Amy Ross-Davis

Establishment success of conservation tree plantations in relation to silvicultural practices in Indiana, USA

In the Central Hardwood Forest region of the United States, the variable and somewhat unpredictable establishment success of hardwood tree plantations has traditionally been attributed to competing vegetation and damage due to animal browse. We examined operational plantation establishment success (1–5 years following planting) as it relates to use of particular silvicultural practices. Silvicultural histories were obtained for 87 randomly selected plantations throughout Indiana and field data were collected from each to determine tree survival, tree vigor, and abundance of surrounding vegetation. Survival was highest at sites that were treated with herbicide prior to planting and that had been mechanically planted (as opposed to hand planted). The percentage of trees with evidence of dieback was highest on sites at which browse protection measures had been used, likely reflecting a combination of damage due to inherently high white-tailed deer (Odocoileus virginianus Zimmermann) populations at such sites and ineffectiveness of current browse protection measures. Sites planted by a professional forester and those with herbicide applied subsequent to planting had a higher percentage of trees deemed free-to-grow. Subsequent herbicide application did not reduce cover or height of competing vegetation; however, when used in conjunction with mechanical site preparation techniques, overall cover and height of herbaceous vegetation was reduced.

Microsatellite markers for Juglans cinerea L. and their utility in other Juglandaceae species

Ten polymorphic microsatellite markers were found to amplify in butternut (Juglans cinerea; Juglandaceae). These microsatellite loci were found to amplify across most of nine other species and five hybrids examined. Loci were highly polymorphic, with 18 to 32 alleles per locus across species. These nuclear microsatellite markers will be useful in examining genetic diversity within and among populations of butternut, and in distinguishing butternut from interspecific hybrids.

Cold hardiness and transplant response of Juglans nigra seedlings subjected to alternative storage regimes

Abstract• Effects of overwinter storage regimes on seedling cold hardiness and physiological vigor are relatively unexplored, particularly for temperate deciduous forest tree species.• We evaluated influence of storage duration (0, 66, 119, or 175 d) on electrolyte leakage of stem and root collar tissues following exposure to a series of freeze-test temperatures in black walnut (Juglans nigra L.) seedlings sampled from cold (3 °C) or freezer (−2 °C) storage. Seedlings were subsequently transplanted into a controlled growth chamber environment for two months.• Regardless of storage temperature, mean LT50 was lowest for seedlings stored for 66 d (≤ −34 °C) and increased dramatically after 119 d (≥ −13 °C).• Root collar tissue had lower LT50 than stem tissue after 119 d for cold-stored seedlings, reflecting importance of evaluative tissue type. Days to bud break shortened with increasing storage duration up to 119 d and stabilized thereafter for both storage regimes. Root growth potential was maximized after 119 d of storage, and subsequently declined for cold-stored seedlings. Height growth increased following storage, regardless of duration.• To promote stress resistance and transplant growth response, we recommend that black walnut seedlings from this genetic source be outplanted after approximately 66–119 d of storage.Résumé• Les effets de différentes modalités de stockage hivernal sur la résistance au froid des semis et sur leur vigueur physiologique ont été relativement inexplorés, en particulier pour les arbres forestiers décidus tempérés.• Nous avons évalué l’influence de la durée de stockage (0, 66, 119 ou 175 jours) sur la perte d’électrolyte de la tige et des tissus du collet racinaire exposés à une série de tests (témoin 4 %C, −10 °C, −20 °C, −40 °C) de température de congélation de semis de noyer noir (Juglans nigra L.), après stockage au froid (3 °C) ou au gel (−2 °C). Les semis étaient ensuite transplantés dans une chambre climatisée pour une durée de deux mois. Indépendamment de la température de stockage, la moyenne de LT50 (température létale correspondant à un endommagement de 50 % des plants) a été plus basse pour les semis stockés pendant 66 jours (≤ −34 °C) et s’est accrue de façon spectaculaire après 119 jours (≥ −13 °C).• Les tissus du collet racinaire avaient un plus bas LT50 que les tissus de la tige, après 119 jours pour les semis stockés au froid, reflétant l’importance du type de tissu pour l’évaluation. Le nombre de jours jusqu’au débourrement a été raccourci avec l’accroissement de la durée de stockage jusqu’à 119 jours et s’est stabilisé par la suite pour les deux modalités de stockage. Le potentiel de croissance racinaire a été maximisé après 119 jours de stockage et a décliné par la suite, pour les semis stockés au froid. La croissance en hauteur s’est accrue à la suite du stockage, indépendamment de sa durée.• Pour promouvoir une résistance élevée au stress et une forte reprise de croissance des semis transplantés, nous recommandons que les semis de noyer noir de cette source génétique soient plantés après approximativement 66 à 119 jours de stockage.

Morphology, gas exchange, and chlorophyll content of longleaf pine seedlings in response to rooting volume, copper root pruning, and nitrogen supply in a container nursery

Few pine species develop a seedling grass stage; this growth phase, characterized by strong, carrot-like taproots and a stem-less nature, poses unique challenges during nursery production. Fertilization levels beyond optimum could result in excessive diameter growth that reduces seedling quality as measured by the root bound index (RBI). We grew longleaf pine (Pinus palustris), a grass stage species, in containers of four different volumes (60–336xa0ml) either coated with copper oxychloride or left untreated and fertilized at low, medium, or high levels of nitrogen (N). In general, N concentration of tissues rose as N rate increased, with larger changes in concentration occurring between low and medium levels than between medium and high levels. N rate influenced root tissue N concentration less than it did stems and needles. Subtle needle color differences caused by N rate were significant, suggesting its potential utility during nursery production. As expected, seedlings grew larger as container volume increased and as N rate increased. Copper treatment, which we posited could influence the RBI, tended to increase root-collar diameter and tap root biomass and decrease total root volume. Chlorophyll abundance was affected more by N rate than by container volume or copper treatment, but photosynthesis was affected more by copper treatment than N rate or container size. Although RBI was 25xa0% greater for seedlings grown in small containers with high N rates than those grown in large containers with low N rates, RBI ranged only from 11 to 15xa0%, well below the critical 27xa0% threshold.

Do Container Volume, Site Preparation, and Field Fertilization Affect Restoration Potential of Wyoming Big Sagebrush?

ABSTRACT: Land management practices, invasive species expansion, and changes in the fire regime greatly impact the distribution of native plants in natural areas. Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), a keystone species in the Great Basin, has seen a 50% reduction in its distribution. For many dryland species, reestablishment efforts have focused on direct seeding but achieved only minor success due to irregular seed germination and poor survival. We investigated the effects of container volume and fertilization on the performance of nursery-grown Wyoming big sagebrush seedlings following outplanting. Additionally, to evaluate the impact of site preparation, one-year-old seedlings were outplanted into tilled and untilled field conditions. Initial seedling size increased with container volume; larger seedlings exhibited significantly higher root collar diameter (RCD) growth than smaller seedlings. As container volume increased from 108 to 251 and 336 cm3, seedling survival on the tilled plot increased from 28 to 44 and 43%, respectively, whereas no influence was observed on the untilled plot (57 to 61, and 60%, respectively). Fertilization reduced seedling survival on tilled (by 25%) and untilled (by 14%) plots. Fertilizer increased RCD growth on the untilled plot but final nutrient status was unaffected. Thus, container volume may influence seedling morphology and optimize establishment, while field fertilization, especially during spring outplanting when planting sites have low moisture availability, may hinder first-year survival.