Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional (CIIDIR) Unidad Oaxaca, Calle Hornos No. 1033, Santa Cruz Xoxocotlán, Oaxaca C.P. 71230, Mexico.
Conserv Biol. 2011 Aug;25(4):797-807. doi: 10.1111/j.1523-1739.2011.01691.x. Epub 2011 Jun 9.
Hundreds of epiphytic bromeliads species are harvested from the wild for trade and for cultural uses, but little is known about the effects of this harvest. We assessed the potential demographic effects of harvesting from the wild on 2 epiphytic bromeliads: Tillandsia macdougallii, an atmospheric bromeliad (adsorbs water and nutrients directly from the atmosphere), and T. violaceae, a tank bromeliad (accumulates water and organic material between its leaves). We also examined an alternative to harvesting bromeliads from trees--the collection of fallen bromeliads from the forest floor. We censused populations of T. macdougallii each year from 2005 to 2010 and of T. violaceae from 2005 to 2008, in Oaxaca, Mexico. We also measured monthly fall rates of bromeliads over 1 year and monitored the survival of fallen bromeliads on the forest floor. The tank bromeliad had significantly higher rates of survival, reproduction, and stochastic population growth rates (λ(s) ) than the atmospheric bromeliad, but λ(s) for both species were <1, which suggests that the populations will decline even without harvest. Elasticity patterns differed between species, but in both, survival of large individuals had high elasticity values. No fallen bromeliads survived more than 1.5 years on the forest floor and the rate of bromeliad fall was comparable to current harvest rates. Low rates of population growth recorded for the species we studied and other epiphytic bromeliads and high elasticity values for the vital rates that were most affected by harvest suggest that commercial harvesting in the wild of these species is not sustainable. We propose the collection of fallen bromeliads as an ecologically and, potentially, economically viable alternative.
数百种附生凤梨科物种被从野外采集用于贸易和文化用途，但人们对这种采集活动的影响知之甚少。我们评估了从野外采集对 2 种附生凤梨科植物的潜在种群效应：气生凤梨（直接从大气中吸收水分和养分）和水槽凤梨（在叶片之间积累水分和有机物质）。我们还研究了一种替代从树上采集凤梨的方法——从森林地面收集掉落的凤梨。我们在 2005 年至 2010 年期间每年对 T. macdougallii 种群进行普查，并在 2005 年至 2008 年期间对 T. violaceae 种群进行普查，地点在墨西哥瓦哈卡州。我们还测量了一年内掉落的凤梨的每月速度，并监测了掉落的凤梨在森林地面上的存活率。水槽凤梨的存活率、繁殖率和随机种群增长率（λ(s)）明显高于气生凤梨，但两种凤梨的 λ(s)都<1，这表明即使没有收获，种群也会减少。物种间的弹性模式不同，但在两种凤梨中，大个体的存活率都具有高弹性值。没有掉落的凤梨在森林地面上存活超过 1.5 年，而掉落的凤梨速度与当前的采集速度相当。我们研究的物种和其他附生凤梨的种群增长率较低，而对收获影响最大的关键生活史特征的弹性值较高，这表明这些物种在野外的商业采集是不可持续的。我们建议收集掉落的凤梨作为一种生态上可行的、潜在的经济上可行的替代方法。
