Tree species identity influences the vertical distribution of labile and recalcitrant carbon in a temperate deciduous forest soil

In terrestrial environments, soil organic matter (SOM) is the largest organic carbon (C) pool. The quantity and quality of organic carbon in soils can be affected by vegetation through influencing the inputs and outputs of SOM. We examined how storage and quality of C in SOM were affected by vegetation under grass cover or single and a polyculture plot of Betula pendula, Alnus glutinosa and Fagus sylvatica. An acid hydrolysis approach was used to quantify three SOM fractions differing in biodegradability. Tree species identity and stand composition had no significant effect on the total amount of C stored in different SOM fractions to a depth of one meter. However, when examining individual SOM fractions in the upper layers of the soil profile, significantly more C was stored in the putatively more labile fractions 1 and 2 under F. sylvatica and A. glutinosa, respectively. In deeper soil layers, the highest storage of recalcitrant organic C was found under the tree polyculture. The vertical distribution of these three soil organic C pools was compared to C inputs via decomposed leaf litter. Our data indicated that in the tree species polyculture, combining litter inputs of multiple species can have a positive impact on the accumulation of acid resistant recalcitrant C in deep soil layers in 4 years. This C fraction has the greatest potential for long-term sequestratio

Evaluation of methods to estimate production, biomass and turnover of ectomycorrhizal mycelium in forests soils : A review

Peer reviewedPublisher PD

Detection of Uranium Contamination in Acacia Cell Sap by Capillary Zone Electrophoresis (CZE) Technique

The study was carried out to detect uranium level in the cell sap of acacia plant cells, for this purpose callus cultures of Acacia albida was used as well as plants. Cell saps from both callus and plant leaf were taken using Micro capillary syringe and detected using Capillary zone electrophoresis technique. It was shown that using citrate buffer of 3.0pH help in detecting uranium accumulated in the cells. Prospective calculation for the level of uranium uptake showed that 1.64mM is the level of uranium in the leaf cells that had been grown on soil with addition of 500 mg.kg-1 uranyl nitrate for 3 months, while for callus which grown on MS medium with addition of 500 mg/l uranyl nitrate for the same time (3 months), uptake of uranium reached 0.8 mM. The comparison between TXRF analysis of uranium accumulated in plant tissues and CZE efficiency in detecting uranium level in cell sap of both leaves and callus cells, it was shown that both techniques prove that A.albida plants can accumulate uranium with a level double as that taken by callus cells

The influence of pH on root morphology and mineral content of Pinus pinaster Ait. seedlings

Two-week old seedlings of Pinus pinaster Ait. were grown in nutrient solutions at pH values ranging from 3.5 to 6.5. Acidity exerted a different influence on the growth of the main and lateral roots, thus changing the morphology of the whole root system. Roots grown at 3.5 pH had the shortest length, but the highest biomass and were markedly thickened. The total number of 2nd order lateral roots per plant was not significantly influenced by pH, whereas their length and the development of 3rd roots were the highest at 3.5 pH and the lowest at 6.5 pH. Mineral nutrition was affected by the pH of the culture solution. The P and Fe concentrations in roots were higher in the 3.5 and 4.5 pH solutions than in 5.5 and 6.5 pH. In contrast, lower K, Ca, Mg and especially Mn contents were found in the roots grown at 3.5 pH. However, needle dry weight was unaffected by low pH and neither chlorosis nor critical levels of mineral elements were observed. These results suggest that the compensatory growth of lateral roots allows P. pinaster seedlings to mantain an adequate nutritional status in the shoot even at highly acidic conditions

Soil properties under Norway spruce differ in spruce dominated and mixed broadleaf forests of the Southern Taiga

In natural forest, disturbance changes tree species composition which in turn affects soil properties. Two areas in the Central Forest State Biosphere Reserve, in the Russian Southern Taiga Zone, differed in the intensity of disturbance: Norway spruce was the dominant species at one site, while at the other spruce was mixed with broadleaves. The presence of broadleaves was due to large gaps in the canopy having been formed, which have triggered vegetation succession. At both sites, five plots were selected to evaluate how the presence of broadleaves influences the properties of the soils under spruce. Soil samples were taken close to spruce trees and the O, A and E horizons were analysed. A difference in the distribution of organic matter in the soil horizons was evident, with a higher concentration in the O and A horizons at the spruce dominated site, while a more homogeneous distribution was found under spruce at the site where broadleaves were abundant. The organic matter did not only differ in quantity, but also in quality as estimated by the C/N ratio, and therefore affected the CEC and element relative availability. No differences at the two sites were found for water-extractable and exchangeable elements, but the ratio between the exchangeable and the acid extractable forms were different, suggesting a higher relative availability of the elements at the spruce dominated site, and thus potentially higher leaching. Both theoretical and empirical studies have suggested that podzolisation and accumulation of organic matter in the O horizon are related to stagnation of ecosystem processes and ecosystem decline. Our data suggest that the presence to windthrow sites and the inclusion of broadleaf species acts to slow or even reverse podzolisation even in spruce dominated sites