石漠化地区苔藓结皮对土壤养分及生态化学计量特征的影响

苔藓结皮是石漠化生态系统的重要地表覆被物,但其在土壤养分累积和元素循环过程中的作用尚不明确。以我国贵州典型喀斯特高原峡谷石漠化区-花江大峡谷两岸不同等级石漠化生境下的苔藓结皮及其覆被土壤为研究对象,研究了苔藓结皮覆被对土壤养分及生态化学计量特征的影响。结果表明：（1）苔藓结皮层养分含量显著高于下层土壤,结皮覆被土壤有机碳（SOC）、全氮（TN）、全磷（TP）、全钾（TK）、碱解氮（AN）、速效磷（AP）、速效钾（AK）平均含量分别为25.95、3.05、1.00、5.10 g/kg和189.61、1.59、275.10 mg/kg,较无结皮覆被的裸土分别增加46.08%、26.50%、53.62%、20.25%、25.24%、110.47%和83.76%。（2）苔藓结皮覆被土壤C/N、C/K、P/K显著高于裸土,且随土层加深而递减;N/P显著低于裸土,且随土层加深而升高。（3）苔藓结皮覆被土壤养分恢复指数为33.16%-72.48%,呈现随石漠化等级升高而增加的趋势,中度和强度石漠化阶段较无石漠化阶段分别增加83.26%和118.58。本研究表明苔藓结皮能有效促进土壤养分累积,加速石漠化土壤养分恢复进程,可作为补充手段联合其它生态恢复措施共同推动石漠化地区的生态恢复与重建。

Effects of moss crusts on soil nutrients and ecological stoichiometry characteristics in karst rocky desertification region

Moss crusts are an important ground cover in rocky desertification ecosystems, but its roles in soil nutrient accumulation and element cycles are still unclear. In this paper, the effects of moss crusts on soil nutrients and ecological stoichiometry characteristics were studied in different degrees of rocky desertification on both sides of Huajiang gorge, a typical karst plateau gorge in Guizhou Province. The results showed that: (1) the soil nutrient content in moss crust layer were significantly higher than those in subsoil. The mean contents of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali-hydrolysis nitrogen (AN), available phosphorus (AP) and available potassium (AK) in moss crusts were 25.95, 3.05, 1.00, 5.10 g/kg and 189.61, 1.59, 275.10 mg/kg, which were 46.08%, 26.50%, 53.62%, 20.25%, 25.24%, 110.47% and 83.76% higher than those in bare soil, respectively. (2) Decreased with the increase of soil depth, C/N, C/K and P/K in moss crusts were significantly higher than those in bare soil. N/P in moss crusts was significantly lower than that in bare soil, while increased with the increase of soil depth. (3) The nutrient restoration index of moss crusts ranged from 33.16% to 72.48%, and showed a trend of increase with the ecological deterioration. The nutrient restoration index in moderate and severe rocky desertification stages was 83.26% and 118.58% higher than that in none rocky desertification stage. Our results demonstrated that moss crusts could effectively promote soil nutrient accumulation and accelerate soil nutrient restoration process, and could be involved as a supplementary method in promoting ecological restoration and reconstruction in karst rocky desertification regions.