@article{KindermannDoblerNiedeggenetal.2021,
  author    = {Kindermann, Liana and Dobler, Magnus and Niedeggen, Daniela and Linst{\"a}dter, Anja},
  title     = {A new protocol for estimation of woody aboveground biomass in disturbance-prone ecosystems},
  series = {Ecological indicators : integrating monitoring, assessment and management},
  volume    = {135},
  journal   = {Ecological indicators : integrating monitoring, assessment and management},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1470-160X},
  doi       = {10.1016/j.ecolind.2021.108466},
  pages     = {16},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@masterthesis{Richter2021,
  type      = {Bachelor Thesis},
  author    = {Richter, Wibke},
  title     = {Einzelbaumbasierte Quantifizierung der oberirdischen Biomasse in zwei Obstkulturen (Prunus avium L. und Malus domestica Borkh.) am Standort Marquart},
  doi       = {10.25932/publishup-50636},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-506369},
  school      = {Universit{\"a}t Potsdam},
  pages     = {vi, 33},
  year      = {2021},
  abstract  = {The quantification of plant biomass using efficient methods is a crucial point in different fields of science. This paper aims to facilitate the determination of hydrogen content of cherry and apple trees at a research site in the north east of Germany using the estimation of their biomass based on the sampling of singletrees. Therefore the volume of 13 cherry and 11 apple trees was determined bydividing them into segments and measuring the specific length and diameter. All segments were grouped by diameter classes. Furthermore the wood density of the branches and the mean leaf biomass was determined. For the calculation of woody biomass a value for wood dry density derived from the literature for each species was used. The biomass allocation across the diameter classes was investigated and a regression analyses implemented using easily measurable tree parameters as well as data derived by a terrestrial laser scanner. The experimental density values increased with increasing branch diameter. The deviation to the literature value was small for the cherry wood but large for the apple wood. The investigation of leaf biomass was carried out independently from measured trees, so no relation could be established between woody and leaf biomass and only mean values were calculated. The proportion of different diameter classes at the whole tree biomass was highly variable and thus an estimation using only the substantial tree compartments does not show appropriate results. The most reliable and efficient way to estimate the aboveground biomass is by utilizing the developed models. A linear regression turned out to provide the best results for the present tree populations of same age and similar size. While the laser scan data did not correlate with the dry wood biomass, the linear models utilizing the stem diameter d or d² as predictor indicated high significance (p - value < 0.001) and a very good model fit (R² > 0.8) for both species.},
  language  = {de}
}
@article{HunzikerSigurdssonHalldorssonetal.2014,
  author    = {Hunziker, Matthias and Sigurdsson, Bjarni D. and Halldorsson, Gudmundur and Schwanghart, Wolfgang and Kuhn, Nikolaus},
  title     = {Biomass allometries and coarse root biomass distribution of mountain birch in southern Iceland},
  series = {Icelandic agricultural sciences},
  volume    = {27},
  journal   = {Icelandic agricultural sciences},
  publisher = {Agricultural University of Iceland},
  address   = {Reykjavik},
  issn      = {1670-567X},
  pages     = {111 -- 125},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}