| China is the country with the largest area of planted forests and the fastest growth rate in the world.These growing plantations not only play a huge role in ensuring the supply of wood,providing forest by-products and industrial raw materials,but also in soil and water conservation and biodiversity,Biodiversity conservation,Carbon fixation and oxygen production,and Purify environmental pollution have played an irreplaceable ecological role.At the same time,the redistribution of atmospheric precipitation by the canopy not only affects the forest hydrological and ecological processes,but also changes the material circulation of the forest ecosystem.Therefore,in-depth study of the impact of different forest forest canopy on precipitation distribution and biological element input has important scientific significance for understanding the process and function of forest ecosystem,and can provide scientific basis for sustainable management and management of plantation.In order to understand the effects of different artificial mixed forest canopy on rainfall redistribution and the fluxes of carbon,nitrogen and phosphorus,the precipitation,throughfall and stemflow were measured simultaneously in Phoebe zhennan and Camptotheca acuminate mixed plantation,Quercus acutissima and C.acuminate mixed plantation,and multi-species mixed plantations,three representative plantations in Rainy Area of Western China.The method of artificial observation in combination with automatic weather station monitoring was used to systematically study the effects of three typical artificial mixed forest canopies on rainfall distribution and the fluxes of carbon,nitrogen and phosphorus.The results would be expected to provide scientific basis for sustainable management and management of regional plantations in this region.The main results were shown as follows.(1)During the experiment period,the total atmospheric rainfall was 1754.20 mm,and the single-field rainfall was in the range of 0.2-135.41 mm.The annual average rainfall intensity was 0.41 mm/h.The frequency of rain and the highest proportion of rainfall in light rain.(2)The throughfall in the Phoebe zhennan and Camptotheca acuminate mixed plantation,Quercus acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 1131.9 mm,995.7mm and 1080.7 mm,respectively,and accounted 62.34%,59.97%,and 60.38%of the total annual atmospheric rainfall.A significant linear relationship was observed between throughfallfall and rainfall.(3)The stemflow of in P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantations were 15.0 mm,8.0 mm and 10.7 mm,which accounted for 0.64%,0.33%,and 0.65%of annual rainfall,respectively.A significant power function relationship was observed between stemflow and rainfall,and the stemflow increased with the increase of rainfall.(4)The canopy in P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation intercepted607.3 mm,750.5mm and 662.8 mm of rainfall,which accounted 37.02%,39.70%,and 38.98%of rainfall.A significant linear relationship was found between canopy interception and atmospheric rainfall.(5)The concentrations of dissolved total carbon(TC),dissolved inorganic carbon(DIC),dissolved total organic carbon(TOC),dissolved total nitrogen(TN)and dissolved total phosphorus(TP)in atmospheric rainfall in the study area were 22.45.19.93,2.52,6.08,0.28 mg/L,respectively;and the concentrations of TC,DIC,TOC,TN and TP in fainwaters were negatively correlated with rainfall.TC,DIC,TOC,TN and TP concentrations in rainwater in the dry season were higher than those in the rainy season.The fluxes of TC,DIC,TOC,TN and TP in rainfall were 376.28,339.33,36.96,81.05 and 4.18 kg/hm~2,respectively,which were significantly and positively correlated with rainfall.Higher concentrations of TC,DIC,TOC,TN,TP in rainwater were observed in the dry season.(6)The TC concentrations in the throughfall of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 27.32,28.50,and 31.96 mg/L,respectively.The TC input of the throughfall was 301.59,266.06,and 302.33 kg/hm~2.The DIC concentrations of throughfall in the mixed forests of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 19.86,21.19 and 24.64 mg/L,respectively.The DIC input of the throughfall was220.28,195.53,and 226.61 kg/hm~2.The TOC concentrations in the throughfall of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 8.11,7.80 and 7.73 mg/L,respectively.The TOC input of the throughfall was 87.59,78.93 and 80.74 kg/hm~2.The TN concentrations in the throughfall of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 7.34,7.13 and 7.23 mg/L,respectively.The TN input of the throughfall was 64.21,59.47,and 61.79 kg/hm~2.The TP concentrations in the throughfall of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 0.36,0.35 and0.37 mg/L respectively.The TP input of the throughfall was 3.78,3.26,and 3.54kg/hm~2.(7)The TC concentrations in the stemflow of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 93.47,102.55 and 79.88 mg/L,respectively.The TC input of the stemflow was 12.57,9.14 and 8.01 kg/hm~2.The DIC concentrations of stemflow in the mixed forests of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 76.36,84.51and 64.57 mg/L,respectively.The DIC input of the stemflow was 10.29,7.71,and6.41 kg/hm~2.The TOC concentrations in the stemflow of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 16.84,17.39,and 16.13 mg/L,respectively.The TOC input of the stemflow was 0.059,0.038,0.043 kg/hm~2.The TN concentrations in the stemflow of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 9.87,8.89 and 10.63 mg/L,respectively.The TN input of the stemflow was 1.062,0.566 and 0.951 kg/hm~2.The TP concentrations in the stemflow of P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation were 0.43,0.61,and 0.57 mg/L respectively.The TP input of the stemflow was0.0527,0.0437 and 0.0587 kg/hm~2.In summary,the atmospheric rainfall in Rainy Area of Western China had high rainfall and frequent rainfall,and the rainfall intensity and rainfall in the rainy season were higher than that in the dry season.The concentrations of carbon,nitrogen and phosphorus decreased with increasing rainfall,and the rainy season was lower than that in the dry season,and the input of carbon,nitrogen and phosphorus increases with increasing rainfall,and the rainy season was higher than that in the dry season.P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation has little difference in throughfall,stemflow and canopy interception,and increases with the increase of atmospheric rainfall,and the rainfall water in rainy season is higher than that in dry season.P.zhennan and C.acuminate mixed plantation,Q.acutissima and C.acuminate mixed plantation and multi-species mixed plantation had a small difference in the concentration of TC,TOC,TN and TP,and were higher than rainfall,which decreased with increasing rainfall.The rainy season is lower than that in the dry season,and the TOC input of throughfall and canopy interception were higher than rainfall,it showed that,while the input of DIC,TN and TP was lower than rainfall,showing interception effect,and the input of DIC,TOC,TN and TP increased with increasing rainfall,and the rainy season is higher than that in the dry season. |
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