Avian behavior in Chinese tallow woodlands and evaluating the potential control and allelopathic interference of Chinese tallow

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Title: Avian behavior in Chinese tallow woodlands and evaluating the potential control and allelopathic interference of Chinese tallow
Author: Conway, Warren C
Abstract: The Chinese tallow tree , (Sapium sebiferum (L ) ) Roxb . ) , has been cultivated for over 14 centuries in China for seed oil . Chinese tallow was introduced to the United States in the mid to late 1800s and has since naturalized throughout much of the southern U . S . Tallow invades a wide variety of habitats , including freshwater wetland basins , coastal prairie , mixed bottomland hardwood forests , as well as disturbed sites . It continues to expand throughout the southern U . S . , but control efforts have been inconsistent . The mechanisms by which it invades are presently unknown , as are the impacts of this invasion on native biota . Therefore , we need to know how to control future tallow expansion , investigate its ecological impacts , and understand the mechanisms for its success . During 1995 and 1996 ,1 studied avian behavior in Chinese tallow woodlands and evaluated potential control and allelopathic interference of Chinese tallow in the coastal prairie region of Texas . My objectives were fourfold . First , I determined total nonstructural carbohydrate (TNC ) movement in Chinese tallow , and identified the period of downward translocation of photosynthate . I linked that specific physiological stage with a visible phenological stage of development in the annual cycle of tallow to determine optimal timing for control treatments . Second , I evaluated the allelopathic potential of Chinese tallow on seed germination and seedling growth and development of plant species native to the coastal prairie region of Texas . Third , I quantified avian use of and behaviors in Chinese tallow woodlands during fall migration along the Texas coast . Finally , I evaluated avian use of Chinese tallow seeds , by subjecting seeds that were fed upon by birds , to bioassay experiments to test for seed germination enhancement by bird feeding activities . Chinese tallow root TNC trends and phenological development were monitored over an annual cycle . Six phenological stages were recorded ; (1 ) dormancy . (2 ) bud break , (3 ) leaf development , (4 ) seed formation . (5 ) seed maturation , and (6 ) leaf fall . Tallow root TNC concentrations varied by phenological stage (P < 0 .001 ) , where concentrations were highest (P < 0 .05 ) during leaf fall (60 .72 % ) and lowest (P < 0 .05 ) during leaf development (41 .11 % ) and seed formation (36 .71 % ) . Chinese tallow root TNC concentrations increased during the period of seed maturation until leaf fall . If foliar applied herbicides are delivered during this period of downward translocation , effective tallow control should be observed . I performed seed germination bioassays using black willow (Salix nigra ) , baldcypress (Taxodium distichum ) , Chinese tallow , and lettuce as test species in 2 different experimental media (i .e . , aqueous extracts and substrates ) prepared from fresh tallow leaves , fallen litter , and tallow woodland soil collected during 4 months to evaluate seasonal differences in allelopathic interference potential . Distilled water was used as a control for aqueous extract treatments , whereas air -dried peat was used as a control for the substrate treatments . There were varied responses by black willow , baldcypress , and lettuce seeds and seedlings exposed to tallow extract and substrate treatments . In some instances , test seeds experienced enhanced (P < 0 .05 ) seed germination and seedling growth , but in others these responses were reduced . When exposed to its own extracts and substrate treatments . Chinese tallow showed more consistent responses . Chinese tallow control (i .e . . distilled water and substrate ) treatments had reduced (P < 0 .05 ) seed germination and seedling growth as compared to control treatments . These data suggest that tallow is not autotoxic . Tallow seed germination and seedling growth and development maybe enhanced when exposed to its own leaves , litter , and soil . Chromatographic analyses performed on the aqueous extracts support these data . No potential allelochemicals were detected during gas chromatography /mass spectrophotometry analyses . The only chemical detected during these analyses was inositol - a naturally occurring a cyclohexanehexanol . Therefore , successful tallow invasion is likely enhanced through mechanisms other than allelopathy . Time -activity budgets were developed for black -and -white (Mniotilta varia ) and yellow -rumped (Dendroica coronata ) warblers . Feeding , resting , moving , maintenance , searching for food , calling while perched , and moving and calling behaviors were quantified . During 1995 and 1996 , searching for food was the predominant (56 .48 % ) activity for black -and -white warblers , whereas resting (55 .89 % ) was the predominant activity for yellow -rumped warblers . Behavior data were also determined for other migrant , permanent resident , and winter resident birds . Migrants were observed feeding or searching for food more (P < 0 .05 ) than either permanent or winter resident birds . These data support the hypothesis that migrant birds allocate more time to feeding and searching for food than either permanent or w inter residents birds . I collected Chinese tallow seeds that had been fed upon by yellow -rumped warblers during 1995 and subjected them to seed germination bioassays . No differences (P > 0 .05 ) were observed for percent germination between seeds fed upon by yellow -rumped warblers (2 .5 % ) and seed that were collected directly from Chinese tallow trees (2 .5 % ) . Bird feeding activities do not enhance tallow seed germination , but birds may still influence future tallow expansion through seed dispersal .
URI: http : / /hdl .handle .net /2346 /11198
Date: 1997-12

Citation

Conway, Warren C Avian behavior in Chinese tallow woodlands and evaluating the potential control and allelopathic interference of Chinese tallow. Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /11198 .

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