Evolution of spatio-temporal patterns in vegetation net primary
productivity and the driving forces on the Loess Plateau
Abstract
Abstract : To address global warming, the carbon
sequestration capacity by net primary productivity (NPP) in vegetation
on the Loess Plateau (LP) is particularly important as it allows us to
adjust the vegetation restoration strategies in response to global
changes. However, the spatial correlation of NPP and its impact on
vegetation restoration remains unclear. MOD17A3 remote sensing products
analyzed the temporal and spatial changes in NPP on the LP over the last
two decades (2000–2020). The resulting spatial autocorrelation indices
identified cold and hot spots in the spatial clustering patterns.
Finally, the effects of climate change and human activities on the
anomalous clustering of NPP were assessed using correlation analysis and
multi-temporal land use land cover (LULC) data. The results indicate (ⅰ)
From 2000 to 2020, the NPP of the LP increased significantly by 6.88
gC m - 2 yr - 1 , and the proportion of revegetated land area
> 400 gC m - 2 yr - 1 increased from 4 % (2000) to 37 %
(2020). (ⅱ) The vegetation NPP on the LP had a strong positive global
spatial autocorrelation (p < 0.01). The hot and cold regions
had obvious polarization, in which the cold spots were clustered in the
northwest, and the hot spots were distributed in the south and east. The
spatial clustering patterns were dominated by high-high (HH) and low-low
(LL) clusters. Abnormal patterns mainly existed in the transition areas
between HH and LL clusters and insignificant regions, which were jointly
affected by human activities and climate change. (ⅲ) Precipitation was
the dominant climatic factor (86.31 %) affecting the variation of NPP
on the LP, with the annual minimum precipitation showing a synergistic
relationship with the interannual variability in NPP and the maximum
precipitations greatly influenced the variation in local spatial anomaly
patterns. Therefore, climatic extremes affect vegetation. Our research
improves our understanding of the driving mechanisms involved in the
regional carbon cycle and provides a reference for green ecological
management and high-quality development in the LP. Keywords:
Net primary productivity, Spatial autocorrelation, Climate change, Human
activities, Land use land cover, Loess Plateau