不同植被恢复类型下土壤碳含量对光伏组件遮阴的响应

Response of soil carbon contents to photovoltaic modules shadingunder different vegetation restoration types

【目的】探究云南石漠化脆弱区光伏场区不同植被恢复类型下,土壤微生物量碳(MBC)、可浸提有机碳(EOC)及总碳(TC)含量对光伏组件遮阴的响应特征,以期为石漠化脆弱区光伏电站退化土地生态恢复中的植被选型优化提供科学依据。【方法】2021年10月,在云南省昆明市东川光伏电站内,选取黄金菊(Euryops pectinatu)和红花檵木(Loropetalum chinense var.rubrum)2种人工建植植被样地,分别在每个样地的光伏板间(IP)、前檐(FP)、后檐(RP)、板下(UP)设置4个平行采样带,并以未受电站建设干扰的场外草地(以黄茅(Heteropogon contortus)为优势物种群落)样地作为对照(CK),测定2种植被恢复类型下光伏场区不同位置的光照强度以及表层(0~20 cm)的土壤温度、土壤碳(TC、MBC、EOC)含量以及土壤理化性质(pH、电导率、含水量),并分析光照强度、土壤温度、土壤碳含量以及土壤理化性质间的相关性。【结果】光伏场区不同位置的光照强度在07:00-19:00差异明显,且光照强度由大到小表现为对照>板间>前檐>后檐>板下,其中对照、后檐及板下位置的光照强度日变化均呈单峰变化,而板间和前檐位置的日变化均呈双峰变化趋势。场外的土壤温度明显高于光伏场区内,光伏场区不同位置的土壤温度差异较小。植被类型和光伏场区不同位置的光照异质性对土壤碳含量均有显著影响。在黄金菊样地,场区不同位置的土壤微生物量碳含量均较对照显著升高,其中前檐位置的土壤微生物量碳含量最高;在红花檵木样地,除了板间位置的土壤微生物量碳含量较对照显著降低外,其他位置均显著升高。2种植被恢复类型下不同位置土壤pH与对照无显著差异,土壤含水量和电导率均显著高于对照。相关性分析结果表明,光照强度与土壤微生物量碳含量和土壤含水量呈显著负相关,与可浸提有机碳含量、电导率、土壤温度呈显著正相关;土壤含水量与土壤可浸提有机碳和总碳含量均呈显著负相关(P<0.05)。【结论】在石漠化脆弱区的光伏场区,光伏组件遮阴与植被恢复均有利于提高土壤微生物量碳含量,但对可浸提有机碳和总碳含量的影响有一定差异,其中黄金菊样地的土壤可浸提有机碳和总碳含量明显高于对照。若短期内想达到较好的恢复效果,应优先选用黄金菊进行植被恢复。

【Objective】This study investigated response characteristics of soil microbial carbon(MBC),extractable organic carbon(EOC)and total carbon(TC)contents to photovoltaic modules shading under different vegetation restoration types in photovoltaic field in a rocky desertification region in Yunnan to provide basis for optimizing vegetation selection for ecological restoration of degraded land.【Method】In October 2021,two artificial vegetation plots of Euryops pectinatus(EP)and Loropetalum chinense var.rubrum(LC)in photovoltaic power station were selected to set sampling points in 4 typical habitats of intervals of panels(IP),front of panel eaves(FP),rear of panel eaves(RP)and underneath of panels(UP).Peripheral grassland with Heteropogon contortus as the dominant species,which was undisturbed by power station construction,was used as the control(CK).Light intensity,temperature,contents of TC,MBC and EOC,and physicochemical properties(pH,conductivity and water content)of surface soil(0-20 cm)were measured and their correlations were analyzed.【Result】The light intensity at different locations varied significantly from 07:00 to 19:00,and it was in a decreasing order of CK>IP>FP>RP>UP.The daily variation of light intensity in CK,RP and UP showed unimodal variation,while that of IP and FP showed bimodal variation.Soil temperature in CK was significantly higher than those inside the field,while the differences among di-fferent locations in PV field was small.Both vegetation types and light heterogeneity at different locations had significant effects on soil carbon contents.In EP,MBC content at different locations was significantly higher than that of CK,and MBC content in FP was the highest.In LC,MBC content in IP location was significantly lower than that of CK,but that in other locations was significantly higher.Soil pH in different locations under the two vegetation restoration types was not significantly different from that of CK,while soil water content and electrical conductivity were significantly higher than those of CK.Correlation analysis showed that light intensity had significantly negative correlation with MBC and EOC contents,while it had significantly positive correlation with EOC content,conductivity and temperature.Soil water content had significantly negative correlation with soil EOC and TC contents(P<0.05).【Conclusion】In the photovoltaic field in the studied rocky desertification region,both PV modules shading and vegetation restoration were conducive to increasing soil microbial carbon contents,but they had different effects on EOC and TC.Soil EOC and TC of EP sample plots were significantly higher than those of the CK.EP is preferred for better restoration effect in short term.