摘要
探索火烧迹地土壤理化性质的驱动因子是解释生态系统响应火干扰机制的重要组成部分。旨在分析兴安落叶松林火烧迹地土壤理化性质的决定因子,深入认识火干扰在北方森林生态系统所扮演的角色,为北方森林火烧迹地火后恢复、林业可持续发展提供科学支持和理论依据。以过火后1 a的兴安落叶松林火烧迹地为研究对象,设置了不同火烈度和立地条件的火烧迹地及对照研究样地共计35块。在每个研究样地记录了树种、胸径、存活状态等乔木数据,测量了坡向、坡位、坡度、海拔等地形数据,利用植被变化情况量化了火烈度。分别采集了0—5 cm和5—10 cm的土壤样品并测定其9种理化指标,对比了过火与未过火样地这些土壤理化指标的差异。然后,分析了各土壤理化指标与火烈度量化结果的关联趋势,比较了火烈度、地形和乔木因子对火烧迹地土壤理化性质的影响程度。与对照样地相比,火干扰提升了土壤理化指标观测值的离散程度,显著提高了0—5 cm土壤含水率(MC)(P<0.05)和5—10 cm土壤MC、总氮(TN)、总有机碳(TOC)含量(P<0.05)。土壤理化性质与火烈度有明显关联趋势的并不多,观察到0—5 cm土壤MC随火烈度指数的增加而减少,0—5 cm土壤无机氮与5—10 cm土层土壤pH、速效钾(AK)、铵态氮(NH_(4)^(+)-N)随火烈度指数的增大而增大。相关分析表明,地形因子与火烧迹地土壤理化性质关联程度较高,坡位、坡度、坡向与土壤吸湿含水率(HMC)、MC、硝态氮(NO_(3)^(-)-N)和5—10 cm土壤总氮(TN)、总有机碳(TOC)均呈显著负相关(P<0.05),而与土壤AK、pH、NH_(4)^(+)-N和有效磷(AP)则以正相关为主,其中坡度与0—5 cm土壤AK、pH、NH_(4)^(+)-N和AP均呈极显著的正相关(P<0.01)。方差分解分析结果表明,对照样地土壤理化指标的变异主要由乔木因子和地形因子共同解释,但在火烧迹地,乔木因子总解释比例降低了,而地形因子单独解释的比例增加了,两者对于土壤理化指标变异的共同解释比例大幅降低了。火干扰能够提升地形对土壤理化性质的影响程度。地形是火烧迹地土壤理化性质差异的主导因子,其影响较火烈度更为深刻,因此,当火烈度相同但地形不同时,火干扰引发的生态系统响应可能不同。所以,地形的主导作用可能是导致在不同区域研究火烈度与土壤理化性质的关系得出不同结果与结论的重要原因之一。
Clarifying the driving factors of post-fire soil physicochemical properties is an important part of explaining ecosystem response to fire disturbance.This study aimed to analyze the determinants of post-fire soil physicochemical properties in Dahurian larch forests,to gain an in-depth understanding of the role of fire disturbance in boreal forest ecosystems,and to provide scientific support and theoretical basis for boreal forest post-fire recovery and sustainable development.The research object was one-year-post-fire Dahurian larch forest in the Greater Khingan Mountains.A total of 35 burned and unburned plots with different fire severity and site conditions were established.In each plot,species,diameter at breast height(DBH),survival status and other arbor data were recorded,and terrain data such as slope aspect,slope position,slope gradient,and altitude were measured,and the fire severity was quantified through vegetation changes.Nine physical and chemical indicators of the collected soil samples from two layers(0-5 and 5-10 cm)were measured,and the differences of these indicators were compared between the burned and unburned plots.Then,the correlation of quantitative results of fire severity and each index were analyzed,and the effects of fire severity,topography and arbor on the soil physicochemical properties in the burned area were compared.Compared with the unburned plots,fire disturbance enhanced the dispersion of soil physical and chemical indexes,significantly(P<0.05)increased total nitrogen(TN),total organic carbon(TOC)content in 5-10 cm soil and both two layers'soil moisture content(MC).There were few soil physicochemical indexes obviously correlated with fire severity.The soil MC in 0-5 cm was observed to decrease with the increase of fire severity index.Available potassium(AK),pH and ammonium nitrogen(NH_(4)^(+)-N)of 5-10 cm soil and inorganic nitrogen of 0-5 cm soil increased with the increase of fire severity index.Correlation analysis showed that topographic factors were highly correlated with soil physicochemical properties in the burned area.Slope position,slope gradient,and slope aspect were significantly negatively correlated with TN and TOC of 5-10 cm soil and hygroscopic water content(HMC),MC,nitrate nitrogen(NO_(3)^(-)-N)(P<0.05),while they were mainly positively correlated with AK,pH,NH_(4)^(+)-N,and available phosphorus(AP),among which the slope gradient were highly significant(P<0.01)positively correlated with AK,pH,NH_(4)^(+)-N and AP of 0-5 cm soil.The variance partitioning analysis(VPA)results showed that the variation of soil physical and chemical indicators in the unburned plots was mainly explained by the sharing of arbor and topographic factors.However,in the burned area,the explained proportion of arbor factors decreased,while the individually explained proportion of topographic factors increased,which resulted in the sharing proportion was greatly reduced.Fire disturbance could enhance the impact of topography on soil properties.Topography was a dominant factor for the differences in soil physicochemical properties in the burned areas,and its impact was more profound than fire severity,so the ecosystem response to fire disturbance depended not only on fire severity.Therefore,the dominant role of topography may be one of the important reasons for the different results and conclusions drawn from the studies on the relationship between fire severity and soil physicochemical properties in different regions.
作者
韩懂懂
杨光
邸雪颖
李兆国
HAN Dongdong;YANG Guang;DI Xueying;LI Zhaoguo(School of Forestry,Key Laboratory of Sustainable Forest Eeosystem Management-Minstry of Eduction,Northeast Forestry Uniersity,Harbin 150040,China)
出处
《生态学报》
CAS
CSCD
北大核心
2023年第21期8727-8738,共12页
Acta Ecologica Sinica
基金
国家自然科学基金项目(31870644)。
关键词
火烈度
兴安落叶松
植被
地形
土壤理化性质
fire severity
Dahurian larch
vegetation
topography
soil physicochemical property
