Cellulose decomposition rate and features of organic matter in forest soils in the Tatra mountains

Abstract

The cellulose decomposition rate measurement and soil micromorphology have been used to determine the influence of parent material and tree species on mechanisms responsible for organic matter form differentiation in woodland soils in the Tatra Mountains in Poland. The study area is located in the lower montane belt of the Tatra Mountains. Investigated soils are developed on dolomites and shale. In the past, beech and beech-fir forests had been the dominant form of vegetation in the study area. Since the 16th century, these areas were deforested until the 19th century, when reforestation efforts were undertaken. Reforestation efforts provided mainly spruce; hence, it is the dominant species in the lower montane belt at the moment, although in some areas, natural or semi-natural beech and beech-fir forests have survived. Four plots were compared – two with soils developed on calcareous material (Rendzic Leptosols), one under beech forest and one under spruce forest, and two developed on shale (Haplic Cambisols), one under beech forest and one under spruce forest. Cellulose filters were placed in organic O-horizons and humus A-horizons in every plot to measure the cellulose decomposition rate. Before being placed in the soil, cellulose filters were boiled in KOH, rinsed in distilled water, dried, weighed, and set on glass plates in a nylon bag (1.5 mm mesh). The bags were placed in the soil vertically at approx. 15 cm intervals. After taken up, the filters were boiled in KOH, rinsed, dried, and weighed. The amount of ash was determined via combustion. The research was carried out during a period of 10 weeks between June and August as well as during a period of 1 year. Measurements were repeated ten times. A weighted average and standard deviation were calculated for every plot. The cellulose filter method is useful because of the homogeneity of the substrate, which helps to exclude differences connected with the chemical composition of the plant material, a factor that affects the decomposition rate. Undisturbed soil samples were taken from humus A-horizons in every soil profile. The thin sections were prepared and features of organic matter were described. It was concluded that the presence of calcarous material negatively affects organic matter decomposition rates which is pronounced in both: higher amount of organic matter residues in humus-A horizons and slower cellulose decomposition rates in Rendzic Leptosols than in Haplic Cabisols. The influence of tree species on organic matter features is observed only in Haplic Cambisols, where the cellulose decomposition rate under spruce is lower than under beech. This suggests that tree species indirectly affect the cellulitic microflora only in acidic soils.