| Chinese fir is one of the important fast-growing timber tree species planted in southern of China. Because theneedles, the pure forest of Chinese fir plantation, management intensive and even planted more generationintensified, Chinese fir plantation ecosystem inherent in the emerging ecological vulnerability, afforestation areaof serious soil erosion, biodiversity decline, decline of soil fertility, diseases and insect pests and the spread of fireand other serious ecological consequences, directly restricts the sustainable development of Chinese fir plantation.From current research of Chinese fir plantation soil fertility decline, while the mechanism of the Chinese firplantation soil fertility decline more research, but is still in debate, soil fertility decline phenomenon of Chinese firplantation soil fertility decline mechanism also is not clear. Decline of cunninghamia lanceolata forest land forcewhile at the same time puts forward some countermeasures and the prevention and control technology of way, butthe way, according to the theory of traditional Chinese fir planting system only a link or a local ecological systemto try to change or improve it, not from the perspective of Chinese fir forest ecosystem integrity to be consideredand radical change. Therefore, how to establish a set of can fundamentally solve the ecological problems such assoil fertility decline a new fir cunninghamia lanceolata plantation was developed cultivation system of sustainabledevelopment has become Chinese fir forests in a major issue. All these problems remains to be further studied anddiscussed.Because of those reason, over the years, research on Chinese fir plantation of various ecological problems, theimportance to absorb domestic and foreign scholars put forward the plantation management, on the basis of newtheory and new method for Chinese fir plantation ecosystem near natural transformation and control. Forest farmin Nanping of Fujian agriculture and forestry university at the same time celery teaching building five forestecosystem model (including natural evergreen broad-leaved forest, old cunninghamia lanceolata forest, the secondgeneration cunninghamia lanceolata sprout forest of natural regeneration mode, the second generation Chinese firplantation in93(no burning method) and91(burning method) of the second generation Chinese fir plantationmodel) as the cunninghamia lanceolata forest ecological system conversion mode of series of sample area, thisstudy attempts to within5forest ecological system model established by the method of field location, withdifferent Chinese fir forest ecosystem conversion mode of the soil physical properties, chemical properties, humuscomposition and morphology and enzyme activity in-depth systematic study, to further reveal the mechanism ofChinese fir plantation soil fertility decline, degradation of Chinese fir forest ecosystem restoration andreconstruction and cunninghamia lanceolata cultivation to provide scientific theoretical basis for institutionalchange. Main research conclusion were as follows:（1）Each system mechanical composition of soil particle at different levels, there is no obvious differencebetween the proportion of soil micro aggregates particles content there is a certain difference at various levels;Soil <0.001particle content basically showing a plantation of91and93plantation> older forest> sprout forest>natural forest trend; Each system0-20cm and20-40cm soil basically showing a grade1~0.25mm and0.25~ 0.05mm grade proportion is higher, the <0.001mm lower proportion of graded pattern; Each system0-20cmand20-40cm soil dispersion coefficients show roughly91and93plantation> old forest plantation> sproutforest> total trend of natural forests, and the structure coefficient are roughly showing a plantation of93<91plantation <sprout forest <Lin the trend of the natural forest.(2)All the systems of soil organic matter content, obvious differences in the performance of93plantation ishigher, sprout forest, natural forest and forest center on aging,91plantation lower trend, and seasonal change isobvious.(3)Soil pH value significant difference, the system is characterized by the second generation Chinese fir forestplantation (sprout forest, plantations of91and91) pH value is slightly higher than the old forest and natural forest.And seasonal change is obvious, and basically showing a October> April> January> July.(4)All systems of soil total nitrogen, total phosphorus, total potassium content is significant,0~20cm eachsystem and20-40cm soil total nitrogen, total phosphorus, total potassium content basically showing a sproutforest,91and93plantation is higher, natural forest and older forest is low, and seasonal change is obvious.(5)Each system soil hydrolytic nitrogen, available phosphorus, available potassium content difference is notobvious, slightly different law system and different soil, and obvious seasonal variation, hydrolyze nitrogen andavailable K were presented higher in January and April, July and October is lower, quick-acting phosphoruspresent a high in April, slightly lower during the other months.(6)No obvious difference of the system total calcium content in soil, and the seasonal variation is not obvious.0-20cm of each system and20-40cm soil magnesium content are all present a second generation Chinese firforest plantation (sprout forest, plantations of91and93) slightly below the older forest and natural forest;Seasonal variation is obvious, each system whole magnesium content present a slightly high, in April,October,January, July were low regularity.(7)Each system soil exchangeable calcium and the exchangeable magnesium content, obvious differences inthe roughly the present older forest, natural forest and sprout forest is higher,93,91plantation is low, and seasonalchange is obvious, all present a high in April,October,January, July were low.(8)Each system total iron and total lead content in soil seasonal changes are not obvious differences anddifferent soil total iron content change rule of each system is complicated, the system whole lead from the secondgeneration Chinese fir forest> natural forest and older forest; Soil copper and manganese content in each systemsignificant difference, seasonal variation are also evident, soil total manganese each system basically showing asprout forest, natural forest and plantation>9191plantation and the trend of aging Lin. Total copper content ofeach system present a second generation Chinese fir> natural forest and the trend of aging Lin Lin. No obviousdifference total zinc content in soil, each system generally present a sprout forest plantations of=93=naturalforest plantation>>91aging trend, Lin and seasonal change is obvious.(9)0-20cm and20-40each system there was some difference of soil effective state of iron content, showing anatural forest is higher, sprout forest and older forest,91plantation and93plantation low of regularity, seasonalvariation is obvious; Each system0-20cm and20-40cm soil effective state of manganese content has certaindifference, both present a sprout forest> natural forest>93plantation>older forest>91plantation. Each systemof0-20cm state and20-40cm soil effective manganese seasonal variation is obvious, generally show higher inJanuary and April, July and October low regularity;0-20cm of each system and20-40cm soil effective copper content has certain differences, present a natural forest and sprout forest is higher,93plantation,91plantation andolder forest is low, seasonal variation is obvious; each system0-20cm and20-40cm soil effective state content ofzinc and seasonal variation are not obvious difference.0-20and20-40cm of each system state soil effective leadhas obvious differences, basically render sprout forest> natural forest>93plantation>91plantation> olderforest and seasonal is not obvious.(10) Each system of0-20cm and20-40soil has some difference of soil effective state of iron content,showing a natural forest is higher,91plantation and93plantation is low, seasonal variation is obvious; Eachsystem of0-20cm and20-40cm soil effective state of manganese content has certain difference, both present asprout forest> natural forest>93plantation> older forest>91plantation.0-20cm and20-40cm of each systemsoil rich in acid, obvious difference in carbon content have presented93plantation is higher, the laws of otherlower system. Humic acid in soil carbon system, obvious difference between in the both presented91plantation islow, other system is higher. Each system humin in0-20cm of soil carbon content, obvious differences in thepresent a sprout forest> old forest> natural forest>93plantation>91plantation, no obvious difference between20-40cm each system.(11)From soil humification degree, the older forest of0-20cm20-40cm soil humic acid the highestproportion of carbon, that old forest soil humification degree is higher, soil humus quality is better; Followed bysprout forest, and next is natural forest and93plantation,91plantation is low.(12)From the perspective of HA/FA ratio, higher HA/FA of older forest, followed by sprout forest, naturalforest and93plantation,the last is91plantation. Indicating that older forest soil humus molecular weight is large,complicated structure, and91plantation soil humus structure is relatively simple, the humus quality is poorer.(13)Humus components are present a fulvic acid carbon> humin carbon> humic acid total tendency ofcarbon. Fulvic acid carbon proportion is higher, humin carbon the proportion of middle and humic acid proportionof carbon is low.(14)0-20cm of each system and20-4093plantation soil humic acid E4value is higher, the old forest, naturalforest and sprout forest center,91plantation low regularity, the system of93plantation soil on the surface of themolecular weight is large, complex degree is high, the aromatic groups increased, the condensation degree ofstrength.(15) Each system of0-20cm and20-40soil of E4/E6a natural forest soil is higher, sprout forest and91plantation in middle,older forest and93plantation are low, that natural forest soil aliphatic structure systemsmaller, activity is stronger, the aggregate function, decomposition and cracking weakened the role of mineral,soil humus quality is good.(16)Soil humic acid in the optical density value with the increase of wavelength gradually reduce, the soillayer are presented93plantation> old forest> natural forest> sprout forest>91plantation.(17)Each system of0-20cm and20-40soil has more obvious differences in loose state combined with carbon,91plantation and natural forest is higher, sprout forest,93plantation and older forest were low; Steady statecarbon also has the obvious difference, roughly the present natural forests is higher, sprout forest, plantations of93and91and older forest is low; Tight combination state carbon difference is more apparent,93plantation andsprout forest is higher, natural forest, old forest and91plantation low trend. From the loose/tight ratio, differentsystem there exist certain differences, natural forest and older forest is higher, basically sprout forest,91plantation and93plantation low trend.(18)From proportion of three kinds of combination mode, high proportion of soil is combined with eachsystem state, between48.09~77.95%; Followed by combining with the state, between24.60~49.41%; Steadystate minimum, between14.48~22.69%.(19)Each system of0-20cm and20-40cm soil catalase activity there is a certain difference, both present anatural forest is higher, sprout forest and93plantation in middle,older forest and91lower trend; Soil invertaseactivity content difference is more obvious, showing older forest is higher, natural forest, plantations of sproutforest, plantations of93and91lower trend; Differences between the content of each system, soil urease activity,roughly the present93plantation and91plantation is low, other system higher trend; Soil acid phosphataseactivity content difference was not significant, presents the older forest and plantation is higher,93and91plantation low regularity. Each system soil catalase, sucrase, urease and acid phosphatase activity basicallypresent along with the deepening of the soil decreased.(20)Through the health evaluation method and principal component analysis, using the soil physical properties,chemical properties, biological indicators for different chemical properties of Chinese fir forest ecosystemconversion mode has carried on the comprehensive evaluation of soil quality. From the perspective of the result ofcomprehensive evaluation, sprout forest and93plantation and aging of forest soil quality is better than91plantation. It shows the three model has good ability to maintain and restore soil, all can be used as the future ofcunninghamia lanceolata plantation geographical recession beneficial reference and the prevention and controltechnology, especially the sprout forest. Sprout forest was based on the natural regeneration and cunninghamialanceolata sprout regeneration of main afforestation technology and form of Chinese fir mixed, because of usingsprout forest system update not subjected to a variety of man-made interference, and can form a high diversity ofecosystems, species diversity and structure as a result, sprout forest system self adjusting and self repair ability isstronger, the soil quality is higher. |
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