Eastern hemlock (Tsuga canadensis [L.] Carr.)is an ecologically important tree species experiencing severe mortality across much of its eastern North American distribution, caused by infestation of the exotic hemlock woolly adelgid (Adelges tsugae Annand). To guide gene conservation strategies for this imperiled conifer, we conducted a range-wide genetic variation study for eastern hemlock, amplifying 13 highly polymorphic nuclear microsatellite loci in 1,180 trees across 60 populations. The results demonstrate that eastern hemlock exhibits moderate inbreeding, possibly a signature of a prehistoric decline associated with a widespread insect outbreak. Contrary to expectations, populations in formerly glaciated regions are not less genetically diverse than in the putative southern refugial region. As expected, peripheral disjunct populations are less genetically diverse than main-range populations, but some are highly genetically differentiated or contain unique alleles. Spatially explicit Bayesian clustering analyses suggest that three or four Pleistocene glacial refuges may have existed in the Southeastern United States, with a main postglacial movement into the Northeast and the Great Lakes region. Efforts to conserve eastern hemlock genetic material should emphasize the capture of broad adaptability that occurs across the geographic range of the species, as well as genetic variability within regions with the highest allelic richness and heterozygosity, such as the Southern Appalachians and New England, and within disjunct populations that are genetically distinct. Much genetic variation exists in areas both infested and uninfested by the adelgid.

Eastern hemlock (Tsuga canadensis [L.] Carr.) is a widespread and ecologically important conifer species of eastern North America that is threatened by the hemlock woolly adelgid (Adelges tsugae Annand), a pest introduced into the United States from Asia in the 1920s. Information about the genetic composition of eastern hemlock is necessary to guide ex situ conservation efforts in the southeastern United States, where the species is expected to harbor relatively high amounts of genetic variation in areas of Pleistocene glacial refuge. Nineteen allozyme markers were used to quantify the genetic variation present in 20 eastern hemlock populations in the southeastern United States. Results indicate that the species has low levels of genetic diversity in the region compared to most other conifers, but greater population differentiation (F ST = 0.126). Populations along the eastern periphery and in the Appalachian interior exhibited higher levels of diversity than those along the western periphery of its geographic range. The results suggest that the glacial refuge area for eastern hemlock was likely located east of the southern Appalachian Mountains, and indicate that ex situ conservation seed collections should be concentrated in these areas of higher diversity.

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Due to a combination of durability, strength, and aesthetically pleasing color, teak ( Tectona grandis L.f.) is globally regarded as a premier timber species. High value, in combination with comprehensive harvesting restrictions from natural populations, has resulted in extensive teak plantation establishment throughout the tropics and subtropics. Plantations directly depend on the production of healthy seedlings. In order to assist growers in efficiently diagnosing teak seedling nutrient issues, a hydroponic nutrient study was conducted at North Carolina State University. The ability to accurately diagnose nutrient disorders prior to the onset of visual symptoms through the use of near infrared (NIR) technology will allow growers to potentially remedy seedling issues before irreversible damage is done. This research utilized two different near infrared (NIR) spectrometers to develop predictive foliar nutrient models for 13 nutrients and then compared the accuracy of the models between the devices. Destructive leaf sampling and laboratory grade NIR spectroscopy scanning was compared to nondestructive sampling coupled with a handheld NIR device used in a greenhouse. Using traditional wet lab foliar analysis results for calibration, nutrient prediction models for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), copper (Cu), molybdenum (Mo), magnesium (Mg), boron (B), calcium (Ca), manganese (Mn), iron (Fe), sodium (Na), and zinc (Z) were developed using both NIR devices. Models developed using both techniques were good for N, P, and K (R2 > 0.80), while the B model was adequate only with the destructive sampling procedure. Models for the remaining nutrients were not suitable. Although destructive sampling and desktop scanning procedure generally produced models with higher correlations they required work and time for sample preparation that might reduce the value of this NIR approach. The results suggest that both destructive and nondestructive sampling NIR calibrations can be useful to monitor macro nutrient status of teak plants grown in a nursery environment.

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