American Chestnut Growth and Survival Five Years after Planting in Two Silvicultural Treatments in the Southern Appalachians, USA

Henry Mcnab,David Loftis,Stanley Zarnoch,Stacy Clark

doi:10.3390/f3041017

Henry Mcnab, David Loftis + Show 2 more

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https://doi.org/10.3390/f3041017

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Abstract

The ability to restore American chestnut (Castanea dentata) through the planting of blight-resistant (Cryphonectria parasitica) trees is currently being tested. Forest-based research on the species’ silvicultural requirements and chestnut blight development are lacking. Pure American chestnut seedlings were planted in a two-age shelterwood forest with low residual basal area and in a midstory-removal treatment with high residual basal area. Survival did not differ between silvicultural treatments and averaged 67 percent across both treatments by the fifth year. Trees in the two-age shelterwood were 2.36 m and 16.8 mm larger in height and ground-line diameter, respectively, compared to trees in the midstory-removal by the fifth growing season. Blight occurrence was not affected by silvicultural treatment. Exploratory analyses indicated that seedling grading at planting and keeping trees free-to-grow through competition control would have resulted in a two-year gain in height and GLD growth in the two-age shelterwood treatment. The two-age shelterwood represented the most efficacious prescription for chestnut restoration, but the midstory-removal prescription may offer a reasonable alternative in areas where harvesting must be delayed.

Highlights

Survival did not differ between silvicultural treatments for any year (F < 0.32, df = 2, P > 0.63) and averaged 67 percent across all stands and treatments by the fifth year (Table 2)
Chestnuts were capable of fast growth under high-light conditions and low canopy cover of the two-age shelterwood stand, growing on average approximately 0.51 m in height and 4.3 mm in ground-line diameter (GLD)
Other studies found that American chestnut maximizes photosynthesis under high-light conditions similar to other shade intolerant species [17,41], and has high growth rates following release from competition [42]

Summary

Introduction

Borkh.) was an abundant and important tree species in eastern North American forests for thousands of years until the 20th century [1]. The American chestnut constituted one-fourth to one-half of the canopy trees in its native range [2,3]. In the early 1900s, the American chestnut provided more than 25 percent of all timber harvested in the southern Appalachians [4]. The species was described as important for forest management in Tennessee [5] and a “promising tree” for artificial regeneration in the early 1900s [6]. The early 1900s, probably through imported Japanese chestnut (C. crenata Siebold and Zucc.) nut cultivars [7], and the American chestnut was ecologically extirpated within a few decades. The species was able to persist from remnant root systems as understory sprouts that infrequently live long enough to flower and bear fruit [8]

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