Browsing by Author "Lhotka J.M."

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A Gingrich-style stocking chart for longleaf pine (Pinus palustris Mill.) forests
(2018-05-28) Kara F.; Loewenstein E.F.; Lhotka J.M.; Kush J.S.
Because of the dramatic decline in longleaf pine (Pinus palustris Mill.) acreage, concern about restoration and management of these ecosystems has increased in recent years and created a need for effective silvicultural management tools. Stocking charts are useful quantitative tools to allocate tree area to meet specific silvicultural objectives including restoration; however, there has not been one created specifically for longleaf pine forests. Because successful management of longleaf pine is often associated with density management at or near the onset of full site occupancy, which is readily determined on a stocking chart, the development of the chart for the species was needed. We developed a Gingrich-style stocking chart for longleaf pine forests using published approaches and models from the literature. Average maximum density (A-line stocking) was determined using forest inventory data whereas onset of full site occupancy (B-line stocking) was derived from an existing open-growth crown width equation. Reduced major axis regression was used to determine size-density relationships because it gives less biased and more efficient estimates than ordinary least squares regression. Previous studies, physiological data, and longleaf pine silvical traits all support the size-density characteristics depicted on this stocking chart. We found that percent stocking was better than basal area as a predictor of tree growth, although the difference between the two measures was not significant in understocked stands. The difference between percent stocking and stand density index as a predictor of tree growth was not statistically significant. With the stocking chart presented in this article, tree area relationships can be effectively and easily used to achieve specific silvicultural objectives.
CLIMATE AND SILVICULTURAL IMPLICATIONS IN MODIFYING STAND COMPOSITION IN MIXED FIR-PINE STANDS
(2020-07-03) Kara F.; Lhotka J.M.
A growing concern exists over the decreasing proportion of Scots pine (Pinus sylvestris L.) trees in mixed Trojan fir (Abies nordmanniana subsp. equi-trojani [Asch. & Sint. Ex Boiss] Coode & Cullen)-Scots pine forests in northern Turkey. Given the changes in mean annual temperature and annual precipitation for the last 40 years in the region, understanding of the sensitivity of Trojan fir and Scots pine trees to changing climate seems to be critical so that better management strategies can be developed against the potential climate extremes of the future in the region. Moreover, our knowledge on the influence of current silvicultural methods on seedling density and growth in these forests is limited. Therefore, in this study, the growth response (i.e., radial growth) of Trojan fir and Scots pine trees to the changing climate were examined. In addition, the influence of current silvicultural practices on seedling growth and density in these forests was also monitored. Trojan fir appeared more sensitive to the climatic variables (i.e., temperature and precipitation) than Scots pine in the region. It was also found that the current silvicultural practices might favor Trojan fir over Scots pine in these forests. Natural dynamics and current silvicultural implications would benefit Trojan fir, however, given the species’ potential sensitivity to the changing climate, current silvicultural approaches can be modified to favor Scots pine, and to increase the resilience of these forests against climate extremes expected in the region’s future.
Comparison of unmanaged and managed trojan fir–scots pine forests for structural complexity
(2020-01-01) Kara F.; Lhotka J.M.
Unmanaged forests may exhibit a higher degree of biodiversity compared to managed forests. We examined and compared the stand structure, density, and volume of deadwood components of managed and unmanaged mixed forests of Trojan fir (Abies nordmanniana subsp. equi-trojani [Asch. & Sint. ex Boiss] Coode & Cullen)–Scots pine (Pinus sylvestris L.) in northern Turkey. The single-tree selection method has been employed in the managed forests. Density of large live trees ha–1, density of standing deadwood (SDW) ha–1, and volume of lying deadwood (LDW) (m3 ha–1) were calculated for both treatments (i.e. managed or unmanaged). Results showed that unmanaged forests had significantly higher density of large live trees and SDW compared to managed forests (P < 0.005). In addition, a lower amount of LDW was observed in the managed forests (P < 0.005). Our data suggest that the managed forests’ lack of Scots pine trees in small-and middle-sized diameter classes indicates the potential risk of conversion of these mixed stands into pure Trojan fir forests. Initial results highlight the importance of large tree retention in managed stands to enhance biological diversity.