How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna

Globally, bush encroachment poses a great threat to the conservation of biodiversity and rangeland productivity. However, control methods of encroaching woody species have rarely been experimentally quantified. We assessed the impact of tree thinning intensities on tree mortality, and the herbaceous...

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Main Authors: Teshome Abate, Tesfaye Abebe, Anna Treydte
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-01-01
Series:Frontiers in Ecology and Evolution
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Online Access:https://www.frontiersin.org/articles/10.3389/fevo.2024.1461573/full
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author Teshome Abate
Teshome Abate
Tesfaye Abebe
Anna Treydte
Anna Treydte
Anna Treydte
author_facet Teshome Abate
Teshome Abate
Tesfaye Abebe
Anna Treydte
Anna Treydte
Anna Treydte
author_sort Teshome Abate
collection DOAJ
description Globally, bush encroachment poses a great threat to the conservation of biodiversity and rangeland productivity. However, control methods of encroaching woody species have rarely been experimentally quantified. We assessed the impact of tree thinning intensities on tree mortality, and the herbaceous community in Borana rangelands, an Ethiopian savannah ecosystem. At two 1.4 ha areas of mono-specific Vachellia drepanolobium stands, we set up 20 m x 10 m experimental plots with four tree-thinning treatments (0%, 33%, 67%, and 100% tree removal), with three replications in a randomized complete block design (RCBD) across two sites. The 0% plot was left uncleared and used as control. Over two growing periods, we monitored resulting tree mortality, coppicing, seedling mortality, and recruitment as well as herbaceous layer attributes (diversity, biomass) and the rangeland conditions. Tree thinning intensity significantly increased abundance of the dominant desirable grass species. Total herbaceous and grass species richness, diversity and biomass were significantly improved under high (100%) and moderate (67%) tree removal intensity. We conclude that tree thinning at moderate intensity (67%) was most effective in enhancing mortality of encroached trees, and improving grass diversity, and herbaceous biomass. We stress that effective tree thinning requires post-thinning management and repeated bush control measures. Our findings contribute to development of recommendations on controlling bush encroachment, species restoration, and rangeland productivity in Ethiopian rangelands.
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spelling doaj-art-e5d1230d4e204e4c982aae2cb628a9d82025-01-06T06:59:15ZengFrontiers Media S.A.Frontiers in Ecology and Evolution2296-701X2025-01-011210.3389/fevo.2024.14615731461573How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savannaTeshome Abate0Teshome Abate1Tesfaye Abebe2Anna Treydte3Anna Treydte4Anna Treydte5College of Agriculture, Hawassa University, Hawassa, EthiopiaCollege of Forestry and Natural Resources, Wondo Genet, Hawassa University, Hawassa, EthiopiaCollege of Agriculture, Hawassa University, Hawassa, EthiopiaDepartment of Sustainable Agriculture and Biodiversity Conservation, School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology, Arusha, TanzaniaEcology of Tropical Agricultural Systems, Hans Ruthenberg Institute, University of Hohenheim, Stuttgart, GermanyDepartment of Physical Geography, Stockholm University, Stockholm, SwedenGlobally, bush encroachment poses a great threat to the conservation of biodiversity and rangeland productivity. However, control methods of encroaching woody species have rarely been experimentally quantified. We assessed the impact of tree thinning intensities on tree mortality, and the herbaceous community in Borana rangelands, an Ethiopian savannah ecosystem. At two 1.4 ha areas of mono-specific Vachellia drepanolobium stands, we set up 20 m x 10 m experimental plots with four tree-thinning treatments (0%, 33%, 67%, and 100% tree removal), with three replications in a randomized complete block design (RCBD) across two sites. The 0% plot was left uncleared and used as control. Over two growing periods, we monitored resulting tree mortality, coppicing, seedling mortality, and recruitment as well as herbaceous layer attributes (diversity, biomass) and the rangeland conditions. Tree thinning intensity significantly increased abundance of the dominant desirable grass species. Total herbaceous and grass species richness, diversity and biomass were significantly improved under high (100%) and moderate (67%) tree removal intensity. We conclude that tree thinning at moderate intensity (67%) was most effective in enhancing mortality of encroached trees, and improving grass diversity, and herbaceous biomass. We stress that effective tree thinning requires post-thinning management and repeated bush control measures. Our findings contribute to development of recommendations on controlling bush encroachment, species restoration, and rangeland productivity in Ethiopian rangelands.https://www.frontiersin.org/articles/10.3389/fevo.2024.1461573/fullbush encroachmentrestorationtree removalVachellia drepanolobiumEthiopia
spellingShingle Teshome Abate
Teshome Abate
Tesfaye Abebe
Anna Treydte
Anna Treydte
Anna Treydte
How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna
Frontiers in Ecology and Evolution
bush encroachment
restoration
tree removal
Vachellia drepanolobium
Ethiopia
title How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna
title_full How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna
title_fullStr How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna
title_full_unstemmed How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna
title_short How much to cut? Finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an East African savanna
title_sort how much to cut finding an optimal thinning intensity of encroaching woody species for the herbaceous community in an east african savanna
topic bush encroachment
restoration
tree removal
Vachellia drepanolobium
Ethiopia
url https://www.frontiersin.org/articles/10.3389/fevo.2024.1461573/full
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