Comparing Physicochemical Properties and Sorption Behaviors of Pyrolysis-Derived and Microwave-Mediated Biochar

Biochar’s ability to amend and remediate agricultural soil has been a growing interest, though the energy expenses from high-temperature pyrolysis deter the product’s use. Therefore, it is urgent to improve the pyrolysis efficiency while ensuring the quality of produced biochar. The present study utilized three types of feedstock (i.e., switchgrass, biosolid, and water oak leaves) to produce biochar via conventional slow pyrolysis and microwave pyrolysis at different temperature/energy input. The produced biochar was characterized and comprehensively compared in terms of their physiochemical properties (e.g., surface functionality, elemental composition, and thermal stability). It was discovered that microwave-mediated biochar was more resistant to thermal decomposition, indicated by a higher production yield, yet more diverse surface functional groups were preserved than slow pyrolysis-derived biochar. A nutrient (NO3-N) adsorption isotherm study displayed that microwave-mediated biochar exhibited greater adsorption (13.3 mg g−1) than that of slow pyrolysis-derived biochar (3.1 mg g−1), proving its potential for future applications. Results suggested that microwaves pyrolysis is a promising method for biochar production.

Winter roost selection of Lasiurine tree bats in a pyric landscape

Day-roost selection by Lasiurine tree bats during winter and their response to dormant season fires is unknown in the southeastern United States where dormant season burning is widely applied. Although fires historically were predominantly growing season, they now occur in the dormant season in this part of the Coastal Plain to support a myriad of stewardship activities, including habitat management for game species. To examine the response of bats to landscape condition and the application of prescribed fire, in the winter of 2019, we mist-netted and affixed radio-transmitters to 16 Lasiurine bats, primarily Seminole bats (Lasiurus seminolus) at Camp Blanding Joint Training Center in northern Florida. We then located day-roost sites to describe roost attributes. For five Seminole bats, one eastern red bat (Lasiurus borealis), and one hoary bat (Lasiurus cinereus), we applied prescribed burns in the roost area to observe bat response in real-time. Generally, Seminole bats selected day-roosts in mesic forest stands with high mean fire return intervals. At the roost tree scale, Seminole day-roosts tended to be larger, taller and in higher canopy dominance classes than surrounding trees. Seminole bats roosted in longleaf (Pinus palustris), slash (Pinus elliotii) and loblolly pine (Pinus taeda) more than expected based on availability, whereas sweetbay (Magnolia virginiana), water oak (Quercus nigra) and turkey oak (Quercus laevis), were roosted in less than expected based on availability. Of the seven roosts subjected to prescribed burns, only one male Seminole bat and one male eastern red bat evacuated during or immediately following burning. In both cases, these bats had day-roosted at heights lower than the majority of other day-roosts observed during our study. Our results suggest Seminole bats choose winter day-roosts that both maximize solar exposure and minimize risks associated with fire. Nonetheless, because selected day-roosts largely were fire-dependent or tolerant tree species, application of fire does need to periodically occur to promote recruitment and retention of suitable roost sites.

Determining an Optimum Tree Species for the Phytoremediation of Cumene and 4-Cumylphenol in Groundwater

Cumene and 4-cumylphenol are the primary constituents of concern in a groundwater plume at a chemical facility located in Plaquemine, Louisiana. Phytoremediation, a method that uses plants to remove contaminants from water and soil, was posed as a solution to removing the constituents of concern and creating hydraulic control of the plume. Five tree species, eastern redcedar, bald cypress, black willow, eastern cottonwood, and water oak, were chosen as potential remediators. Eastern redcedar and water oak did not tolerate the saline, contaminated water. Bald cypress, black willow, and eastern cottonwood trees were irrigated with deionized water, deionized water containing 0.5 mg·L−1 (0.5 ppm) cumene and 1 mg·L−1 (1 ppm) 4-cumylphenol as the low concentration, or deionized water containing 1 mg·L−1 (1 ppm) cumene and 4 mg·L−1 (4 ppm) 4-cumylphenol referred to as the high concentration. Both bald cypress and black willow were the best tree species for remediation of the groundwater as they were able to sequester the constituents of concern in their lower root tissue. Mean concentration of 4-cumylphenol detected in bald cypress roots at the end of the study were 1.72 mg·kg−1 in the low concentration water treatment and 1.50 mg·kg−1 in the high concentration water treatment. Mean concentration of 4-cumylphenol detected in black willow roots at the end of the study were 16.58 mg·kg−1 in the low concentration water treatment and 25.65 mg·kg−1 in the high concentration water treatment. Bald cypress was ultimately chosen for full scale planting in the fall of 2008.

Utilizing Forest Biomass by Adding a Small Chipper to a Tree-Length Southern Pine Harvesting Operation

We investigated the addition of a small chipper (Conehead 565) to a mechanized, tree-length system to harvest tops, limbs, and understory (1–4 in. dbh) biomass. Three replicates of three treatments (A, tree-length only; B, tree-length with limbs and tops chipped; and C, tree-length with limbs, tops, and understory chipped) were evaluated in a 33-year-old slash pine plantation on a flatwoods site in the lower coastal plain of Echols County, Georgia. The site contained an estimated 7.7 green tons/ac of understory biomass with an average dbh of 2 in. Water oak, swamp bay, and red maple accounted for 73% of the stems. Roundwood production averaged 65.8 tons/ac and did not differ significantly across the three clearcut treatments. A vanload of chips was produced for every 18 and 5 truckloads of roundwood in Treatments B and C, respectively. There were significant differences in the weight per acre of chips produced between Treatment B (3.8 green tons/ac) and Treatment C (10.8 green tons/ac) at the α = 0.1 significance level but not at the 0.05 significance level. Total production averaged 28.6 tons per scheduled machine-hour and did not differ significantly across the three treatments. Green chips averaged 45% moisture content when produced, and laboratory results showed heat content values of 19.1 MJ/kg, which is comparable to other woody biomass. Nutrient removals from the site were relatively low, with losses associated with Treatment B comparable to annual atmospheric deposition. Raking costs associated with site preparation were significantly reduced (by $23/ac) on Treatment C, where the understory was also chipped. Both Treatment B and Treatment C had significantly less area lost to debris piles (1.0%) after site preparation than tree-length harvesting without chipping residuals (1.7%). Chipping logging residues along with understory stems in a clearcut harvest produced quality energy chips at a competitive cost, reduced site preparation cost, and increased plantable area.

Fifth-Year Response to Thinning in a Water Oak Plantation in North Louisiana

A 21 ac, 28-yr-old water oak (Quercus nigra L.) plantation, on an old-field loessial site in north Louisiana, was subjected to three thinning treatments during the winter of 1987–1988: (1) no thinning, (2) light thinning to 180 dominant and codominant trees/ac, and (3) heavy thinning to 90 dominant and codominant trees/ac. Prior to thinning, the plantation averaged 356 trees/ac and 86 ft2/ac of basal area, with a quadratic mean diameter of 6.7 in. Thinning reduced stand basal areas to 52 and 34 ft2/ac for the light and heavy thinning treatments, respectively. After 5 yr, both thinning treatments increased diameter growth rates of individual residual trees, both when all trees were considered and when the analysis was limited to dominant and codominant trees only. Neither thinning treatment affected either stand-level volume growth or total yield 5 yr after treatment. However, thinning distributed total volume growth among fewer trees, such that, when trees of all crown classes were considered in the analysis, average annual volume growth per tree increased with increasing intensity of thinning. Both basal area growth and volume growth following light thinning appear to be sufficient to promote rapid recovery of the stand to a fully stocked condition in the near future. In contrast, heavy thinning reduced density to a severely understocked condition that will prohibit optimum occupancy of the site for a long period. Among the treatments evaluated in this study, light thinning produced the most desirable combination of individual-tree diameter growth and stand-level basal area growth. South. J. Appl. For. 25(1):31–39.