Influence Of Edaphic Factors Research Articles

Influence of Edaphic Factors on Sugar Maple Nutrition and Health on the Allegheny Plateau

Sugar maple (Acer saccharum Marsh.) decline has been a problem on the Allegheny Plateau for the last two decades. Previous work found that sugar maple is predisposed to decline by poor nutrition and incited to decline by severe insect defoliation. Nutritional diagnoses have been based on foliar chemistry; there is little information on soil attributes that influence susceptibility. We evaluated relationships among soil characteristics, foliar chemistry, and sugar maple decline for 43 stands on the Allegheny Plateau in New York and Pennsylvania using correlation and stepwise regression techniques. Foliar Ca and Mg concentrations correlated with soil exchangeable cations expressed on a concentration or site capital basis. Expression of base cation availability as a saturation value, or in ratio with Al, slightly improved the relationships, suggesting that antagonistic cations are important to sugar maple nutrition. The best predictions of foliar chemistry were made by regressions that considered soil chemistry across the depth of the B horizon, suggesting the importance of looking at more than one depth to assess nutrition. Landscape position and glacial history determined whether weathering products were effectively delivered to the rooting zone, resulting in the observed landscape gradients. All declining stands were on unglaciated upper landscape positions where soils had lower Ca and Mg levels compared with other landscape positions. Declining stands had <2% Ca saturation and <0.5% Mg saturation in the upper B and <4% Ca saturation and <0.6% Mg saturation in the lower B. These thresholds may be useful in predicting susceptibility to sugar maple decline.

Influence of Edaphic Factors on Sugar Maple Nutrition and Health on the Allegheny Plateau

Sugar maple (Acer saccharum Marsh.) decline has been a problem on the Allegheny Plateau for the last two decades. Previous work found that sugar maple is predisposed to decline by poor nutrition and incited to decline by severe insect defoliation. Nutritional diagnoses have been based on foliar chemistry; there is little information on soil attributes that influence susceptibility. We evaluated relationships among soil characteristics, foliar chemistry, and sugar maple decline for 43 stands on the Allegheny Plateau in New York and Pennsylvania using correlation and stepwise regression techniques. Foliar Ca and Mg concentrations correlated with soil exchangeable cations expressed on a concentration or site capital basis. Expression of base cation availability as a saturation value, or in ratio with Al, slightly improved the relationships, suggesting that antagonistic cations are important to sugar maple nutrition. The best predictions of foliar chemistry were made by regressions that considered soil chemistry across the depth of the B horizon, suggesting the importance of looking at more than one depth to assess nutrition. Landscape position and glacial history determined whether weathering products were effectively delivered to the rooting zone, resulting in the observed landscape gradients. All declining stands were on unglaciated upper landscape positions where soils had lower Ca and Mg levels compared with other landscape positions. Declining stands had &lt;2% Ca saturation and &lt;0.5% Mg saturation in the upper B and &lt;4% Ca saturation and &lt;0.6% Mg saturation in the lower B. These thresholds may be useful in predicting susceptibility to sugar maple decline.

Influence of edaphic factors and tree nutritive status on the productivity of Pinus radiata D. Don plantations in northwestern Spain

Relationships among soil parameters, tree nutrition and site index (SI) were examined in Pinus radiata plantations growing on soils developed from different parent materials (acid schist, granitic rocks and basic rocks) in a climatically homogeneous areas of NW Spain. Soil depth, in association with soil water balance and nutrient store, had the greatest influence on the productivity of these plantations. Although foliar N and K were sufficient in every stand studied, widespread deficiencies of P, Mg and, to a lesser extent, Ca were diagnosed. Foliar concentrations of Ca and Mg were positively correlated with soil nutrient concentrations. The main factors affecting site quality were identified with principal component analysis. The SI was positively correlated with foliar P concentrations, soil depth and pH, and negatively correlated with soil total N. Approximately 60% of the observed SI variation was accounted for by these soil properties. The results suggest the importance of site selection and fertilizer treatments in reforestation programmes.

Small-Scale Variations in Species Composition of Miombo Woodland in Sengwa, Zimbabwe: The Influence of Edaphic Factors, Fire and Elephant Herbivory

Small-Scale Variations in Species Composition of Miombo Woodland in Sengwa, Zimbabwe: The Influence of Edaphic Factors, Fire and Elephant Herbivory

Atrazine mineralisation in New Zealand topsoils and subsoils: influence of edaphic factors and numbers of atrazine-degrading microbes

The mineralisation of 14C-ring-labelled atrazine to 14CO2 was measured in 3 contrasting New Zealand soils under controlled conditions of temperature and moisture. The numbers of atrazine-degrading organisms were measured by a most probable number technique. Decomposition rates were slow, with a maximum of 41% of atrazine being mineralised over 263 days. Mineralisation was generally very low in subsoils and was much reduced by low moisture content. However, one subsoil from 60–90 cm depth had unusually high numbers of atrazine-degrading microbes and showed mineralisation greater than or equivalent to the surface soil. Mineralisation was approximately doubled by a 10°C rise in temperature over the range 16–28°C. In general, the rate of atrazine mineralisation over 7–96 days could be predicted from the number of atrazine-degrading microbes and the cation exchange capacity of the soil (R2 = 0·86). A large amount (54–77%) of 14C remained in the soil as non-extractable residues after 263 days, but only trace amounts of the added atrazine or the decomposition products de-ethyl atrazine and de-isopropyl atrazine were detected by extraction in organic solvent.

The Influence of Edaphic Factors on the Species Composition of Early Stages of the Subsere

The secondary succession (subsere) on the sandy soils of the Transvaal Highveld has been described by Innes (1939), based on examination of disturbed sites of known history, and the terms ruderal stage, primary grass stage, secondary grass stage, grassland subclimax and scrub climax were proposed. It seems preferable to divide the early stages into communities which are distinctive when grazing and other biotic factors operate, and the following stages are proposed: