植物生态学报 ›› 2018, Vol. 42 ›› Issue (4): 487-497.DOI: 10.17521/cjpe.2017.0298

• 研究论文 • 上一篇    下一篇

季节性雪被对天山雪岭云杉凋落叶分解和碳氮磷释放的影响

陈文静,贡璐*(),刘雨桐   

  1. 新疆大学资源与环境科学学院, 绿洲生态教育部重点实验室, 乌鲁木齐 830046
  • 出版日期:2018-04-20 发布日期:2018-03-08
  • 基金资助:
    国家自然科学基金(31760142);Supported by the National Natural Science Foundation of China (31760142).

Effects of seasonal snow cover on decomposition and carbon, nitrogen and phosphorus release of Picea schrenkiana leaf litter in Mt. Tianshan, Northwest China

Wen-Jing CHEN,Lu GONG*(),Yu-Tong LIU   

  1. College of Resources and Environment Science, Xinjiang University, Key Laboratory of Oasis Ecology, Ministry of Education, ürümqi 830046, China
  • Online:2018-04-20 Published:2018-03-08

摘要:

季节性雪被下显著的冻融格局差异可能对干旱区山地森林凋落叶分解过程产生重要影响, 但一直未见深入研究。2015年10月至2016年10月, 采用凋落物分解袋法, 研究了天山典型树种雪岭云杉(Picea schrenkiana)凋落叶在季节性雪被覆盖下的3个关键时期(冻融期、深冻期、融冻期)以及生长季(生长季早期和生长季末期)的分解动态和碳、氮、磷释放特征。结果表明: (1)经过一年的分解, 不同雪被厚度下雪岭云杉凋落叶分解率为24.6%-29.2%, 且存在显著性差异。分解系数k值厚雪被覆盖最大, 无雪被覆盖最小。(2)冬季雪被覆盖期雪岭云杉凋落叶分解对当年分解总量的贡献达46.0%- 48.5%, 其中对冻融期凋落叶分解影响较为明显。(3)随着凋落叶的分解, 雪岭云杉凋落叶氮含量总体呈增加趋势; 碳含量和碳氮比大致呈下降趋势, 在深冻期和生长季末期不同雪被处理下碳含量呈显著性差异; 而凋落叶磷含量呈不规则变化趋势, 且在冻融期和融冻期不同雪被厚度下呈显著性差异。(4)整个雪被覆盖季节凋落叶氮元素表现为富集, 碳和磷元素表现为释放; 其中, 在融冻期薄雪被和中雪被处理下碳元素富集率最大, 在冻融期薄雪被、中雪被和厚雪被处理下, 融冻期无雪被和厚雪被下以及生长季早期中雪被和厚雪被下氮元素富集率最大, 而雪被对凋落叶磷释放的影响不显著。

关键词: 天山, 凋落叶分解, 雪岭云杉, 雪被厚度

Abstract:

Aims The effects of freeze-thaw cycles on seasonal snow thickness may play a significant role in the decomposition process of forest litter in arid areas, whereas the understanding on this issue remains poor. Therefore, our objective was to understand the effects of snow cover on the decomposition and the carbon, nitrogen and phosphorus release of Picea schrenkiana leaf litter, the representative species in arid areas in northwest China.

Methods A field experiment was conducted in Mt. Tianshan of Xinjiang from October 2015 to October 2016 using litterbag method. Air-dried leaf litter of P. schrenkiana was put into nylon litterbags and the litterbags were placed on the forest floor along the gradient of snow cover depth from forest gap to full canopy. Mass loss rates and carbon, nitrogen and phosphorus release of P. schrenkiana leaf litter were measured at three critical stages (freeze-thaw period, deep-freeze period, thawing period) under snow cover and the growing seasons (early growing season and late growing season) during one year of decomposition.

Important findings The results showed that (1) after one year’s decomposition, the decomposition rates of the P. schrenkiana leaf litter under different snow depths were 24.6%-29.2%, and there were significant difference (p < 0.05) between the decomposition rates under different snow depths. The decomposition constant (k) was highest under thick snow cover and lowest under no snow cover. (2) The decomposition during the winter snow cover period contributed 46.0%-48.5% of total decomposition of P. schrenkiana leaf litter in the whole year, and the litter decomposition was the fastest during the freeze-thaw cycles. (3) With the decomposition of leaf litter, the nitrogen content of P. schrenkiana leaf litter increased while the content of carbon and C:N decreased roughly. There was a significant difference (p < 0.05) in carbon content between different snow treatments in the deep freezing period and late growing season. The phosphorus content in leaf litter is irregular with the decomposition of leaf litter. Snow thickness significantly influenced the phosphorus content in leaf litter during freeze-thaw period and thawing period (p < 0.05). (4) Net N immobilization during leaf litter decomposition was observed in the whole snow cover season, C and P were mainly released. Among them, thin and medium snow patches showed higher carbon enrichment rates in the thawing period. Thin, medium and thick snow treatments in the freeze-thaw period, no and thick snow treatments in the thawing period and medium and thick snow patches in the late growing season showed higher nitrogen enrichment rates. In contrast, the effect of snow cover on the release of leaf litter phosphorus was not significant (p > 0.05).

Key words: Mt. Tianshan, leaf litter decomposition, Picea schrenkiana, snow cover thickness