Soil,Fine Root And Litter In Different Forest Types In Northern Subtropical

In order to understand the effects of forest types on soil physicochemical properties,fine roots and litterfall,we conducted this research.In this study,three subtropical forest types,dominated by broadleaves,conifers and their mixture,were chosen.We examined physical and chemical properties of soil,aboveground and belowground productivity under the three forest types.We discussed the trend of changes of soil physicochemical properties under three forest types and their underlying factors to provide theoretical reference for the wide application of optimization of forest types in the area.The main results are as follows:?1?The effects of forest type on soil physical propertiesIn the 0-30cm,soil bulk density decreased from coniferous forest,mixed forest to broadleaved forest.Soil bulk density in coniferous forest and mixed forest increased gradually with the increase of soil depth,whereas in broadleaved forest it increased at first and then decreased slightly.Soil porosity decreased from broadleaved forest,mixed forest to coniferous forest.Soil moisture,however,did not differ among the three forest types.?2?The effects of forest type on soil dissolved organic carbon?DOC?and dissolved organic nitrogen?DON?Among forest types,soil DOC and DON in the 0-30 cm soil layer were different.Soil DOC was the highest(188.5 mg kg^-1)in the mixed forest and the lowest(157.9mg.kg^-1)in the coniferous forest with the broadleaved forest being intermediate(163.9 mg.kg^-1).Soil DON did not differ significantly among forest types,although there was a trend of the highest in the mixed forest(51 mg kg^-1),intermediate in broadleaved forest(49.4 mg kg^-1),and the lowest(45.8 mg kg^-1)in coniferous forest.Both soil DOC and DON of the three forest types showed a similar soil depth-related trend:they increased slightly at first and then decreased,with increasing soil depth.?3?The effects of forest types on soil nutrient content and cyclingSoil organic C,soil total N,soil total P decreased from broadleaved forest,mixed forest to coniferous forest.And the soil organic C content was highest in the broadleaved forest(224.6 g.kg^-1)and least in the coniferous forest(168.8 g.kg^-1)with the mixed forest being intermediate(184.5 g.kg^-1);the content of soil N was highest in the broadleaved forest(5.42 g.kg^-1)and least in the coniferous forest(4.78 g.kg^-1)with mixed forest being intermediate(4.56 g.kg^-1);the content of soil P was also highest in the broadleaved forest(0.51 g.kg^-1)and least in the coniferous forest(0.42 g.kg^-1)with mixed forest being intermediate(0.36 g.kg^-1).Among the different soil layers,the three elements decreased gradually with the increase of soil layer in three forest types.In the 0-30cm,the soil K,Ca and Mg decreased from coniferous forest,broadleaved forest to mixed forest.The variance analysis showed that these three kinds of elements in different forest types were not significantly different,indicating that the soil K,Ca,Mg content in soil is relatively stable and more time of observation are needed to understand the variation of its content.?4?The effects of forest types on soil stoichimetrySoil C/N,C/P and N/P in coniferous forest was less than that in broadleaved forest and coniferous forest.In all three forest types,stoichimetry of C/N,C/P and N/P decreased with the increase of soil depth,indicating that forest types could influence soil stoichimetry.?5?The effects of forest types on litterfall and fine root productionAmong three forest types,litterfall decreased from broadleaved forest,mixed forest to coniferous forest.And annual fine root production in mixed forest was significantly higher than other two forest types,showing that the forest types have an influence on both aboveground and belowground productivity.