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Description:
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Saltcedar (Tamarix spp . ) has been a problem invasive plant species in the US since its introduction in the 1800's and subsequent escape and naturalization in the 1850's . Saltcedar is a riparian species but has been able to exploit upland sites when adequate moisture conditions occur for seedling establishment . Saltcedar is a perennial shrub that can reach heights of 7 .6 m (25 ft ) , and has a life span of about 100 years . It tolerates extremely saline soil conditions and increases the salt content of the upper soil crust . It is a prolific seed producer with an affinity for disturbed sites in proximity to water . Saltcedar will spread by seeds or vegetatively by stems or roots . It often occurs in tightly habitated monocultures resulting in a closed canopy .
Studies were conducted near Fritch , Texas at Lake Meredith National Recreation Area . Total nonstructural carbohydrate (TNC ) trends , invasion patterns , plant response to fire and rollerchopping , and plant response to triclopyr and imazapyr were monitored . These studies were conducted from January 1999 through October 2000 . Trees treated with triclopyr and imazapyr during the dormant season of early winter of 1999 and late winter of 2000 were evaluated after the 2000 growing season . The objectives of this study were to : (1 ) determine seasonal TNC trends in saltcedar , (2 ) determine 1 >JC differences in burned verses non -burned saltcedar , (3 ) determine mortality of saltcedar following summer wildfire , rollerchopping , and herbicidal treatment , (4 ) monitor invasion capabilities of saltcedar , and (5 ) develop economical , practical , and sound recommendations for saltcedar management .
TNC trends indicate that saltcedar has the lowest TNC concentrations in the spring of the year as it initiates budbreak in May . TNC trends increase and then stabilize during the growing season until after the first hard freeze . After the first freeze until budbreak there is a gradual decline in TNC due to plant metabolism in the absence of vegetative material . Results indicate that the time to optimize saltcedar mortalit ) with mechanical treatment would be during May . This research indicates that there is a slight difference in TNC concentration between burned and non -burned saltcedar for one growing season after burning . Due to the ability of saltcedar to rapidly acquire new vegetative material and its extensive root system and reserves , the difference will only occur during the first growing season after fire .
Triclopyr is an effective herbicidal control of burned , resprouting saltcedar with individual plant basal bark treatments . Lower concentrations (15 % ) of triclopyr were as lethal as higher concentrations (25 % ) with JLB oil alone providing no mortalit ) . Triclopyr was effective in all seasons of treatment . Imazapyr was not an effective herbicidal control of burned , resprouting saltcedar with individual plant basal bark treatments . Imazapyr altered the growth form of the saltcedar leaves and might have caused mortality of saltcedar if more than one growing season was allowed before assessment of treatment .
The following thesis is arranged in four chapters as follows : Chapter I is a review of the literature , Chapter II is invasion monitoring . Chapter III pertains to seasonal TNC trends in burned and non -burned saltcedar , and Chapter IV discusses saltcedar response to fire , rollerchopping , and herbicides . Chapters II , III , and IV were written in journal format for submission for publication as refereed journal articles . The following appendices provide a GIS map of Alibates Creek , data and forms used to record data , and procedures . |