Landscape-scale tree growth dynamics at three southern West Virginia National Parks: Bluestone National Scenic River, Gauley River National Recreation Area, and New River Gorge National River

Saladyga, Thomas; Maxwell, R.; Perles, Stephanie

We used tree core samples collected between 2015 and 2018 at 186 long-term forest monitoring plots distributed across three National Park Service units in southern West Virginia (Figure 1) to assess landscape-scale climate-tree growth relationships and patterns of canopy gap disturbance. We must stress that the tree core samples analyzed herein were not collected with these objectives in mind. Therefore, our analyses and interpretation of results should be viewed in the context of potential applications for regional tree-ring datasets, rather than as the final word on local forest patterns and processes. Specifically, our investigation answered the following questions: What are the climatic drivers of growth in three dominant, or common, tree species, Liriodendron tulipifera L. (tuliptree or poplar), Quercus alba L. (white oak), and Quercus prinus L. (chestnut oak)? Tree growth of dominant species is positively correlated with moisture in the current growing season (May – August) and previous growing season (July – October). Tree growth in the study region is responsive to climate over the broader central portion of the eastern United States. How have climate-tree growth relationships changed over time? The tree growth response to climate shifted over time in Quercus species with decreasing positive correlations to current growing season moisture and increasing positive correlations to previous growing season moisture. L. tulipifera growth-climate relationships remained mostly stable. Shifts in the growth response to climate are linked to significant shifts in moisture in June and August. Does the timing and spatial extent of canopy gap disturbance vary across Park units or by terrain position? There is little evidence of spatial clustering of canopy gap disturbance at BLUE, GARI, and NERI during the 20th century, suggesting that canopy gap disturbance typically occurred in a random spatial pattern, consistent with the concept of small gap formation in closed-canopy deciduous forests. Canopy gap disturbance is dependent on terrain position, with more growth releases occurring than expected at plots located on steep slopes. For all plots combined, canopy gap disturbance was most extensive during the 1930s, 1960s, 1970s, and 1990s. Based on our results, what additional research questions might be addressed with more systematic data collection, either at the landscape or local scale? We suggest that targeting species with low representation in the data set (e.g., eastern hemlock, eastern white pine, and red maple) would provide a fuller understanding of the variable response of tree species to changes in climate both past and present. A second method for expanding the analysis would be to include tree core data from throughout the central Appalachian region. In addition, systematic sampling (e.g., large plots) would be necessary to improve our understanding of past disturbances at multiple spatial scales.

Landscape-scale tree growth dynamics at three southern West Virginia National Parks: Bluestone National Scenic River, Gauley River National Recreation Area, and New River Gorge National River

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