Study On Seed Germination Ecology Of Pinus Tabulaeformis

Pinus tabulaeformis is one of pioneer species for barren hill afforestation and ecological forest in North and Northwest of China.It plays an important role in conserving soil and water and protecting environment.Seed germination ecology of Pinus tabulaeformis were discussed in order to understand vegetation restoration and succession rule of Pinus tabulaeformis forest.Seeds of Pinus tabulaeformis were collected from Ziwuling.Seed germination ecology of Pinus tabulaeformis were examined in laboratory and forest,including seed germination and seedling emergence in relation to temperature,light conditions,soil water content and covering depth. The preliminary conclusions were as follows:(1) Temperature affected on germination of Pinus tabulaeformis seed significantly.①The optimum temperature of seed germination were 25℃and 30℃, and seed germination percent were 96% and 95.5%,respectively.Seeds germinated most quickly at 30℃.②At 20℃/25℃,seed germination percent was 92.5%,seed germination percents decreased at 15℃/25℃and 15℃/30℃. The higher diurnal temperature variation inhibited seed germination of Pinus tabulaeformis.③At average temperature 10℃on April in the wood of Pinus tabulaeformis, germination percentage and seedling emergence rate were 11.7% and 1%,respectively. At average 21.5℃on August,that germination percentage and seedling emergence rate were 86.6% and 63.3%,respectively.(2)At 25℃, 30℃and 35℃, the higher germination percentage was obtained from Pinus tabulaeformis maintained in the light than under the dark. Seed germination required illumination.(3) Seed germination rate and seedling emergence rate were difference under different soil water content.①At 15℃/25℃,the suitable soil water content for seed germination was 20%～30%, and the optimum soil water content was 25%.The suitable soil water content for seedling emergence was 25%～35%,and the optimum soil water content was 30%.when soil water content was above 40% or below 15%,a few seedlings emerged. Regression analysis indicated that germination percentage (y1) and seedling emergence rate (y2)of Pinus tabulaeformis were significantly nagtively related to soil water content (x) which can be expressed by: y1 = -1617.6x2+786.96 x+5.2281(R2= 0.9512),y2 = -2202.3x2 +1287.7x-117.62(R2= 0.8281).②At 15℃/30℃, the suitable soil water content for seed germination was 15%～30%,the most suitable soil water content was 20%.The suitable soil water conten for seedling emergence was 20%～35%, and the optimum soil water content was 25%..Regression analysis indicated that germination percentage (y1) and seedling emergence rate (y2) of Pinus tabulaeformis were significantly nagtively related to soil water content (x) which can be expressed by: y1 = -2885.5x2 +1479.1 x-91.495(R2= 0.8412),y2 = -3472.9x2 +1852.6x-168.81 (R2= 0.7995).③At 20℃/25℃, the suitable soil water conten for seed germination was 15%～30%.The suitable soil water content for seedling emergence was 20%～35%, and the optimum soil water content was 35%.Regression analysis indicated that germination percentage (y1) and seedling emergence rate (y2) of Pinus tabulaeformis were significantly nagtively related to soil water content (x) which can be expressed by:y= -961.57x2+490.77x+34.544 (R2=0.8618),y=-3085.9x2+1728.5x-144.79 (R2= 0.9311).(4)The seedling emergence rates were greater than 90% when seeds were buried in 0.5～1cm depth below the surface of soil. Seedling emergence rates decreased with increasing covering depth and were less than 62% at 1.5cm covering depth. The most suitable covering depth was 0.5cm. Seedlings emergence rate was greater in soil than in coverage of litter in laboratory and the wood of Pinus tabulaeformis.