海南热带雨林国家公园3种半天然林特征

Characteristics of three semi-natural forests in Hainan Tropical Rainforest National Park

为揭示海南热带雨林国家公园32年生杉木、34年生加勒比松和27年生马占相思3种半天然林特征,采用主要测树因子分析林分生长特征,运用重要值与生物多样性指标分析树种组成与多样性特征。结果表明:3种半天然林整体上均已是充分郁闭林分,乔木层均已经明显分异出2个亚层,直径分布均已表现为异龄林结构,林分密度分别为3600、2472和1540株·hm^(-2);灌木层林分密度分别高达8374、6828和9776株·hm^(-2);2500 m^(2)样地面积的乔木层树种丰富度分别为79、61和49,Shannon-Wiener指数分别为3.12、3.83和3.98;虽然乔木层优势种仍然为人工造林树种,但天然更新乡土树种重要值合计分别高达46.3%、54.0%和65.1%,其中乔木树种重要值占比分别高达87.1%、81.1%和93.1%;灌木层均为乡土树种天然更新林木,树种丰富度分别为137、113和91,Shannon-Wiener指数分别为4.66、5.25和3.89,其中乔木树种重要值占比分别为49.4%、54.8%和70.2%。3种半天然林都已是乔木层分异明显、乡土树种多样性异常丰富、异龄林结构特征明显的复层混交异龄林,天然更新乡土树种(80%以上为乔木树种)重要值合计已接近甚至是人工造林树种的2倍,其树种多样性高于30年生海南山地雨林皆伐伐后林和海南低地雨林残次林,乔木层和灌木层中均有不少珍贵或高价值乡土树种。

This study examines the characteristics of three semi-natural forests,including a 32-year-old Cunninghamia lanceolata,a 34-year-old Pinus caribaea,and a 27-year-old Acacia mangium forest,located in Hainan Tropical Rainforest National Park.The growth characteristics of the forests were analyzed using tree measurements,and species composition and diversity characteristics were assessed using biodiversity indicators.The results indicate that the three semi-natural forests exhibit a fully canopy-closed stand.The arbor layer densities for the three forests were 3600,2472,and 1540 stems·hm^(-2),respectively.The density of trees in the shrub layer reached as high as 8374,6828,and 9776 stems·hm^(-2),respectively.The arbor layer richness in a 2500 m 2 plot was 79,61,and 49 species,respectively,with Shannon-Wiener indices of 3.12,3.83,and 3.98,respectively.Although the dominant species in the arbor layer were artificial afforestation species,the total important values of naturally regenerated native tree species accounted for 46.3%,54.0%,and 65.1%,respectively,with the important values of arbor species accounting for 87.1%,81.1%,and 93.1%,respectively.Respectively,the richness of tree species in the shrub layer of the three forests was 137,113,and 91,with Shannon-Wiener indices of 4.66,5.25,and 3.89,and the important value of arbor species accounted for 49.4%,54.8%,and 70.2%.The three semi-natural forests exhibited multi-layered mixed uneven-aged forests characteristics with obvious arbor layer differentiation,an extremely rich diversity of native species,and the structural characteristics of uneven-aged forests.The total important values of naturally regenerated native species(over 80% of which were arbor species)were close to or even two times higher than those of artificial afforestation species.The diversity of these forests was higher than that of the 30-year-old stand after clear-cutting of the mountain rainforest and the residual forest of the lowland rainforest in Hainan,and there were many precious or high-value native tree species in the arbor layer and shrub layer.