Abstract:
Understanding variation in the foliar nutrient among indigenous species of the
bushveld is crucial for rural livelihoods, in particular the integration of trees into
agroecosystems. The study explored nutrient composition of common browse
species with regard to nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca)
using leaf spectra (400–2500nm) and chemical data collected from nine bushveld
species, along with partial least squares (PLS) analysis. The work further explored
the relationship between canopy reflectance of Sentinel-2 image and foliar properties
of the identified species.
Spectroscopic analysis reveals useful information about nitrogen at leaf and canopy
scales whereas modelling reflectance using satellite image did not yield satisfactory
results. At the leaf level, nitrogen was highly correlated with leaf spectral reflectance
(R2=0.72, p<0.05) for winter and (R2=0.88, p<0.05) for summer. The coefficient of
determination for the relationships between leaf reflectance and concentrations of
phosphorus, potassium and calcium were low. Modelling the relationship using
Sentinel-2 data also showed higher correlations (R2=0.44, p<0.05) for nitrogen
compared with the other nutrients investigated.
