滨海围垦湿地芦苇凋落物分解对模拟增温的响应

Responses of decomposition of Phragmites australis litter to simulated temperature enhancement in the reclamed coastal wetland

采用开顶式生长室(Open-top chambers,OTC)模拟增温,结合网袋法,研究了空气增温(1.984±0.7)℃对崇明东滩滨海围垦湿地代表植物——芦苇(Phragmites australis)不同凋落物组分(茎和叶)分解速率的影响,并分析增温和非增温条件下凋落物分解速率与1.2 m高度的空气温度、0～5 cm土壤温度及0～5 cm土壤湿度3种主要环境因子的相关性及其变化.结果表明:①增温与不增温处理下,OTC组和对照(CG)组芦苇茎的年分解率分别为49.20%和45.11%,而叶的年分解率分别为63.52%和58.53%,增温对叶的分解促进作用更加显著;②增温增大了湿地芦苇凋落物分解常数K值,OTC组和CG组茎的平均K值分别为0.028和0.027,叶的平均K值分别为0.093和0.080,叶的增幅显著大于茎的增幅;③3种主要环境因子与滨海围垦湿地芦苇凋落物的分解速率相关性由大到小依次是1.2 m空气温度>0～5 cm土层温度>0～5 cm土层湿度,且增温使分解速率与3种环境因子相关性程度均增大,其中,叶分解速率与土壤温度的相关性变化最显著,增大6.43%.综上所述,气温是影响滨海围垦湿地芦苇凋落物分解的关键环境因子,增温不仅会增大滨海围垦湿地芦苇凋落物的分解速率,同时也会改变芦苇凋落物分解速率与主要环境因子的相关性.

By using open-top growth chambers（OTC） to simulate short-term warming and mesh bags,the study was carried out in the reclaimed wetland in the east Chongming tidal flat. The effects of short-term simulated warming（1.984±0.7）℃on the decomposition of Phragmites australis litter were studied and the changes of correlations between decomposition rate and environmental parameters were analysed.The results are as follows：①stem decomposition rates in OTC plots and CG plots are 49.20%and 45.11%,and leaves decomposition rates are 63.52%and 58.53%,respectively,which shows that warming has increased the decomposition rates;②stems average decomposition coefficients（K） in OTC plots and CG plots are 0.028 and 0.027,while the average decomposition coefficients of leaves are 0.093 and 0.080,respectively, which shows that the increment of leaves K is bigger than stems K;③the order of correlation degree between environmental factors and decomposition rate is：1.2 m air temperature 0～5 cm soil temperature 0～5 cm soil moisture,and the correlation coefficient between leaves decomposition rate and 1.2 m air temperature is biggest which is 6.43%.In summary,air temperature is the key factor affecting the Phragmites australis litter decomposition;meanwhile warming not only improves litters decomposition rates,but also changes the relevance between decomposition rate and environmental factors.