Effects of Abiotic Factors on Forest Net Ecosystem Production

Net ecosystem production(NEP) is the rate of net carbon accumulation in an ecosystem,and can be used to indicate the status of carbon sinks or sources.When NEP is positive,it indicates that the ecosystem is a carbon sink; when it is negative,it indicates that it is a carbon source.Under global environmental change,NEP has been considered as a central concept in ecosystem carbon cycles.This paper assessed the effects of abiotic factors such as water dynamics,temperature change,nitrogen deposition,atmospheric CO₂ enrichment and temporal-spatial scale on forest NEP in recent years.Our review showed that NEP is not only affected by ecosystem characteristics,but also regulated by environmental factors and their interactions.Future research challenges include:(1)furthering meta-analyses when examining one environmental factor;(2)developing ecological networks for examining environmental effects at regional to global scale; and (3)conducting experiments with long-term,multi-scales and multi-factors.Fundamentally,more studies are needed to investigate and predict the impacts of global environmental change on terrestrial carbon cycling.