| Combined with sampling outdoor and analysis of indoor experiment,a total of seven elite stand community structures including natural forest and six kinds of plantation such as Liriodendron,Sample,Zizyphus jujube,Liquidambar,Chinese fir and Masson pine,between whose community structure including importance values of tree layer,shrub layer,herb layer,adding to vegetation species,stand density,tree of volume,height and diameter,biomass in tree layer,soil enzyme activities including urinary enzyme activity,invertase activity and catalase activity,phosphatase activity and its physical and chemical properties,principal component analysis and relative evaluation conducted were studied,which are chosen starts nearly natural degree evaluation,and the results showed that:(1)Different plantations consist with natural broad-leaved forest in the distribution regularity of diameter at breast height and tree height,are approximate normal distribution curve.But tree height distribution in Masson pine plantation and Liquidambar plantation are approximate "J" type curve,which attribute to accidental errors like visual effects,among whose plantations of Diameter at peak point of breast height among them is liquidambar plantation,whose peak point is 22 cm,next is sample,as 18cm,and the smallest one is south Zizyphus jujube only with 14cm,which all were close to or lower than natural broad-leaved forest with 22 cm.Among 8?16cm,16?24cm and 24?30cm in diameter proportion,diameter order with 28.02%of natural broad-leaved forest in 8?16 cm are only lower than Zizyphus jujube plantation of only 28.02%and the Sample plantation proportion of 28.89%,whose diameter order in 16-24cm is only 38.07%higher than Zizyphus jujube plantation as 38.07%,whose diameter in 24?30cm is only less than Liriodendron as 40.65%and Chinese fir as 36.93%;the largest plantation in the peak of tree height distribution is Chinese fir as 12m,followed by sample as Sample,and the minimum is Masson pine as 6 m,while natural broad-leaved forest to 10 m high,only short to Chinese fir plantation.Among 6?8m,8?12m and 12?17m in proportions between tree high grades,natural broad-leaved forest with 25.60%in 6?8m is 5.76%higher than Chinese fir plantation as 19.83%,at 8?12m diameter with 42.86%compare with Sample,Liquidambar and Masson pine three plantations,higher above 11.51%,2.08%and 12.42%,whose height of 31.55%in 12-17m is just 2.21%and 1.97%lower than Chinese fir plantation and Sample plantation.The volume of Masson pine plantation is the largest as 234.30m3/km2,next to Chinese fir plantation as 226.38 m3/km2,and the minimum volume is liquidambar plantation only with 114.74m3/km2,is less than natural broad-leaved forest with 243.04 m3/km2.(2)Among tree layer,shrub layer and herb layer In six kinds of plantations,the vegetation diversity levels of shrub layer and herb layer are obviously higher than that of tree layer,six kinds of plantations undergrowth species with a total of sixty-four families and seventy-eight genera,among which tree layer only owe to seventeen families and twenty-seven genera,shrub layer with a total of twenty-one families and thirty-one genera,while twenty-three families and thirty-three genera are herb layer.Important values between Plantations and broad-leaved forest community generally show that shrub layer is higher than herb layer,which exceeds tree layer.There are main dominant species such as Lophatherum gracile Brongn,Miscanthus floridulus(Lab.)Warb.ex Schum et Laut,Dicranopteris linearis(Burm)Underw,Maesa japonica(Thunb.)Moritzi.ex Zoll,Adinandra millettii(Hook.et Arn.)Benth.et Hook.f.ex Hance and Ampelopsis cantoniensis(Hook.et Arn).The total biomass of tree layer in Plantations range from 38.82 t·hm2 to 149.05 t·hm2,results show that performance for Liriodendron>Masson pine>Liquidambar>Chinese fir>south Zizyphus jujube>Sample,all which are lower than 220.18t*hm-2 of natural broad-leaved forest,the average individual biomass stand in 55.82?136.62 kg one plant,show that Masson pine>Liriodendron>Liquidambar>south Zizyphus jujube>Chinese fir>Sample,which are all less than 205.32 kg one plant of natural broad-leaved forest;The total biomass of artificial forests accounts for the proportion of each part show that stem>branch>root>leaf,and the stem and roots t of Masson pine and Liriodendron,the branch of Liriodendron and the leaf part of liquidambar,accounted for 74.14%,21.10%,20.01%and 7.79%.(3)By comparisons with soil physical,chemical properties,soil PH value,the maximum moisture capacity and total potassium in six different plantations,results show that:?soil PH value,soil total potassium,and soil bulk density in different forest types is 4.61-5.29?37.84-52.57mg/kg and 0.96-1.45g/cm3,results show that coniferous plantations including Chinese fir and Masson pine)>broadleaf forest plantations including liriodendron,liquidambar,south Zizyphus jujube and Sample>natural broad-leaved forest,besides values of broadleaf forest plantations in soil bulk density are higher than coniferous plantations,the smaller is that of natural broad-leaved forest which is 0.59 and 0.49 g/cm3 lower,accounting for12.85%and 40.69%than the maximum Values of Masson pine in soil PH value and soil bulk density.Soil total potassium is 37.84?52.57mg/kg,The minimum of which Liriodendron plantation is 14.73 mg/kg lower than the maximum of natural forestry below 38.93%,while the maximum moisture capacity is 293.79?506.72 g/kg,The maximum of which Alniphyllum fortunei plantation is 212.93 g/kg more than the minimum of Masson pine plantation above 72.48%,which is 15.08 g/kg more than natural broad-leaved forest.The deeper the soil layers are,the lower whose indicators including soil PH value,the maximum moisture capacity and total potassium become.?Indicators among Soil organic matter,effective potassium,total phosphorus,total nitrogen,effective phosphorus and hydrolytic nitrogen show that natural broad-leaved forest>broadleaf forest plantations including liriodendron,liquidambar,south Zizyphus jujube and Sample>coniferous plantations including Chinese fir and Masson pine.Among them soil organic matter is 1.44?4.50%,the maximum of which natural forestry is 3.06%high than that of Chinese fir plantation,effective phosphorus is 4.01?13.77 mg/kg,The maximum of which natural forestry is 9.76mg/kg more than Liquidambar above2.43 times,total phosphorus is 0.59-1.01g/kg,the maximum of Alniphyllum fortunei plantation is 0.42g/kg more than the minimum of Masson pine plantation above 71.19%,Soil total nitrogen is 0.12-0.28g/kg,the minimum of which Chinese fir plantation is 0.16g/kg lower than the maximum of natural forestry below 57.14%,above indicators decrease gradually with soil depths.In a word,natural forest is generally higher than that of broadleaf plantations such as liriodendron,liquidambar,and those indicators of broadleaf plantations exceeds coniferous plantations for example,Masson pine forest.Soil unit weight and PH values are contrary to above soil indicators.In each plantation forest and natural forest soil,four kinds of soil enzyme activities including urine enzyme,sucrase,catalase and phosphatase gradually decrease with soil depths.The rates of decreases vary from different enzyme.For comparison with soil enzyme activity:natural forest>plantation,broadleaf plantations such as Masson pine,sweet gum and wild jujube,the activities of urine enzyme,sucrase and phosphatase are weaker than like Chinese fir and Masson pine coniferous plantations,and sucrase is contrary to above regulars.Urinary enzyme activity in the soil is relevant to phosphatase activity is significant correlation between soil,soil catalase and sucrase in deep soil layer in 20-40cm between soil 0-10cm and 10-20 cm has more significant correlation,while the topsoil 1-10 cm and 10-20 cm has no significant correlation(4)By using analysis method of sensitivity,as the standard of independent sensitivity(CV?0.1),Low sensitivity(0.1?CV?0.3),Medium sensitivity(0.3?CV?0.6)and high sensitivity(CV?0.6),as classification standard system of four sensitive degree,From two angles of forest characteristics and soil quality(including the soil physical and chemical properties of soil enzymes and other characteristics),including horizontal structure,vertical structure,organic matter,biomass of tree layer such as effective phosphorus,total nitrogen,hydrolyze nitrogen,in total of 7 high sensitivity evaluation indicators,the community important value of shrub layer,the herb layer and tree layer,stand density,maximum water holding capacity,total potassium and total phosphorus,available potassium,urinary enzyme activity,invertase activity and catalase activity,phosphatase activity,in total of 11 sensitivity evaluation indicators,besides,stand density,average diameter at breast height and soil PH value these three low sensitivity,adding to the average tree height,the maximum water holding capacity of two independent indicators.using the principal component analysis method and the relative evaluation method,accounting for eighteen indicators Medium-senior obtained weight values of each evaluation indicators and comprehensive indicators of naturalness degrees in different plantations,results relevant to comprehensive matter about naturalness values of different artificial plantains show that:Natural broad-leaved forest(100%)>south Zizyphus jujube plantation(74.82%)>Liriodendron plantation(73.95%)>liquidambar plantation(68.72%)>Sample plantation(65.33%)>Masson pine plantation(57.48%)>Chinese fir plantation(55.72%).(5)Based on close relative evaluation and principal component analysis methods of natural degree evaluation,the relative evaluation methods is highly affected by selections of stand,the article selects the natural broad-leaved forest for reference,because of its various evaluation indices are higher than the other six plantations on the whole,which also reflects selection of the reference stand scientifically and reasonably,in combination with principal component analysis method,which is little influenced by subjective factors.Close natural evaluation results provide a relatively reliable guarantee. |
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