Effects of Whole-Tree Harvesting on Species Composition of Tree and Understory Communities in a Northern Hardwood Forest

In the northeastern United States, whole-tree harvesting is widely used to supply fuel to biomass energy facilities, but questions remain regarding its long-term sustainability. We have previously reported findings indicating no short-term decrease in forest productivity in whole-tree harvested sites when compared with similar conventionally (stem-only) harvested sites. Here we present additional results of the same study, but focus on the effect harvest treatment has on the species composition of the regenerating forest. Within northern hardwood forests in central New Hampshire and western Maine, regeneration surveys were conducted on four (4) small clearcuts in 2010 and twenty-nine (29) small clearcuts in 2011. The species and diameter of trees > 2 m in height were recorded within 1 m or 2 m-radius plots and used to calculate the biomass fraction of each species. The 2010 study additionally measured the density of trees 2 m in height and the diversity of understory non-tree species. Non-metric multidimensional scaling and multi-response permutation procedures were used to determine the effect of harvest treatment had on community-wide tree species composition. Potential differences were also examined on a species-by-species basis. Both analytic methods indicated no significant differences in species composition of tree species or understory communities. Within the limits of our data, we conclude that no significant effects of residue removal on species composition are observed within our sample of northern hardwood sites at this early stage of stand development.

Temporal characteristics of agarwood formation in Aquilaria sinensis after applying whole-tree agarwood-inducing technique

Objective: Agarwood—a resinous wood produced by Aquilaria plants in response to injury or artificial induction—is a valuable medicinal and fragrance resource. Whole-Tree Agarwood-Inducing Technique(Agar-WIT) has been widely used to produce agarwood. However, the time-dependent characteristics of agarwood formation induced by Agar-WIT are yet to be clarified. To promote technologically efficient utilization and upgradation of Agar-WIT, the dynamic process and mechanism of agarwood formation were analyzed for one year.Methods: Agarwood formation percentage, barrier layer microscopic properties, extract levels, compound level, and characteristic chromatograms of agarwood were examined by referring to the Chinese Pharmacopeia(2020 version).Results: Agar-WIT could maintain a high percentage of agarwood formation over one year compared with that of healthy plants. Alcohol-soluble extract and agarotetrol levels showed fluctuating cyclic changes with peaks occurring first during the fifth and sixth months, and subsequently in the 11th month.Aquilaria trees subjected to Agar-WIT treatment for 1–12 months showed significant characteristics of a dynamic agarwood formation process. The barrier layer began to appear in the fourth month after treatment. Alcohol-soluble extractive levels in agarwood formed in the second month, and thereafter,exceeded 10.0%, and agarotetrol in agarwood produced after four months or later, exceeded 0.10%.Conclusion: According to the Chinese Pharmacopoeia, alcohol-soluble extractive levels in agarwood should not be less than 10.0% and agarotetrol level should exceed 0.10%. After four months of Agar-WIT treatment, the formed agarwood theoretically met these standards and was suitable for developed and utilization. However, the optimal harvest time was found to be the 11th month, followed by the sixth month after Agar-WIT treatment. Therefore, Agar-WIT resulted in swift agarwood formation and stable accumulation of alcohol-soluble extracts and agarotetrol. Thus, this method is efficient for large-scale cultivation of Aquilaria sinensis to produce agarwood and provide raw materials for the agarwood medicinal industry.

Production of high-quality agarwood in Aquilaria sinensis trees via whole-tree agarwood-induction technology

We used whole-tree agarwood-induction technology to produce agarwood from Aquilaria sinensis trees within 20 months, and evaluated the quality of this agarwood. The results showed its characteristics were similar to those of high-grade wild agarwood in terms of texture, chemical constituents, essential oil content, and ethanol-soluble extract content, with the lattermost quality far surpassing the requirement of traditional Chinese medicine agarwood, as indicated in Chinese Pharmacopoeia 2010. To the best of our knowledge, this is first study to show that high-quality agarwood can be produced in whole A. sinensis trees via a chemically induced technology.

Field Performance of Quercus bicolor Established as Repeatedly Air-Root-Pruned Container and Bareroot Planting Stock

Benefits of repeated air-root-pruning of seedlings when stepping up to progressively larger containers include excellent lateral root distribution immediately below the root collar and an exceptionally fibrous root ball. To evaluate long-term field performance of repeatedly air-root-pruned container stock, three plantings of swamp white oak (Quercus bicolor Willd.) 10 to 13 years old were located that also included bareroot planting stock. Initial and final stem diameter and height and above-ground green weights were determined on randomly selected trees at each site. On a site with a sandy, excessively drained, high pH soil, trees (age 10) from container stock were 1.5 times taller, 2.3 times larger in dbh, and 2.8 times greater in green weight than trees from bareroot stock which averaged only 2.9 m tall, 3.9 cm dbh, and 16.3 kg green weight. On a site with high clay, poor internal drainage, and frequent flooding, trees (age 12) from container stock were 1.4 times taller, 1.8 times larger in dbh, and 4.1 times greater in green weight than trees from bareroot stock which averaged 4 m tall, 7.3 cm dbh, and 28 kg green weight. On an upland site with deep loess soils, there was a trend for trees (age 13) from container stock to be only slightly larger than trees from bareroot stock with each stock type averaging 9.6 m tall, 20 cm dbh, and 177 kg green weight. Repeated air-root pruning produced lateral roots immediately below the root collar that resulted in large container stock with large well-balanced root systems that were competitive on harsh or less than ideal oak sites. Although the process is relatively labor intensive, propagation of repeatedly air-root-pruned container stock is readily adaptable internationally to locally available sources of organic matter and open-bottom containers.