Botanic gardens are an untapped resource for studying the functional ecology of tropical plants

Abstract

Functional traits are increasingly used to understand the ecology of plants and to predict their responses to global changes. Unfortunately, trait data are unavailable for the majority of plant species. The lack of trait data is especially prevalent for hard-to-measure traits and for tropical plant species, potentially owing to the many inherent difficulties of working with species in remote, hyperdiverse rainforest systems. The living collections of botanic gardens provide convenient access to large numbers of tropical plant species and can potentially be used to quickly augment trait databases and advance our understanding of species' responses to climate change. In this review, we quantitatively assess the availability of trait data for tropical versus temperate species, the diversity of species available for sampling in several exemplar tropical botanic gardens and the validity of garden-based leaf and root trait measurements. Our analyses support the contention that the living collections of botanic gardens are a valuable scientific resource that can contribute significantly to research on plant functional ecology and conservation.This article is part of the theme issue 'Biological collections for understanding biodiversity in the Anthropocene'.

Keywords: conservation; diversity; global vegetation models; leaf economics spectrum; rank abundance; root economics spectrum.

Figure 1.

The per cent of woody Amazonian seed plants and woody North American species represented by one of three Leaf Economic Spectrum (LES) traits from TRY's public dataset; leaf mass area (LMA), leaf nitrogen content (N) and photosynthetic rate per dry mass (A_max).

Figure 2.

The family, genus and species richness for FTBG, MBC, Yasuni forestry plot, Pasoh forestry plot, MBG and Barro Colorado Island's forestry plot (BCI). Shaded bars are overlapping, not stacked, so that the height of each coloured bar indicates total richness. Sites are ranked from greatest to least species diversity; asterisks indicate gardens.

Figure 3.

Species rank-abundances for FTBG, MBC, Barro Colorado Island forestry plot (BCI), Pasoh forestry plot and Yasuni forestry plot. Lines correspond to each site, and the horizontal dotted line indicates a sample size of five individuals. (Online version in colour.)

Figure 4.

The relationship between species' mean LMA measured in FTBG and the global species' mean from the TRY database. The solid line indicates the relationship of the FTBG and TRY data, the shaded area is the 95% confidence internal of the linear model (y = 0.59 [±0.18 s.e.] × x + 28.95[±17.68 s.e.]; r² = 0.38; p < 0.001; d.f. = 15), and the dashed line shows the 1 : 1 relationship.

Figure 5.

The three-dimensional relationship between LMA, N, A_max traits of the leaf economic spectrum. Orange dots and blue triangles represent the three-dimensionality of the data for GLOPNET and FTBG data, respectively. Grey dots and black triangles represent the two-dimensional relationships of the LES traits.

Figure 6.

The three-way relationship between SRL, diameter and RTD root traits. Orange and yellow circles represent the non-woody and woody species from the FRED ([38] https://roots.ornl.gov/), respectively; green triangles indicate data from FTBG. Grey points and black triangles represent the two-dimensional relationships of the root traits.