Inventory-based estimation of forest biomass in Shitai County, China: A comparison of five methods

X. Tang, L. Fehrmann, F. Guan, D. I. Forrester, R. Guisasola, C. Kleinn

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Several comparative studies have reported that there can be great discrepancies between different methods used to estimate forest biomass. With the development of carbon markets, an accurate estimation at the regional scale (i.e. county level) is becoming increasingly important for local government. In this study, we applied five methodologies [continuous biomass expansion factor (CBEF) approach, mean biomass density (MB) approach, mean biomass expansion factor (MBEF) approach, national continuous biomass expansion factors (NCBEF) proposed by Fang et al (2002), standard IPCC approach] to estimate the total biomass for Shitai County, China. The CBEF is generally considered to provide the most realistic estimates in term of regional biomass because CBEF reflects the change of BEF to stand density, stand age and site conditions. The forests of the whole county were divided into four forest types, namely Chinese fir plantations (CF), hardwood broadleaved forests (HB), softwood–broadleaved forests (SB) and mason pine forests (MP) according to the local forest management inventory of 2004. Generally, the MBEF approach overestimated forest biomass while the IPCC approach underestimated forest biomass for all forest types when CBEF derived biomass was used as a control. The MB approach provided the most similar biomass estimates for all forest types and could be an alternative approach when a CBEF equation is lacking in the study area. The total biomass derived from MBEF was highest at 1.44×107 t, followed by 1.32 ×107 t from CBEF, 1.31 ×107 t from NCBEF, 1.25 ×107 t from MB and 1.16 ×107 t from IPCC. Our results facilitate method selection for regional forest biomass estimation and provide statistical evidence for local government planning to enter the potential carbon market.

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Tourists’ perception of deadwood in mountain forests

Fabio Pastorella, Admir Avdagić, Azra Čabaravdić, Amiina Mraković, Merisa Osmanović, Alessandro Paletto

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In the traditional forest management the non-living woody biomass in forests was perceived negatively. Generally, deadwood was removed during the silvicultural treatments to protect forests against fire, pests and insects attacks. In the last decades, the perception of forest managers regarding forest deadwood is changing. However, people’s opinions about the presence of deadwood in the forests have been few investigated. In view of this gap, the aim of the paper is to understand the tourists’ perception and opinions towards the deadwood in mountain forests. The survey was carried out in two study areas: the first one in Italy and the second one in Bosnia-Herzegovina. A structured questionnaire was administered to a random sample of visitors (n=156 in Italy; n=115 in Bosnia-Herzegovina). The tourists’ preferences were evaluated through a set of images characterized by a different amount of standing dead trees and lying deadwood. The collected data were statistically analyzed to highlight the preferred type of forests related to different forms of management of deadwood (unmanaged forests, close-to-nature forests, extensive managed forests and intensive managed forests). The results show that both components of deadwood are not perceived negatively by tourists. More than 60% of respondents prefer unmanaged forests and close-to-nature managed forests, 40% of respondents prefer intensive managed forests in which deadwood is removed during the silvicultural treatments.

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Response of the dominant rodent species to close-to-nature logging practices in a temperate mixed forest

Peter Lešo, Andrea Lešová, Rudolf Kropil, Peter Kaňuch

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The paper aims to answer the question whether differences exist in microhabitat preferences of the yellow-necked mouse and the bank vole between the natural forest and close-to-nature managed forest in the phase of stand regeneration. The two species were live-trapped during two periods in 2006 and 2007 on a square trapping grid established in a managed forest and a natural one. Ten microhabitat variables of each trapping point were measured to analyse their influence on the spatial distribution of the two species. At trapping points, the number of capture records for each species as a dependent variable was modelled using Generalised Linear Models. The herbal cover and a distance to the nearest woody debris were the most important measured microhabitat variables which affect the spatial distribution of both species. In the natural forest, the number of captures in both species increased significantly (p < 0.05) with a decreasing number of trees, increasing undergrowth coverage and decreasing distance to the nearest woody debris. In the managed forest, an increasing distance to the nearest tree and increasing herbal cover had a negative effect on the yellow-necked mouse occurrence (p < 0.001), while in contrast, the increase in values of the same variables increased frequency of occurrence of the bank vole (p < 0.001). Moreover, the bank vole was more frequent in the presence of woody debris (p < 0.002). The study demonstrated clearly that these species modify their spatial activity depending on the management of the woodland.

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Carbon and nitrogen stocks in dead wood of tropical lowland forests as dependent on wood decay stages and land-use intensity

Selis Meriem, Soekisman Tjitrosoedirjo, Martyna Malgorzata Kotowska, Dietrich Hertel, Triadiati Triadiati

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Rapid transformation of natural forests into other land-use systems in the lowlands of Sumatra, Indonesia, strongly reduces total aboveground biomass and affects nutrient cycling. However, the consequences of this conversion for C and N stocks of dead wood remains poorly understood particularly in natural forests and jungle rubber. This study examined the differences in dead wood abundance, and C, N and lignin concentrations of three decay stages of dead wood as well as the stocks of these chemical components stored in dead wood. Standing and fallen dead wood was determined as coarse woody debris with diameter ≥ 10 cm and classified into three decay stages of wood. Mass of dead wood was estimated using allometric equation. Total C and N stocks in dead wood in the natural forests (4.5 t C ha^-1, 0.05 t N ha^-1, respectively) were three times higher than those in the jungle rubber (1.5 t C ha^-1, 0.02 t N ha^-1, respectively). The stocks of C and N at early and advanced wood decay stages in the natural forests were also higher than those in the jungle rubber. The decay stages showed pronounced differences in concentrations of chemical components. With advancing stage of wood decay, N concentration increased and C/N ratio decreased, while concentrations of C and lignin were variable. The distribution of dead wood mass and stocks of C, and lignin were found to be higher in the early decay than those in the advanced decay stage. Higher input of dead wood in natural forests indicated a higher importance of dead wood decay in natural forests than in jungle rubber systems. Thus, replacing natural forests with jungle rubber strongly reduces total C and N stocks which might have a marked negative effect on the ecosystems' nutrient turnover and cyle.

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