Philip W. Rundel

Ecological Relationships of Desert Fog Zone Lichens"l3

Abstract. Patterns of environmental conditions prevailing in coastal desert fog zones provide habitats extremely favorable for lichen growth. Phylogenet- ically related groups of lichens occur in geographically isolated desert fog zones, but endemism at both the species and genus levels is relatively high. The ecological importance of lichens in these regions is related to morpholog- ical and physiological adaptations to water uptake in both a liquid and vapor form. Much of this moisture is unavailable to vascular plants, allowing a large biomass of lichens to occur in areas with little or no vascular plant cover. The relative importance of fruticose lichens in such habitats, in comparison to crustose and foliose forms, is determined largely by the physical form of at- mospheric moisture. Coastal deserts share many environmental features common to all deserts. Rainfall is low and vegetation is commonly sparse or lacking. At the same time, coastal deserts have certain distinctive characteristics not shared by inland deserts. Temperature differences between night and day are moderated by the proximity of the sea. More important for lichens, however, is the typical occurrence of high atmospheric humid- ity, fog and/or dew along the coast. Extensive coastal deserts occur in three areas of the world: the Peruvian and Chi- lean Atacama deserts, the coastal Sonoran Desert in Baja California and the Namib Desert in southwestern Africa. Each of these areas shares the same origin of climatic development in the movements of sub-tropical high pressure centers resulting in the transport and upwelling of cold currents adjacent to their coasts. Details of the general climatology of these regions has been described in many publications (e.g. Meigs, 1966; Rumney, 1968). Each of these coastal fog deserts is characterized by lichen floras rich in both diversity and biomass. This review describes the ecological and floristic relationships of lichens in these coastal fog deserts with particular emphasis on the coastal Atacama and Baja California regions. Coastal Atacama Desert.-The Atacama desert along the coasts of Peru and north- ern Chile, perhaps the driest region in the world in terms of measurable precipitation, extends from the region north of Trujillo near the Ecuadorian border of Peru (50?S) south to La Serena (30?S) in Chile, a total distance of more than 3500 km. Along this belt is a narrow strip of coastal desert whose biological characteristics are profoundly influenced by frequent maritime fogs. The cold northward flowing Humboldt current

The Ramalina intermedia Complex in North America

Ramalina intermedia has a North American distribution ranging from New Brunswick south along the eastern seaboard, inland throughout Quebec and Ontario, and has been reported from the Northwest Territories and Alberta. This species is abundant in the Great Lakes region, and has been collected in mountainous areas of Colorado, New Mexico, and Arizona. This species has a single chemical race in North America containing sekikaic, homosekikaic, and usnic acids and variably possessing atranorin and an unknown. Fertile thalli are reported from North America. A new species, Ramalina petrina, is described from the Appalachian Mountains. This small sorediate species is characterized by conspicuous terminal soralia borne on recurved lobe tips. Ramalina petrina is PD+ and contains protocetraric acid, usnic acid, and atranorin. Ramalina intermedia is one of the most widespread, yet most often misidentified small sorediate species of Ramalina in North America. Although it is common and abundant in much of its range and is well represented in herbaria, the species has been poorly understood. It is the purpose of this study to clarify the chemical ecology and distribution of this species in North America. The distribution of R. intermedia is sympatric, in part, with R. farinacea, R. pollinaria, and R. roesleri. All three are species with which it has been confused. Examination of herbarium specimens and field collections has shown that R. intermedia consistently contains sekikaic and homosekikaic acids. The identity of homosekikaic acid in R. intermedia was determined by Chicita Culberson (pers. comm.). Surveys of thallus chemistry were carried out by thin-layer chromatography with Merck Silica Gel F254 pre-coated glass plates using a benzene:dioxane: acetic acid (90/25/4, v/v/v) solvent system as described by Culberson and Kristinsson (1970). Microextraction was effected upon thallus fragments using warm acetone. The plates were developed with 10% H2SO4 and heat. All of the 140 thalli tested by thin layer chromatography contained sekikaic, homosekikaic, and usnic acids. Atranorin and an unknown (Rf class 3 in this solvent system) were found in a few plants. Usnic and homosekikaic acids appeared to vary greatly in concentrations, occasionally present only in trace amounts. Taylor (1968) reported no medullary acids in individuals of R. intermedia from Ohio. We have been unable to confirm the existence of this strain in our studies. Ramalina intermedia has a much broader ecological amplitude and range of substrate This content downloaded from 164.67.185.210 on Fri, 18 Jul 2014 18:06:56 PM All use subject to JSTOR Terms and Conditions 618 THE BRYOLOGIST [Volume 77

Taxonomy and ecology : proceedings of an international symposium held at the Department of Botany, University of Reading

Taxonomy and ecology; proceedings of an international symposium held at the Dept. of Botany, University of Reading , Taxonomy and ecology; proceedings of an international symposium held at the Dept. of Botany, Univers... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی