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Geographical distribution and productivity dynamic change of Eucalyptus spp. in China
  • yuxing zhang,
  • xuejun wang
yuxing zhang
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xuejun wang
State Forestry and Grassland Administration of the People's Republic of China

Corresponding Author:[email protected]

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Abstract

Eucalyptus spp. is the most widely planted broad-leaf tree species in the world. Ninety-five countries have Eucalyptus spp. as plantations (Iglesisas-Trabado, 2008), and the total area exceeds 22.57 million hm2 worldwide (Wen, 2018). The Eucalyptus spp. is fast-growing, which enables efficient and sufficient supply of timber, but its negative impact on soil fertility also incurs discussions. It is therefore necessary to study the growing traits of Eucalyptus spp. to help and provide guidance on its plantation management and associated policy making in a scientific way. In this work, we report and analyze how the spatial distribution of Eucalyptus plantations in China changes with time. We quantitatively characterize and evaluate the productivity, carbon accumulation capacity, and abandonment rate of Eucalyptus spp. and its plantations. Statistical models on how Eucalyptus spp. productivity and abandonment rate change with time are established that can be used to evaluate the soil fertility and feasibility for growing Eucalyptus spp., and predict how its productivity changes with time. We summarize, report, and interpret sample plot data from nine National Forest Inventories (1973-2018), data from China Forestry Land Database Map in 2003 and 2016, and weather and elevation data of southern China in this work. Our work shows that regions with mean annual temperature of 19-21 ℃, precipitation of 1400-1600 mm, and elevation of 0-300 m above sea level suit the growth of Eucalyptus spp. The mean annual productivity of Eucalyptus spp. ranges from 4.14-8.57 m3hm-2a-1. Higher productivity (9.32~10.88 m3hm-2a-1) could be reached for newly cultivated lands. Based on data from the ninth inventories (2014-2018), the mean carbon fixation of Eucalyptus spp. per year is 5.29 t hm-2a-1, which is 2.95 and 2.18 times greater than Pinus massoniana Lamb. and Cunninghamia lanceolata Lamb., respectively. Eucalyptus spp. has high productivity, and is an important source for limber. Its plantations takes up 6.85% of all plantations in China areawise, but contribute to more than 17.96% of total annual cut from plantations. The growing of Eucalyptus spp. consumes soil fertility significantly. The cumulative abandonment rate (based on area) is about 25%, 50%, and 75% five, ten, and twenty years after the start of the plantations, respectively. The soil fertility decreases rapidly after 50 years of growing Eucalyptus spp. continuously. In such cases, it is difficult to restore soil fertility. We propose that with improved management and measures such as outcrop rotation, it is possible that the abandoned plantations can be reused for growing Eucalyptus spp. Planning Eucalyptus spp. plantations properly is critical to the sustainability and soil fertility restoration of the corresponding lands. Eucalyptus spp. helps protect natural forests, and contributes to carbon fixation. Therefore we support the development of Eucalyptus spp. plantations for the economic value they generated, and for their positive effects on the society and natural environments.