珠海淇澳岛无瓣海桑种苗天然更新与扩散分析

无瓣海桑(Sonneratia apetala Buxh-Ham Buxh-Ham.)在珠海淇澳岛抑制互花米草(Spartina alterniflora Loisel.)蔓延恢复红树林方面发挥了积极的作用。然而,由于它是外来引进种,在当地能否繁殖更新或造成种苗大量扩散成灾?为此,针对1999年以来在淇澳岛种植的大片无瓣海桑林及其周边湿地进行了种子产量与种苗天然扩散性的调查。结果表明:淇澳岛4年生无瓣海桑果实年产量为30.51kg·棵^-1,果粒数为2706粒·棵^-1,每果粒内含30～50粒种子。无瓣海桑幼苗在水沟两边分布最多,为40株·16m^-2,其次是其林分边缘的光滩,为8株·16m^-2,互花米草内为3.5株·16m^-2,最少是无瓣海桑林内,1株·16m^-2,种子多但幼苗少,且这些扩散苗绝大多数为当年生幼苗,很少发现多年生小苗,极难更新成林。

The analysis natural regeneration and diffusion of the seeding of Sonneratia apetala in the Qi'ao Island, Zhuhai

Sonneratia apetala plays an active role in restraining the extend of Spartina alternifloral and restoring the mangrove wetland,however it is an introduced species S.apetala has been planted in the Qi'ao Island since 1999.This article surveyed the seed output and seedling natural diffuse of the S.apetala and its circumjacent wetland.The result showed that the output of the four year'old S.apetala in Qi'ao Island was 30.51 kg per tree per year,the number of the fruits was about 2706 per tree,and every fruit included 30 to 50 seeds.S.apetala seedlings were most distributed about 40 seedlings per 16m² at ditches; secondary were about 8 seedlings per 16m² at bare beaches near by the forest,about 3.5 seedlings per 16m² inside the Spartina alterniflora,and the least were inside the forest of S.apetala with only 1 seedlings per 16m².This study showed that the fruits were much more than seedlings,and perennial seedling was hard to see.Therefore,it was difficult for S.apetala to naturally regenerated and succeeded in the Qi'ao Island.