Abstract:

Most of natural Quercus variabilis forests in China have degenerated to be secondary forests after overexploitation and continuously cutting. Stump sprouting is the most significant asexual reproduction type in this kind of forests. In this study, 192 Q. variabilis stumps located in sunny slope and shady slope of Foping, Shaanxi Province, China, were investigated in order to understand the stump sprouting capability, sprout growth characteristics and the relationship between sprouting and stump. All stumps formed after small scale clear cutting conducted in 2007 winter. The results showed: 1)The sprout number per stump was more in sunny slope than that in shady slope, in contrast sprout growth amount(base diameter, height and crown width)were all greater in shady slope than those in sunny slope; sprout number had a negative relation with growth amount at similar environment conditions. 2)Sprout number per stump increased at first and then decreased slightly along with the increasing of stump diameter, and the stumps with their base diameter of 15-25 cm had the strongest sprouting capacity; and sprout growth amount increased with increasing stump diameter. 3)There was no relationship between stump height and sprout number, however, there was a positive relationship between stump height and sprout growth amount. 4)Base diameter of sprout declined along with the growing of sprout number per stump, sprout height showed an almost opposite tendency; sprout growth amount was influenced by sprout number more heavily in sunny slope than in shady slope. 5)The percentage of sprouting stump and sprout growth amount in both habitats all declined significantly after two years of cutting, moreover, sprouts in sunny slope had lower annual growth compared with those in shady slope. All the results implied that sprouting capacity was influenced by habitats condition especially irradiation, stump diameter and stump age(years after cutting); sprout growth were influenced not only by the factors described above, but also by stump height and sprout number per stump. Therefore, selective cutting the individuals which are 15-25 cm in base diameter and leaving the stump height more than 30 cm are propitious to forestland recovering in short time. Meanwhile, controlling stump sprouting after two years of cutting and thinning overstocked sprouts have positive influence on sprout growth.

Key words: Quercus variabilis, stump sprouts, stump diameter, stump height, regression analysis