Forest Litter Features in Floodplain Forest of the “Bolshaya Kokshaga” Reserve

Abstract

The studies, carried out in the floodplain ecotopes of the Bolshaya Kokshaga reserve (Russia, the Republic of Mari El) are relevant due to the need to understand the patterns of formation of the forest litter properties, which are a sensitive integral indicator of the biogeocenoses conditions. The work has been carried out on 20 test plots located in different parts of the floodplain in areas with a point bar type of river bed evolution, and, in addition to the main physicochemical parameters, the weight of the litter, its fractional composition and seasonal dynamics, as well as carbon reserves in it, were estimated. It was established that the weight of the litter on the studies sites decreased during the growing season from 20 to 33% of its value at the end of May. The main loss of its mass was observed in the first half of summer. The variability of the litter’s physicochemical parameters, especially its acidity, the degree of base saturation, the exchangeable calcium content, as well as the content of mobile phosphorus and potassium compounds, was found to be tied mainly to the features of the ecotopes, and their seasonal changes turned out to be statistically insignificant. It was determined that the greatest differences between the ecotopes were in the litter mass and the carbon stock in it. The mobile potassium and exchangeable calcium content were the highest in the litter of biotopes from the central part of the floodplain, and the content of ash and mobile phosphorus was the highest in the near-river zone. The ecotopes differed least of all in terms of the litter acidity and the degree of base saturation. It was shown that the carbon mass and stock in the litter of floodplain forests were significantly lower than in watershed stands, which was explained by its partial removal during floods, having the strongest effect in near-river ecotopes. The litter from the floodplain ecotopes, compared to the watershed ecotopes, also had significantly lower values of acidity, ash content, the sum of exchangeable bases, and the mobile potassium content. They surpassed the litter of lichen and mossy pine forests only in the mobile phosphorus content.