摘要
次生林演替和造林对波多黎各西南部美国鱼类和野生动物局的罗霍角(Cabo Rojo)野生动物保护区(总部和盐沼区)及卡塔赫纳泻湖(Laguna Cartagena)保护区(泻湖和碗形潭)的恢复有很大作用。过去25年,在44hm^2土地上种植了约80个物种,其中主要是原生种,其目的是努力减轻地表火的威胁和恢复野生动物生境。2007年对泻湖区9年造林的调查显示,16个原生种的生长速度令人满意。单株树木地表处通常长出多个茎干。在整个109hm^2的碗形潭区,对次生林的取样显示有141个原生树种,或波多黎各原生树木区系的25%,还有20个外来种。有5个树种约占总胸高断面积的58%,有7个种是岛屿特有种。1998～2003年间,在碗形潭区内较低的30hm^2面积上,树木数量和胸高断面积,还有树高和胸径(距地面1.4m高处的直径)都增加了。在此区域内,大部分面积受到1996年火和放牧的影响,外来树种占物种总量的25%。遍及热带的干燥森林是一种濒危生境,它的恢复(即在生物量、结构和物种组成方面的恢复)在碗形潭会超过500年。但未来的森林有可能会保留一些外来种。
Secondary forest succession and tree planting are contributing to the recovery of the Cabo Rojo refuge (Headquarters and Salinas tracts) and Laguna Cartagena refuge (Lagoon and Tinaja tracts) of the Fish and Wildlife Service in southwestern Puerto Rico.About 80 species,mainly natives,have been planted on 44 ha during the past 25 y in an effort to reduce the threat of grass fires and to restore wildlife habitat.A 2007 survey of 9-y-old tree plantings on the Lagoon tract showed satisfactory growth rates for 16 native species.Multiple stems from individual trees at ground level were common.A sampling of secondary forest on the entire 109 ha Tinaja tract disclosed 141 native tree species,or 25% of Puerto Rico's native tree flora,along with 20 exotics.Five tree species made up about 58% of the total basal area,and seven species were island endemics.Between 1998 and 2003,tree numbers and basal area, as well as tree heights and diameter at breast height values (diameter at 1.4 m above the ground),increased on the lower 30 ha of the Tinaja tract.In this area,much of it subject to fires and grazing through 1996,exotic trees made up 25% of the species. Dry forest throughout the tropics is an endangered habitat,and its recovery (i.e.,in biomass,structure,and species composition) at Tinaja may exceed 500 y.Future forests,however,will likely contain some exotics.
