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

Show simple item record Mograbi, P.J. Erasmus, B.F.N. Witkowski, E.T.F. Martin, R.E. Main, R. Asner, G.P. Wessels, K.J. Mathieu, R. Knapp, D.E. 2016-06-03T08:06:24Z 2016-06-03T08:06:24Z 2015-05
dc.identifier.citation Mograbi, 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.issn 1932-6203
dc.description.abstract Woody 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.language.iso en en_ZA
dc.publisher Public Library of Science en_ZA
dc.subject biomass en_ZA
dc.subject harvesting en_ZA
dc.subject landscape en_ZA
dc.subject nonhuman en_ZA
dc.subject plant growth en_ZA
dc.subject plant height en_ZA
dc.subject rangeland en_ZA
dc.subject rural area en_ZA
dc.subject South Africa en_ZA
dc.subject subcanopy en_ZA
dc.subject vegetation dynamics en_ZA
dc.subject woody plant en_ZA
dc.title Biomass increases go under cover: Woody vegetation dynamics in South African rangelands. en_ZA
dc.type Article en_ZA

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