Geographical distribution and productivity dynamic change of Eucalyptus spp. in China
Authors: zhang yuxing , wang xuejun 
Published: January 2024

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.