Biomass increases go under cover: Woody vegetation dynamics in South African rangelands.

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dc.contributor.authorMograbi, P.J.
dc.contributor.authorErasmus, B.F.N.
dc.contributor.authorWitkowski, E.T.F.
dc.contributor.authorMartin, R.E.
dc.contributor.authorMain, R.
dc.contributor.authorAsner, G.P.
dc.contributor.authorWessels, K.J.
dc.contributor.authorMathieu, R.
dc.contributor.authorKnapp, D.E.
dc.date.accessioned2016-06-03T08:06:24Z
dc.date.available2016-06-03T08:06:24Z
dc.date.issued2015-05
dc.description.abstractWoody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR) to measure aboveground biomass and subcanopy structure, as an explanatory tool to unravel vegetation dynamics in structurally heterogeneous landscapes. We sampled three communal rangelands in Bushbuckridge, South Africa, utilised by rural communities for fuelwood harvesting. Woody biomass estimates ranged between 9 Mg ha-1 on gabbro geology sites to 27 Mg ha-1 on granitic geology sites. Despite predictions of woodland depletion due to unsustainable fuelwood extraction in previous studies, biomass in all the communal rangelands increased between 2008 and 2012. Annual biomass productivity estimates (10-14% p.a.) were higher than previous estimates of 4% and likely a significant contributor to the previous underestimations of modelled biomass supply. We show that biomass increases are attributable to growth of vegetation <5 m in height, and that, in the high wood extraction rangeland, 79% of the changes in the vertical vegetation subcanopy are gains in the 1-3m height class. The higher the wood extraction pressure on the rangelands, the greater the biomass increases in the low height classes within the subcanopy, likely a strong resprouting response to intensive harvesting. Yet, fuelwood shortages are still occurring, as evidenced by the losses in the tall tree height class in the high extraction rangeland. Loss of large trees and gain in subcanopy shrubs could result in a structurally simple landscape with reduced functional capacity. This research demonstrates that intensive harvesting can, paradoxically, increase biomass and this has implications for the sustainability of ecosystem service provision. The structural implications of biomass increases in communal rangelands could be misinterpreted as woodland recovery in the absence of three-dimensional, subcanopy information.en_ZA
dc.identifier.citationMograbi, P.J. et al. 2015. Biomass increases go under cover: Woody vegetation dynamics in South African rangelands. PloS ONE 10(5).en_ZA
dc.identifier.issn1932-6203
dc.identifier.urihttp://hdl.handle.net/10539/20418
dc.language.isoenen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.subjectbiomassen_ZA
dc.subjectharvestingen_ZA
dc.subjectlandscapeen_ZA
dc.subjectnonhumanen_ZA
dc.subjectplant growthen_ZA
dc.subjectplant heighten_ZA
dc.subjectrangelanden_ZA
dc.subjectrural areaen_ZA
dc.subjectSouth Africaen_ZA
dc.subjectsubcanopyen_ZA
dc.subjectvegetation dynamicsen_ZA
dc.subjectwoody planten_ZA
dc.titleBiomass increases go under cover: Woody vegetation dynamics in South African rangelands.en_ZA
dc.typeArticleen_ZA
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