| In this study,the understory planting of Masson pine in the state-owned forest farm of Dushan County,Guizhou Province(1978)was studied.Three kinds of understory compound management modes were set Masson pine+Polygonatum cyrtonema(forest medicine mode),Masson pine+Vicia villosa(forest grass mode),and Masson pine+Amorphophallus konjac(forest agricultural mode).The experimental control group was designed as Masson pine artificial pure forest.By measuring the soil’s physical properties,soil chemical properties,soil microorganisms,soil enzyme activities,and field investigation of the incidence of forest diseases and insect pests in each treatment site,the effects of different planting patterns(forest agricultural,forest grass,forest medicine,pure forest)on the soil and forest health of Masson pine plantation forest land were understood,and the undergrowth planting mode beneficial to the healthy management of Masson pine plantation was screened,to provide reference and technical support for the maintenance of soil fertility and ecological management of Masson pine plantation.The results are as follows:(1)Effects of understory planting on soil physical and chemical properties of Masson pine plantation.The soil physical properties of four different planting modes of Masson pine forest were analyzed,and it was found that compared with the control group of pure forest land,the soil water content of the forest pesticide mode and the forest agricultural mode could significantly increase(P<0.05),reaching 32.35%and 34.31%,respectively.The forest-grass model could significantly increase soil porosity(P<0.05),reaching 58.31%.The soil chemical properties of four different planting patterns under Masson pine forest were analyzed.Compared with the pure forest land control group,the soil pH under the forest medicine,forest-agriculture,and forest agricultural mode were improved to a certain extent.The soil organic matter content increased significantly under the forest pesticide model(P<0.05).The contents of total nitrogen,available nitrogen,and total phosphorus in the soil of forest medicine,forest agricultural,and forest grass were significantly increased(P<0.05).Forest medicine and agroforestry models significantly increased soil available phosphorus,total potassium,and available potassium(P<0.05).Through the development of understory planting in Dushan County,Guizhou Province,it was found that the forest medicine model and the forest farm model can effectively improve the soil nutrients of local Masson pine forest.(2)Effects of understory planting on soil microorganisms and enzyme activities in Masson pine plantations.Through understory planting,compared with the pure forest control group,the number of culturable bacteria,actinomycetes,and fungi in soil could be significantly increased by forest pesticides and forest agricultural(P<0.05).Compared with the pure forest control group,the catalase activity,sucrose activity,and urease activity of the forest medicine,forest grass,and forest agricultural were significantly increased(P<0.05).The development of understory planting in Dushan County of Guizhou Province found that the compound planting mode of forest grass,forest-agriculture,and forest medicine can significantly increase the number of soil bacteria and enhance soil enzyme activity.(3)Effects of understory planting on pests and diseases of Masson pine plantation.The investigation of pests and diseases in Masson pine forests after undergrowth showed that there were five main pests and diseases,namely Dioryctria rubella,Dendrolimus punctatu,Laspeyresia,Gryllotalpa orientalis Burmeister,and Lophodermium.Through the development of understory planting,the forest medicine model and forest agricultural model can significantly reduce the occurrence of Dendrolimus punctatu pests(P<0.05),and the forest medicine model has the best effect.Different planting patterns had a certain effect on the number of Dioryctria rubella and Laspeyresia,but the difference between groups was not significant.The incidence of Lophodermium decreased under the forest medicine model,the forest grass model,and the forest agricultural model,and the forest medicine model had obvious effects.There was an extremely significant negative correlation between the number of Dendrolimus punctatu and the number of Dioryctria rubella and soil organic matter(P<0.01),and there was a significant negative correlation between Laspeyresia and soil organic matter(P<0.05).Overall:Masson pine understory composite planting can enhance soil water holding capacity,improve soil pH,increase soil fertility,effectively promote the number of soil microorganisms and soil enzyme activity,and has a good fertilizer effect,significantly improving the quality of forest soil,improve the health of seedlings.Among them,Masson pine+Polygonatum cyrtonema mode(forest medicine mode)has the most obvious effect on soil quality improvement and forest health regulation. |
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