Climate Change Affects Forest Productivity in a Typical Climate Transition Region of China

Abstract

As global climate change has a large effect on the structure and function of vegetation, it is very important to understand how forests in climate transition regions respond to climate change. The present study investigates the net primary productivity (NPP) of two planted forests (Robinia pseudoacacia and Pinus tabulaeformis) and one natural forest (Quercus wutaishanica) from 1951–2100 using the LPJ-GUESS model in the Shaanxi province of China, which is a typical transition region from humid to dry climates. We found that: (1) Future annual precipitation and mean temperature exhibited nonsignificant and significant increasing trend in the region, respectively, indicating a drier climate in future; (2) although precipitation would increase in the dry area and decrease in the humid area, the NPP of each species in the dry area would be lower than that of the humid area, possibly because increasing temperature and CO2 concentration could restrain forest growth in dry areas and promote forest growth in humid areas; (3) of the three species, P. tabulaeformis forest exhibited the highest average NPP and R. pseudoacacia forest exhibited the highest NPP trend in both dry and humid areas, indicating these planted species may be adaptable to future climate change. Our results provide novel insights into the potential response of forest productivity to a changing climate in the transition region from humid to dry climates.

Carbon Cycles of Forest Ecosystems in a Typical Climate Transition Zone under Future Climate Change: A Case Study of Shaanxi Province, China

“…Shaanxi Province, located in the north of China, is one of the regions where climate change is obvious. Our previous study predicted that the temperature in this area would rise 1.4-3.1 • C by the end of this century, while precipitation showed no obvious change [10]. This region is also a transition zone from a temperate arid to a subtropical humid climate [11].…”

“…From south to north the climatic types found in this area are subtropical humid climate, warm temperate humid climate, and temperate arid climate, with great differences between the north and south. Within our study Shaanxi Province was divided into three geographical units, according to topography, hydrology, climate, and other factors from north to south, named Northern Shaanxi Plateau (NSX), Guanzhong Plain (MSX), and Southern Shaanxi Mountains (SSX) [10]. The average annual temperature in the study area is 8-16 • C, of which the temperatures in SSX, MSX, and NSX are 14-16 • C, 12-13 • C, and 8-l0 • C, respectively.…”

“…The annual average precipitation increased from north to south; precipitation was 964.6 mm in SSX, 590.4 mm in MSX, and 461.7 mm in NSX, with total precipitation of 320-1400 mm for the entire study area. Due to the unique climate and geographical conditions, a temperate grassland zone, warm temperate deciduous broad-leaved forest zone, and subtropical evergreen broad-leaved forest zone appear successively from north to south in Shaanxi Province [10]. Robinia pseudoacacia has become the main tree species in afforestation and has the largest plantation area in Shaanxi Province because of its developed root system, rapid growth, drought tolerance, barren tolerance, and high survival rate.…”

“…Historical temperature, precipitation, and CO 2 concentration data were used as the main driving variables. Our previous study concluded that the maximum possible future increase of temperature in the study area was about 30% [10], and the average atmospheric CO 2 concentration in the future (510 ppmv) [1] will be about 30% higher than the current atmospheric CO 2 concentration (380 ppmv). To measure the variables uniformly, we set the maximum increase of the three indicators of sensitivity analysis as 30% and compared them with the current value 0% and the intermediate value 15%.…”

“…Our previous work in this region focused on the response of net primary productivity (NPP) of forests to future climate change [10]. However, NPP only considers net carbon sequestration by vegetation within forest ecosystems [12], ignoring carbon emissions from heterotrophic respiration (Rh) of forest soils into the atmosphere, which may limit our overall understanding of the carbon cycle of forest ecosystems in this region.…”