Vegetation Productivity Dynamics in Response to Climate Change and Human Activities under Different Topography and Land Cover in Northeast China

Abstract

Net primary productivity (NPP) is the total amount of organic matter fixed by plants from the atmosphere through photosynthesis and is susceptible to the influences of climate change and human activities. In this study, we employed actual NPP (ANPP), potential NPP (PNPP), and human activity-induced NPP (HNPP) based on the Hurst exponent and statistical analysis to analyze the characteristics of vegetation productivity dynamics and to evaluate the effects of climate and human factors on vegetation productivity in Northeast China (NEC). The increasing trends in ANPP, PNPP, and HNPP accounted for 81.62%, 94.90%, and 89.63% of the total area, respectively, and ANPP in 68.64% of the total area will continue to increase in the future. Climate change played a leading role in vegetation productivity dynamics, which promoted an increase in ANPP in 71.55% of the area, and precipitation was the key climate factor affecting ANPP. The aggravation of human activities, such as increased livestock numbers and intensified agricultural activities, resulted in a decrease in ANPP in the western grasslands, northern Greater Khingan Mountains, and eastern Songnen Plain. In particular, human activities led to a decrease in ANPP in 53.84% of deciduous needleleaf forests. The impact of climate change and human activities varied significantly under different topography, and the percentage of the ANPP increase due to climate change decreased from 71.13% to 53.9% from plains to urgent slopes; however, the percentage of ANPP increase due to human activities increased from 3.44% to 21.74%, and the effect of human activities on the increase of ANPP was more obvious with increasing slope. At different altitudes, the difference in the effect of these two factors was not significant. The results are significant for understanding the factors influencing the vegetation productivity dynamics in NEC and can provide a reference for governments to implement projects to improve the ecosystem.

Disentangling Climatic Factors and Human Activities in Governing the Old and New Forest Productivity

“…This is the possible reason why precipitation has a negative contribution to the NPP of the lower YRB. This result is consistent with many previous studies [5,27,30]. We found that from 2016 to 2019, NPP showed a flat development and a small value.…”

“…Persistent extreme precipitat happened in the lower YRB in May 2016 due to the super EI Niño [31] and heavy rain events often occur in summer due to the monsoon climate [32]. This is the possible rea However, in the middle YRB, the climate has a warming-drying trend (Figure 10b) and the temperature has a negative effect because the temperature is too high to exceed the limitation [27]. With region warming, the vapor pressure deficit could cause plants to close stomata, resulting in decreasing intercellular CO 2 concentration in the leaves and a lower photosynthesis rate [28].…”

“…More importantly, temperature, precipitation, and solar radiation all have positive effects on the forest dynamics in the upper reaches of YRB (Figure 6a-c). However, in the middle YRB, the climate has a warming-drying trend (Figure 1 and the temperature has a negative effect because the temperature is too high to exc the limitation [27]. With region warming, the vapor pressure deficit could cause plant close stomata, resulting in decreasing intercellular CO2 concentration in the leaves an lower photosynthesis rate [28].…”

Assessment of Climate Change and Human Activities on Vegetation Development in Northeast China

“…In turn, vegetation changes are commonly considered as indicators of environmental changes at various spatial and temporal scales. Recent studies have documented vegetation response to climate change in NEC in terms of the relationship between temperature, precipitation, and vegetation status [ 13 , 18 ], vegetation drought risk to climate change [ 17 ], and the response of different vegetation types to water availability and the timescale of vegetation response to drought [ 7 ]. Despite the growing interest in vegetation growth trends in response to changing climate, there is still a lack of comprehensive assessments of long-term vegetation response to water availability using the full satellite record.…”

Can Neural Networks Forecast Open Field Burning of Crop Residue in Regions with Anthropogenic Management and Control? A Case Study in Northeastern China

“…Most of this region has a temperate, humid or semi-humid continental monsoon climate, with annual average temperatures between −1.3 and 6.6 ℃ and annual total precipitation between 500 and 1000 mm [24,25]. Northeastern China is rich in fertile black soil resources, and the agricultural area encompasses approximately 40,000 km 2 , planted with a large number of commercial grains and representing an important region for grain production [26]. The main crops grown in Northeast China are rice, corn, soybeans and wheat, which have growing periods of one year, with sowing in spring and harvesting in autumn.…”