Growth,dry matter allocation and moisture content in 1-year-old seedlings of Phoebe bournei(Hemsl.)Yang were compared under simulated nitrogen depositions of 0(the control),5,10,15,20,25 and 30 g·m^-2·a^-1.T...Growth,dry matter allocation and moisture content in 1-year-old seedlings of Phoebe bournei(Hemsl.)Yang were compared under simulated nitrogen depositions of 0(the control),5,10,15,20,25 and 30 g·m^-2·a^-1.The results show that with enhancing of nitrogen deposition,height,basal diameter,dry masses of root,stem,leaf and above-ground part per plant,and dry mass of whole plant of P.bournei show a trend of“increasing-decreasing-increasing”,each index under nitrogen depositions of 5,10 and 15 g·m^-2·a^-1 is generally significantly higher than that of the control.Root/shoot ratio and dry matter allocation percentage of root of P.bournei under nitrogen depositions are lower than those of the control,and those under nitrogen depositions of 5,10 and 30 g·m^-2·a^-1 are significantly lower than those of the control;while dry matter allocation percentage of stem is higher than that of the control,and that under nitrogen depositions of 5,10 and 30 g·m^-2·a^-1 is significantly higher than that of the control;and the change of dry matter allocation percentage of leaf is not obvious.Under nitrogen depositions,the change of moisture contents in root,stem and leaf of P.bournei is small,but that in whole plant is obvious.It is suggested that there is a certain effect of nitrogen deposition on growth,dry matter allocation and moisture content in P.bournei seedlings,in addition,low nitrogen deposition can promote the growth of P.bournei seedlings,while high nitrogen deposition can inhibit their growth.展开更多
在马尾松皆伐迹地营造针阔混交林是近年来南方林区松林改造过程中主要的营林实践.许多针阔混交林常面临着季节性干湿交替和地形异质性导致的临时性干旱,这对混交林幼林生长及林下更新均产生较大影响.从水分平衡的角度选择合适的混交树...在马尾松皆伐迹地营造针阔混交林是近年来南方林区松林改造过程中主要的营林实践.许多针阔混交林常面临着季节性干湿交替和地形异质性导致的临时性干旱,这对混交林幼林生长及林下更新均产生较大影响.从水分平衡的角度选择合适的混交树种是成功营造混交林的前提.以杉木和闽北山区常与之混交的木荷、枫香和南酸枣树种为研究对象,通过不同的土壤水分含量梯度设计(CK:正常水分;LD:轻度干旱;MD:中度干旱;SD:重度干旱),从“光合-耗水”的能量同化和水分消耗角度对4个树种进行综合评价.结果表明:(1)在CK条件下,木荷、枫香和南酸枣的日间耗水量可达93.69-111.68 g,最大耗水速率为131.42-177.30 g m^(-2)h^(-1),均显著高于杉木.在CK和LD条件下,杉木的日间耗水量和日间耗水速率较低,而在MD和SD条件下,南酸枣的日间耗水量和日间耗水速率较低.(2)在LD和MD条件下,3种阔叶树种净光合速率(P_(n))下降幅度排序为枫香>南酸枣>木荷,且降幅明显.SD条件下,3种阔叶树种降幅在41.98%-52.05%之间,较为接近.在不同水分条件下,4种苗木的气孔导度(G_(s))与蒸腾速率(T_(r))变化趋势保持一致.在LD和MD条件下枫香和南酸枣水分利用效率(WUE)较高,在SD条件下木荷和杉木WUE更高.在土壤不同水分条件下,木荷光化学效率(F_(v)/F_(m))较其他树种更高,南酸枣F_(v)/F_(m)总体水平较低.(3)光合-耗水能力综合评价结果显示,CK和MD条件下3种阔叶苗木中木荷得分最高,枫香在LD和SD条件评价较好.综上所述,在造林初期,杉木-枫香混交林在阳坡陡坡造林地的适生性相对更强;而在水肥条件较好的缓坡地,杉木-木荷混交林的生产力可能更高.(图2表3参51)展开更多
文摘Growth,dry matter allocation and moisture content in 1-year-old seedlings of Phoebe bournei(Hemsl.)Yang were compared under simulated nitrogen depositions of 0(the control),5,10,15,20,25 and 30 g·m^-2·a^-1.The results show that with enhancing of nitrogen deposition,height,basal diameter,dry masses of root,stem,leaf and above-ground part per plant,and dry mass of whole plant of P.bournei show a trend of“increasing-decreasing-increasing”,each index under nitrogen depositions of 5,10 and 15 g·m^-2·a^-1 is generally significantly higher than that of the control.Root/shoot ratio and dry matter allocation percentage of root of P.bournei under nitrogen depositions are lower than those of the control,and those under nitrogen depositions of 5,10 and 30 g·m^-2·a^-1 are significantly lower than those of the control;while dry matter allocation percentage of stem is higher than that of the control,and that under nitrogen depositions of 5,10 and 30 g·m^-2·a^-1 is significantly higher than that of the control;and the change of dry matter allocation percentage of leaf is not obvious.Under nitrogen depositions,the change of moisture contents in root,stem and leaf of P.bournei is small,but that in whole plant is obvious.It is suggested that there is a certain effect of nitrogen deposition on growth,dry matter allocation and moisture content in P.bournei seedlings,in addition,low nitrogen deposition can promote the growth of P.bournei seedlings,while high nitrogen deposition can inhibit their growth.
文摘在马尾松皆伐迹地营造针阔混交林是近年来南方林区松林改造过程中主要的营林实践.许多针阔混交林常面临着季节性干湿交替和地形异质性导致的临时性干旱,这对混交林幼林生长及林下更新均产生较大影响.从水分平衡的角度选择合适的混交树种是成功营造混交林的前提.以杉木和闽北山区常与之混交的木荷、枫香和南酸枣树种为研究对象,通过不同的土壤水分含量梯度设计(CK:正常水分;LD:轻度干旱;MD:中度干旱;SD:重度干旱),从“光合-耗水”的能量同化和水分消耗角度对4个树种进行综合评价.结果表明:(1)在CK条件下,木荷、枫香和南酸枣的日间耗水量可达93.69-111.68 g,最大耗水速率为131.42-177.30 g m^(-2)h^(-1),均显著高于杉木.在CK和LD条件下,杉木的日间耗水量和日间耗水速率较低,而在MD和SD条件下,南酸枣的日间耗水量和日间耗水速率较低.(2)在LD和MD条件下,3种阔叶树种净光合速率(P_(n))下降幅度排序为枫香>南酸枣>木荷,且降幅明显.SD条件下,3种阔叶树种降幅在41.98%-52.05%之间,较为接近.在不同水分条件下,4种苗木的气孔导度(G_(s))与蒸腾速率(T_(r))变化趋势保持一致.在LD和MD条件下枫香和南酸枣水分利用效率(WUE)较高,在SD条件下木荷和杉木WUE更高.在土壤不同水分条件下,木荷光化学效率(F_(v)/F_(m))较其他树种更高,南酸枣F_(v)/F_(m)总体水平较低.(3)光合-耗水能力综合评价结果显示,CK和MD条件下3种阔叶苗木中木荷得分最高,枫香在LD和SD条件评价较好.综上所述,在造林初期,杉木-枫香混交林在阳坡陡坡造林地的适生性相对更强;而在水肥条件较好的缓坡地,杉木-木荷混交林的生产力可能更高.(图2表3参51)
