洞庭湖滩地造林成活率的关键影响因子

Key Influential Factors of Afforestation Success on the Beaches of Dongting Lake

用样行法对洞庭湖滩地新造速生丰产纸浆林的成活率进行调查,同时了解造林地连续4 a汛期的水文规律和海拔高程的演变过程,通过分析造林成活率与主要影响因子之间的关系,发现淹水时间为滩地造林的限制性因子,营造速生丰产林、一般用材林和短周期工业原料林时,造林地年淹水天数依次不能超过19、35和62 d;苗木等级对造林成活率有重大影响,特级苗、Ⅰ级苗、Ⅱ级苗、Ⅲ级苗的平均成活率在海拔低于32 m的造林地上分别为68.8%、49.3%、18.7%、2.4%,在海拔超过32 m的造林地上分别为98.8%、79.6%、36.4%、14.7%;采用开沟抬垄整地可减轻涝渍胁迫,从而大幅度提高造林成活率.

The survival ratio of East-growing and high-yielding pulp wood plantation on the beaches of Dongting Lake was investigated by line sampling method, and the changing processes, of hydrological rules and elevation in flood season, of 4 continuous years were revealed in the afforestation area. Water logging time is the primary limiting factor to any afforestation on the beaches according to an analysis of the relationship between survival ratios and key influential factors. Water logging time of afforestation area can not be over 19 days for fast-growing and high-yielding plantation, can not be over 35 days for normal timber production forest, and can not be over 62 days for fast-growing plantation. Furthermore, the grade of seedling has a great influence on the survival ratio of plantation. The average survival ratios of superfine seedlings, grade Ⅰ seedlings, grade Ⅱ seedlings and grade Ⅲ seedlings are respectively 68.8%, 49.3%, 18. 7% and 2.4% in afforestation area with its elevation under 32 m. In the afforestation area with an elevation over 32 m, the average survival ratios of each grade above are respectively 98.8%, 79.6%, 36.4% and 14.7%. Site preparation of ridge tillage can decrease the influence of floods and significantly increase seedling survival ratios. The research results provide a firm technological support to the afforestation success on the beaches of Dongting Lake.