| Under the Betula platyphylla secondary forest,two-years-old Fraxinus mandshurica, Juglans mandshurica, Quercus mongolica, Phellodendron amurense seedlings was planted in different light intensity (high light (HL,64% of full light), medium light (ML,45% full light), low light (LL,15% of full light), fertilizing nitrogen (N), phosphorus(P), nitrogen + phosphorus(N+P) and no fertilizer.In two growing seasons, seedling growth indicators(seedling height, basal diameter,biomass and its distribution) and physiological indicators (root,stem and leafN, Pcontent,photosynthetic indexes) were determined,analyzing the effects of light and fertilization on artificial regeneration of 4 Tree species. The results showed that:(1) Different light intensity and fertilization had obvious effects on seedling height growth of F. mandshurica, J. mandshurica, Q. mongolica, P. amurense, higher light intensity and fertilizing treatment promoting them, and less obvious effects on basal diameter growth.After two growing season, in the same fertilizer treatments but between different light intensity, height growth of F. Mandshurica and J. Mandshurica sedlings ranking was HL> ML>LL,Q. mongolica and P. Amurense’s being lowest in low light intensit, and there is no unified rule as HL compared with ML.HL increased by 65.2%,96.5%,55.0%,97.0% respectively than LL(P< 0.05). ML increased by 22.7%,33.5%,63.4%,102.1% respectively than LL.In the different light intensity but same fertilizer treatments ,height growth of 4 seedlings generally shows the rule that fertilization treatment is higher than no fertilizer, N+P treatment increased by 46.2%,31.3%,28.2%,115.1% ,102.1% respectively than no fertilizer .In different light intensity and fertilizer treatments, basal diameter growth of 4 seedings increment is slightly different, being similar with height growth trends.(2) Different light intensity and fertilization had obvious effects on seedling biomass of F. mandshurica, J. mandshurica, Q. mongolica, P. amurense, higher light intensity and fertilizing treatment promoting them.After two growing season, in the same fertilizer treatments but between different light intensity, biomass of F. Mandshurica and J. Mandshurica sedlings ranking was HL> ML> LL, Q. mongolica and P. Amurense’s being lowest in low light intensity, and there is no unified rule as HL compared with ML.HL increased by 113.6%, 222.7%, 26.9%, 214.1% respectively than LL(P< 0.05).ML increased by 57.4%, 83.1%, 29.9%, 174.7% respectively than LL.In the same light intensity but between different treatments fertilize, biomass of 4 seedlings generally shows the rule that fertilization treatment is higher than nofertilizer, N+P treatment increased by 27.8%,81.3%,12.2%,40.5%respectively than no fertilizer. In different light intensity and fertilizer treatments, ratio of shoot to root of 4 seedings generally shows the rule that higher light intensity than is higher low light intensity and fertilization treatment is higher than no fertilizer ,but some is inconsistent.(3) Different light intensity and fertilization had obvious effects on N, P content of per plant and organs of F. mandshurica, J. mandshurica, Q. mongolica, P. Amurense seedling, and higher light intensity and fertilizing treatment can promote them.After two growing season, in the same fertilizer treatments but between different light intensity, N, P content of per plant gradually decreased as the light intensity weakening. For N content, HL increased by 158.3%,200.4%,30.0%,244.6% respectively than LL(P<0.05),For P content,by 121.9%,197.4%,31.8%,180.5%(P<0.05).For N content, ML increased by 55.2%、37.4%、 23.7%、164.1% respectively than LL.For P content,by 69.6%、63.1%、51.3%、200.9%. In the same light intensity but between different fertilizer treatments, N,P content was the highest in N+P treatment,by 57.0%,91.0%,23.8%,66.5% for N content and 69.6%,63.1%,51.3%,200.9% than LL.In different light intensity and fertilizer treatments, N,P content of root,stem and leaf showed no regularity because of biomass allocation and nutrient concentrations.(4) Different light intensity and fertilization had obvious effects on photosynthetic rate, chlorophyll, and leaf area of F. mandshurica, J. mandshurica, Q. mongolica, P. Amurense seedling, and higher light intensity and fertilizing treatment can promote them.After two growing season,in the same fertilizer treatments,photosynthetic gradually decreased as the light intensity weakening, and HL increased by 36.1%、43.3%、27.5%、39.8% respectively than LL(P< 0.05).In the same fertilizer treatments but between different light intensity, chlorophyll of 4 seedling ranking was LL>HL>ML. LL increased by 21.6%,3.0%,9.2% ,19.1% respectively than LL (P< 0.05).HL increased by 6.1%,0.2%,6.3%,12.4%respectively than ML.In the same fertilizer treatments but between different light intensity, except for Q. Mongolica,total leaf area of per plant seedling ranking was HL> ML> LL,HL increased by 221.2%,413.7%,284.5% respectively than LL(P<0.05).ML increased by 161.6%、153.9%、 187.9% respectively than LL(P< 0.05).Total leaf area of per plant Q. Mongolica seedling was the hightest in ML treatment ,higher 32.5%,55.3% than HLand LL respectively.In the same fertilizer treatments but between different light intensity,fertilization increased photosynthetic rate, chlorophyll, and leaf area of 4 seedlings in a way,and N+P treatment was the most obvious For photosynthetic of 4 seedlings,N+P treatment increased by 24.5%,31.6%,112.1%,14.9% respectively than CK treatment,for chlorophyll by 24.5%,11.7%,7.2%,20.0%,and for leaf area of per plant by 106.3%,92.9%,129.8%,166.1%(P< 0.05).In a word, high light (64% full,45% of full light) and fertilization treatment was conducive to seedlings growth under canopy. |
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