4.3 Environmental effects on forest productivity and stability
Unlike natural forests, plantation location is determined by humans. The
location of these two forest types had a significant difference (Fig.
1). The plantation in this study was located in the southern portion of
the rainy zone in West China (Sichuan
Vegetation Cooperation Group, 1980); the annual precipitation
(911.69±118.66 mm) is greater in this area than in the area of natural
forest (787.08±137.08 mm). This may make natural forests in less
precipitation environment more sensitive to annual precipitation
changes. Higher forest productivity at sites with suitable conditions
suggested that a favorable resource (e.g., soil depth and annual
precipitation) increased productivity (Forrester and Bauhus, 2016). MAT
did not significantly affect productivity. While, links between rainfall
and total productivity are highly temperature-dependent, where at least
at tropical mountain rainforest sites experiencing low temperatures (16
℃), increasing rainfall exerted a negative effect on productivity
(Taylor et al. 2017). This may stem from the climatic context in our
study region, which is characterized by a low MAT (0 ~17
℃). In addition, the response of forests to climate change strongly
depends on forest composition and structure, and most of the natural
forests in this study were composed of multiple late-successional Fir,
Spruce and Betula in this study. It is consistent with Chen and Luo
(2015), which showed that coniferous forest was more sensitive to
climate change. The trees species and community compose in natural
forest may explain differences between the two forest types.