Availability and Structure of Coarse Woody Debris in Hemiboreal Mature to Old-Growth Aspen Stands and Its Implications for Forest Carbon Pool

Silva Šēnhofa,Āris Jansons,Līga Liepa,Guntars Šņepsts,Kārlis Bičkovskis,Inga Straupe,Ieva Jaunslaviete

doi:10.3390/f12070901

Abstract

European aspen deadwood is extensively studied as a habitat for saproxylic species, while less is known of its dynamics and role in carbon sequestration. We studied unmanaged mature (41–60 years), moderately overmature (61–80 years), overmature (81–100 years), and old-growth (101–140 years) and managed mature and moderately overmature aspen stands on fertile mineral soils. In unmanaged stands, marginal mean CWD volume was from 67.3 ± 12.1 m3 ha−1 in moderately overmature to 92.4 ± 5.1 m3 ha−1 in old-growth stands, with corresponding marginal mean CWD carbon pool 8.2 ± 1.6 t ha−1 and 12.5 ± 0.7 t ha−1 (all p > 0.05), respectively. High CWD volume was present in most stands, by at least two-thirds of plots comprising more than 20 m3 ha−1, and about half of CWD was larger than 30 cm in diameter. Changes in CWD species composition toward a higher proportion of deciduous deadwood in old-growth stands, together with a high volume of recently dead trees, suggest early senescence of the dominant aspen cohort.

Highlights

European aspen (Populus tremula L.) is an early-succession species in boreal and hemiboreal forests [1], with scattered occurrence [2,3,4] but high ecological importance.Aspen is commonly regarded as ‘keystone species’ in the boreal and hemiboreal forests because both living and dead aspen trees host more specialist and endangered species than other tree species in the region [4,5,6,7]
Besides the maintenance of biodiversity [13,14], deadwood has an important role in carbon dynamics [15], estimated to comprise 8% of the total carbon pool in forests globally [16]
This was conducted in European aspen (Populus tremula L.) stands in hemi2

Summary

Introduction

European aspen (Populus tremula L.) is an early-succession species in boreal and hemiboreal forests [1], with scattered occurrence [2,3,4] but high ecological importance.Aspen is commonly regarded as ‘keystone species’ in the boreal and hemiboreal forests because both living and dead aspen trees host more specialist and endangered species than other tree species in the region [4,5,6,7]. European aspen (Populus tremula L.) is an early-succession species in boreal and hemiboreal forests [1], with scattered occurrence [2,3,4] but high ecological importance. Besides the maintenance of biodiversity [13,14], deadwood has an important role in carbon dynamics [15], estimated to comprise 8% of the total carbon pool in forests globally [16]. The deadwood persistence and turnover are affected by a number of factors, including disturbance dynamics, forest zone, site type and soil moisture regime, dominant species, stand age, and productivity [17,18,19]. Latest studies show that even seemingly small improvement by empirical-based variables has a substantial effect on estimated global carbon stock [20]

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