Missouri Bladderpod Status at Wilson’s Creek National Battlefield


The Missouri bladderpod (Physaria filiformis), listed as threatened under the Endangered Species Act, grows in southwestern Missouri and northwestern Arkansas. It occurs at several locations at Wilson’s Creek NB, where staff continues to adapt landscape management practices to meet needs of cultural and natural resources, while protecting bladderpod populations.

Photo of Missouri Bladderpod at Wilson's Creek NB
Missouri Bladderpod at Wilson's Creek National Battlefield.

Long Term Monitoring: Population monitoring using cover classes

The Heartland Inventory and Monitoring Network has used various methods to estimate the number and density of bladderpods at Wilson’s Creek NB over 25 years. Scientists currently use a grid-based approach to estimate abundance in each glade. They tally plant abundance estimates using cover classes, such that cover class 1 represents 1 to 19 plants in the sample through cover class 7, which represents between 5,000 to 9,999 plants. Scientists then combine sample tallies to estimate total bladderpod abundance in each glade.

Graph depicting population variability of Missouri Bladderpod over time at one site.
Missouri bladderpod population size at one site shows variability over time. Data points are taken from the median of each cover class estimate. Error bars represent highs and lows of the cover classes. Red lines represent prescribed fire events. Green lines represent eastern red cedar clearing.

Status and Trends:
Population size linked to environmental factors

Scientists have documented relatively large variability in population sizes at each sample site during the years. Some data suggest a relationship between bladderpod population size and prescribed fire events, but response varied too greatly to say that fire consistently increases population size. Reducing competition from eastern red cedars appears to be beneficial to bladderpod, but here again, response varied too much to find a consistent relationship with population size. Additionally, scientists found:

  • Fire intensity may determine the degree and type of change in population size. Fire timing and frequency may affect population size also.
  • In some cases precipitation, temperature, and microhabitat conditions may have influenced population size more strongly than fire alone.

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