By Mike Proctor
Senior Research Associate 1
A little more than 100 years ago, G.W. Stevens traveled across Oklahoma collecting plant specimens as the director of the Oklahoma State Botanical Survey. A portion of his first collecting trip brought him through Love and Carter counties, where several of the ranches operated by Noble Research Institute are located, ranches where I’ve spent much of the last nine years involved in various research projects.
Stevens’ field survey was the first major undertaking to identify what plants occurred in Oklahoma. Up until that point and for the next 50 years or so, the study of natural history mostly revolved around two questions: what and where. In other words, finding out what species were present and where they occurred. The only way to answer those questions was to go out and collect specimens which then were dried, mounted and deposited in herbariums, usually at universities. While people could come along and make maps or study the anatomy of all the specimens of a particular species, nothing really exciting happened in those collections.
As new technologies were developed and improved in the 1980s and ’90s, the attention shifted to looking at how species and groups were related to one another based on DNA and pollen analysis. This was pretty attractive to folks because it all took place under air conditioning and didn’t involve chiggers and ticks. Tissue samples for a study could easily be extracted from preserved herbarium specimens. Natural history studies dropped off dramatically and are continuing to decline.
There are a lot of questions out there today that didn’t exist when G.W. Stevens and other early collectors were stumbling around through the prairies and woods of Oklahoma. Natural history collections and surveys can contribute a great deal to the answers.
VEGETATION REFLECTS ECOSYSTEM HEALTH
From historical collections and newer samples collected in particular habitats, we can begin to develop a concept of ecosystem health. How many native species are present versus non-natives? How closely do the species present today represent those documented for the site in the past? How have environmental changes affected native vegetation? How have land use practices influenced native vegetation? What can be inferred from the current vegetation about historical land use?
If we detect a difference — some species are absent that were present and new species have appeared — we can ask: What about this site has changed? How rapidly are changes taking place? Can we implement management practices to reverse the changes? Rarely do species invade an intact community. There is usually some disturbance that has taken place that sets the stage. Often the culprit is overgrazing, but it also may be something like a lack of fire. For example, eastern redcedar takes advantage of both situations and causes havoc by invading grassland plant communities.
A great deal of information about the status of vertebrate and invertebrate species can be inferred by the status of the plant communities present. In most cases, the plant community is the habitat for those species. If it’s gone, they’re gone.
During field work in the heavily forested Big Thicket in southeast Texas, I occasionally came across single pitcher plants under closed-canopy pine forests. If they’re only supposed to grow in pine savannas, why were they growing in the middle of the forest? Fires had been suppressed for so long that the pines had taken over the original savannas, which were the habitat for the pitcher plants. I was finding relict populations. Collections data can let us know where such habitats once occurred and where they might occur again, if properly managed.
Collecting Provides Insight Into Invasive and Endangered Species When dealing with invasive species, other questions arise. Have those species always been around, or are they introduced? When did they first turn up? If they have always been around, why are they causing problems now? What has changed? How fast is the change occurring? Collections data can help answer those questions as well.
Natural history collections may also provide insight into endangered species that are particular about where they live. Data on specimen labels about geology and soils can be put into a GIS system and analyzed to locate other potential sites where those species might be found or could be reintroduced. It is also possible that what we thought was an endangered species based on museum collections isn’t nearly as endangered once someone starts to focus on collecting them. Many organisms are easy to overlook and just are seldom collected.
COLLECTING HELPS ANSWER BIODIVERSITY QUESTIONS
How many species occur on a site? Do some appear only during or after really dry periods, or really wet ones? Several native forbs dramatically increase in abundance after fires. It’s not that they are suddenly invading, but it’s how that plant community is responding to fire. After every fire, those species behave in that fashion. Two years after the fire, the forbs will once more be minor components of that community. Some of the species occurring on a site don’t show up every year, or even every decade. Seeds remain viable in the soil for extended periods of time and may germinate only when conditions are just right. This may occur only when the overhead canopy has been removed, such as in the case of a fire or after a severe drought.
Collecting in an area, even over an entire season, still doesn’t capture all of the biodiversity that is likely to be present there. I’m specifically referring to plants here, but I think that trend holds true for whatever group of organisms one might study. Collecting is the only way to answer many biodiversity questions. We use some other technologies such as camera surveys or acoustic surveys to help measure biodiversity with animals, but they don’t work with plants.
Read more in the December issue of Oklahoma Farm & Ranch.