木麻黄原生境种子萌发及幼苗存活的影响因素分析

木麻黄无法天然更新已严重影响了海南岛木麻黄海防林发挥其永续的防护效能。该文以海口木麻黄海防林为原生境试验基地,采用5因素2水平的因子试验设计方法,共设计36个处理组合,探究木麻黄种子萌发及幼苗存活的影响因素及障碍因子。结果表明:(1)木麻黄种子发芽率最高的处理组合为林窗-不浇水-沙土-保水-盖土(GJ0SBM),发芽率为37.33%,显著高于其他处理组合(P<0.05); 平均株高最高的处理组合为林窗-浇水-红土-不保水-不盖土(GJRB0M0),平均株高为6.43 cm/53 d,显著高于其他处理组合(P<0.05); 存活率最高的组合为林窗-浇水-沙土-保水-盖土(GJSBM),存活率为79.00%/73 d,显著高于其他处理组合(P<0.05)。(2)林分光照条件和盖土方式是木麻黄种子发芽率及发芽势的影响因素,保水方式对种子发芽速度有显著影响。(3)林分光照条件是影响木麻黄幼苗株高的影响因素。(4)浇水方式是影响木麻黄幼苗存活率的主要影响因素。综上所述,木麻黄自身无法天然更新的障碍机制不在于种子萌发,而是因为木麻黄幼苗在海南旱季因缺乏必要的水分而无法存活,从而导致其自身无法天然更新。

Impact factors on seed germination and seedling survival in Casuarina equisetifolia natural habitat

The sustainable protective efficiency of Casuarina equisetifolia coastal protection forest(CCPF)in Hainan Island has been seriously affected as C. equisetifolia itself can not regenerate naturally. In this paper, Haikou CCPF was taken as the test area of the natural habitat, and a total of 36 treatment combinations were designed by using 5-factor 2-level factor test method to explore the impact factors and barrier factors of C. equisetifolia seed germination and seedling survival. The results were as follows:(1)The treatment combination with the highest seed germination rate of C. equisetifolia was canopy gap-not watering-sandy soil-water retention-covering soil(GJ0SBM), with 37.33% of the germination rate, which was significantly higher than those of other treatment combinations(P<0.05). The treatment combination with the highest average plant height was canopy gap-watering-red soil-no water retention-not covering soil(GJRB0M0), with the plant height of 6.43 cm in 53 d, which was significantly higher than those of other treatment combinations(P<0.05). The treatment combination with the highest survival rate was canopy gap-watering-sandy soil-water retention-covering soil(GJSBM), with 79.00% of the survival rate for 73 d, which was significantly higher than those of other treatment combinations(P<0.05).(2)Stand light conditions and covering soil patterns were the impact factors for seed germination rate and germination potential of C. equisetifolia, while water retention patterns had significant effects on seed germination speed.(3)Stand light conditions were the impact factors for C. equisetifolia seedling plant height.(4)Watering treatment was the main factor affecting the survival rate of C. equisetifolia seedlings. In summary, the barrier mechanism of C. equisetifolia natural regeneration unable to survive in Hainan dry season is not for the seed germination, but for the lack of necessary water, resulting in the failure of C. equisetifolia itself natural regeneration.