Summer's end, 'round the bend
And what a summer it has been!
We've been busy, with six undergraduate students working on internships or research projects, graduate student fieldwork across Missouri, and several new projects around Baskett Center. We had three MS students graduate last May or August and are looking at recruiting for several new graduate projects and a post-doc. As it is time to return focus to the classroom, it is good to reflect on activities and accomplishments from the summer.
Field work at Deer Ridge Conservation Area in northern Missouri picked up this summer, with Isaac and Alex spending much of the summer sampling bottomland hardwood forests within a large field experiment that combines regeneration harvest with midstory release treatments to encourage regeneration of oak species. We are nearly 20 years after the original harvest treatments and now two years after the release treatments, with both pin oak and swamp white oak underplanted throughout the study areas. This summer, the conditions surrounding individual seedlings were also quantified, including abundance of competitors, soil moisture levels, microtopographic position, and light availability. These data will help us determine factors that limit the establishment of new oak trees in these productive sites.
In another, new project in collaboration with Missouri Department of Conservation, Dacoda and Dominic were busy working to restore savannas by establishing trees within reconstructed prairies and working to restore woodlands through seeding of herbaceous species following thinning within overgrown sites at Prairie Fork Conservation Area. This is an interesting project in that it includes two different approaches to a similar restoration challenge: one in which ground flora is largely restored but trees are missing and the other in which the forest structure is restored but the ground flora is missing. These approaches each face different specific challenges. Establishing planted trees within reconstructed prairies is difficult due to high levels of belowground competition for the new trees, harsh conditions in the fully exposed sites, and ripping fires when prescribed burning comes around. We will be testing some different treatments (local competition control with weed cloth and mechanical fuel removal prior to burning) to determine best practices for tree establishment. For woodland restoration, seeding desirable ground flora species is not commonly done in this region. We will evaluate the effects of light availability and the seedbed condition on the success of ground flora establishment, with specific interest in certain species.
Ethan (with help from Alex, Dominic, Nick, and Bennett) rehabilitated a neglected black walnut plantation originally set up in the late 1990s. The site was overgrown with invasive shrubs (as well as Baskett's notorious vine, Asian bittersweet) and full of ingrowth from cedar and sycamore. After the major renovation, we've got cleared rows with trees measured and mapped. Next steps: release the best trees with a thinning operation to regain growth response. With several rows kept in the overgrown condition, this has become a nice demonstration site for plantation rehabilitation.
Through a collaborative effort with NRCS and the Forest Service, Sara led a soil mapping project across Baskett. The project incorporated long-term forest succession plots and a network of plots describing legacy effects of agricultural land use. By first characterizing the soils, we are now establishing soil pits and sampling for chemical and biological analyses. Data from the agricultural legacy plots will be integrated with vegetation data and wildlife use (camera trap) data to describe long-term impacts of agricultural abandonment. In particular, impacts of agricultural legacy on soil biota will inform restoration efforts through possible limits to beneficial biotic interaction.
Related to impacts of past agriculture on current conditions, Spencer was interested in the distribution of invasive species across Baskett and adjacent portions of the Mark Twain National Forest. He established a grid of sampling points throughout the entire area, navigated to each grid point, and recorded information on the forest structure and composition. His data indicate relationships among stand density, tree composition, light availability, abundance of native tree species, and abundance of invasive shrubs, vines, and herbaceous plants. The dataset is mapped across the property to allow additional information, derived from remote-sensing, to be used to consider drivers of abundance and distribution of invasive species. This project has helped identify that Baskett has an extremely abundant population of Asian bittersweet (Celastrus orbiculatus) - much higher than has been reported in other areas of the region. We also learned of some pockets of tree-of-heaven (Ailanthus altissima) that are appearing to spread through gap dynamics...:(
Together, the Baskett team has moved several additional projects forward. Through annual monitoring of tagged tree seedlings within a network of long-term forest inventory plots, we are documenting the dynamics of seedling establishment, persistence, and turn-over. In general, we observe that many mature forest areas have very few tree seedlings (other than ash, which is very common), even though oak dominates the overstory and maple dominates the midstory. We are pursuing some new projects to determine the limiting factors to oak and maple regeneration. We will incorporate some of this work into an area of Baskett where timber is currently being harvested to create demonstration sites of forest management practices. That project has been moving forward and will result in examples of commercial thinning (to improve the residual stand) and several regeneration harvests (clearcut, shelterwood, and single-tree selection). These areas will increase the opportunity to show forests in different stages of stand development at Baskett, adding to several 35-year-old clearcuts throughout the property, originally established to study effects of habitat on grouse. This summer, we tagged and measured all trees in one acre areas of four of these clearcuts, so we can track growth rates and mortality of different tree species as the stands develop through time.
Now we are looking forward to a busy year in the classroom and the field, with several new members joining the lab (welcome Dacoda, Justin, and Hope!!). We hope to highlight projects, papers, conferences, and activities through the webpage - please stay in touch!