Biotic and Abiotic Determinants of Soil Organic Matter Stock and Fine Root Biomass in Mountain Area Temperate Forests—Examples from Cambisols under European Beech, Norway Spruce, and Silver Fir (Carpathians, Central Europe)

Marcin K. Dyderski,Grzegorz Smułek,Anna Zielonka,Marek Drewnik,Łukasz Musielok,Dariusz Struzik,Katarzyna Ostapowicz

doi:10.3390/f12070823

Abstract

Forest ecosystems significantly contribute to the global organic carbon (OC) pool, exhibiting high spatial heterogeneity in this respect. Some of the components of the OC pool in a forest (woody aboveground biomass (wAGB), coarse root biomass (CRB)) can be relatively easily estimated using readily available data from land observation and forest inventories, while some of the components of the OC pool are very difficult to determine (fine root biomass (FRB) and soil organic matter (SOM) stock). The main objectives of our study were to: (1) estimate the SOM stock; (2) estimate FRB; and (3) assess the relationship between both biotic (wAGB, forest age, foliage, stand density) and abiotic factors (climatic conditions, relief, soil properties) and SOM stocks and FRB in temperate forests in the Western Carpathians consisting of European beech, Norway spruce, and silver fir (32 forest inventory plots in total). We uncovered the highest wAGB in beech forests and highest SOM stocks under beech forest. FRB was the highest under fir forest. We noted a considerable impact of stand density on SOM stocks, particularly in beech and spruce forests. FRB content was mostly impacted by stand density only in beech forests without any discernible effects on other forest characteristics. We discovered significant impacts of relief-dependent factors and SOM stocks at all the studied sites. Our biomass and carbon models informed by more detailed environmental data led to reduce the uncertainty in over- and underestimation in Cambisols under beech, spruce, and fir forests for mountain temperate forest carbon pools.

Highlights

Our study provides new data on soil organic matter (SOM) stocks and fine root biomass (FRB) for mountain temperate ecosystems and discusses their determinants
The estimation error is smaller if the species composition of the forest as well as the impact of abiotic factors are taken into account, which was clearly shown by the root mean square error values
Referring to the specific objectives of our study, we found the largest woody aboveground biomass (wAGB) and SOM stocks in beech-dominated forests

Summary

Introduction

Forest ecosystems significantly contribute to global organic carbon (OC) sequestration [1,2], storing 80% of the aboveground OC pool and 40% of the soil organic carbon (SOC) pool [3,4]. In the case of forests, a very high heterogeneity of the OC stock was noted, which was explained via both abiotic factors—such as topographic effects [5,6,7,8,9], morphogenetic processes [10], and soil properties [11,12,13,14]—and biotic factors—such as the tree species composition [15,16,17,18,19,20], silviculture treatment [10,12] and stand age [21,22]. The total OC pool in a forest is partitioned between OC accumulated in aboveground biomass (AGB), belowground biomass (BGB) and the soil organic matter (SOM) stock [9] The quantification of the OC pool in forests that cover large areas of land is important from a research point of view but more importantly in the context of expected changes due to climate change and deforestation observed all over the world [23,24,25,26].

Objectives

Methods

Results

Discussion

Conclusion