Coarse woody debris density and carbon concentration by decay classes in mixed montane wet tropical forests

Abstract

The role of coarse woody debris (CWD) in the global carbon (C) cycle is growing under increasing tree mortality driven by climate variability and disturbances. Quantifying C in CWD critically depends on accurate estimates of CWD density and C concentration in CWD. This study considered the main decomposition pathways (the proportions of CWD decomposed by fungi vs. invertebrates; fungal decay types) and the relationships between decay class, wood density, moisture, and C content of CWD in old‐growth mixed monsoon montane tropical forests in Vietnam based on the inventory of 359 CWD pieces. The bulk density of wood of the 1st, 2nd, 3rd, 4th, and 5th decay classes averaged 0.56, 0.49, 0.37, 0.28, and 0.15 g cm−3, respectively. The density reduction across decay classes did not significantly differ for snags, stumps, branches, leaning, and lying logs. Wood density was negatively related to wood moisture. The wood mass loss averaged 0%, 20%, 37%, 54%, and 74% in the CWD of the 1st, 2nd, 3rd, 4th, and 5th decay classes, respectively. Signs of invertebrate activity were recorded on 3% of CWD pieces. Among CWD samples with identifiable decay type, 88% were decomposed by white‐rot, 8% were decomposed as brown‐rot, and 4% of pieces contained both white‐ and brown‐rot patches. The mean C concentration in wood was 46.5%. It did not change with decay class. Our research provides an empirical basis for future inventories of CWD carbon stocks in Asian montane tropical mixed forests.

Influencia de parámetros físicos y microambientales en macromicetos degradadores de madera de Abies religiosa (Pinaceae)

“…Por lo general los troncos recién caídos son más densos y están poco descompuestos, por lo que contienen una baja humedad; por el contrario, los troncos menos densos y que están más descompuestos tienen mayores contenidos de humedad (Mäkinen et al, 2006). La relación entre densidad y humedad ya ha sido reportada en diferentes estudios (Christensen y Vesterdal, 2003;Fukasawa et al, 2009;Rajala et al, 2012;Shorohova et al, 2022) y se explica porque al avanzar el proceso de descomposición se crean espacios vacíos dentro de la madera y al ser ésta un material higroscópico, se almacena cada vez más agua en dichos espacios (Flournoy et al, 1991;Rawat et al, 1998;Karppanen et al, 2008). También se sabe que los cambios en el contenido de humedad pueden deberse a los cambios en la composición química y al agua que producen los hongos como resultado de la respiración fúngica (Thybring, 2017).…”

“…También se ha reportado la relación de la densidad con la humedad de la madera y su incorporación a los esquemas de etapas de descomposición (Rajala et al, 2012;Shorohova et al, 2022), que anteriormente estaban más determinados por aspectos visuales como la dureza de la madera (p. ej., cantidad de centímetros que se entierra un cuchillo dentro de los troncos caídos).…”

Woody debris removal modifies carbon stocks and soil properties in a fragmented tropical rainforest

“…Sometimes referred to as the living dead, standing and fallen coarse woody debris (CWD) sustains remarkable biodiversity and contributes to forest ecosystem functioning (Thorn et al, 2020). CWD constitutes a significant carbon pool-ranging from less than 10 Mg/ ha to over 150 Mg/ha across temperate and tropical forests-that sometimes matches the size of the live vegetation carbon pool (Harmon et al, 1986(Harmon et al, , 2013Martin et al, 2021;Palace et al, 2012;Shorohova et al, 2022). CWD also contributes to the transport of organic residues from vegetation to soil, thereby impacting ecosystem carbon and energy flows (Gora et al, 2019;Jordan & Kline, 1972;Magnússon et al, 2016).…”

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].…”