TY - JOUR A1 - Kindermann, Liana A1 - Dobler, Magnus A1 - Niedeggen, Daniela A1 - Linstädter, Anja T1 - A new protocol for estimation of woody aboveground biomass in disturbance-prone ecosystems JF - Ecological indicators : integrating monitoring, assessment and management N2 - Almost one third of global drylands are open forests and savannas, which are typically shaped by frequent natural disturbances such as wildfire and herbivory. Studies on ecosystem functions and services of woody vegetation require robust estimates of aboveground biomass (AGB). However, most methods have been developed for comparatively undisturbed forest ecosystems. As they are not tailored to accurately quantify AGB of small and irregular growth forms, their application on these growth forms may lead to unreliable or even biased AGB estimates in disturbance-prone dryland ecosystems. Moreover, these methods cannot quantify AGB losses caused by disturbance agents. Here we propose a methodology to estimate individual-and stand-level woody AGB in disturbance-prone ecosystems. It consists of flexible field sampling routines and estimation workflows for six growth classes, delineated by size and damage criteria. It also comprises a detailed damage assessment, harnessing the ecological archive of woody growth for past disturbances. Based on large inventories collected along steep gradients of elephant disturbances in African dryland ecosystems, we compared the AGB estimates generated with our proposed method against estimates from a less adapted forest inventory method. We evaluated the necessary stepwise procedures of method adaptation and analyzed each step's effect on stand-level AGB estimation. We further explored additional advantages of our proposed method with regard to disturbance impact quantification. Results indicate that a majority of growth forms and individuals in savanna vegetation could only be assessed if methods of AGB estimation were adapted to the conditions of a disturbance-prone ecosystem. Furthermore, our damage assessment demonstrated that one third to half of all woody AGB was lost to disturbances. Consequently, less adapted methods may be insufficient and are likely to render inaccurate AGB estimations. Our proposed method has the potential to accurately quantify woody AGB in disturbance-prone ecosystems, as well as AGB losses. Our method is more time consuming than conventional allometric approaches, yet it can cover sufficient areas within reasonable timespans, and can also be easily adapted to alternative sampling schemes. KW - Damage assessment KW - Disturbance impacts KW - Tree growth classes KW - Method KW - comparison KW - Flexible sampling strategy KW - Tree allometry KW - Woody KW - aboveground biomass Y1 - 2021 U6 - https://doi.org/10.1016/j.ecolind.2021.108466 SN - 1470-160X SN - 1872-7034 VL - 135 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hunziker, Matthias A1 - Sigurdsson, Bjarni D. A1 - Halldorsson, Gudmundur A1 - Schwanghart, Wolfgang A1 - Kuhn, Nikolaus T1 - Biomass allometries and coarse root biomass distribution of mountain birch in southern Iceland JF - Icelandic agricultural sciences N2 - Root systems are an important pool of biomass and carbon in forest ecosystems. However, most allometric studies on forest trees focus only on the aboveground components. When estimated, root biomass has most often been calculated by using a fixed conversion factor from aboveground biomass. In order to study the size-related development of the root system of native mountain birch (Betula pubescens Ehrh. ssp. czerepanovii), we collected the coarse root system of 25 different aged birch trees (stem diameter at 50 cm length between 0.2 and 14.1 cm) and characterized them by penetration depth (< 1 m) and root thickness. Based on this dataset, allometric functions for coarse roots (> 5 mm and > 2 mm), root stock, total belowground biomass and aboveground biomass components were calculated by a nonlinear and a linear fitting approach. The study showed that coarse root biomass of mountain birch was almost exclusively (> 95 weight-%) located in the top 30 cm, even in a natural old-growth woodland. By using a cross-validation approach, we found that the nonlinear fitting procedure performed better than the linear approach with respect to predictive power. In addition, our results underscore that general assumptions of fixed conversion factors lead to an underestimation of the belowground biomass. Thus, our results provide allometric functions for a more accurate root biomass estimation to be utilized in inventory reports and ecological studies. KW - mountain birch KW - belowground biomass KW - root depth distribution KW - aboveground biomass KW - Betula pubescens Ehrh. ssp czerepanovii Y1 - 2014 SN - 1670-567X VL - 27 SP - 111 EP - 125 PB - Agricultural University of Iceland CY - Reykjavik ER -