Clonal growth of Populus Pruinosa Schrenk and its role in the regeneration of riparian forests

Abstract

The aim of this study is to explore clonal growth in Populus pruinosa Schrenk and its role in the restoration and regeneration of desert riparian forests. From April to October 2014 and 2015, the survey of clonal growth was conducted in riparian forests along the Tarim River in Xinjiang, China. The study results showed that (1) From the aspect of space, the horizontal lateral roots distributed in 10–30cm soil layer was the main body of P. pruinosa clone growth, and the adventitious buds, unearthed ramets and earthed ramets occurred and concentrated within 50cm of clonal ramets. (2) From the aspect of time, no matter in the same year with different habitats, or in different year with same habitats, both the adventitious buds and unearthed ramets occurred concentrated in April–June, while earthed ramets occurred concentrated in May–October. (3) From the aspect of clonal ramets growth, conversion rates from adventitious buds to unearthed clonal ramets per unit length of horizontal lateral horizontal lateral roots were 41%, 5.0%, and 45%, and conversion rates from unearthed clonal ramets to earthed clonal ramets were 83.2%, 82.4% and 86% for edge (2014), internal (2014) woodland and edge (2015), respectively. The ramets growth rate and ramets population density in the unoccupied regions of woodland edge was more higher than that in internal woodland, at the end of growing season, the density of ramets population were up to 50 clusters/25m2, plant height of clonal ramet up to 159.17cm. (4) From April to July, soil moisture content was very significantly correlated with the number of adventitious buds and unearthed clone ramets. From August to October, the number of adventitious bud was significantly or very significantly correlated with land surface temperature and air temperature, the number of unearthed clonal ramets was very significantly correlated with the soil moisture content. In conclusion, in the process of P. pruinosa clonal growth, they adjust the number of ramets in each cluster and ramets density by changing number of adventitious bud occurrence and their conversion rate changed into unearthed ramets, and this adjustment process was affected by the seasonal variation of soil moisture content, land surface temperature and the temperature. clonal growth of P. pruinosa play an important role in the regeneration and restoration of natural woodland.