Influence of herbaceous and woody competition on white pine regeneration in a uniform shelterwood

Abstract

We investigated the effects of herbaceous and woody vegetation control on the survival and growth of planted and natural eastern white pine (Pinus strobus L.) seedlings through six growing seasons following a uniform shelterwood regeneration harvest on two independent sites. Subsequent to chain scarification, white pine seedlings were planted at 2-m spacing, augmenting natural regeneration (full stocking and >3000 seedlings per ha). Herbaceous vegetation control involved the suppression of grasses, forbs, ferns, and low shrubs, and was maintained for zero, two, or four growing seasons after planting. Woody control involved the removal of all tall shrubs and deciduous trees, and was conducted at the time of planting, at the end of the second or fifth growing seasons, or not at all. White pine seedling growth responded positively to increased duration of herbaceous vegetation control and negatively to delayed woody control. Maximum growth was not realized unless both types of vegetation were suppressed. During the first six growing seasons, the height growth of planted pine was more than twice that of naturally regenerating pine, regardless of tending regime. The study suggests that successful white pine regeneration may be achieved by thinning from below to allow 50% to 60% of full sunlight in the understory, followed by the proactive, early suppression of woody and herbaceous vegetation to maintain optimum light levels and reduce competition for soil moisture and nutrients.Key words: eastern white pine (Pinus strobus L.), trembling aspen (Populus tremuloides Michx.), red maple (Acer rubrum L.), uniform shelterwood; competition, vegetation management, silviculture RÉSUMÉ Nous avons étudié les effets du contrôle de la végétation herbacée et ligneuse sur la survie et la croissance de semis plantés et naturels de pin blanc (Pinus strobus L.) au cours des six années de croissance qui ont suivi une exploitation selon un mode de régénération par coupes progressives uniformes sur deux sites indépendants. À la suite d'un scarifiage par chaîne, des semis de pin blanc ont été plantés selon un espacement de 2 m pour accroître la régénération naturelle (densité relative complète et > 3000 semis par ha). Le contrôle de la végétation herbacée comportait la suppression des graminées, des plantes herbacées, des fougères et des arbrisseaux de faible taille et a été effectué l'année même de la plantation, deux ans ou quatre ans après. Le contrôle de la végétation ligneuse comportait la coupe de tous les arbrisseaux de grande taille et des feuillus et a été réalisé au moment de la plantation, à la fin de la seconde ou de la cinquième année de croissance ou pas du tout. La croissance des semis de pin blanc s' est avérée être positive selon la durée accrue de contrôle de la végétation herbacée, mais elle a été négative dans le cas du contrôle retardé de la végétation ligneuse. Le maximum de croissance n'a été atteint que lorsque les deux types de contrôle avaient été effectués. Au cours des six premières années de développeme...

Pre-logging Treatment of Invasive Glossy Buckthorn (Frangula alnus Mill.) Promotes Regeneration of Eastern White Pine (Pinus strobus L.)

“…Buckthorn influence was reduced sufficiently by cutting and flaming so that white pine seedlings were released, a response consistent with an extensive literature indicating that white pine grows better with little competition, e.g., [32,33]. The response of pine seedling density in 2012 to buckthorn removal, however, suggested a complex relationship to logging, with greatest pine response to buckthorn removal occurring in stands that were not logged.…”

Influence of herbaceous and woody vegetation control on seedling microclimate, leaf gas exchange, water status, and nutrient relations of Pinus strobus L. seedlings planted in a shelterwood

“…The underlying field study contains 72 treatment plots and a response surface design to quantify the effects of duration of herbaceous vegetation control and the timing of woody vegetation control on performance of planted white pine (Pitt et al, 2011). Our investigation was confined to the four treatments situated at the extremes of the response surface: herbaceous and woody vegetation control, each at two levels (none vs. applied).…”

“…The stand was chain scarified in spring 2001. Further details on pre-and post-harvest stand structure are presented in Pitt et al (2011).…”

“…The four vegetation control treatments were initiated at the end of the 2001 GS and maintained for the first four GSs after underplanting (2002GSs after underplanting ( -2005 (Pitt et al, 2011). Herbaceous-only control (H) and complete vegetation control (both herbaceous and woody) (B) treatments were implemented using a combination of manual weeding and directed foliar applications of glyphosate (2% solution of Vision Ò ) at the end of each GS.…”

“…In a parallel study established in a nearby uniform shelterwood, and using the same experimental design (Pitt et al, 2011), we addressed three primary research questions:…”