基于祁连山树轮宽度指数的区域NDVI重建

doi:10.3773/j.issn.1005-264x.2010.09.004

摘要/Abstract

摘要：

利用祁连山自东向西5条树轮宽度年表序列和1986-2003年间的归一化植被指数(NDVI), 分析了NDVI的时空变化及其与树轮宽度年表之间的关联。结果表明, 祁连山地区植被的生长主要集中在6-8月。空间上, NDVI值从祁连山东段向西段逐渐减小; 在1986-2003时段内, 东、中和西段生长季的NDVI值分别增长了3.28%、4.82%和7.75%。整个祁连山地区的NDVI变化与5个宽度年表的第一主成分相关性较高(r = 0.74, p < 0.01)。基于此, 利用树轮宽度RES年表的第一主成分重建了1843-2003年间祁连山地区生长季的NDVI变化曲线。重建的NDVI曲线表现出6个高值期和6个低值期, 其中1923-1932的10年间植被生长状况最差。另外, 在1989-2003时段内NDVI年际波动较大, 总体上表现为NDVI低于平均值, 但是从1991年开始, NDVI有上升的趋势。

关键词: 归一化植被指数, 祁连山, 树轮宽度指数

Abstract:

Aims Many recent studies indicated that the regional climate of northwest China had changed from a warm-dry to a warm-wet pattern. Therefore, it is important to assess vegetation cover change in this area. Our objective is to evaluate the normalized difference vegetation index (NDVI) record in eastern, middle and western parts of the Qilian Mountains and assess past long-term vegetation cover change with tree-ring chronologies.

Methods Temporal and spatial changes of NDVI, and its relationship with tree-ring width were analyzed using 8 km × 8 km resolution multi-temporal NOAA/AVHRR-NDVI data from 1986-2003 and five ring-width chronologies in the Qilian Mountains. Then, we used liner regression to reconstruct annual NDVI varieties for 1843-2003.

Important findings Vegetation cover in the Qilian Mountains decreased from east to west, and the main growing season lasted from June to August. In addition, during the period 1986-2003, an increasing NDVI-trend was evident in three regions in the Qilian Mountains, indicating that vegetation activity has been rising recently. In the eastern, central and western parts of the Qilian Mountains, values of NDVI during the growing season have increased by 3.28%, 4.82% and 7.75% per year, respectively. We also found a strong relationship between NDVI and the first principal component (PC1) of the five tree-ring width chronologies (r = 0.74, p < 0.01). Growing season NDVI was reconstructed based on correlation analysis. Six periods characterized by high and low values were reflected in the NDVI curve, and the poorest period of plant growth was 1923-1932. Moreover, the amplitude of the fluctuation was larger during 1989-2003, accompanied by an increasing trend since 1991.

Key words: normalized difference vegetation index (NDVI), Qilian Mountains, tree-ring width index

王文志, 刘晓宏, 陈拓, 安文玲, 徐国保. 基于祁连山树轮宽度指数的区域NDVI重建. 植物生态学报, 2010, 34(9): 1033-1044. DOI: 10.3773/j.issn.1005-264x.2010.09.004

WANG Wen-Zhi, LIU Xiao-Hong, CHEN Tuo, AN Wen-Ling, XU Guo-Bao. Reconstruction of regional NDVI using tree-ring width chronologies in the Qilian Mountains, northwestern China. Chinese Journal of Plant Ecology, 2010, 34(9): 1033-1044. DOI: 10.3773/j.issn.1005-264x.2010.09.004

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https://www.plant-ecology.com/CN/Y2010/V34/I9/1033

图/表 9

表1 祁连山地区树轮年表与气象站信息

Table 1 Description of the study sites and the meteorological stations in the Qilian Mountains

	地点 Location	经纬度 Latitude and longitude	海拔 Altitude (m)	时段 Range of years
样点 Sampling site	昌岭山 Changlingshan	37.4° N, 103.7° E	2 440	1843-2003
	哈溪 Haxi	37.5° N, 102.4° E	2 800	1829-2003
	东大山 Dongdashao	39.1° N, 100.8° E	2 660	1789-2003
	寺大隆 Sidalong	38.4° N, 99.9° E	3 360	1700-2003
	祁丰 Qifeng	39.4° N, 98.6° E	2 780	1730-2003
气象站 Meteorological station	乌鞘岭 Wushaoling	37.2° N, 102.9° E	3 045	1986-2003
	张掖 Zhangye	38.9° N, 100.4° E	1 483	1986-2003
	酒泉 Jiuquan	39.8° N, 98.5° E	1 477	1986-2003

图1 祁连山树轮样点、附近气象站与归一化植被指数(NDVI)区域范围。

Fig. 1 Locations of the sampling sites, meteorological stations and normalized difference vegetation index (NDVI) grids in the Qilian Mountains.

图2 祁连山地区东(E)、中(M)、西(W) 3段NDVI的月变化。

Fig. 2 Changes of average monthly NDVI values in the east (E), middle (M) and west (W) areas of the Qilian Mountains.

图3 祁连山地区生长季(6-8月) NDVI的年际变化(1986- 2003)。 E, 祁连山东部; M, 祁连山中部; W, 祁连山西部。

Fig. 3 Interannual changes and spatial distribution of the growing season NDVI in the Qilian Mountains during the period of 1986-2003. E, Eastern of the Qilian Mountains; M, Middle of the Qilian Mountains; W, Western of the Qilian Mountains.

表2 生长季NDVI指数(6-8月)与平均温度、降水量和湿润指数的关系

Table 2 The correlation between growing season NDVI and mean temperature, precipitation and humidity index

		东部 Eastern			中部 Middle				西部 Western
		温度Temperature (T)	降水量Precipitation (P)	湿润指数P/T		温度Temperature (T)	降水量Precipitation (P)	湿润指数P/T		温度Temperature (T)	降水量Precipitation (P)	湿润指数P/T
月份 Month	9p	0.223	0.388	-0.111	0.314		0.482^*	0.458	0.302		0.107	0.093
	10p	0.458	0.356	0.273	0.219		-0.067	-0.126	0.307		0.117	0.088
	11p	0.004	-0.286	-0.343	-0.153		0.237	0.525^*	-0.042		-0.085	0.109
	12p	-0.483^*	-0.385	-0.043	-0.338		-0.129	0.267	-0.188		0.311	-0.251
	1	-0.152	0.429	-0.472^*	0.102		0.400	-0.460	0.017		0.395	-0.385
	2	-0.009	-0.170	0.123	0.324		-0.100	-0.025	0.146		-0.175	0.092
	3	0.171	0.039	-0.021	0.224		0.156	0.075	0.186		-0.077	-0.129
	4	-0.201	-0.104	-0.172	0.265		-0.027	-0.046	0.101		0.030	0.015
	5	0.093	0.003	0	-0.121		0.577^*	0.572^*	0.044		0.149	0.134
	6	-0.111	0.205	0.179	-0.165		0.216	0.206	-0.076		0.390	0.367
	7	0.267	-0.193	-0.176	0.132		0.354	0.323	0.153		0.198	0.193
	8	0.155	-0.040	-0.046	0.112		0.140	0.131	0.236		-0.387	-0.387
	5-7	0.129	-0.050	-0.011	-0.095		0.719^**	0.705^**	0.059		0.418	0.398
	11p-12p	-0.239	-0.478^*	-0.368	-0.338		0.158	0.537*	-0.172		0.121	0.090

图4 祁连山地区树轮残差(RES)年表与NDVI的关系。 A, 祁连山东部。B, 祁连山中部。C, 祁连山西部。

Fig. 4 Correlation between the NDVI and residual (RES) chronology. A, Eastern of the Qilian Mountains. B, Middle of the Qilian Mountains. C, Western of the Qilian Mountains.

表3 祁连山地区树轮残差(RES)年表PC1与生长季(6-8月)的归一化植被指数的关系

Table 3 Correlation between growing season normalized difference vegetation index (NDVI) values and the first principal component (PC1) of RES chronology

	树轮残差(RES)年表第一主成分(PC1) PC1 of the tree-ring RES chronologies
生长季NDVI NDVI in growing season		东部 Eastern	中部 Middle	西部 Western	区域 Area
	东部 Eastern	0.500^*
	中部 Middle		0.723^**
	西部 Western			0.606^**
	平均 Average				0.739^**

图5 重建NDVI值与实际值的比较。

Fig. 5 Comparison of reconstructed and observed NDVI values.

图6 A, 利用树轮RES年表PC1重建祁连山地区1843-2003年间生长季(6-8月)NDVI平均值的变化。B, 德令哈地区1843-2001年间6-9月NDVI平均值的变化(He & Shao, 2006)。C, 祁连山地区1891-2003年间帕默尔干旱指数(PDSI)的变化(刘晓宏等, 2010)。(直线为平均值; 平滑曲线为10年低通滤波)

Fig. 6 A, Variations of reconstructed, growing season (June-August) NDVI values during 1843-2003 in the Qilian Mountains by using tree ring width RES chronologies PC1. B, Averaged NDVI from June to September during 1843-2001 in Delingha (He & Shao, 2006). C, Palmer drought severy index (PDSI) during 1891-2003 in the Qilian Mountains (Liu et al., 2010). (Average of NDVI (line) and 10 years low pass filtering (smoothed curve))

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