Changes in net primary production in the Tianmu Mountain Nature Reserve, China, from 1984 to 2014

Nature reserve establishment can lead to conflict with some stakeholders. Zoning management is useful to mitigate against the conflict between human development and nature reserves, and a nature reserve can be divided into three zones: the core zone, buffer zone, and experimental zone. So far, how to monitor and evaluate the effectiveness of zoning management in nature reserves is a problem faced by remote sensing scientists and ecologists. Net primary productivity (NPP) is a key indicator which can be used to monitor and evaluate the effectiveness of zoning management in nature reserves. However, to date there has been no research on the effectiveness of zoning management on NPP, and the estimation of NPP in the Tianmu Mountain Nature Reserve also has not been studied. Based on remote sensing data and in situ measurements, the Carnegie-Ames-Stanford approach (CASA) model was used to estimate NPP in the Tianmu Mountain Nature Reserve during the period 1984-2014. We used the observed NPP to verify the simulated NPP, and the results show that the simulated NPP was consistent with the observed NPP (R-2 = 0.85, p = 0.0002, RMSE = 52.62 g C m(-2) year(-1), where R-2 represents coefficient of determination, p represents statistical significance, and RMSE represents root mean square error). This means that the CASA model is suitable for NPP estimation in the Tianmu Mountain Nature Reserve. The results also indicate that NPP showed an increasing trend during the period 1984-2014, and the increase over the whole period was 6.66%. The total of the annual averaged NPP was 3.07 x 10(10) g C year(-1), while the annual averaged NPP per unit area was 708 g C m(-2) year(-1). The largest averaged annual NPP per unit appeared in the core zone (720 g C m(-2) year(-1)), followed by the buffer zone (711 g C m(-2) year(-1)), with the experimental zone having the smallest averaged annual NPP per unit (706 g C m(-2) year(-1)). At the p < 0.1 level, there was no region where NPP had decreased significantly in the core zone and buffer zone, and the area of the regions where NPP had decreased significantly in the experimental zone was 8.04 ha. At the p < 0.05 level, there was no area where NPP had decreased significantly in the three zones of the Tianmu Mountain Nature Reserve. The results show that the zoning management on NPP was effective in the Tianmu Mountain Nature Reserve.