Wesley Knapp, Ph.D.

Botanist · Conservationist · Scientist · Leader

Category: Current Research

Things I’m currently working on

  • U.S. Tree Assessment

    U.S. Tree Assessment

    Assessment · Data · Conservation Priorities

    U.S. Tree Assessment

    Conservation action begins with a deceptively simple set of questions: What species are here? Where do they occur? And which are most at risk? This collaboration created a standardized checklist of native U.S. trees and a common conservation framework for answering them.

    U.S. Tree Assessment research graphic

    Why it matters

    The contiguous United States supports nearly 900 native tree species. Yet conservation efforts had been limited by inconsistencies in the underlying information: which plants qualify as trees, which species are native, where they occur, and how threatened they are. Without a shared baseline, it is difficult to coordinate priorities across agencies, gardens, conservation organizations, and researchers.

    Building a common foundation

    Our collaboration assembled a standardized checklist, mapped distributions, and brought conservation-status information together in a form that could be shared and acted upon. The work was led by a broad partnership that included The Morton Arboretum, the United States Botanic Garden, NatureServe, Botanic Gardens Conservation International, the U.S. Forest Service, and others.

    From data to priorities

    The value of a national assessment is not simply the list itself. Standardized information makes it possible to identify gaps, compare risk, coordinate collections and recovery work, and direct limited conservation capacity toward the trees that need it most. That connection between authoritative biodiversity data and practical action has remained a central theme of my work.

    The publication

    Carrero, C., E. Beckman Bruns, A.L. Frances, D. Jerome, W. Knapp, A. Meyer, R. Mims, D. Pivorunas, D. Speed, A. Treher Eberly & M. Westwood. 2022. Data sharing for conservation: A standardized checklist of US native tree species and threat assessments to prioritize and coordinate action. Plants, People, Planet.

    View publication →

    Related work

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  • Vascular Plant Extinction in the United States and Canada

    Vascular Plant Extinction in the United States and Canada

    Extinction · Research · Conservation

    Vascular Plant Extinction in the United States and Canada

    Extinction is permanent, but even in one of the most botanically studied parts of the world we did not have a reliable accounting of how many plants had already been lost. I led a national team to find out.

    Counting what had disappeared

    We queried conservation databases, searched the botanical literature, and then vetted candidate extinctions with experts across the United States and Canada. Because taxonomy itself can complicate extinction counts, we also developed an Index of Taxonomic Uncertainty to evaluate the strength of each taxon’s scientific standing.

    65

    taxa assessed as extinct in the study

    51

    species, plus 14 infraspecific taxa

    64%

    of extinct plants were single-site endemics

    What surprised us

    The study identified 65 extinct taxa, representing 51 species and 14 infraspecific taxa. That was a 109% increase over the number previously reported for the United States and Canada. Seven persisted in cultivation despite being extinct in the wild. Perhaps most strikingly, 64% of the extinct plants had been known from only a single site, and many losses occurred outside places typically recognized as biodiversity hotspots.

    The conservation lesson

    The work changed how I think about extinction prevention. Species known from one or a few places can disappear before broad-scale conservation strategies ever reach them. Preventing extinction therefore requires both landscape conservation and an ability to identify and act on the most imperiled species individually, using complementary in situ and ex situ approaches.

    New York Botanical Garden Symposium

    Here Today, Gone Forever

    In November 2020, I presented this research at NYBG’s international symposium on plant extinction alongside Thomas Lovejoy, Stuart Pimm, Maria Vorontsova and other conservation leaders. The symposium connected the North American evidence with the larger global extinction crisis and the strategies needed to prevent future losses.

    Watch the NYBG symposium recording →

    A continuing question

    Our count was not the end of the story. Extinction records change as taxonomy improves, historical evidence is reexamined, and occasionally a species is rediscovered. The larger conclusion remains: documented losses are a minimum, not a ceiling. Better biodiversity data must ultimately lead to earlier conservation action.

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