滨海盐沼湿地植被净初级生产力变化对土壤因子的响应

Response of variation of net primary productivity to edaphic factors in the coastal salt marshes

以辽河三角洲滨海盐沼湿地为研究区,基于遥感数据、气象数据、野外调查和实验室分析数据,采用CASA模型模拟并分析该区域植被净初级生产力(Net Primary Productivity,NPP)的变化特征,利用统计分析方法定量分析土壤因子对植被NPP的影响。结果表明:(1)研究区植被NPP空间分异显著,区域变异系数为43.71%,且同种植被类型内部NPP也变化显著;(2)N、P和K对芦苇NPP的限制形式是协同限制,且随土壤电导率的增加呈抛物线形式,因子敏感性从大到小依次为K、P和N;营养限制程度从大到小依次为K、N和P;(3)土壤水盐对芦苇NPP的影响也基本符合抛物线模式,芦苇NPP对土壤电导率的敏感性和土壤电导率对芦苇NPP的影响程度都大于土壤含水量,且土壤含水量越高,芦苇NPP对土壤电导率的敏感性越低。本文最终得出只有各土壤因子达到组合最优时,芦苇NPP才最大,这对滨海盐沼湿地植被的管理和保护具有重要意义。

Net primary productivity(NPP)in the coastal salt marshes of the Liaohe River Delta was estimated using Carnegie-Ames-Stanford Approach(CASA)model with remote sensing,the meteorological and field observation data.The spatial difference of NPP and its causes were analyzed.The results showed the following:(1)the spatial differentiation of NPP in the study area was significant with the variation coefficient 43.71%.The NPP within the same vegetation type also changed significantly.(2)N,P,and K limitation of NPP occurred in the form of co-limitation,and it took the form of a parabola with the increase of soil conductivity.The sensitivity was in the order of K>P>N,while the degree of nutrient limitation was K>N>P.(3)The influence of soil moisture and salinity on NPP also had the form of a parabola.Compared with soil moisture,the sensitivity of NPP to soil conductivity and influence degree of soil conductivity on NPP were greater.Meanwhile,the higher soil moisture,the lower sensitivity of NPP to soil conductivity.Our findings highlight the importance of the optimal combination of edaphic factors,which is significance of the management and conservation of wetland vegetation.