History Of Tree Species Research Articles

Genetic diversity in North American Cercis Canadensis reveals an ancient population bottleneck that originated after the last glacial maximum

Understanding of the present-day genetic diversity, population structure, and evolutionary history of tree species can inform resource management and conservation activities, including response to pressures presented by a changing climate. Cercis canadensis (Eastern Redbud) is an economically valuable understory tree species native to the United States (U.S.) that is also important for forest ecosystem and wildlife health. Here, we document and explain the population genetics and evolutionary history of this deciduous tree species across its distributed range. In this study, we used twelve microsatellite markers to investigate 691 wild-type trees sampled at 74 collection sites from 23 Eastern U.S. states. High genetic diversity and limited gene flow were revealed in wild, natural stands of C. canadensis with populations that are explained by two major genetic clusters. These findings indicate that an ancient population bottleneck occurred coinciding with the last glacial maximum (LGM) in North America. The structure in current populations likely originated from an ancient population in the eastern U.S. that survived LGM and then later diverged into two contemporary clusters. Data suggests that populations have expanded since the last glaciation event from one into several post-glacial refugia that now occupy this species’ current geographic range. Our enhanced understanding benchmarks the genetic variation preserved within this species and can direct future efforts in conservation, and resource utilization of adaptively resilient populations that present the greatest genetic and structural diversity.

Mexican Bark Paper: Evidence of History of Tree Species Used and Their Fiber Characteristics

Mexican Bark Paper: Evidence of History of Tree Species Used and Their Fiber Characteristics. The use of bark fibers (secondary phloem) for the manufacture of the Mexican bark paper called amate can be traced back to the pre–Hispanic period. This paper was used extensively during this period, and for the last four decades has been produced as a handicraft by the Nahnus of San Pablito village in the Sierra Norte de Puebla region of Mexico. Due to the high demand for this product, new species are now used as a source of bark and specific phases of the traditional production technique have been modified. The focus of this study was to register all the species that have been used for bark paper manufacturing, both traditionally and more recently, and to analyze their fiber characteristics, mainly fiber length and lignin content. The main questions addressed by this study were: a) Which species have been used for bark paper production, both prior to and following its commercialization as a handicraft? b) Which anatomical and histochemical fiber characteristics of these species enable their use for bark paper production, regardless of taxa? And c) is there a relationship between the adoption and use of new species and recent changes in traditional paper making techniques? Based on an ethnobotanical study, a list of 13 species used for bark paper production was compiled and bark samples from each species were collected for phloem anatomical and histochemical analysis. Artisans and local healers were also asked to determine the main characteristics of each fiber and paper type. The results demonstrate that bark from currently used species differs anatomically and histochemically from species used during the pre–Hispanic period and until a few decades ago, and in terms of the quality assessed by local healers and artisans. Among other characteristics, the fibers of the new species have higher lignin content than the traditional ones, and this constitutes the main reason behind the modification of certain phases of the traditional paper making process.