地形对红壤区马尾松林土壤特性与生态化学计量的影响OA

To investigate the impacts of topographic factors on the sustained recovery of degraded vegetation in red soil zones,this study focused on the Pinus massoniana forests in two small watersheds—the Zhuxi River and Luodi River—in a typical red soil erosion area of Changting,Fujian Province.A kilometer grid sampling method was employed to establish the study plots,and soil physicochemical properties and stoichiometric characteristics were investigated and measured across different slopes,aspects,and altitudes within the P.massoniana forests.The relationships between these parameters and topographic factors such as slope,aspect,and altitude were analyzed.The results indicated that in the 0-20 cm soil layer,the non-capillary porosity,total potassium(TK),total phosphorus(TP),and total nitrogen(TN)content of the P.massoniana forest soil with a slope of 10°-15° were significantly lower than those in the forest with a slope of 0°-5°(P<0.05),while P/K ratio showed the opposite trend(P<0.05).The capillary water holding capacity of the soil on the sunny slope was higher than that on the semi-shady and shady slopes(P<0.05).The TK,available potassium(AK)content,and C/P ratio of the soil on the shady slope and the AK and available nitrogen(AN)content of the soil on the semi-shady slope were higher than those on the sunny slope(P<0.05),while the P/K and N/K ratios exhibited the opposite trend(P<0.05).The maximum water holding capacity of the soil at an altitude of 300-350 m was significantly higher than that at 0-300 m(P<0.05).The TN,available phosphorus(AP),and AK content,as well as the P/K and N/K ratios,of the soil at an altitude of 0-300 m were lower than those at other altitudes(P<0.05),while the C/N and C/P ratios presented the opposite trend(P<0.05).In the 20-40 cm soil layer,the capillary water holding capacity,AK content,and N/K ratio of the P.massoniana forest soil with a slope of 10°-15° were lower than those of the soil with other slopes(P<0.05),while the AP content showcased the opposite trend.The soil with a slope of 0°-5° had higher total organic carbon(TOC)content than that with a slope of 10°-15°(P<0.05)and higher TK,TP,and AN content than that with other slopes(P<0.05).The P/K and C/K ratios of the P.massoniana forest soil with a slope of 5°-10° were higher than those of other slopes(P<0.05).The capillary porosity and N/K ratio of the soil on the sunny slope were significantly higher than those on the shady slope.The capillary water holding capacity,natural water content,non-capillary porosity,TK and AK content,and C/K and C/N ratios of the P.massoniana forest soil on the shady slope were significantly higher than those on the sunny slope,and the P/K ratio demonstrated the opposite trend(P<0.05).The soil at an altitude of 0-300 m had significantly higher capillary water holding capacity,natural water content,capillary porosity,and TOC content than that at 350-400 m and significantly lower TK and AP content than that at other altitudes.The AN content and the P/K,C/K,and N/K ratios of the P.massoniana forest soil at an altitude of 350-400 m were higher than those at other altitudes(P<0.05).The random forest model indicated that the main factors influencing the soil physical and chemical properties and ecological stoichiometric characteristics in the 0-20 cm soil layer are aspect and altitude,while the main factors influencing those in the 20-40 cm soil layer are slope and aspect.