Tree stumps — an important but undervalued dead wood pool

Abstract

Key message Dead wood in forests is an important resource due to its role for nutrient cycles, carbon budgets, and biodiversity, among other. While standing and downed dead wood are typically monitored in National Forest Inventories (NFI), stumps have not received comparable attention. Based on the detailed stump inventory in the current Swiss NFI, this study demonstrates the important contribution of stumps to the dead wood pool. Context Dead wood (DW) in forests is an important resource due to its role for nutrient cycles, carbon budgets, and biodiversity, among other. NFIs provide representative DW estimates focusing primarily on standing and downed DW. Little is known on stumps as a DW pool. Aims The aim of this study is to obtain an accurate assessment of the stump volume and biomass in the Swiss NFI to identify its significance for the DW pool, to evaluate the development over the last 30 years, and to examine the need for additional measurements for improving estimates compared to commonly applied assumptions for stump height such as a constant stump height or a fraction of tree height. Methods The current NFI includes a detailed stump inventory to improve accuracy and completeness of the aboveground DW pool estimate. Based on available data, stump volume estimates were derived at different accuracies to evaluate the contribution to the total DW pool over time. Results Based on the extended stump inventory in the NFI5, the contribution of stumps to the total DW pool is approximately 25%. The effect of simplifying assumptions or limited measurements to estimate stump volume can result in a significant underestimation of up to $$2/3$$ 2 / 3 of the more accurate and comprehensive assessment of this pool. Conclusion This study demonstrates that stumps can be a significant proportion of DW in forests, which should be accounted for in order to improve accuracy and completeness of NFI estimates and derived data such as C stocks for greenhouse gas reporting.

Nutrient Element Stocks and Dynamic Changes in Stump–Root Systems of Eucalyptus urophylla × E. grandis

“…Due to its significant quantity and slow turnover, CWD plays a crucial role in nutrient release and long-term forest productivity, as well as maintaining ecosystem integrity and ecological processes [1,2]. Previous studies on CWD have mainly focused on standing dead trees, fallen logs, and large branches, primarily in natural forests or forests at higher latitudes or altitudes [3][4][5][6]. In intensively managed plantations, the main type of CWD is often stump-root systems left after logging [7][8][9][10].…”

“…For instance, Debeljak et al found that the underground biomass in Slovenian plantations ranged from 40.0 t/hm 2 to 48.2 t/hm 2 , while natural forests only had 2.0 t/hm 2 to 22.8 t/hm 2 [11]. Typically, the aboveground biomass of stump-root systems only represents a small portion of the total CWD biomass of plantation ecosystems, with the coarse roots being the main component [3]. However, excavating the underground part is labor-intensive, time-consuming, and costly [12][13][14].…”

“…Stump-root systems are a long-term nutrient source in plantation ecosystems [1,3,[7][8][9]13,[17][18][19][20][21][22][23]. For example, Palviainen et al studied the changes in C, N, P, K, Ca, and Mg content and storage during the stump-root system decomposition of three tree species in southern Finland over 40 years, and found that stump-root systems alleviated the nutrient loss caused by water-soil erosion after clearcutting [7,8].…”

“…However, due to long-term continuous planting and improper management, the soil fertility of Eucalyptus plantations has degraded, leading to a decline in productivity. Although the nutrient content is not as high as that of fallen leaves and fine roots, stump-root systems' high biomass and strong resistance to decomposition make them a long-term nutrient reservoir for Eucalyptus plantations [1,3,[27][28][29]. However, our current knowledge regarding the nutrient storage of stump-root systems in Eucalyptus plantations, the release patterns of nutrient elements over time, and the factors that influence them remains limited.…”