渭河流域地表植被覆盖对气候变化的响应研究

Study on Response of Surface Vegetation Cover to Climate Change in Weihe River Basin

气候变化通过改变植物生长环境,从而影响植物生长。了解植物与气候之间的内在关系,长期动态监测和评估植被覆盖情况至关重要,同时有利于深刻理解生态恢复机制。渭河流域地理位置特殊,生态环境脆弱,在其周围及黄河下游生态环境保护中有重要地位。为揭示植被时空变化格局以及对气候变化的响应,以渭河流域作为研究对象,采用差值法、线性回归斜率法及相关系数法分析2000-2019年渭河流域在不同气候分区下NDVI分布特征及NDVI与降水、气温的相关性和滞后性。研究结果显示:(1)2000-2019年,渭河流域NDVI呈波动上升的趋势,各分区NDVI增长率表现为半干旱区(0.053 8/10 a)>半湿润区(0.044 3/10 a)>干旱区(0.036 6/10 a);(2)2000-2009年、2009-2019年NDVI均表现为改善态势,但2009-2019年改善程度减缓,斜率从0.072 7/10a降低为0.035 1/10a,差值法改善区面积由98.20%降低到86.12%,线性回归斜率法改善区面积由87.69%减小到61.86%;(3)在季尺度、月尺度上,与降水相比,气温对渭河流域植被生长影响更为显著;(4)渭河流域及其各分区(除干旱区短期气温对NDVI的滞后效应)NDVI与降水、气温双向滞后效应在短期(1-3月)与长期(3-6月)同时存在。在不同气候分区下,NDVI与降水双向滞后效应表现出1-3月为正,3-6月为负的特征;NDVI对气温的滞后效应表现为1-3月为正,4-6月为负;气温对NDVI的滞后效应1-2月为正,3-4月为负。

Climate change affects plant growth by altering its growing environment.Understanding the intrinsic relationship between plants and climate and long-term monitoring and assessments of vegetation cover are essential,as well as facilitate a deep understanding of ecological restoration mechanism.The Weihe River basin has a special geographical location and a fragile ecological environment.It plays an important role in the ecological environmental protection of its surroundings and the downstream of the Yellow River.To reveal the spatiotemporal change pattern of vegetation and its response to climate change,this paper takes the Weihe River basin as the research object and uses the difference,linear regression slope and correlation coefficient methods to analyze the NDVI distribution characteristics and the correlation and lag time between NDVI and precipitation and temperature in the Weihe River basin under different climate zones from 2000 to 2019.The results showed that(1)from 2000 to 2019,NDVI in the Weihe River basin showed a fluctuating upward trend.The NDVI growth rate of each zone showed the following order:semi-arid zone(0.0538/10 a)>semi-humid zone(0.0443/10 a)>arid zone(0.0366/10 a);(2)NDVI showed improvement from 2000 to 2009 and from 2009 to 2019.However,the improvement slowed down from 2009 to 2019,and the slope decreased from 0.0727/10 a to 0.0351/10 a.The area of improvement calculated by the difference method was reduced from 98.20%to 86.12%,and the area of improvement calculated by the linear regression slope method was reduced from 87.69%to 61.86%;(3)on the seasonal or monthly scale,temperature had a more significant effect on vegetation growth in the Weihe River basin compared to precipitation;(4)the bi-directional lagged effects between NDVI and climatic factors in the Weihe River basin and its zones existed both in the short term(1–3 months)and in the long term(3–6 months)(except for the lagged effect of temperature on NDVI in the arid zone in the short term).The bi-directional lagged effects of NDVI and precipitation under different climate zones were positive for 1–3 months and negative for 3–6 months.The lagged effect of NDVI on temperature showed positive for 1–3 months and negative for 4–6 months.The lagged effect of temperature on NDVI was positive for 1–2 months and negative for 3–4 months.