三种常见挺水植物凋落物的分解动态及养分释放规律

Dynamic characteristics of litter decomposition and nutrient release of three common emergent plants

湿地植物凋落物的分解对维持湿地生态系统结构和功能稳定具有重要作用。为探究湿地植物凋落物分解动态及养分释放规律,以芦苇(Phragmites australis Trin. ex Steud)、南荻(Triarrhena lutarioriparia L. Liu ex Renvoize&S. L. Chen)和菰(Zizania latifolia Stapf)3种常见挺水植物为研究对象,模拟受控实验,研究单一物种及两两混合物种分解过程中的分解速率、碳氮磷元素的含量及其比例的变化。结果显示,无论是单一物种还是混合物种,均呈现出前5 d分解最为迅速,随即分解速率急剧下降,而后缓慢降低直至趋于稳定的变化规律。分解速率与凋落物的初始氮、磷含量相关,养分归还与瞬时分解速率常数呈显著正相关。混合分解可能受到养分的迁移和分解的影响,在分解初期和末期呈协同效应,而在分解中期呈拮抗效应。研究结果说明混合分解并不是单一分解的简单加和,还需进一步深化对凋落物分解机理的研究。

The decomposition of wetland plant litter is important for maintaining the structural and functional stability of wetland ecosystems. Here, to explore the dynamics of litter decomposition and nutrient release in wetland plants, we selected three common emergent aquatic plants, i.e., Phragmites australis, Triarrhena lutarioriparia, and Zizania latifolia. We investigated their decomposition rates, contents and stoichiometric ratios of carbon, nitrogen, and phosphorus, and the process of decomposition of single and mixed species. Results showed that whether single or mixed species, the most rapid litter decomposition occurred in the first 5 d. Subsequently, the decomposition rate decreased sharply, then slowly decreased until stable. The decomposition rate was correlated with initial nitrogen and phosphorus content of the litter, and nutrient return was significantly positively correlated with the instantaneous decomposition rate constant. Mixed decomposition may be influenced by nutrient migration and decomposition, showing synergistic effects in the early and end decomposition stages, and antagonistic effects in the middle decomposition stages. Our research indicated that mixed litter decomposition was not the additive effect of single litter decomposition, and further study of the mechanisms of litter decomposition is needed.