Although modern mass tourism in China has a history of only about 30 years, the market has expanded quickly. Endowed with the spectacular scenery of turquoise water lakes and marvelous waterfalls, Jiuzhaigou is one of the most visited tourist destinations in China. Between 1984 and 2012, the region witnessed a tourism growth of 130 times, resulting in extreme economic and environmental impacts. The fast increasing and large tourist population in the limited area has caused many changes in the local environment, including: increasing algae in water, increasing nutrients in water, increasing sediment in lakes, degrading travertine, and increasing threat on biodiversity. These changes will threaten the sustainability of tourism in Jiuzhaigou. Carrying capacity represented by daily visitor numbers theoretically has been used to control the number of tourists but has proved not useful in practical management. Efforts have been made to reduce the environmental impacts of the increasing number of tourists, but environmental degradation continues to develop as the number of tourists is not controlled. The sustainability issue in Jiuzhaigou is mired in the conflict between the conservation of the natural beauty and local economic development. To promote sustainable tourism, the number of tourists must be controlled. A daily numeric limit, based on adequate environmental monitoring and well‐designed scientific research, will help determine the daily number of visitors in Jiuzhaigou.

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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.

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