Fine Root Dynamics in Afromontane Forest and Adjacent Land Uses in the Northwest Ethiopian Highlands

Dessie Assefa,Douglas Godbold,Boris Rewald,Hans Sandén

doi:10.3390/f8070249

Dessie Assefa, Douglas Godbold + Show 2 more

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https://doi.org/10.3390/f8070249

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Abstract

Fine roots are a major pathway of C input into soils. The aim of this study was to quantify fine root stocks, production and turnover in natural forest and land use systems converted from forests in Ethiopia. The study was conducted in a remnant Afromontane forest, eucalyptus plantation and grass and cropland in NW Ethiopia. Fine root dynamics were investigated using three different methods: sequential coring, in-growth cores and in-growth nets. Soil cores for sequential analyses were taken in quarterly intervals, while in-growth cores and nets were harvested corresponding to 1-, 2-, 3-, 4-, 5-, 8- and 12-month interval. Fine root stocks averaged 564, 425, 56 and 46 g·m−2 in the forest, eucalyptus, grazing land and cropland ecosystems, respectively. The values decreased exponentially with increasing soil depth. In forest and eucalyptus, fine root biomass and necromass were highest in the dry season. Estimates of fine root production differed according to the method used. Fine root production based on in-growth coring averaged 468, 293, 70 and 52 g m−2·year−1. In general, land use conversion from forest to open lands reduced fine root production by 85–91%. The turnover rate of fine roots was 1.5 for forest and 2.1 for eucalyptus plantation.

Highlights

Assessments of fine roots by simple excavation techniques were started as early as the 18thCentury [1]
Several methods have been developed for measuring fine root production, mortality and eventually decomposition in situ [9], all have drawbacks and are often confounded by artifacts [10,11,12]
Due to the importance of fine root turnover in soil C storage [41,42], we investigated the fine root biomass and turnover on a remnant church forest, eucalyptus plantation, grazing land and cropland in the Ethiopian highland landscapes of the Amhara region

Summary

Introduction

Assessments of fine roots by simple excavation techniques were started as early as the 18thCentury [1]. Worldwide and regional ecosystem estimates of fine root production, turnover and carbon fluxes remain uncertain [6]. Several methods have been developed for measuring fine root production, mortality and eventually decomposition in situ [9], all have drawbacks and are often confounded by artifacts [10,11,12]. The sequential coring method has been widely used [13,14], but may miss root turnover between sampling dates. This results in a zero estimate [15] because root mortality and production occur simultaneously [16]. The sequential coring method relies on a calculated rather than a measured estimate of fine root production

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