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Abstract Detail

Floristics in North America: Current needs, priorities and opportunities

Alba, Christina [1], Levy, Richard [2], Islam, Melissa [3], Hufft, Rebecca [4].

The full story on plant biodiversity: Botanical collections and quantitative ecological data richly complement each other.

The plant survey approaches used by botanical collectors and ecologists generate different kinds of data. Botanists employ a random walk approach, covering a lot of area and therefore generating excellent estimates of plant richness. Ecologists test hypotheses by using plots or transects to subsample the “universe” of plant species in relationship to an environmental gradient of interest. Ecologists estimate both species richness and species relative abundances, with abundance estimates providing a layer of information that cannot be garnered using the botanical approach. However, transects cover less area than the random walk and thus can miss species that are not abundant. We expect that botanical surveys capture more species than ecological transects, although the magnitude of potential differences has not been explored. It also remains uncertain whether divergent richness estimates differentially shape interpretation about ecological conditions, for example what proportion of the plant community is native versus introduced. Further, because botanical surveys are not paired with ecological transects, exhaustive documentation of species richness is rarely contextualized by which species are most abundant. To address these gaps, we sampled plant richness (botanical random walk and ecological transects) and abundance (transects only) along a 66-mile recreational greenway in Colorado, USA. We compared richness estimates of the two approaches and evaluated whether differences in richness led to different ecological interpretations. We further evaluated species abundance to better contextualize findings associated with richness.
The botanical survey captured 438 species, while the ecological transects captured 116. This discrepancy reflects that the botanical survey captured both abundant and uncommon species, while the transects captured predominantly abundant species. Across the entire greenway, the botanical (53%) and ecological (43%) approaches estimated similar proportions of native species, providing a comparable ecological interpretation. When partitioning richness across habitat types, the richness estimates more strongly diverged. Ecological transects more severely underestimated species richness, and overestimated the proportion of introduced species, in habitat types of smaller areal extent (i.e., with less replication). However, abundance estimates provided critical context to patterns of richness, revealing that three species of introduced grasses comprised ~50% of the plant cover. Thus, while the botanical approach best captured the full range of species present, the ecological approach highlighted which species are likely to drive ecosystem processes, such as biological invasions, that are of interest to land managers. These findings highlight the complementary nature of the two approaches for describing different dimensions of ecosystem integrity.

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1 - Denver Botanic Gardens, Research & Conservation, 1005 York Street, Denver, CO, 80206, United States
2 - Denver Botanic Gardens, 909 York Street, Denver, CO, 80206, United States
3 - Denver Botanic Gardens, Research & Conservation, 909 York Street, Denver, CO, 80206, United States
4 - Denver Botanic Gardens, 909 York Street, 909 York Street, Denver, CO, 80206, United States

Species Richness
Species Abundance.

Presentation Type: Colloquium Presentations
Session: CO13, Floristics in North America
Location: Tucson J/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 2:45 PM
Number: CO13004
Abstract ID:718
Candidate for Awards:None

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