Response of natural regeneration of Picea crassifolia forest to soil physical and chemical properties in the northern foot of Qilian mountains
[Objective]Picea crassifolia is a unique tree species on the northeastern edge of Qinghai-Tibet Plateau in our country,this study provides a theoretical basis for the restoration,management and sustainable utilization of P.crassifolia secondary forest in Qilian mountains.[Method]By setting up a fixed plot with an elevation gradient in the P.crassifolia forest distributed in the Pailugou valley of Qilian mountains,investigation of natural regeneration seedlings and sampling and determination of soil bulk density,water,pH,organic carbon,total N,p,K and their available nutrients were carried out,the response of natural regeneration seedlings of P.crassifolia forest to soil physical and chemical properties was analyzed.[Result]The regeneration index of P.crassifolia forest at different altitudes was 2 800-2 900 m(0.63)＞2 700-2 800 m(0.58)＞3 100-3 300 m(0.57)＞2 900-3 100 m(0.56),the best updated altitude was 2 800-2 900 m.Soil water content,organic carbon,total nitrogen,and hydrolyzed nitrogen in H1 and H2 were significantly lower than those in H3 and H4(P＜0.05).Soil bulk density,pH,total potassium and available potassium had no significant difference(P＞0.05).Soil total phosphorus and available phosphorus were significantly higher in H2 than in other altitudes(P＜0.05),there was no significant difference in total phosphorus(P＞0.05).The content of available phosphorus was the lowest in H4,and there was no significant difference in H1 and H3(P＜0.05).The correlation analysis showed that the regeneration index of 2 800-2 900 m was only positively correlated with soil bulk density,total phosphorus and available phosphorus(P＜0.05),the maximum of the absolute value of correlation coefficient between renewal index and soil physical and chemical properties mainly concentrated in this altitude region.The regeneration index was negatively correlated with soil water content,organic carbon,total nitrogen and hydrolyzed nitrogen(P＜0.05),and positively correlated with bulk density and total phosphorus(P＜0.05).There was a significant positive correlation between available phosphorus and 20-40cm soil layer(P＜0.05).Principal component analysis showed that the contents of soil organic carbon,available phosphorus and total phosphorus were the main factors affecting natural regeneration of P.crassifolia forest.[Conclusion]The interaction between natural regeneration of P.crassifolia forest in Qilian mountains and soil physical and chemical properties is close,especially the accumulation of organic carbon and the release of phosphorus in soil.
Picea crassifolia forestnatural renewalphysical and chemical properties of soilPailugou watershed of Qilian mountains
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