Evaluating Spatial-Temporal Dynamics of Net Primary Productivity of Different Forest Types in Northeastern China Based on Improved FORCCHN Junfang Zhao 1,3 , Xiaodong Yan 2,3 *, Jianping Guo 1 , Gensuo Jia 3 1 Chinese Academy of Meteorological Sciences, Beijing, People’s Republic of China, 2 State Key Laboratory of Earth Surface Processes and Resource Ecology (ESPRE), College Of Global Change and Earth System Science, Beijing Normal University, Beijing, People’s Republic of China, 3 Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, People’s Republic of China Abstract An improved individual-based forest ecosystem carbon budget model for China (FORCCHN) was applied to investigate the spatial-temporal dynamics of net primary productivity of different forest types in northeastern China. In this study, the forests of northeastern China were categorized into four ecological types according to their habitats and generic characteristics (evergreen broadleaf forest, deciduous broadleaf forest, evergreen needleleaf forest and deciduous needleleaf forest). The results showed that distribution and change of forest NPP in northeastern China were related to the different forest types. From 1981 to 2002, among the forest types in northeastern China, per unit area NPP and total NPP of deciduous broadleaf forest were the highest, with the values of 729.4 gC/(m 2 Nyr) and 106.0 TgC/yr, respectively, followed by mixed broadleaf- needleleaf forest, deciduous needleleaf forest and evergreen needleleaf forest. From 1981 to 2002, per unit area NPP and total NPP of different forest types in northeastern China exhibited significant trends of interannual increase, and rapid increase was found between the 1980s and 1990s. The contribution of the different forest type’s NPP to total NPP in northeastern China was clearly different. The greatest was deciduous broadleaf forest, followed by mixed broadleaf- needleleaf forest and deciduous needleleaf forest. The smallest was evergreen needleleaf forest. Spatial difference in NPP between different forest types was remarkable. High NPP values of deciduous needleleaf forest, mixed broadleaf- needleleaf forest and deciduous broadleaf forest were found in the Daxing’anling region, the southeastern of Xiaoxing’anling and Jilin province, and the Changbai Mountain, respectively. However, no regional differences were found for evergreen needleleaf NPP. This study provided not only an estimation NPP of different forest types in northeastern China but also a useful methodology for estimating forest carbon storage at regional and global levels. Citation: Zhao J, Yan X, Guo J, Jia G (2012) Evaluating Spatial-Temporal Dynamics of Net Primary Productivity of Different Forest Types in Northeastern China Based on Improved FORCCHN. PLoS ONE 7(11): e48131. doi:10.1371/journal.pone.0048131 Editor: Ben Bond-Lamberty, DOE Pacific Northwest National Laboratory, United States of America Received July 5, 2012; Accepted September 27, 2012; Published November 7, 2012 Copyright: ß 2012 Zhao et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported under the auspices of National Natural Science Foundation of China (No. 31101073), National Basic Research Program of China (No. 2010CB950903), Special Fund for Meteorological-scientific Research in the Public Interest (No. GYHY201106020), and Key Projects in National Science & Technology Pillar Program during the Twelfth Five-year Plan Period (No. 2011BAD32B01). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: yxd@bnu.edu.cn Introduction As a key variable in our understanding of ecosystem processes and carbon exchange between biota and atmosphere, both currently and under climate change scenarios [1], net primary productivity (NPP) is defined as the difference between accumu- lated photosynthesis and accumulated autotrophic respiration by green plants per unit of time and space [2]. Relative to other ecosystems, forest ecosystems play an important role both in global and regional carbon cycles regulation because of their larger carbon stocks, sequestration capacity, and productivity [3,4,5,6]. A slight change in NPP of forests can significantly influence atmospheric CO 2 concentration and, consequently, climate change. Therefore, it is important to quantify carbon storage and fluxes for different forest types and analyze mechanisms involved in carbon cycling to better monitor the processes that regulate the uptake, storage, and release of CO 2 [7]. In China, forests are mainly composed of young to middle-aged secondary forests and plantations [8], and therefore, the ecosys- tem9s carbon cycle is far from being stabilized. Hence, quantifi- cation of forest carbon cycle is an important part of national inventories of net greenhouse gas emissions in a country [9,10]. The forest ecosystems in northeastern China play an important role in the national carbon budget because they comprise more than 30% of the total forest area [11] and 40% of the total forest biomass of China [6], including the southern boundary boreal forests of Eurasia in the Da Hinggan Mountains of the Heilongjiang Province and Inner Mongolia, which are especially sensitive to projected climate change [12]. In the past decade, large-scale NPP characteristics of forest ecosystems have been studied based on different methodologies such as national forest inventory data [13–18] and process-based terrestrial biosphere models [1,19,20,21]. The results showed that China’s terrestrial NPP has been significantly increased due to the increases in temperature, precipitation, and CO 2 concentrations, and the PLOS ONE | www.plosone.org 1 November 2012 | Volume 7 | Issue 11 | e48131