Exploring influences of human activities and natural factors on NDVI
changes in the upper reaches of Minjiang River,China
Abstract
Quantifying the influences of factors on Normalized Difference
Vegetation Index (NDVI) changes is critical to understanding the
functions of terrestrial ecosystems. However, identification of the
causes responsible for vegetation changes is still limited. We applied
the Geographic Detector to quantify the individual and interactive
influences of human and natural factors on the change in the vegetation
NDVI,and determined the optimal characteristics of factors that are
beneficial to vegetation growth. Our results show that vegetation cover
for 2000 and 2015 is in good condition, and regions with NDVI
> 0.6 showed a significant transformation, whereas areas
with mid-high vegetation or lower and areas with high vegetation
increased and decreased, respectively. Vegetation cover changes were
mainly in the upper reaches of the Minjiang River and its tributaries.
We illustrated that the elevation, annual average temperature, and soil
type can satisfactorily account for the vegetation changes with
explanatory powers of 60%, 52% and 39% or larger, respectively. Land
use types and distance from the road had enhanced influences in the NDVI
changes with explanatory powers of less than 16% and 12%,
respectively. We proposed that there are interactive effects between the
impact factors on vegetation NDVI, and the synergistic effects of the
impact factors showed mutual enhancement and nonlinear enhancement. The
interaction between the two factors strengthens the influence of each
individual factor on the vegetation changes. This study provides
important references that policymakers can use to intervene and promote
vegetation change for ecological protection and vegetation restoration,
while alleviating environmental degradation.