Soil databases and the problem of establishing regional biogeochemical trends (original) (raw)
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Land cover changes affect soil chemical attributes in the Brazilian Amazon
Acta Scientiarum. Agronomy
Forest plantations may minimize the effects of deforestation in the Amazon. However, there are differences among species in terms of their influences on soil recovery. The effects of monospecific plantations of Acacia mangium, Dipteryx odorata, Jacaranda copaia, Parkia decussata,and Swietenia macrophylla, and areas of pasture and native forest on the chemical soil attributes of the Brazilian Amazon were evaluated. One bulked soil sample was collected per plot (0.00-0.05, 0.05-0.10, and 0.10-0.30 m; three plots of 128 m 2) in each area. No significant differences in most of the soil attributes were observed among the forest plantations. However, soil K + and P were higher in the Swietenia macrophylla plantations, while higher values of Ca 2+ , sum of bases, and pH occurred in Jacaranda copaia plantations. In the native forest, the pH, and P content were lower, whereas the soil organic matter (SOM) content, soil organic carbon (SOC) content, cation exchange capacity (CEC), N content, H+Al content, and Al 3+ content were higher than in the plantations. The lowest values of SOM, SOC, CEC, K + , Mg 2+ , N, H+Al, and Al 3+ occurred in the pasture. None of the forest species led to the return of the original soil chemical attributes of the native forest. However, S. macrophylla and J. copaia plantations presented the highest positive edaphic influences.
Effects of Land Use Change on Soil Quality Indicators in Forest Landscapes of the Western Amazon
Soil Science, 2017
Western Amazon has the highest forest biodiversity in the world; however, farming, pasture, or subsistence farming has cleared extensive forest areas, impacting soil quality. This study evaluates the variations in soil quality indicators such as organic carbon (OC), NH 4 + , available P, soil texture, and pH, taking into account changes of land use from forest to disturbed areas in four different landscape positions: plains, peneplains, piedmont, and periandes piedmont. We used three vegetation cover maps of 1990-2000-2008 and 1,820 soil samples in an estimated area of 40,000 km 2. Cokriging and regression kriging of each edaphic attribute and maps of land use were crossed. Analysis of variance for each landscape position was applied in order to identify significant differences in soil quality indicators between different land use categories (forest and disturbed areas). Results suggest changes in biogeochemical soil dynamics. We reported statistically significant reduction in the percentage of OC for disturbed areas and an increase in available P, which is remarkable. NH 4+ stocks were lower for disturbed areas; however. In piedmont and periandes piedmont landscapes, forests presented the highest concentrations of OC (3.99 ± 1.1 and 5.06 ± 1.41, respectively) in comparison to disturbed areas (3.56 ± 0.87 and 3.98 ± 1.41, respectively). Changes in soil quality main indicators suggest a potential drop in ecosystem services production for the western Amazon of Ecuador. Management decisions should consider sustainable land use strategies oriented to maintain the resilience of soil quality indicators.
Land cover changes affect soil chemical attributes in the Brazilian Amazon
2021
ABSTRACT. Forest plantations may minimize the effects of deforestation in the Amazon. However, there are differences among species in terms of their influences on soil recovery. The effects of monospecific plantations of Acacia mangium, Dipteryx odorata, Jacaranda copaia, Parkia decussata,and Swietenia macrophylla, and areas of pasture and native forest on the chemical soil attributes of the Brazilian Amazon were evaluated. One bulked soil sample was collected per plot (0.00-0.05, 0.05-0.10, and 0.10-0.30 m; three plots of 128 m2) in each area. No significant differences in most of the soil attributes were observed among the forest plantations. However, soil K+ and P were higher in the Swietenia macrophylla plantations, while higher values of Ca2+, sum of bases, and pH occurred in Jacaranda copaia plantations. In the native forest, the pH, and P content were lower, whereas the soil organic matter (SOM) content, soil organic carbon (SOC) content, cation exchange capacity (CEC), N con...
Soil and Tillage Research
Ecosystem in responses to land use change create feedbacks in soils and ecological processes in Critical Zone (CZ). The identification and quantification of such changes is needed as a part of understanding the relationship between climate, CO 2 emission, humidity, biological activity, soil carbon, surface redox, and plant nutrient cycling and lithology, mineralogy, biogeochemistry of bedrocks. The CZ observation as complex investigation of three Luvic Phaezoem soils under secondary deciduous forest, grassland and cropland from Moscow region, Russia, was fulfilled with the main goal to study weathering processes in soils along global gradients of environmental change. Detailed study of mineralogy and chemistry (XRD, XRF), surface area, porosity, organic matter, carbon/microbial biomass, moisture content, monitoring of total soil respiration was performed. Ecosystem in responses to land use change the parameters of CZ (CO 2 emission, humidity, biological activity). Land use change result in climate parameter on a local scale (soil climatic gradients) and formed feedback in weathering intensity and basic soil properties-organic matter, acidity, bulk density, WHC, surface properties and porosity, mineralogy and geochemical changes. The decreasing of smectites in the upper parts of the profile and the increasing of illite and vermiculite content was observed. Montmorillonite into vermiculite transformation, which took place only under the forest, which caused the decreasing of pH, soil vermiculite may also derive from muscovite. The intensity of the given process increases as the following: forest soil < grassland < cropland. The given tendency was explained by both the mineral transformations and redistribution of mineral components within the soil profile. The redistribution of chemical elements between the different sub-fractions of silt and clay is in relationship to the land use. As a general trend, we can conclude that clay fractions in a comparison with bulk soil samples are enriched in both OC and N. Mineralogical and chemical changes influenced the surface properties and porosity. The 50-150 years of different land use resulted in these feedbacks with maximum in aboveground zone and soils as main point of surface of a given CZ.
Geoderma, 2004
Our main objective in the present study was to assess the spatial variation of chemical and physical soil properties and then use this information to select an appropriate area to install a pasture rehabilitation experiment in the Amazon region, Brazil. A regular 25 m grid was used for collecting a total of 2955 soil samples (from 985 georeferenced soil pits) at 0 to10, 10 to 20 and 20 to 30 cm layers. Soil samples were analyzed for total carbon and nitrogen, d 13 C and d 15 N, pH in H 2 O, pH in KCl, clay, and sand contents. Conventional statistical methods and geostatistics were performed in order to analyze soil properties spatial dependence. Mean, standard deviation, skewness, and kurtosis for all measured variables were evaluated. All variograms generally were well structured with a relatively large nugget effect. Total C, total N, pH in H 2 O, pH in KCl, d 13 C and d 15 N semivariograms were best fitted by spherical models, while clay and sand contents were best fitted by exponential models. Two types of validation (''Jackknife'' or cross-validation and external validation) were conducted, indicating a lack of bias for the used prediction models. Block kriging was used to interpolate the values at unmeasured locations, generating maps of spatial variation for each soil property. Those maps were processed using Geographic Information System and restrictive criteria were adopted in order to select the best area in which to install the pasture rehabilitation experiment. The study field was then divided into zones with similar homogeneity. The selected zone can now be subjected to different treatments once the natural initial conditions are well known, and could also be used as a baseline in carbon sequestration projects within the scope of the Kyoto Protocol's Clean Development Mechanism. D
Multi-scale variability in tropical soil nutrients following land-cover change
2005
The effects of land-cover change on soil properties have reached regional proportions in the southwestern Amazon, and can be detected in their patterns at the scale of hundreds of thousands of square kilometers. Spatial analysis of an extensive soil profile database revealed four nested spatial scales at which different patterns in soil properties occur:< 3,< 10,< 68, and> 68 km.
Proceedings of the National Academy of Sciences, 2011
Accurately quantifying changes in soil carbon (C) stocks with landuse change is important for estimating the anthropogenic fluxes of greenhouse gases to the atmosphere and for implementing policies such as REDD (Reducing Emissions from Deforestation and Degradation) that provide financial incentives to reduce carbon dioxide fluxes from deforestation and land degradation. Despite hundreds of field studies and at least a dozen literature reviews, there is still considerable disagreement on the direction and magnitude of changes in soil C stocks with land-use change. We conducted a meta-analysis of studies that quantified changes in soil C stocks with land use in the tropics. Conversion from one land use to another caused significant increases or decreases in soil C stocks for 8 of the 14 transitions examined. For the three land-use transitions with sufficient observations, both the direction and magnitude of the change in soil C pools depended strongly on biophysical factors of mean annual precipitation and dominant soil clay mineralogy. When we compared the distribution of biophysical conditions of the field observations to the area-weighted distribution of those factors in the tropics as a whole or the tropical lands that have undergone conversion, we found that field observations are highly unrepresentative of most tropical landscapes. Because of this geographic bias we strongly caution against extrapolating average values of land-cover change effects on soil C stocks, such as those generated through meta-analysis and literature reviews, to regions that differ in biophysical conditions. 6318-6322 | PNAS | April 12, 2011 | vol. 108 | no. 15 www.pnas.org/cgi/
Sensitivity of a biogeography model to soil properties
Ecological Modelling, 1998
This paper presents the changes in vegetation distribution and hydrological balance resulting from a change in soils input data to the biogeography model MAPSS . The model was run for the conterminous United States using three different sets of soil characteristics: (1) all soils were assumed to be sandy loam; (2) soils characteristics came from the Food and Agriculture Organization (FAO) soils map of the world (FAO, 1974(FAO, -1979 and soil characteristics came from the Natural Resource Conservation Service (NRCS) National Soil Geographic (NATSGO) dataset. Resulting changes in vegetation distribution appear small on a country-wide basis, but large changes in simulated runoff in savannas, shrublands and deserts reflect the importance of using the best available soils dataset. In the state of Oregon, a 16% relative decrease in forest areal extent is accompanied by an 18% relative increase in shrubland when switching from FAO to NATSGO datasets. Conversely, forest cover increases by 24% while shrubland extent decreases by 14% when all Oregon soils are assumed to be sandy loam. MAPSS vegetation distribution projections were compared to Kü chler's potential vegetation map . The generalization of all US soils to sandy loam soils decreases the similarity between MAPSS predictions and Kü chler's map and is clearly inappropriate. If the similarity between MAPSS projections and Kü chler's map does not clearly improve by using NATSGO rather than FAO soils data, NATSGO soil representation is more reliable and thus we recommend using it in the future.
Projecting the evolution of soil due to global change
2018
Soil is a critical natural resource that inherently changes through time. This change is affected by a variety of natural and anthropogenic factors and their combined impacts. To preserve the soil and protect it, it is necessary to predict the consequences of human activities and global change on soil evolution. This can be achieved using soil evolution modelling. However, only a model that includes a large coverage of physical, chemical and biological processes, that considers feedback mechanisms between soil and soil forming factors, that has a detail description of flow of water, and that accounts for human activities on land (land use, agricultural practices) would be suitable for projection purposes. However, the evolution of key soil characteristics such as organic carbon (OC), are often simulated by models focusing on that specific soil characteristic and the sole soil processes acting on it. In this study, we first tested the sensitivity to variation of climate, land use and...