Inter-ite incubation with leaf decomposition for three forest types

Key words: 
• forest ecology /
• eaf litter /
• inter-site incubation /
• decomposition /
• untrient release /
• lOlson exponential model

Abstract: The litter bag method was used to conduct an inter-site incubation experiment to study leaf decomposition changes and nutrient release for three forest types in the hilly areas of southern Jiangsu Province from January 2010 to May 2011. The Olsen exponential model and correlation analysis were employed. Results showed that the decomposition rate（k） of broadleaf ＞coniferous species with Quercus acutissima （k = 0.391 4）＞Pinus massoniana（k = 0.238 8）＞Cunninghamia lanceolata （k = 0.209 1）. The initial N concentration and k were significantly and positively correlated（P＜0.01，r = 0.843 0），but k was significantly and negatively correlated to initial C/N（P＜0.05，r = －0.791 0）. Meanwhile，the weight loss rates were significantly and positively correlated to the release rates of N （P＜0.05，r =0.264 0），P （P＜0.01，r =0.340 0），and organic carbon （OC）（P＜0.01，r =0.910 0） but significantly and negatively correlated to C/N （P＜0.05，r =－0.766 0）. During decomposition，N and K were totally released；whereas P was released or immobilized. The OC release rate gradually increased，and the C/N value of leaf litter decreased. Inter-ite incubation showed that a faster litter k occurred with coniferous species incubated in broadleaf forests and a lower k for broadleaf species incubated in coniferous forests. The Olson exponential model for leaf litter decomposition indicated that inter-ite incubation decreased k for Q. acutissima and increased k for P. massoniana and C. lanceolata. After inter-ite incubation for Q. acutissima，decomposition of 50% and 95% of the leaf litter extended 0.09－0.20 years and 0.10－0.29 years，respectively，and for C. lanceolata shortened 0.60－0.11 years and 2.91－2.97 years，respectively；however，for P. massoniana incubated in a Q. acutissima forest，decomposition shortened 0.06 years and 0.09 years，respectively，and in a C. lanceolata forest extended 0.19 years or 0.36 years，respectively. For 50% organic carbon decomposition，incubation for Q. acutissima shortened 0.09－0.11 years, for C. lanceolata it extended 0.01－0.09 years，and for P. massoniana it shortened 0.07－0.08 years. Also，for 95% OC decomposition, decomposition for Q. acutissima extended 0.10－0.23 years，and for P. massoniana shortened 0.3 years. However，for C. lanceolata incubated in a Q. acutissima forest，decomposition shortened 0.01 years and in a P. massoniana forest extended 0.32 years.［Ch，3 fig. 6 tab. 30 ref.］