| Since 1950s people in the Southeast coastal area adopted Casuarina equisetfolia from abroad, it has become the main tree that makes shelter-forest in coastal area because of the drought enduring, leanness enduring, salt toleration and anti-sandstorm abilities, and it has played a very important part in improving the soil and water conservation ability, improving the ecological environment of coastal area, supplying wood materials and ensuring the people's livelihood and the development of the economy. The research was based on the object of the pure forest with different continuous generations and the forest with different mixed patterns in Chishan forest farm of Fujian Dongshan country. The environmental effects of different forests have been investigated and compared, and a serious of indexes of sustainable management of Casuarina equisetfolia were chosen combined the analysis methods of mathematics to judge the sustainability of the management quantized. At last, to synthesize the investigation and analysis, some supporting measures were summarized including from the sustainable management of sandy bare land in the wind and the main forest belts to shelter-forest network for fields.Under the comparison of different management modes of Casuarina equisetfolia shelter forests with the age of 8a, 15a and 46a in the coastal area which were third, second and first generation individually, the soil fertility was studied. The results showed that the soil fertility was decreased gradually with the increase of the generation number. The organic matter, whole nitrogen and hydrolysable nitrogen contents in the soil of the second and third generations were lower than those of the first generation. The pH value of different forests with a different generation all presented faintly acid, and the pH value didn't show an obvious variation law with the change of the depth in the soil. With the increase of CPR, the soil bulk density of Casuarina equisetfolia increased gradually and the total porosity decreased gently, and the capillary porosity also had the trend of decreasing.In the mixed forests of capillary porosity with different mixed ratio modes, the mixed forest of Pinus elliottii and Casuarina equisetfolia showed more advantages than other forests with different mixed modes. The site condition of mixed forests with continuous plantation was improved well compared with the pure forest. From the comparison of nutrient contents in 0～20cm,it presented that the organic matters content of the mixed forest with Casuarina equisetfolia and Acaciamangium was higher than that in the soil of other kind mixed forests, and the Total-N and hydrolysable nitrogen content also showed the same rule. The Total-P content in the surface soil of the mixed forest of Casuarina equisetfolia and Acacia crassicarpa was higher than that in other mixed modes, and the average pH value of Casuarina equisetfolia and Eucalyptus Citriodora mixed forest was also higher than other mixed modes. The full water capacity and field water capacity of the soil in the mixed forest of Pinus elliottii and Casuarina equisetfolia were superior than other mixed modes, and the soil bulk density in that mixed mode forest was lower than the forests of other mixed modes. The ranking order of soil total-porosity was: Pinus elliottii>Eucalyptus citriodora >Acacia crassicarpa>Acaciamangium, and the order of capillary porosity was: Acaciamangium> Acacia crassicarpa>Pinus elliottii>Eucalyptus citriodora.The mixed mode of understory intercropping had some superiority than pure forest in CPR. the forest stock of different interplant modes were: bamboo intercropping (4591.69 m3/hm2)> Casuarina equisetfolia intercropping(3303.14m3/hm2)>monolayer forest(1073.57m3/hm2).The maximum water holding capacity and capillary moisture and field water capacity of pure forest of Casuarina equisetfolia and its bamboo interplant or the renewed Casuarina equisetfolia seeding interplant modes all showed a decrease trend generally with the depth of soil increasing. The maximum value of maximum water holding capacity(0.31g/kg) existed in the forest of bamboo and Casuarina equisetfolia interplant mode, and the moisture-holding capacity of monolayer forest was also better than that in Casuarina equisetfolia intercropping mode. There was a close relationship between the wind preventing effects and the wood density, and the tree belt with a draught mesh structure had the strongest windbreaking effects which were above 70% on the whole, while the forest belts with a tight and ventilating structure had a relatively poor effect.Under the instruction of scientific, understanding hierarchy, independence, integrity and maneuverability disciplines, aimed at the sustainable management of Casuarina equisetfolia, 15 three class indexes were chosen under the theory of ecological sustainability, social sustainability and economy sustainability. The comprehensive value of the sustainable management ability of Casuarina equisetfolia shelter forest in Dongshan country was 0.6089 which belonged to weak sustainable management level. From the three indexes value of whole sustainable management ability we can see that the ecological sustainability value was higher than social and economical sustainability value which indicated that the ecological effect of Casuarina equisetfolia shelter forest's sustainable management was relatively stable. While the preventing effect of shelter forests was the most important duty, the sustainability of the shelter forests was not realized completely.Due to the non-substitutable function and the decrease of resources by degrees of Casuarina equisetfolia shelter-forests, the technological modes of the sustainable management were proposed in the landscape level and the standing forest level combined with the analysis of the affecting factors for the sustainable management of Casuarina equisetfolia shelter-forests. The key point of the sustainable management in landscape level was strictly controlling the transformation of the original Casuarina equisetfolia shelter-forests. Using the renew methods of the excellent resistance clone breeding, strengthened the spread ability and then enlarged the plaque area on the basis of keeping the present area and the spatial distribution patterns. The sustainable management in standing forest level was under the request of that in landscape level, and improved the productivity of the forest from keeping the long-term health, vitality, renewing ability and species diversity. The sustainable management mode in standing forest level was a set of strategies including from the sustainable management of sandy bare land in the wind and the main forest belts to shelter-forest network for fields which was mainly the configuration mode of mixed forests from best planting density, the best planting strategies, the best renew modes, and the best forest belt structure according to the different situations of coastal areas.Combined the influence factors of the sustainable management of Casuarina equisetfolia shelter forest, under the instruction of the results above, to synthesize the investigation and analysis, some supporting measures were summarized including from the sustainable management of sandy bare land in the wind and the main forest belts to shelter-forest network for fields. |
