滨海重盐碱地人工栽植柽柳生长动态及生态效应

Growth dynamics of Tamarix chinensis plantations in heavy-saline coastal lands and related ecological effects

  • 摘要: 柽柳(Tamarix chinensis)是盐碱地土壤改良和植被构建的先锋物种, 但仅靠柽柳的自然扩散难以在滨海重盐碱地形成灌木优势群落, 对盐碱地的改良作用不明显, 因此探索重盐碱地人工栽植柽柳的生态效应有重要意义。本研究以撂荒地为对照, 对不同树龄的人工柽柳群落的个体生物量、碳储量动态、植物物种组成及其重要值和土壤特性进行分析, 以评估重盐碱地栽植柽柳的生态效应。结果显示: 3年生、5年生和7年生柽柳个体单株生物量逐渐增加, 群落的植被碳密度分别为4.78 t(C)·hm-2、5.56 t(C)·hm-2和6.89 t(C)·hm-2, 而对照撂荒地碳密度只有0.98 t(C)·hm-2; 与对照地相比, 栽植柽柳显著降低了土壤表层的含盐量, 对照地土壤0~10 cm的平均盐分含量高达10.53 g·kg-1, 而3年生、5年生和7年生0~10 cm土壤平均含盐量分别为3.35 g·kg-1、1.86 g·kg-1和5.54 g·kg-1。栽植柽柳后土壤有机质和有效氮呈增高趋势, 有效钾含量显著增加, 7年生柽柳土壤0~5 cm和5~15 cm的有效钾含量分别比对照地高出65.59%和28.90%。随着柽柳树龄增加群落中草本植物的丰富度逐渐升高, 对照地的草本物种只有8种, 7年生柽柳群落达到15种; 耐盐物种在群落中的重要值随着栽植的时间逐渐降低, 盐地碱篷的重要值由34.8下降到0.7, 以种子兼营养繁殖的植物如獐毛和苦荬菜的优势度逐渐增大。这证明, 重盐碱地人工栽植柽柳可以快速构建灌木优势群落, 固碳作用明显; 同时栽植柽柳为生态系统提供了进展演替的动力, 灌草结合的群落结构和稳定的群落环境不仅促进盐碱地土壤表层盐分含量的降低, 也促进了物种多样性的增加和群落的进展演替, 是提高滨海重盐碱地利用率的有效途径。

     

    Abstract: Tamarix chinensis, a pioneering native salt-tolerant plant in abandoned coastal saline lands, has high potential as eco-engineering plant species for re-vegetation and soil quality improvement. However, field experiments on the effectiveness of T. chinensis in re-restoration of saline lands along the coastal areas of China have been largely lacking. T. chinensis was planted in 2005, 2007 and 2009 to assess the effectiveness of plants on vegetation and saline soil restoration in this study. The individual biomass, sequenced carbon amount, herb species diversity and soil characteristics of T. chinensis plantations with different planting years and of adjacent abandoned lands without T. chinensis were investigated. The results showed that T. chinensis grew well in the research area and with increasing individual biomass during the experimentation period. T. chinensis plantations produced significant ecological benefits which increased plot vegetation carbon density from 4.78 t(C)·hm-2 in 3-year plots to 5.56 t(C)·hm-2 in 5-year plots and then to 6.89 t(C)·hm-2 in 7-year plots. On the average, there was only 0.98 t(C)·hm-2 in abandoned lands without T. chinensis. Significant soil quality improvement was indicated by lower saltiness and higher organic matter and available N and K in T. chinensis plantation lands. Salt content in the 0 10 cm soil layer of abandoned lands was 10.53 g·kg-1. It was 3.35 g·kg-1 in the 3-year plots, 1.86 g·kg-1 in the 5-year plots and 5.54 g·kg-1 in the 7-year plots with T. chinensis. Compare with abandoned lands, soil available K in the 0 5 cm and 5 15 cm soil layer in the 7-year plots respectively increased by 65.59% and 28.90%. In addition, T. chinensis played a significant "eco-engineering" role in terms of increasing volume and species of grass during T. chinensis plant development. Whereas only 8 grass species existed in the abandoned lands without T. chinensis, a total of 15 grass species existed in the 7-year plot with T. chinensis plantation. However, other important salt-tolerant species decreased in T. chinensis plots. Colon plants like Aeluropus sinensis and Ixeris polycephala became more dominant than seed plants such as Suaeda salsa after planting T. chinensis. This suggested that T. chinensis plant progressively alleviated salt stress in the coastal environments. The study demonstrated via field experiments that T. chinensis was effective in vegetation regeneration, soil enhancement and carbon sequestration in saline lands.

     

/

返回文章
返回