Water retention of soils with coarse texture under forest stands using classical method and PTFs

A changing climate brings more extreme weather and uneven distribution of rainfall events. These effects are already being observed, and although the average of the many annual rainfall totals is not changing significantly, the length and frequency of periods without rainfall and droughts have increased significantly. These changes are also felt by forest stands and their sensitivity to drought is a crucial factor in their growth and health. Our research team has been collecting data on the organic matter content and water-holding capacity of Hungarian soils for many years and has now also produced pF measurements. The sub-region of the Transdanubian Mountains region has provided a comprehensive picture of coarse-textured soil on which forest soil-forming processes take place. Soil samples were taken up to the limit of the occurrence of soil-forming processes, but at least up to 100 cm. Acidic Arenosols developed on the sand parent material. On these, mixed stands of beech and turkey oak-sessile oak associations developed. The pH, CaCO₃ content, organic matter content, texture, and bulk density of the soils were determined under laboratory conditions in 10 cm layers. The majority of the soil samples had an acidic pH between 4.4-6.4, with fine sand and sandy loam physical texture and free of calcium carbonate, with low humus content (0.9% in the upper 40 cm) compared to forest soils. From the pF measurements and using pedotransfer functions, we determined the potential water availability for plants, and using local climate data and measured soil data, we constructed a Thornthwaite-type water balance model for the area and used it to estimate the drought sensitivity of the area. These models improve and speed up the methods and therefore its accuracy and applicability to forest soils is a primary concern of this research.

The present publication was supported by the National Research Development and Innovation Fund of the Ministry of Innovation and Technology (successor: Ministry of Culture and Innovation) under the project TKP2021-NKTA-43, funded by the TKP2021-NKTA grant programme, and by the New National Excellence Programme of the Ministry of Culture and Innovation, code number ÚNKP-23-3-I-SOE-172, funded by the National Research, Development, and Innovation Fund. The field and laboratory tests were also carried out using equipment purchased with the support of the project "GINOP-2.3.3-15-2016-00039 - Investigation of the conditions for growing woody biomass".