Plant development and gas exchange of Alnus maritima in dry and flooded soil

Abstract

CHAPTER 1. GENERAL INTRODUCTION The cause of population isolation in A. maritima is controversial. Some theorize that indigenous people carried seeds from the Delmarva population to Oklahoma due to the use of Alnus in various medicinal remedies (Stibolt, 1981). However, the more recently discovered population in Georgia, and fossil evidence of other Clethropsis subgenera in the northwestern United States, tend to discount this theory (Furlow, 1979; Schrader, 1999; Schrader and Graves, 2000a; 2000b; Stibolt, 1981). The populations in Georgia and on the Delmarva Peninsula more closely resemble each other than the population in Oklahoma, both morphologically and developmentally (Schrader and Graves, 2000a). These findings, along with the fossil evidence, indicate the three populations are vestiges of a larger population, with the population in Oklahoma becoming isolated and diverging before the populations in Delmarva and Georgia (Furlow, 1979; Schrader and Graves, 2000a; Stibolt, 1981). Urban landscapes Plants are an integral part of our managed landscapes (Grey and Deneke, 1986). Trees in urban environments often suffer greater stress than trees in more natural settings. Urban trees are planted because of their aesthetic and physical benefits, while trees found in nature are adapted to their habitats (Kramer, 1987). In general, urban landscape plantings use only a few species known to tolerate the environmental stresses unique to urban areas (Hunt, • 1989). In New York City, four species constituted 82% of 375 trees planted on land of the Consolidated Edison Company (Berrang et al., 1985). Two of the predominant abiotic stresses plants in managed landscapes must tolerate or avoid are extreme and varied soil

`September Sun' Seaside Alder: An Autumn-blooming Shrub Native to North America

“…Therefore, its useful range includes areas with mean annual minimum temperatures at least as mild as -15 °C, and attempts to use ʻSeptember Sunʼin somewhat milder climates are warranted. ʻSeptember Sunʼ thrives in wet soils, can survive complete inundation of its root zone with fresh water indefinitely, and is more resistant to drought than are other alders cultivated in North America (Gardner, 2001). Indigenous plants of A. maritima subsp.…”

“…This fact, along with our observations of plants in greenhouses and field trials, indicates that ʻSeptember Sunʼ should be planted at exposed sites only. Its symbiotic relationship with Frankia, a ubiquitous, nitrogen-fixing soil bacterium, make ʻSeptember Sunʼ an excellent choice for nitrogen-poor soils (Benson and Sylvester, 1993;Kratsch and Graves, 2004). Soil pH is as high as 8.4 adjacent to indigenous A. maritima subsp.…”