Life Sciences Commons^™

Intermolecular Potential Surfaces From Electron Gas Methods. Ii. Angle And Distance Dependence Of The A’ And A” Ar–No(X^2ii) Interactions, Glen C. Nielson, Gregory A. Parker, Russell T. Pack

Faculty Publications

Angle dependent intermolecular potential energy surfaces for the two states (2A’ and 2A”) that arise from the interaction of ground (X^2II) state NO with Ar are calculated using the electron gas model to obtain the short range interactions. The average and difference of the two interaction energies are fit to analytic forms convenient for use in scattering calculations and joined smoothly onto the long range van der Waals potential previously determined. The results, which appear to be of useful accuracy, and the applicability of the electron gas model to such open shell–closed shell interactions are discussed.

Aggregation Of The Southern Pine Beetle In Response To Attractive Host Trees, Jack E. Coster, T.L. Payne, E.R. Hart, L.J. Edson

Faculty Publications

Dendroctonus frontalis Zimmerman were attracted to shortleaf pines, Pinus echinata MilL, using infested shortleaf pine bolts. Response was monitored during the ensuing mass attack period by the use of sticky traps suspended along the tree boles. Uninfested host materials or host materials containing only male beetles did not elicit mass attack of trees. Female beetles either alone or in combination with males, usually stimulated mass attack within 24 h. Traps at 3-4 m above the ground caught the greatest number (26.7%) of beetles. Trap catches peaked on the 3rd day of attack and declined rapidly thereafter. Daily flight activity was …

Distribution Of Some Predators And Parasites Of The Southern Pine Beetle In Two Species Of Pine, Jack E. Coster, Catherine Stein

Faculty Publications

Southern pine beetle, Dendroctonus frontalis Zimmerman, and its natural insect enemies were reared from infested loblolly pines, Pinus taeda L., and shortleaf pines, P. echinata Mill. Southern pine beetle broods were most dense during spring (Mar.-May) and least dense in late summer. Populations were higher in late winter than in midsummer. There were no differences in beetle densities between the pine species. Twelve predators and 9 parasites comprised ca. 99% of the natural enemy complex.

Total density of the 12 predators did not vary with either season or tree species. Total parasite density, however, was highest in midsummer, lowest in …

Crown Positions Within Unthinned Loblolly Pine Plantation Canopies, J. David Lenhart, Dwight R. Hicks, Chi-Yun Ho

Faculty Publications

Crown class percentages are not affected by age or trees/acre. The percentage of dominant and suppressed trees is affected by land productivity.

Site Factors Affecting Growth Of Slash Pine In The Texas Post Oak Belt, W. D. Hacker, M. Victor Bilan

Faculty Publications

A study was conducted in the Post Oak Belt of East Texas to determine which site factors affected height growth of slash pine (Pinus elliottii Engelm.). Height-age pairs were developed from stem analysis data. Nonlinear regression was implemented to develop a generalized height-age model. After curves were developed, stepwise regression was used to determine impacts of environmental variables on height growth. Environmental factors correlated with height growth included A horizon depth and those related to moisture relations including seasonal precipitation, average daily temperature, and texture of the A horizon. South. J. . Appl. For. 21(2):71-74.

Stomatal Opening, Transpiration, And Need/E Moisture In Loblolly Pine Seedlings From Two Texas Seed Sources, M. Victor Bilan, C.T. Hogan, H.B. Carter

Faculty Publications

Relationships among percentage of open stomates, transpiration, and needle moisture content in seedlings of loblolly pine of two Texas provenances were studied under changing soil moisture conditions. Needle moisture content correlated very well with transpiration under favorable moisture conditions, and with percentage of open stomates under soil moisture stress. Transpiration and percentage of open stomates were correlated under a wide range of moisture conditions. Foliage moisture content was still relatively high in both ecotypes when stomates closed and transpiration drastically declined. The "Lost Pines" seed source appeared to have superior ability to conserve moisture under droughty conditions by closure of …

Towards Integrated Protection From The Southern Pine Beetle, Jack E. Coster

Faculty Publications

Current southern pine beetle ( Dendroctonus frontalis Zimm.) control depends heavily upon direct approaches having short-term payoffs. Chemical or physical tactics have fidled to check epidemics in the Gulf South. A major challenge lies in developing and using indirect methods for managing this pest. Promotion of stand resistance and biotic agents, and manipulation of stand density and cutting practices, hold prospect for reducing the incidence and severity of beetle-caused losses.

Sex-Ratio Estimation, Sequential Sampling, And The Programmable Packet Calculator, Paul C. Johnson

Faculty Publications

No abstract provided.