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  • 1
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    Improving estimation of woody aboveground biomass in drylands by accounting for disturbances and spatial heterogeneity (2020)
    CRC/TRR228 Database (TRR228DB)
    Details
    Publication Date: 2022-01-04
    Description: Abstract
    Description: Existing methodologies for estimating woody aboveground biomass and carbon stored therein have been developed for forests but are not tailored to the vast dryland ecosystems where vegetation is heterogenous and highly disturbed. Still, those methods are widely applied with questionable results and possible problematic implications, not only for biomass quantification but also for disturbance ecology, biodiversity research, and ecosystem service assessments. We hereby propose a new methodology especially designed to encompass small, disturbed, and irregular woody growth while keeping sampling effort within reasonable limits. Meaningful demographic growth classes are deployed which enable a stratified sampling design and structure a practicable workflow for integration of different allometric models. To account for the high natural and anthropogenic disturbance levels typically shaping dryland vegetation, our method incorporates a detailed damage assessment by harnessing the ecological archive contained in trees. This allows for quantification of biomass losses to certain disturbance agents, uncovers interactive effects between disturbance agents, and enables assessing the impact of disturbance regime shifts. Extrapolation of biomass losses to stand or landscape level also greatly improves the usual reference state comparison approach. Here, we review the problems of conventional methodologies being applied to drylands, develop and present the improved method proposed by us, and perform a formal method comparison between the two. Results indicate that the conventional allometric method is systematically underestimating biomass and carbon storage in disturbed dryland ecosystems. The bias is highest where general biomass density is lowest and disturbance impacts are severest. Damage assessment demonstrates a dependency between main disturbance agents (elephants and fire) while generally biomass is decreased by increasing elephant densities. The method proposed by us is more time consuming than a conventional allometric approach, yet it can cover sufficient areas within reasonable timespans. Consequent higher data accuracy with concomitant applicability to a wider range of research questions are worth the effort. The proposed method can easily be attuned to other ecosystems or research questions, and elements of it may be adapted to fit alternative sampling schemes.
    Description: Other
    Description: This article is a preprint and has not been certified by peer review. The finally published paper can be accessed at: https://doi.org/10.1016/j.ecolind.2021.108466
    Keywords: Ecology ; Biota ; Biomass ; Carbon ; Carbon Storage Dynamics ; Conservation Areas ; Ecology ; Ecosystem ; National Park ; Vegetation ; Vegetation Structure ; Wildlife
    Type: Text , Text
    Format: PDF
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  • 2
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    Microcopter-based colour infrared (CIR) close-range remote sensing as a subsidiary tool for precision farming (2011)
    Geographisches Institut der Universität zu Köln - Kölner Geographische Arbeiten
    Details
    Publication Date: 2022-01-12
    Description: Abstract
    Description: Microcopters as a highly flexible and low-cost sensor platform provide new opportunities of data acquisition for various environmental and geoscientific purposes (e.g. environmental monitoring, forestry, geospatial data etc.). One promising field of application for this technique is precision farming. Thereby, the application of capital equipment like crop protection products (also fertilizer) can be adapted to the spatial and temporal dynamics of soil and population parameters to reduce costs and keep processes more environmentally-compatible. In this context, the objective of this project is to produce CIR photographs and other remote sensing products in the visible (VIS) and near infrared (NIR) range as classified input data for subsequent procedures of precision farming and for efficiency tests in a user-defined spatial and temporal resolution. Therefore a remotely controlled microcopter has been equipped with a modified compact digital camera now capable of taking images not only in the VIS but also in the ultraviolet (UV) and NIR spectra (about 320 nm to 1100 nm), depending on the applied optical filters. The aerial surveys are conducted with a microcopter which is capable of autonomously completing a GPS waypoint track specified by the user. The localizations of exposures, height above surface, the camera heading, and other parameters can be set up in advance using a flight software. The microcopter itself represents an ultraflexible multi-sensor platform, where the camera provides a modular setup for generating high-resolution aerial CIR photographs. The images obtained from the surveys are being rectified and subjected to object orientated texture analysis for supervised classifications regarding surface anomalies like albedo variations of green vegetation. The results are processed to generate accurate position data for the distinction of various vegetation types like weed and crop, or different states of vegetation health due to soil dryness, precipitation damages or pest infestation.
    Description: SeriesInformation
    Description: Proceedings on the Workshop of Remote Sensing Methods for Change Detection and Process Modelling, 18-19 November 2010, University of Cologne, Germany, Kölner Geographische Arbeiten, 92, pp. 49-54
    Keywords: Other ; None ; Vegetation ; Remote Sensing
    Type: Text , Book Section
    Format: 2303 Kilobytes
    Format: 6 Pages
    Format: PDF
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  • 3
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    Dataset on conservation with elevated elephant densities sequesters carbon in soils despite losses of woody biomass (2020)
    CRC/TRR228 Database (TRR228DB)
    Details
    Publication Date: 2022-03-09
    Description: Abstract
    Description: Nature conservation and restoration in terrestrial ecosystems is often focused on increasing the numbers of megafauna, expecting them to have positive impacts on ecological self-regulation processes and biodiversity. In sub-Saharan Africa, conservation efforts also aspire to protect and enhance biodiversity with particular focus on elephants. However, elephant browsing carries the risk of woody biomass losses. In this context, little is known about how increasing elephant numbers affects carbon stocks in soils, including the subsoils. We hypothesized that (1) increasing numbers of elephants reduce tree biomass, and thus the amount of C stored therein, resulting (2) in a loss of soil organic carbon (SOC). If true, a negative carbon footprint could limit the sustainability of elephant conservation from a global carbon perspective. To test these hypotheses, we selected plots of low, medium, and high elephant densities in two national parks and adjacent conservancies in the Namibian component of the Kavango Zambezi Transfrontier Area (KAZA), and quantified carbon storage in both woody vegetation and soils (1 m). Analyses were supplemented by the assessment of soil carbon isotopic composition. We found that increasing elephant densities resulted in a loss of tree carbon storage by 6.4 t ha−1. However, and in contrast to our second hypothesis, SOC stocks increased by 4.7 t ha−1 with increasing elephant densities. These higher SOC stocks were mainly found in the topsoil (0–30 cm) and were largely due to the formation of SOC from woody biomass. A second carbon input source into the soils was megaherbivore dung, which contributed with 0.02–0.323 t C ha−1 year−1 to ecosystem carbon storage in the low and high elephant density plots, respectively. Consequently, increasing elephant density does not necessarily lead to a negative C footprint, as soil carbon sequestration and transient C storage in dung almost compensate for losses in tree biomass.The dataset contains the raw data of soil analyses up to 1 m soil depth and vegetation data on plot level. A third sheet of the excelfile contains necessary information about abbreviations used within the dataset.
    Keywords: Ecology ; Environment ; Carbon ; Soil Organic Carbon ; Conservation Areas ; Ecosystem ; Vegetation
    Type: Dataset , Dataset
    Format: MS Excel
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  • 4
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    Dataset on effects of conservation with wildlife and agriculture on plant lignin and n-alkanes components in soils (2022)
    TRR228 Database (TRR228DB)
    Details
    Publication Date: 2022-03-09
    Description: Abstract
    Description: 1.Nature conservation is fostered through the expansion of protected areas. This is particularly evident in Sub-Saharan Africa (SSA), where conservation is intended to simultaneously promote the recovery of megafauna like elephants. Rising numbers of megaherbivores induce woody biomass losses but restore soil organic carbon (SOC). We hypothesized that increases of SOC under conservation with wildlife in SSA go directly along with increases in the preservation of plant residues in soil organic matter (SOM), traceable by plant biomarkers such as lignin and n-alkane. In contrast, intensification with agriculture leads to a reduction of them. To test this, we sampled topsoil (0-10 cm) and corresponding plant samples along different intensities of conservation and intensification in the Zambezi Region of Namibia, comprising a) conservation sites with low, medium and high elephant densities and b) adjacent intensification sites with rangeland and cropland. We found that lignin and n-alkane patterns of the above-ground vegetation were preserved in the soil. Confirming our hypothesis, increasing SOC contents with rising elephant densities went along with increasing accumulation of lignin-derived phenols. Under conservation, lignin concentrations were influenced by the input of woody debris into the soil, traced by carbon isotopes, clay, and total woody biomass. This could not be proved for n-alkanes. Under intensification, lignin derived phenols were lower than under conservation, but again, there was no clear pattern for n-alkanes. We showed that conservation with wildlife leads to an increase of SOC, which was accompanied by an accumulation of lignin-derived phenols in the soil organic matter. Increased input of woody debris, clay content and total biomass were important parameters for this lignin accumulation. In contrast, intensification with agriculture leads to a loss of lignin. Contrary, n- alkanes were not sensitive to detect effects of conservation or intensification. We conclude that increasing incorporation of woody residues into soil is a key mechanism controlling SOC accrual and to offset losses of aboveground biomass on SOC in sites under conservation with wildlife. The dataset contains raw data of lignin and n-alkanes and related soil properties. A third sheet contains a legend with information on abbreviations.
    Keywords: Ecology ; Environment ; Conservation ; Intensification ; Soil Organic Carbon ; Carbon Storage Dynamics ; Carbon Sequestration ; Biomarker ; Lignin ; n-Alkanes
    Type: Dataset , Microsoft excel file
    Format: MS Excel
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  • 5
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    Preprint: Understanding the consequences of refaunation in coexistence landscapes: integrating social and ecological dimensions (2024)
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    Details
    Publication Date: 2024-05-03
    Description: Abstract
    Description: Human-wildlife conflict poses a significant challenge to 21st-century conservation, with a limited understanding of these interactions within the broader social and ecological context of coexistence. Specifically, the impact of large-scale refaunation efforts on social-ecological dynamics in landscapes shared by humans and wildlife remains poorly understood. This study aims to enhance this understanding by jointly analyzing the consequences of refaunation involving wildlife and cattle in a mixed-use landscape in sub-Saharan Africa. Applying an interdisciplinary approach encompassing ecology, soil science, agricultural economics, and environmental anthropology, we reconstruct the coupling processes in social-ecological systems triggered by refaunation over the last five decades in Namibia&039;s portion of the Kavango-Zambezi Transfrontier Conservation Area (KAZA TFCA). To assess ecological impacts of refaunation with cattle or elephants, space-for-time substitutions are used. The findings demonstrate that post-1960s increases in cattle numbers, and the surge in wildlife numbers since the 1990s have shaped the coexistence landscape. Elephant refaunation positively impacted herbaceous vegetation and soil conditions at intermediate elephant densities but negatively affected vegetation at higher densities. Wildlife refaunation, achieved through conservation and tourism, reduced income inequality. However, this effect was outweighed by the concentration of wealth among affluent cattle owners. Increasing rural inequality contributed challenges of local resource governance. Our study highlights that refaunation has profound ecological and socio-economic repercussions, challenging existing forms of resource governance in KAZA-TFCA and similar coexistence landscapes in Africa, and emphasizing the need for further research on the simultaneous increase of wildlife and cattle and its socio-ecological consequences.
    Description: Other
    Description: Article impact statement: Simultaneous refaunation with cattle and elephants poses both ecological and governance challenges, emphasizing the need for balanced conservation policies.
    Keywords: Ecology ; Environment ; Carbon ; Conservation Areas ; Ecology ; National Park ; Vegetation Structure ; Wildlife ; Livestock Grazing ; Future-making ; Economy ; Anthropology ; Human-Environment Interactions ; Tree-Grass Interactions ; Rewilding ; Refaunation
    Type: DataPaper , Scientific Publication
    Format: PDF
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