Department of Biology, University of Miami, Coral Gables, FL, 33146, USA.
Fairchild Tropical Botanic Garden, Coral Gables, FL, 33156, USA.
Am J Bot. 2020 Oct;107(10):1457-1464. doi: 10.1002/ajb2.1535. Epub 2020 Sep 18.
The use of functional traits has surged in recent decades, providing new insights ranging from individual plant fitness to ecosystem processes. Global plant trait databases have advanced our understanding of plant functional diversity, but they remain incomplete because of geographic and taxonomic biases. Herbarium specimens may help fill these gaps by providing trait information across space and time. We tested whether herbarium specimen-derived measurements are reliable estimates of three important, commonly measured functional traits-specific leaf area (SLA), branch wood specific gravity, and leaf thickness.
Leaves and branches were collected from species cultivated at Fairchild Tropical Botanic Garden and Florida International University in Miami, FL, USA. Fresh components of SLA (area), branch wood specific gravity (volume), and leaf thickness were measured following standard trait measurement protocols. We compared these trait values to corresponding measurements using plant tissues dried in a plant press following standard herbarium plant collecting protocols.
Herbarium-derived trait measurements (dried tissues) were highly correlated with those measured using fresh tissues following standard protocols (SLA: R = 0.72-0.97, p < 0.01; wood specific gravity: R = 0.74-0.75, p < 0.01; leaf thickness: R = 0.96, p < 0.01). However, except for leaf thickness, linear model slope or intercept coefficients differed from 1, indicating herbarium-derived trait measurements may provide biased estimates of fresh traits without the use of correction factors.
Herbarium-derived traits cannot always be used interchangeably with those measured from fresh tissues because of tissue shrinkage. However, herbarium-derived trait data still have the potential to drastically expand the temporal, geographic, and taxonomic scope of global trait databases.
近几十年来，功能性状的应用呈激增态势，为从单个植物适应能力到生态系统过程等各个方面提供了新的见解。全球植物性状数据库已经提升了我们对植物功能多样性的理解，但由于存在地理和分类偏见，这些数据库仍然不完整。植物标本可能有助于填补这些空白，提供跨越时空的性状信息。我们测试了植物标本衍生的测量值是否可以可靠地估计三个重要的、常用的功能性状——比叶面积（SLA）、树枝木质比重和叶片厚度。
从美国佛罗里达州迈阿密的费尔柴尔德热带植物园和佛罗里达国际大学种植的物种中采集了叶片和树枝。按照标准性状测量方案，测量了 SLA（面积）、树枝木质比重（体积）和叶片厚度的新鲜成分。我们将这些性状值与使用按照标准植物标本采集方案在植物标本压制器中干燥的植物组织进行的相应测量值进行了比较。
按照标准协议，使用植物标本干燥组织进行的性状测量（干燥组织）与使用新鲜组织进行的测量高度相关（SLA：R = 0.72-0.97，p < 0.01；木质比重：R = 0.74-0.75，p < 0.01；叶片厚度：R = 0.96，p < 0.01）。然而，除了叶片厚度外，线性模型斜率或截距系数与 1 不同，这表明在不使用校正因子的情况下，植物标本衍生的性状测量可能会对新鲜性状提供有偏差的估计。
由于组织收缩，植物标本衍生的性状不能总是与从新鲜组织测量的性状互换使用。然而，植物标本衍生的性状数据仍然有潜力极大地扩展全球性状数据库的时间、地理和分类范围。
