Type of Document Master's Thesis Author Khanal, Puskar Nath Author's Email Address email@example.com, firstname.lastname@example.org URN etd-08062010-100101 Title Predicting First Year Seedling Survival from Quality Distributions of Bareroot Seedlings and Microsites Degree Master of Science (M.S.) Department Renewable Natural Resources Advisory Committee
Advisor Name Title Dean, Thomas J Committee Chair Cao, Quang V Committee Member Wang, Jing Committee Member Keywords
- microsite quality
- seedling quality
- seedling survival
Date of Defense 2010-06-08 Availability unrestricted AbstractSeeding survival has been a continuing problem since the start of the commercial pine plantation in 1950s. The first-year survival of bare-root loblolly pine seedlings at intensively prepared sites in Louisiana has reached a survival plateau of 75 to 85 % with an average of almost 80 %. The major hypothesis of this research was that the survival plateau is a function of the interaction between the frequency distribution of seedling quality and the frequency distribution of microsite quality. This study examined bare-root seedlings and microsite variation, and analyzed the possible options to increase the first-year seedling survival.
The study was approached with simulation and field studies. In simulation study, twenty hypothetical seedling and microsite quality distributions were paired in a manner that simulated 400 plantings. In field study, caliper, stem height, shoot-root ratio, leaf area, and xylem pressure potential were measured for a bale of nursery seedlings and the quality distribution was computed from the seedling volume. Similarly, the microsite variables soil penetration, bed height, moisture content, total mineral nitrogen, and texture were measured and the quality distribution of 8 Weyerhaeuser planting sites was generated from the height increment of associated seedlings. The distributions were combined to predict the first year survival from the assumptions about proportional survival for each pairing.
The simulation results provided initial support to the hypothesis that consistent survival results from random pairing of initial seedling and site quality distributions. The average caliper was 4.22 mm for the seedling sample obtained from a local nursery. The sample contained at least 31 % inferior quality seedlings and, the planting sites contained 21 % adverse microsites. Analysis showed that the significant proportion of inferior seedlings and adverse microsites would result in lower average survival based on assumed survival matrix. The elimination of seedlings below 5 mm caliper of the nursery stock increased the survival to 90 % at the cost of 40.9 ¢ per seedling, an increase of 37 ¢ per seedling.
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