario because this scenario puts more weight on environmental sustainability. The land use spatial pattern in China under the B2a scenario is simulated. The results are important to identify hotspots of land use change that need specific attention by the governments and the researchers.

River-margin habitat of Ardipithecus ramidus at Aramis, Ethiopia 4.4 million years ago

The nature and type of landscape that hominins (early humans) frequented has been of considerable interest. The recent works on Ardipithecus ramidus, a 4.4 million years old hominin found at Middle Awash, Ethiopia, provided critical information about the early part of human evolution. However, habitat characterization of this basal hominin has been highly contested. Here we present new sedimentological and stable isotopic (carbon and oxygen) data from Aramis, where the in situ, partial skeleton of Ar. ramidus (nicknamed 'Ardi') was excavated. These data are interpreted to indicate the presence of major rivers and associated mixed vegetations (grasses and trees) in adjacent floodplains. Our finding suggests that, in contrast to a woodland habitat far from a river, Ar. ramidus lived in a river-margin forest in an otherwise savanna (wooded grassland) landscape at Aramis, Ethiopia. Correct interpretation of habitat of Ar. ramidus is crucial for proper assessment of causes and mechanisms of early hominin evolution, including the development of bipedalism.