Gotsch S G, Williams C B, Bicaba R, Cruz-de Hoyos R, Darby A, Davidson K, Dix M, Duarte V, Glunk A, Green L, Ferguson B, Muñoz-Elizondo K, Murray J G, Picado-Fallas I, Nӕsborg R, Dawson T E, Nadkarni N
Department of Biology, Franklin and Marshall College, Lancaster, PA, USA.
Conservation and Research, Santa Barbara Botanic Garden, Santa Barbara, CA, USA.
Oecologia. 2022 Mar;198(3):645-661. doi: 10.1007/s00442-022-05140-9. Epub 2022 Mar 13.
Epiphyte communities comprise important components of many forest ecosystems in terms of biomass and diversity, but little is known regarding trade-offs that underlie diversity and structure in these communities or the impact that microclimate has on epiphyte trait allocation. We measured 22 functional traits in vascular epiphyte communities across six sites that span a microclimatic gradient in a tropical montane cloud forest region in Costa Rica. We quantified traits that relate to carbon and nitrogen allocation, gas exchange, water storage, and drought tolerance. Functional diversity was high in all but the lowest elevation site where drought likely limits the success of certain species with particular trait combinations. For most traits, variation was explained by relationships with other traits, rather than differences in microclimate across sites. Although there were significant differences in microclimate, epiphyte abundance, and diversity, we found substantial overlap in multivariate trait space across five of the sites. We found significant correlations between functional traits, many of which related to water storage (leaf water content, leaf thickness, hydrenchymal thickness), drought tolerance (turgor loss point), and carbon allocation (specific leaf area, leaf dry matter content). This suite of trait correlations suggests that the epiphyte community has evolved functional strategies along with a drought avoidance versus drought tolerance continuum where leaf succulence emerged as a pivotal overall trait.
附生植物群落就生物量和多样性而言，是许多森林生态系统的重要组成部分，但对于这些群落中多样性和结构背后的权衡取舍，或者小气候对附生植物性状分配的影响，我们却知之甚少。我们在哥斯达黎加一个热带山地云雾森林地区，跨越一个小气候梯度的六个地点，对维管束附生植物群落中的22个功能性状进行了测量。我们对与碳和氮分配、气体交换、水分储存及耐旱性相关的性状进行了量化。除了海拔最低的地点外，所有地点的功能多样性都很高，在该海拔最低的地点，干旱可能限制了某些具有特定性状组合的物种的生存。对于大多数性状而言，变异是由与其他性状的关系来解释的，而非各地点小气候的差异。尽管小气候、附生植物丰度和多样性存在显著差异，但我们发现五个地点在多变量性状空间中存在大量重叠。我们发现功能性状之间存在显著相关性，其中许多与水分储存（叶片含水量、叶片厚度、贮水组织厚度）、耐旱性（膨压丧失点）和碳分配（比叶面积、叶片干物质含量）有关。这一系列性状相关性表明，附生植物群落已经沿着一个避旱与耐旱连续体进化出了功能策略，其中叶片肉质化成为一个关键的总体性状。
