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Effects Of Nitrogen And Phosphorus Addition On Soil Carbon,Nitrogen And Phosphorus Stoichiometry Across Chronosequence In Pinus Elliottii Forest For Timber And Resin Production

Posted on:2021-02-24Degree:MasterType:Thesis
Country:ChinaCandidate:R YangFull Text:PDF
GTID:2370330602496848Subject:Garden Plants and Ornamental Horticulture
Abstract/Summary:PDF Full Text Request
Slash pine?Pinus elliottii?has been introduced into China for more than 80 years and is an excellent tree species for both for timber and resin production in southern China.It is of great significance for the adjustment of regional forestry industrial structure and the promotion of sustainable development of forestry economy.In this study,three forests at different ages?13a,24a,28a?which are tapped and not tapped,were selected as the research object,nitrogen and phosphorus addition levels included the following treatments:CK[no nitrogen and phosphorus additions],N[nitrogen addition,100 kg N/?hm2·a?],N+LP[nitrogen and low phosphorus addition,100 kg N/(hm2·a+100 kg P2O5/?hm2·a?],N+HP[nitrogen and high phosphorus addition,100 kg N/?hm2·a?+200 kg P2O5/?hm2·a?].The short-term experiment of the effects of nitrogen and phosphorus addition on soil carbon,nitrogen,and phosphorus stoichiometry in Pinus elliottii forest for timber and resin production was carried out to reveal the effects of tapping,forest age,and fertilization on soil carbon,nitrogen,and phosphorus stoichiometric characteristics,explore the long-term maintenance techniques of soil fertility in Pinus elliottii forest for timber and resin production.The research results will provide theoretical basis and practical guidance for the multi-objective sustainable management of Pinus elliottii forest for timber and resin production.The results are as follows:?1?The soil organic carbon?SOC?content,total phosphorus?TP?content,and C:P ratio of all stands in the experiment had no obvious seasonal dynamic changes under different treatments.But in May,the soil total nitrogen?TN?content and N:P ratio were the smallest,C:N ratio reached the maximum.?2?N application significantly improved SOC,TN content,C:P ratio,N:P ratio?p<0.05?in the 0-20cm soil layer of the 28a tapped stand.N+LP significantly increased SOC and TP content in the upper soil of 13a untapped stand,and significantly decreased N:P ratio?p<0.05?.SOC and TP contents in the upper soil of 24a stand were significantly increased by N+LP?P<0.05?.N+HP significantly reduced the TN content in the surface soil of 13a untapped stand?p<0.05?,and significantly improved the soil C:N ratio and surface soil C:P ratio.N+HP significantly increased TP content in 28a untapped stand?p<0.05?.SOC and TP contents in the upper soil of the 24a stand were significantly increased by N+HP?p<0.05?.?3?The SOC,TN and TP content of 13a and 28a Pinus elliottii forests were increased by tapping,the C:N ratio,C:P ratio and N:P ratio of 13a and 28a were decreased,while the effect of tapping on soil index of 24a Pinus elliottii forest was opposite.?4?By analyzing the average annual content of soil indexes,it was found that the SOC and TN in the tapped stand were 28a>13a>24a,and the TP was 13a>28a>24a.SOC and C:P of tapped stand were 24a>13a>28a.TP,C:N,C:P and N:P in the soil of the tapped stand were 24a>28a>13a.The TN and N:P sequences of tapped stand were 28a>24a>13a and13a>24a>28a.?5?The multi-factor variance analysis of fertilization,forest age and tapping showed that fertilization significantly affected the TP content of 0-20cm soil layer?p<0.05?.SOC,TP,C:N ratio,C:P ratio?p<0.05?were significantly affected by forest age and tapping.SOC,TN,TP,C:N ratio,C:P ratio,N:P ratio and N:P ratio were significantly affected by the interaction between forest age and tapping?p<0.05?.The interaction between forest age and fertilization had significant effects on C:N,C:P and N:P?p<0.05?.The interaction of tapping,forest age and fertilization had significant effects on SOC,TN and TP content and C:P,N:P in 0-20cm soil layer?p<0.05?.?6?Correlation analysis showed that SOC was significantly positively correlated with TN,TP,C:P,N:P?p<0.01?,and SOC and TN were significantly positively correlated with NH4+-N,respectively?p<0.05?.TN and C:P,N:P showed extremely significant positive correlation?p<0.01?,C:N and N:P showed significant negative correlation?p<0.05?,C:P and N:P showed extremely significant positive correlation.pH was negatively correlated with SOC and TN?p<0.05?.
Keywords/Search Tags:Nitrogen and phosphorus addition, resin tapping, soil carbon,nitrogen and phosphorus content, stoichiometric ratio, Pinus elliottii forest for timber and resin production
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