Current Research Projects
Evie Von Boeckman
Shifting Composition in Upland Oak Forests: Potential Impacts on Forest Flammability Due to Changing Fuel Moisture and Drying Rates.Senior wildlife, fisheries and aquaculture major Evie Von Boeckman studied how an increase in fire-sensitive, shade-tolerant species (mesophytes) impacts moisture content and drying rates in fuel beds, and if fuel bed wetting method (soaking, rainfall simulation, natural rainfall event) influences these response variables. Mesophytes are becoming dominant in historically fire-maintained and oak-dominated (Quercus spp.) forests in the eastern U.S. This could have large impacts on forest flammability, and thus maintenance of oak forests, if mesophyte leaf litter traits influence fuel moisture. This study hypothesized that as mesophyte contribution increases, moisture would be retained longer causing slower drying rates. We also anticipated that the natural rain event method would most closely represent the conditions leaf litter would normally experience, so differences among fuel bed types would be most distinct. To test these hypotheses, we constructed fuel beds in the lab comprised of upland oak litter (Q. stellata, Q. coccinea) and increasing amounts of mesophyte (Liquidambar styraciflua, Carya spp, Ulmus alata) litter (0%, 33%, 66%, and 100%). We wetted fuel beds by, (1) soaking for 24 hr, (2) simulating a summer precipitation event (0.0072 cm over 10 min), and (3) exposing litter to a natural winter rain event (0.19 cm over 4 hr). All treatments exhibited a rapid initial (within 4 hr) decrease of moisture followed by a more gradual decline over the 48 hr drying period; however, beds comprised only of mesophyte litter dried slowest, while those with high oak contribution (66% and 100%) dried fastest. The simulated rainfall and rain event produced similar drying rates; soaking, however, showed the highest moisture content initially and less distinction and separation between drying rates. These findings suggest that increased contribution of mesophyte leaf litter to fuel beds will increase moisture and slow drying rates, which could hinder forest flammability in upland oak systems.
Does sampling more than one increment core in growth-index-ratio-based stand table projection improve forest yield prediction precision?Senior forestry major Leah Leonard conducted research to investigate whether sampling more than one tree for previous diameter growth measurement significantly improves the precision of forest yield predictions from stand table projections. Obtaining future forest yield is not a straightforward process in comparison to obtaining current yields, which can be measured directly in the field. Stand Table Projection (STP) is one of the approaches of predicting future yields of forest stands. STP is simple to apply because it only requires previous diameter growth measurements from a sample of the trees in the stand, which can be measured from increment cores taken from the sample trees. Usually, one increment core is sampled per tree dbh class. One increment core may not be a good representation of a dbh class due to possibility of various measurement and growth ring formation issues. Thus, taking more than one increment core per tree dbh class may help minimize the effect of increment core measurement errors on yield predictions from STP. Individual tree measurements from 364 longleaf pine research plots in the Southeastern United States were used to investigate whether sampling more than one tree per tree size class, for previous diameter growth measurements, would significantly reduce future yield prediction errors from STP. Findings from the research indicated that sampling more than one tree per dbh class, for STP increment cores, may not result in lower STP prediction errors. In addition, it was observed that STP prediction errors for stands that were less than 50 years old were more than 2 times larger than the errors for stands that were older than 50 years.
Removing the Adhesive Layer of Gulf Killifish (Fundulus Grandis) Eggs to Increase the Number of Eggs Available for CollectionMatthew Virden, a senior in the Department of Wildlife, Fisheries and Aquaculture, studied improved production of Gulf killifish. Killifish are intertidal spawners found in estuaries in Northeast Florida and along the northern coast of the Gulf of Mexico. There is a high demand for Gulf killifish from bait shops and anglers for use as live bait for sport fishes. This demand has led to a shortage in the overall supply of Gulf killifish, creating an increased interest in production. Adult killifish enter interior marshes during spring high tides to spawn by laying eggs in marsh grasses. The eggs have an adhesive layer, allowing them to stick to the vegetation for incubation until the next high tide. Hatching occurs once the eggs are re-submerged. While this adhesive layer is beneficial in their natural habitat, it makes it difficult to collect the eggs off spawning mats in recirculating aquaculture systems. Currently mats are shaken or tapped against a mesh screen; however, clumps of eggs are still visible within the mat. Studies were performed to assess different treatments to remove the adhesive layer to increase the number of eggs available for collection. Gulf killifish eggs were collected on 20 X 10 cm (8" X 4") Spawntex mats that were placed 8-20 cm below the water's surface in 9-3600 L recirculating aquaculture systems. Individual mats underwent randomized treatments and there was a total of nine treatments with three replicates each. Treatments consisted of 2g urea, 3g urea, 4g urea, 500 mg L-1 tannic acid, 1000 mg L-1 tannic acid, 1500 mg L-1 tannic acid, 12g cow's powdered milk, 24g cow's powdered milk, and 8ppt water. The removal efficiency for all treatments were slightly higher than the control. The three urea solutions were the only treatments that were significantly different from the control. Survival and hatching rates did not show any relation to treatments, but this could be the cause of inadequate sample size. Future studies should focus on increasing sample size and focusing on fewer solutions.