Based on the multiple cropping index (MCI) and“heat-precipitation”quantitative relation model,
this paper analysed the changing trends and pattern evolution of the MCI from the 1990 to 2015 and its influencing
factors. The results indicated that from 1990 to 2015,the MCI values of Yunnan,Guizhou,and Sichuan decreased
by 27.04%,1.67%,and 25.83%,respectively. The average values of MCI values were 147.37%,239.69%,and
206.05%,respectively. The greatest change in the three provinces occurred from 2006 to 2015. The inter-annual
variations in the grain crop MCIs were ranked as follows: Sichuan > Guizhou > Yunnan,with values of -41.01%,
-33.55% and -29.60%,respectively. The MCI in the Southwest China as a whole,the spatial pattern was signifi-
cantly higher in the Eastern Region than that in the Western Region and higher in the Central Region than in theNorthern and Southern Regions. In 2010-2015,in Southwest China,the PMCIs in the Eastern and Southern Re-
gions were higher than those in the Central and Northwestern Regions; among them,the PMCI in Eastern Sichuan
was the largest. The PIMCI was significantly higher in Yunnan Province than in Guizhou and Sichuan. Guizhou
Province had the least potential area for promotion. The interannual variation of the MCI was greatly affected by nat-
ural factors and human activities,among which the MCI had a significant positive correlation with the year average
temperature,accumulated temperature ≥0℃,population,and gross farm production. The spatial variation in the
MCI was closely related to the terrain. Generally,the MCI in the hilly area is lower than that in the plain area;
There was a significant positive correlation between the temperature change in the climatic factors and the change in
the MCI in the Southwest China (P<0.01),but the temperature change was the key factor affecting the MCI changes.
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