The study on the relationship between the soil aggregates stability assessed using water stable aggregate (WSA) index and the selected terrain and soil properties was performed on a morphologically diverse study site in Chernozem soil region of Southern Moravia. Soil analyses and detailed digital elevation model processing were the main methods adopted in the study. The soil structure stability is negatively influenced by the soil material removal from the steep parts of the back-slope and re-deposition of the mineral loess material at the base of the slope. The highest aggregates stability was identified in the upper flat parts of the study plot, undisturbed by erosion processes, and at the concave parts of the back-slope with intensive accumulation of organic matter. Statistical analysis showed a significant dependence of aggregates stability on organic carbon content and plan curvature index.

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[1] We describe spatiotemporal variation in land cover over 80,000 km 2 in central Rondônia. We use a multistage process to map primary forest, pasture, second growth, urban, rock/savanna, and water using 33 Landsat scenes acquired over three contiguous areas between 1975 and 1999. Accuracy of the 1999 classified maps was assessed as exceeding 85% based on digital airborne videography. Rondônia is highly fragmented, in which forests outside of restricted areas consist of numerous, small irregular patches. Pastures in Rondônia persist over many years and are not typically abandoned to second growth, which when present rarely remains unchanged longer than 8 years. Within the state, annual deforestation rates, pasture area, and ratio of second growth to cleared area varied spatially. Highest initial deforestation rates occurred in the southeast (Luiza), at over 2%, increasing to 3% by the late 1990s. In this area, the percentage of cleared land in second growth averaged 18% and few pastures were abandoned. In central Rondônia (Ji-Paraná), deforestation rates rose from 1.2% between 1978 and 1986 to a high of 4.2% in 1999. In the northwest (Ariquemes), initial deforestation rates were lowest at 0.5% but rose substantially in the late 1990s, peaking at 3% in 1998. The ratio of second growth to cleared area was more than double the ratio in Luiza and few pastures remained unchanged beyond 8 years. Land clearing was most intense close to the major highway, BR364, except in Ariquemes. Intense forest clearing extended at least 50 km along the margins of BR364 in Ji-Paraná and Luiza. Spatial differences in land use are hypothesized to result from a combination of economic factors and soil fertility.

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ABSTRACT1. Aerial photograph classification was used to map perennial thick canopy seagrass presence/ absence over a large area (85 km 2 ) off the coast of Western Australia. Within those areas mapped as seagrass, a geostatistical nonparametric interpolation method was applied to map the probability of seagrass species presence from underwater tow video. Multiple species mixtures were mapped at fixed probability thresholds of 0.95, 0.75, 0.50, and 0.25. Taxa included Amphibolis spp., Posidonia coriacea, P. sinuosa, P. australis and ephemeral species (Halophila and Zostera tasmanica (newly named as Heterozostera polychlamys)).2. The most commonly occurring species were respectively Amphibolis spp., Posidonia coriacea, P. sinuosa, P. australis, and the ephemeral species. Amphibolis, P. coriacea, and the ephemeral species were mapped predominantly as mixed assemblages (71-89% mixed), whereas P. sinuosa and P. australis were typically mapped as single species.3. Different species growth habits led to distinctive differences in large area distributions. All species were highly variable over short distances (5500 m), and spatial dependence persisted over more than 5 km. However, Posidonia sinuosa meadows were oriented with the longest axis running north-south, and a shorter axis running east-west perpendicular to the coastline (spatial dependence to 2.8 km and 0.8 km, respectively). The ephemeral species were less successfully mapped, largely owing to the potentially different growth patterns of the grouped species, and because their full extent could not be captured by the aerial photograph classification.4. The individual biology of each species results in unique landscape features where Posidonia sinuosa forms larger continuous and predominantly monospecific meadows, whereas the more common Amphibolis and P. coriacea form multi-species patchy meadows. These mapped features suggest that the emergence of species patterns in seagrass landscapes is influenced by differences in clonal growth among seagrass species.5. Probabilistic species mapping provided information unavailable from discretely classified maps, and facilitates targeted sampling for improving map accuracy, and for more realistically evaluating *Correspondence to: K.W. Holmes, School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. E-mail: kholmes@segs.uwa.edu.au species and mixed species distribution predictions. The kriging approach, although not well suited for all types of vegetation data, performed well for clonal seagrasses.

[1] Studies of tropical soil organic carbon (SOC) response to deforestation present conflicting results, confounding estimates of the regional effects of land-cover change on carbon storage. We calculated the change in SOC stocks due to deforestation through 1996 for the state of Rondônia, Brazil, in the southwestern Amazon basin. Whereas the net change in SOC for the state as a whole was slightly negative (À0.5% or À5012 Gg), spatially explicit maps suggest dramatic local changes, ranging from À76% to +74%, with outliers as high as +330%. The direction and magnitude of change in SOC following forest clearing is related to original forest soil carbon and pH, which in turn provides a general measure for overall nutrient availability and possible toxicities. When native soil carbon is high, SOC decreases in response to land-cover conversion from forest to pasture; conversely, low soil carbon and low soil fertility lead to gains in carbon under pasture. Mapping variability, rather than relying on large-area averages, illustrates why results from individual field sites have been contradictory.

1) to investigate the spatial distribution of fine roots and its correlation with selected soil properties on an artificial ecosystem dominated by woody vegetation species, and (2) to compare the root distribution to that predicted using a global model for natural ecosystems. Root diameter distribution (≤5 mm), root biomass density (RBD), root length density (RLD), soil pH, soil electrical conductivity and dry soil bulk density were measured on soil core samples (217) collected from a trench wall using a 20×20-cm grid sampling. Approximately 90% of the RBD (mean ± standard error: 0.27±0.027 kg m −3 ) and RLD (1.57±0.023 cm cm −3 ) occurred in the top 40 cm, decreasing exponentially to a maximum rooting depth of 150 cm. RBD exhibited a vertical spatial structure associated with soil pH (p<0.05; r 2 = 0.48), and a random lateral distribution. Coefficients of variation (CV) of RBD were high irrespective of orientation (vertical: 79-200%, lateral: 50-236%). The root extinction parameter β (0.944) for the global model was lower (p<0.05) than that of woodlands (β= 0.964-0.976), indicating a shallow root distribution resembling that of grasslands (β=0.943). The superficial root distribution indicated subsoil chemical constraints to root growth, while high lateral variability was attributed to sparse vegetation. The findings stress the need to account for both vertical and lateral variability of roots for accurate modelling of water use and productivity on certain artificial ecosystems with sparse vegetation.Keywords Global root distribution model . Vegetated engineered cover . Root biomass density . Root diameter distribution . Root length density Abbreviations ECSoil electrical conductivity in 1:5 soil to water suspension Plant Soil (2011) 344:255-272