Determining fPAR and leaf area index of several land cover classes in the Pot River and Tsitsa River catchments of the Eastern Cape, South Africa. Issue 1 (22nd March 2017)

• Record Type: Journal Article
• Authors: Palmer, Anthony R; Finca, Andiswa; Mantel, Sukhmani K; Gwate, Onalenna; Münch, Zahn; Gibson, Lesley A
• Is Part Of: African journal of range & forage science. Volume 34:Issue 1(2017)
• Page Start: 33
• Page End: 37
• Publication Date: 2017-03-22
• Subjects: agroforestry -- ecosystem ecology -- remote sensing; Range ecology -- Africa -- Periodicals; Range ecology -- South Africa -- Periodicals; Range management -- Africa -- Periodicals; Range management -- South Africa -- Periodicals; Pasture ecology -- Africa -- Periodicals; Pasture ecology -- South Africa -- Periodicals; Pastures -- Management -- Periodicals; Forage plants -- Africa -- Periodicals; 633.202096
• DOI: 10.2989/10220119.2017.1306582
• Languages: English
• ISSNs: 1022-0119

Abstract

Abstract : Determining the quantum (both annual maxima and minima) and the temporal variation in the leaf area index (LAI), and the fraction of photosynthetically active radiation (fPAR), are three fundamental biophysical characteristics of the plant canopy that should parameterise ecophysiological models of water use (evapotranspiration) and carbon sequestration. Although Earth observation provides values and time series for both these parameters, in-field validation of these values is necessary. Following a very wet summer season, we conducted field surveys of several land cover classes within two quaternary catchments in the Eastern Cape province, South Africa, to determine maximum values of LAI and fPAR that occur within each of these land cover classes. To assist in up-scaling these point measures to the landscape, we present a regression relationship between Landsat 8 NDVI and LAI measured using an Accupar Ceptometer ( r 2 = 0.92). Peak wet season LAI varied from extremely high (>7.0) under the canopy of invasive black wattle ( Acacia mearnsii ) trees to ∼2.0 under the canopy of a Eucalyptus plantation. Ungrazed native grassland displayed an intermediate LAI value of 3.84. The black wattle stand absorbed 97% of the available PAR, whereas the mature Eucalyptus plantation only absorbed 66% of PAR.