بومشناسی جنگلهای ایران (May 2024)
Comparison of Soil Organic Matter in Pure and Mixed Types of Oak in North Zagros (Case Study: Armardeh Baneh Forests)
Abstract
Extended Abstract Background: The spatial patterns of trees, as the main components of a forest ecosystem, depend on their internal characteristics, interspecific relationships, and external environmental and habitat characteristics. The tree species that make up the forest types are among the major factors influencing soil characteristics through the production of litterfall, and they play an essential role in the quantity and quality of soil organic matter and the release of soil nutrients. Organic matter is one of the important parts of the soil, which includes tissue remains of plants and animals, their undecomposed to partially decomposed components, and dead microorganisms. The presence of organic matter, in addition to indicating the soil fertility and quality, is considered a suitable indicator for soil fertility, resulting from the interaction of physical, chemical, and biological processes. By improving soil granulation conditions, organic matter improves soil porosity and permeability; therefore, it has an important role in the stability of the ecosystem. For this reason, examining its various aspects is one of the main needs and the basis of studies on soil quality, carbon cycles, and climate change. Since there is very little information about the organic matter that can be extracted with hot water as a qualitative indicator of soil organic matter in forests, the need to pay attention to better understand the effect of different vegetation types on the soil leads to a more accurate prediction of the effect of species on ecosystems and their optimal management for managers and foresters. The present study investigates soil organic carbon and nitrogen with hot and cold water extraction methods as an indicator of soil material changes in two pure (Quercus infectoria) and mixed (Quercus libani- Quercus infectoria) types of North Zagros forests (Armardeh Baneh). Methods: Different forest types were determined using the opinions of forestry experts and statistics in the study area. The forestry characteristics were measured with five random 400 m2 sample plots in each type. The topsoil of the studied types was collected using 10 mixed samples from a depth of 0-10 cm (after removing the litterfall layer). After transporting the soil samples to the laboratory with plastic bags, the soil samples were passed through a 2 mm sieve and divided into two parts. A part of the sample was immediately exposed to 4 °C to measure the microbial mass of carbon and nitrogen, and a part of the sample was placed in the open air to measure organic carbon and total nitrogen. After measuring the studied variables, the statistical comparison of the average variables in forest types was evaluated using the independent samples t-test, analysis of variance, and their correlations with Pearson's correlation coefficient. Results: The contents of soil organic carbon and total nitrogen in the pure Q. infectoria and Q. libani-Q. infectoria types did not show significant differences. Although the amounts of hot and cold water extractable carbon and nitrogen, the microbial carbon, and nitrogen biomass were higher in Q. libani-Q. infectoria types, this difference was not significant, except for hot-water extractable carbon. There was a significant correlation between hot-water extractable carbon, microbial biomass of carbon, and cold-water extractable carbon. A significant correlation was also observed between hot-water extractable nitrogen and microbial nitrogen and carbon. Finally, there was a significant correlation between soil nitrogen with microbial biomass carbon and cold-water extractable nitrogen, but the correlation coefficient was lower than that of soil organic carbon with microbial biomass carbon and cold-water extractable carbon. Conclusion: There is an interaction between trees and soil. The growth and production of trees are related to the soil characteristics; on the other hand, the trees with their leaves and unique characteristics affect the understory soil. Based on the study outcomes, it can be concluded that extractable organic matter with hot water can be used as a sensitive indicator of changes in organic matter quality in forest soils.
