Evolutionary pathways in soil-landscape evolution models

Soils and landscapes can show complex, non-linear evolution, especially under changing climate or land use. Soil-landscape evolution models (SLEMs) are increasingly equipped to simulate the development of soils and landscapes over long timescales under these changing drivers, but provide large data output that can be difficult to interpret and communicate. New tools are required to analyse and communicate large model output. In this work, I show how spatial and temporal trends in previously published model results can be summarized and conceptualized with evolutionary pathways, which are possible trajectories of the development of soil patterns. Simulated differences in rainfall and land use control progressive or regressive soil development and convergence or divergence of the soil pattern. These changes are illustrated with real-world examples of soil development and soil complexity. The use of evolutionary pathways for analysing the results of SLEMs is not limited to the examples in this paper, but they can be used on a wide variety of soil properties, soil pattern statistics and models. With that, evolutionary pathways provide a promising tool to analyse and communicate soil model output, not only for studying past changes in soils, but also for evaluating future spatial and temporal effects of soil management practices in the context of sustainability.

Soil Pattern and Breeding of Sandfly in Endemic Areas of Bangladesh

Introduction: Sandfly breeds in soil but is selective to identify soil favourable for their breeding. Soil covered by vegetation, marshy land, orchards and settlements shows high sandfly breeding in an endemic region. Besides,the presence of inorganic constituents of the soil was found to affect sandfly breeding. Objective: To identify soil pattern in Kala-azar endemic areas suitable for sandfly breeding, and the relationship of soil’s physical and chemical properties with their breeding which may help in taking feasible measure to control the vector of Kala-azar or Visceral Leishmaniasis (VL). Materials and Methods: The cross-sectional type of descriptive study was conducted in the Kala-azar endemic areas of Trishal and Fulbaria of Mymensingh, Madhupur of Tangail and Chatmohor of Pabna district, Bangladesh during the period of July 2015 to December 2015. From each site, 250 gm soil was collected and packed in a plastic container. All the samples were taken in the laboratory and were kept as it is for one week to configure the moisture and soil temperature maintaining the lab room temp at 28±2ºC and relative humidity at 75.0%±2.0. Soil samples were analysed for physical and chemical properties at the Soil Science Department of Sher-e-Bangla Agricultural University, Dhaka. Results: Total 48 soil samples were collected from Trishal, Fulbaria, Madhupur, Chatmohor and each sample was analysed for physical property (sand, silt, clay, porosity, water content), chemical constituents (pH, C, N, Ca, Mg, K, P, Fe). The mean from each district’s soil constituents (sand, silt, clay, porosity, water content) ranged from 17.36%-18.83%, 44.10%-45.46%, 35.70%-38.06% 41.98%-47.24% respectively and among the chemical constituents, pH ranged from 7.46-7.98, Carbon 0.92-0.98 Cmolkg-1, Nitrogen 0.174-0.184 Cmolkg-1, Calcium 4.83-6.21 Cmolkg-1, Magnesium 1.97-2.46 Cmolkg-1, Potassium as K2O 1.37-1.79 Cmolkg-1, Phosphorus as P2O5 12.60-13.78 Cmolkg-1, Iron as Fe2O3 9.54-10.06 Cmolkg-1 respectively. Conclusion: Physical and chemical characteristics of soil by area of endemicity have been postulated to afford suitable environment for sandfly breeding. This information of the breeding sites of phlebotomine sandflies could help to plan environmental intervention measures that would impede the breeding of these insects. Journal of Armed Forces Medical College Bangladesh Vol.13(1) 2017: 3-7

Equivalent latitude for prediction of soil development in a complex mapunit

Whitson, I. R. 2015. Equivalent latitude for prediction of soil development in a complex mapunit. Can. J. Soil Sci. 95: 125–137. Soil pattern in the Hillwash complex mapunit from Saskatchewan is too variable to be resolved spatially with conventional mapping approaches. The equivalent latitude metric allows identification of an index based on gradient and aspect that ranks sites based on differences in direct radiant energy inputs. Effects on soil development with reference to surface horizon color and soil classification were investigated at three study areas in southern Saskatchewan. At the first, sites with equivalent latitude greater than local latitude (north group) had a higher frequency of darker soil colors than sites where equivalent latitude was less than local latitude (south group). Black Chernozemic profiles made up nine of 13 profiles from the north group compared with none in the south group or in local controls. Similar color and classification trends in a north sample group were found at a second study area. Results from a third study area more than 200 km away and in a drier ecoregion found similar differences albeit a different set of subgroups between north and south group soils at that location. The equivalent latitude metric could be used in a GIS context to better resolve soil characteristics within this complex mapunit, but only after additional work to include a climate parameter such as potential transpiration into the model.

Root colonization with arbuscular mycorrhizal fungi and glomalin-related soil protein (GRSP) concentration in hypoxic soils in natural CO2 springs

Changed ratios of soil gases that lead to hypoxia are most often present in waterlogged soils, but can also appear in soils not saturated with water. In natural CO2 springs (mofettes), gases in soil air differ from those in typical soils. In this study, plant roots from the mofette area Stavešinci (Slovenia) were sampled in a spatial scale and investigated for AM fungal colonization. AM fungi were found in roots from areas with high geological CO2 concentration, however mycorrhizal intensity was relatively low and no correlation between AM fungal colonization and soil pattern of CO2/O2 concentrations (up to 37% CO2) was found. The relatively high abundance of arbuscules in root cortex indicated existence of functional symbiosis at much higher CO2 concentrations than normally found in soils. In addition, concentration of two different glomalin-related soil protein fractions – EE-GRSP and TG-GRSP – was measured. No significant correlation between any of the fractions and soil gases was found, however the concentration of both fractions was significantly higher in the upper 0–5 cm, compared to the 5–10 cm layer of the soil.