Changes in vegetation photosynthetic activity trends across the Asia–Pacific region over the last three decades Baozhang Chen a,b, ⁎, Guang Xu a , Nicholas C. Coops b , Philippe Ciais c , John L. Innes b , Guangyu Wang b , Ranga B. Myneni d , Tongli Wang e , Judi Krzyzanowski b , Qinglin Li f , Lin Cao b , Ying Liu g, ⁎⁎ a State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, University of Chinese Academy of Sciences, 11A, Datun Road, Chaoyang District, Beijing, China b Department of Forest Resource Management, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada c Laboratoire des Sciences du Climat et de l'Environnement, Unité Mixte de Recherche Commissariat à l'Energie Atomique-Centre National de la Recherche Scientifique-Université de Versailles Saint-Quentin-en-Yvelines, Batiment 709, CE L'Orme des Merisiers, Gif-sur-Yvette F-91191, France d Department of Earth and Environment, Boston University, 675 Commonwealth Avenue, Boston, MA 02215, USA e Centre for Forest Conservation Genetics, Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada f Forest Analysis and Inventory Branch, Ministry of Forests, Lands, and Natural Resource Operations, Victoria, BC V8W 9C2, Canada g School of Soil and Water Conservation, Beijng Forestry University, Beijing 100083, China abstract article info Article history: Received 19 June 2013 Received in revised form 22 December 2013 Accepted 23 December 2013 Available online xxxx Keywords: Climate change Vegetation growth dynamics NDVI Time series analysis Gradual changes Trend breaks Breakpoint Turning point Asia–Pacific region The updated Global Inventory Modeling and Mapping Studies (GIMMS) third generation global satellite Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference Vegetation Index (NDVI) dataset provides very detailed global information on the state of vegetation from 1982 to 2011. Using these data we investigated the changes in the vegetation photosynthetic activity in the Asia–Pacific (AP) (including Australia, South East Asia, China, and the Pacific Coast of North America) region, by discerning gradual changes into two key metrics: 1) the cumulative annual NDVI in each year and 2) the seasonality or variance in that index. We then assessed changes using break and turning points using three statistical models (least-square linear, expand- ed paired-consecutive linear and piecewise regression models). We found that the AP region overall experienced increasing NDVI from 1982 through 2011 with an average rate of 5.30 × 10 -4 NDVI yr -1 (0.13% yr -1 ). The annual NDVI increased from 1982 at a faster rate of 26.14 × 10 -4 NDVI yr -1 (0.65% yr -1 ) until a break in the trend after 1991 (after that the trend reduced to 5.78 × 10 -4 NDVI yr -1 ). In the Asia–Australia (AA) subarea of the AP, vegetation greening slowly increased at 8.71 × 10 -4 NDVI yr -1 before 2003 and then increased to 28.30 × 10 -4 NDVI yr -1 after 2003. In contrast, in the North America (NA) subarea NDVI rapidly increased initially at 18.72 × 10 -4 NDVI yr -1 before 1992 and then marginally increased (3.96 × 10 -4 NDVI yr -1 ) after 1992. The turning points were found to be 2008 and 1987 for the AA and NA subareas respectively. Analysis of monthly NDVI data showed that the trends were positive for most of the months of the study period, particularly during the growing season. Geospatial analyses demonstrated that cumulative annual NDVI and the variance or seasonality across the large AP region varied across the different subareas. As well, we found evidence for different spatial patterns of the NDVI changes with strong spatial heterogeneity in the patterns of the break and turning points. This suggests complex and nonlinear responses of vegetation photosynthetic activity to regional climatic changes and other drivers. © 2014 Elsevier Inc. All rights reserved. 1. Introduction Vegetation, as the most important component of terrestrial ecosystems, fundamentally regulates the energy budget, water cycle and biogeochemical cycle in the land surface through photosynthesis, respiration, transpiration, surface albedo, and roughness (Jackson, Randerson, Canadell, et al., 2008). Photosynthetic activity affects the Earth climate system and maintains climate stability, through its coupling with transpiration (Anderson, Canadell, Randerson, et al., 2010). Understanding the dynamics of photosynthetic activity and its correlations with climate variability and climate change is one of the im- portant issues of global change research (Nemani et al., 2003). Satellite remote sensing is unique and useful for monitoring vegetation dynamics and environmental changes over large coverage in a repeatable manner (Goward, Tucker, & Dye, 1985; Myneni, Hall, Sellers, & Marshak, 1995; Nemani et al., 2003; Tucker et al., 2001; Zhou et al., 2001). Remote Sensing of Environment 144 (2014) 28–41 ⁎ Correspondence to: B. Chen, State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A, Datun Road, Chaoyang District, Beijing, China. Tel./ fax: +86 10 64889574. ⁎⁎ Corresponding author. E-mail addresses: baozhang.chen@igsnrr.ac.cn (B. Chen), 1191184845@qq.com (Y. Liu). 0034-4257/$ – see front matter © 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.rse.2013.12.018 Contents lists available at ScienceDirect Remote Sensing of Environment journal homepage: www.elsevier.com/locate/rse