火烧对三江平原湿地土壤养分状况的影响

The Effects of Fire on the Nutrient Status of Wetland Soil in Sanjiang Plain

在三江平原腹地 ,洪河国家级自然保护区当年火烧地段以及中国科学院三江生态实验站烧后一年地段 ,设置当年火烧、火烧后一年与未烧湿地对照区 ,用对比法分析了火烧对湿地土壤养分状况的影响。结果表明 ,火烧会减少湿地土壤的有机质含量 ,火烧当年洪河保护区草根层与腐殖质层有机质含量下降尤为明显 ;火烧次年生态实验站火烧地表层土壤有机质含量仍低于未烧湿地。同时 ,伴随有机质的迅速分解与矿化 ,无论火烧当年还是次年 ,土壤草根层与腐殖质层全氮、全磷含量都较未烧湿地低 ,而全钾含量提高。火烧当年保护区土壤速效氮、速效磷含量虽然降低 ,但速效氮、速效磷占全量的比例较未烧湿地高 ;草根层土壤内速效钾含量较未烧湿地高 ,占全量比例也较高 ,但在其他层次内未见提高。三江生态实验站内火烧后一年的土壤 ,除速效氮占全氮的比在腐殖质层及潜育层内仍高于未烧湿地外 ,其他速效养分含量占全量比值普遍低于未烧地。另外 ,火烧后湿地土壤的 pH值略有升高。以上结果均在湿地草根层与腐殖质层表现明显 ,火烧对湿地土壤潜育层影响不明显。

Long time studying indicates that fire is a unique, important environmental factor of most ecosystems. Fire also plays an important role in both the preservation and evolution of wetland. The studies on the effects of fires on wetlands are few compared with terrestrial habitats. Moreover, a disproportionate amount of research on wetland fires has focused on the recovery of flora and fauna related to abiotic changes that can subsequently influence these processes. Typically, fire alters the level of soil nutrition although the nature of these alterations can be quite variable, however, studies on that are few. According to the data of field survey at Honghe NNR and the Ecological Experimental station of Mire-wetlands,CAS, in the Sanjiang Plain, the effects of fire on the Nutrient Status of Wetland Soil in Sanjiang Plain were discussed in this article. Soil samples from three wetland soil layers(O、A、G) were taken .The results showed, burning can reduce the content of organic matter (SOM) in the surface layer, and it's most obvious in the O and A soil layers at the same year after burning. first year after burning, the content of organic matter is still lower than that in unburned site. In addition, fire resulted in losses of total nitrogen(TN)、total phosphorus(TP) and increases of total potassium(TK). The concentration of available nitrogen(N 0) and available phosphorus(P 0) decreased at the year after burning at Honghe NNR, but the ratio of N 0/TN、P 0/TP increased compared with that in unburned site. The concentration of available potassium(K 0) in the O soil layer increased obviously with the increase of ratio of K 0/TK, but that not found in mid-layer and deep-layer. One year after burning in the Ecological Experimental area, the ratio of N 0/TN in A and G soil layers was still higher than that in unburned site; but the ratio of P 0/TP and K 0/TK were lower than those in unburned site. Fire can also increase the soil pH slightly. Meanwhile, It's obviously that fire affects the O and A soil layers, but slightly for the G soil layer. Anyway, the nutrients were lost in the surface soil layers through volatilization, leaching, and/or export of ash particles by updrafts during the burning process and wind.