Heather T. Root

Lichen habitat may be enhanced by thinning treatments in young Tsuga heterophylla-Pseudotsuga menziesii forests

Abstract Forest structural characteristics manipulated by alternative thinning treatments were associated with increases in cyanolichen and alectorioid species richness and changes in lichen community compositions. At two sites in moist conifer forests of western Oregon, lichen community monitoring plots were established before thinning treatments; the most diverse plots in each treatment were retained as diversity islands whereas the less diverse plots were treated in the thinning prescription. We resampled these plots approximately 10 years after thinning. At one site we found that lichen communities in diversity plots were quite similar to those in the surrounding treated forest and that the proportion of Tsuga heterophylla in the stand was negatively associated with alectorioid and cyanolichen richness. At both sites, hardwood gaps and open-grown trees were positively associated with cyanolichen species richness. At the other site, surrounding plots were more like diversity “leave-islands” after thinning than before. Furthermore, thinned plots had more hardwood gaps following the thinning. These thinned plots hosted more Bryoria, Candelaria concolor, Leptogium polycarpum, Peltigera collina, Nephroma laevigatum and Physcia tenella than had been observed prior to thinning. We concluded that thinning treatments retaining remnants, open-grown trees and hardwood gaps have potential to favor lichen communities rich in cyanolichen and alectorioid species.

Biotic soil crust lichen diversity and conservation in shrub-steppe habitats of Oregon and Washington

Abstract Biological soil crusts are ecosystem engineers in arid and semi-arid habitats; they affect soil chemistry, stability, and vegetation. Their ecosystem functions may vary depending on species composition; however, lichen species diversity is poorly known in the Pacific Northwestern drylands of North America. We sampled 59 random and 20 intuitive plots throughout central and eastern Oregon identifying 99 lichen taxa, 33 of which occurred in only one plot and seven of which were new to Oregon (Acarospora obpallens, A. terricola, Catapyrenium psoromoides, Placidium fingens, P. pilosellum, P. yoshimurae and Psora luridella). We compile records from herbaria and other studies to evaluate the rarity of observed species and potentially rare species known from nearby locations. We conclude that 37 species are likely rare or uncommon in our study area. Many of these appear to be associated with calcareous substrates. We model occurrences in relation to climate and soil variables for four uncommon lichen species: Acarospora schleicheri, Fuscopannaria cyanolepra, Rhizocarpon diploschistidina, and Texosporium sancti-jacobi. Based on climate and soil variables, we map regions of Oregon that may support new populations of these species and overlay habitats unsuitable for biotic crusts due to development and agriculture. These species, except Fuscopannaria cyanolepra, are strongly associated with the fine soils along the Columbia and Treasure Valleys that are most intensively used for agriculture. We anticipate that our summaries will further the understanding of lichen component of biological soil crust communities in eastern Oregon and suggest focal species for future conservation efforts.

Arboreal Mite Communities on Epiphytic Lichens of the Adirondack Mountains of New York

Abstract We describe the mite fauna inhabiting the canopies of remnant old-growth Acer saccharum (sugar maple) trees in northern hardwood stands under different silvicultural treatments in the Adirondack Mountains. We also compare mites on different arboreal substrates, including bare bark, the crustose lichen Pertusaria velata, and three foliose lichens: Flavoparmelia caperata, Parmelia squarrosa, and Punctelia rudecta. A total of 877 individual mites were collected representing 25 oribatid mite species, at least three of which are undescribed, and nine non-oribatid mite families. Mite abundance was sevenfold greater in Punctelia rudecta than on bare bark, and communities differed among bark, crustose lichen, and foliose lichens, but not among the different species of foliose lichens. Trees in old growth and reserve shelterwood stands supported different mite communities.

Effects of two silvicultural regimes with large tree retention on epiphytic macrolichen communities in Adirondack northern hardwoods, New York, USA

We sampled epiphytic lichen communities in nine Adirondack northern hardwood stands: three old growth, three reserve shelterwood, and three single-tree selection systems. Our objectives were to assess the effects of treatment, tree diameter at breast height, and their interaction on lichen communities and to determine whether lichen traits were associated with particular habitats. Lichen community composition was strongly related to tree diameter at breast height and differed between old growth and reserve shelterwoods. Lichen community composition was also related to an interaction between tree size and stand type. Lobaria pulmonaria (L.) Hoffm. was associated with large trees in old growth, whereas Evernia mesomorpha Nyl., Parmelia sulcata Taylor, and Physcia millegrana Degel. characterized those in shelterwood stands. Nitrophilous lichens were most common on small trees and in reserve shelterwoods, whereas small trees in selection systems and old growth supported lichens that were found to be most asso...

Forest floor lichen and bryophyte communities in thinned Pseudotsuga menziesii - Tsuga heterophylla forests

Abstract While a great deal of research has illustrated the importance of late-successional forests for maintaining biodiversity in the Pacific Northwest of North America, over 76% of the forests in the region are less than 100 years old. To preserve landscape-level biodiversity, forest managers are increasingly interested in how young stands can be manipulated to favor late-successional species. We sought to understand how stand-level gradients in canopy structure, particularly those affected by thinning, relate to dominant forest floor bryophyte and lichen species composition and abundance. We sampled forest floor lichen and bryophytes ten years after alternative thinning treatments at two sites in western Oregon. Relationships of forest floor communities to canopy structure were site-specific. At the first site, moss and lichen abundance had small-scale geographic patterns and mosses were negatively associated with epiphytic cyanolichen species richness, however, we found no strong associations between forest floor communities and stand structural characteristics. At the second site, lichens, particularly Cladonia, was negatively associated with canopy cover and was most in thinned plots. Bryophyte abundance was positively associated with Tsuga basal area. This relationship was stronger in the thinned stands, which had a different community composition than those left unthinned. Overall, the forest floor communities were fairly homogeneous at both sites and relationships with stand structural variables were subtle, indicating that thinning did not have a strong impact.

Native and exotic plant cover vary inversely along a climate gradient 11 years following stand-replacing wildfire in a dry coniferous forest, Oregon, USA

Community re-assembly following future disturbances will often occur under warmer and more moisture-limited conditions than when current communities assembled. Because the establishment stage is regularly the most sensitive to climate and competition, the trajectory of recovery from disturbance in a changing environment is uncertain, but has important consequences for future ecosystem functioning. To better understand how ongoing warming and rising moisture limitation may affect recovery, we studied native and exotic plant composition 11 years following complete stand-replacing wildfire in a dry coniferous forest spanning a large gradient in climatic moisture deficit (CMD) from warm and dry low elevation sites to relatively cool and moist higher elevations sites. We then projected future precipitation, temperature and CMD at our study locations for four scenarios selected to encompass a broad range of possible future conditions for the region. Native perennials dominated relatively cool and moist sites 11 years after wildfire, but were very sparse at the warmest and driest (high CMD) sites, particularly when combined with high topographic sun exposure. In contrast, exotic species (primarily annual grasses) were dominant or co-dominant at the warmest and driest sites, especially with high topographic sun exposure. All future scenarios projected increasing temperature and CMD in coming decades (e.g., from 4.5% to 29.5% higher CMD by the 2080s compared to the 1971-2000 average), even in scenarios where growing season (May-September) precipitation increased. These results suggest increasing temperatures and moisture limitation could facilitate longer term (over a decade) transitions toward exotic-dominated communities after severe wildfire when a suitable exotic seed source is present.

Lichen communities and species indicate climate thresholds in southeast and south-central Alaska, USA

Abstract Because of their unique physiology, lichen communities are highly sensitive to climatic conditions, making them ideal bioindicators for climate change. Southeast and south-central Alaska host diverse and abundant lichen communities and are faced with a more rapidly changing climate than many more southerly latitudes. We develop sensitive lichen-based indicators for tracking the effects of climate change in south-central and southeast Alaska. Using 196 plots, we model community composition and 12 individual species abundances in relation to synthetic climate variables. Both types of lichen indicator are closely related to the climate variable describing a transition from warm, wet oceanic climates to cooler, drier suboceanic climates. Lichen communities and individual species exhibited thresholds associated with average December minimum temperatures between −10.2 and −7.8°C and annual precipitation between 106 and 172 cm, suggesting rapid turnover with relatively small changes within these ranges. These climate conditions occur close to the coast in northern portions of the region and further inland in southeast Alaska. Because lichen communities in the threshold region may be most sensitive to a changing future climate, they should be targeted for monitoring efforts.

Geographic, climatic, and chemical differentiation in the Hypogymnia imshaugii species complex (Lecanoromycetes, Parmeliaceae) in North America

Abstract Hypogymnia imshaugii is one of the most common, conspicuous and morphologically variable epiphytic lichens of the Pacific coastal states and provinces. The species varies greatly in morphology and chemistry, suggesting multiple closely related species or one or more phenotypically plastic species. We sought to determine whether additional ecologically meaningful species might be present within the H. imshaugii complex. Improving our species concepts could potentially improve ecological inferences based on community sampling. Three relatively well-defined genetic groups and one residual group in the H. imshaugii complex were detected with haplotype networks based on the ITS locus; however, phylogenetic reconstructions on combined ITS, mtSSU, GPD1 and TEF1 loci did not reflect this pattern. At present, we have insufficient evidence to support defining any of these groups as new taxa. The four major chemotypes in H. imshaugii differed in frequency among the genetic groups. None of the genetic groups was, however, qualitatively uniform in chemotype. Only one chemotype occurred in a single genetic group, but several chemotypes occurred in that group. While broadly sympatric, each chemotype had a distinct geographic distribution, and each chemotype showed its own relationship to climate, as shown by regression of occurrences of chemotypes against climatic variables. The genetic variation detected within H. imshaugii did not correspond to geographic variation in morphology, chemistry, or climate. Within the broader H. imshaugii complex, we recommend treating H. amplexa as a synonym of H. imshaugii unless it can be more distinctly separated from the clinal variation in morphology, chemistry, or DNA sequences. In contrast to H. amplexa, however, H. inactiva and H. gracilis are both easily separated morphologically from H. imshaugii and do not intergrade with it.

Wind farm potential is higher in prime habitat for uncommon soil crust lichens

IntroductionBiotic soil crust communities contribute valuable ecosystem services and biodiversity in steppe ecosystems. The uncommon crust lichens Acarospora schleicheri, Fuscopannaria cyanolepra, Rhizocarpon diploschistidina, and Texosporium sancti-jacobi are associated with fine-textured soils along rivers of the Columbia Basin. A. schleicheri and R. diploschistidina indicate late-successional habitat and may serve as indicators for other rare or cryptic species associated with similar habitats. Much of the most favorable habitat for these species has been lost to urban and agricultural development. We sought to overlay favorable habitats with wind farm development potential to assess whether these species are likely to be affected by renewable energy development.MethodsWe overlaid habitat models for four lichen species on land use and wind farm potential maps. Using a sample of 5,000 points, we determined whether there were differences in probability of occurrence among wind farm potential classes within developed and natural lands using Multi-Response Permutation Procedures. Sites with modeled probability of occurrence greater than 60% were considered “favorable” habitats; for these, a χ 2 test allowed us to determine whether favorable habitats were associated with wind farm potential categories.ResultsSites that are developed for agriculture or have higher wind farm potential coincide with more favorable habitats for uncommon soil crust lichens. Of the favorable habitats for the four focal lichens, 28–42% are already affected by development or agriculture; 5–14% of favorable habitats remain in natural vegetation and are considered sites with fair or good potential for wind farms.ConclusionsDevelopment of wind energy has the potential to negatively impact uncommon soil crust lichen species because favorable sites coincide with especially good habitat for these species. However, as these renewable energy resources are developed, we have the opportunity to ensure that valuable soil crust functions and diversity are maintained by surveying before construction and planning new facilities such that disturbance to existing habitat is minimized.

A Field Guide to Biological Soil Crusts of Western U.S. Drylands

This is a perfect field guide for casual forays in soil crust country, and as a teaching tool for the uninitiated. The printed book is pocket-sized and printed on water-resistant paper with a spiral binding and thick plastic cover; mine has withstood the inevitable abuses of fieldwork quite well. It is not currently in print, but used copies may be available and the pdf can be found online. The book begins with an introduction to soil crusts describing their roles and community composition. The discussion of ecological functions, habitats and monitoring techniques of soil crusts is effective but short; a technical reference with two of the same authors (Belnap et al. 2001) provides a more in-depth discussion of these topics. Photos of smooth, rugose, pinnacled, and rolling overall crust morphology allow the reader to visualize crusts from different regions and set a nice context. The introduction includes photos of crustose, continuous, areolate, gelatinous, squamulose, foliose, and fruticose lichens, which are helpful for those unfamiliar with lichens. The body of the book is composed of three sections, each with a key and page descriptions for featured taxa, including 11 mosses, three liverworts and 49 lichens. It seems these have been selected to highlight differing morphologies and illustrate the most common taxa. At the beginning of each section is a structure diagram with labels, which is useful for those unfamiliar with the terminology. Furthermore, the glossary at the end of the book is inclusive and simple. The keys to species are effective and avoid unnecessary jargon. However, as soil crusts can be quite diverse, not all taxa are included, and identifications should likely be verified using keys in more complete floras such Nash et al. (2002, 2004, 2008) and McCune & Rosentreter (2007). Each featured taxon has a habit photograph together with an inset showing more detail; these are helpful for learning to see the subtleties and differences among soil crusts. The descriptions are fairly short, with simple language, and diagnostic features highlighted. Habitat descriptions are informative, and the lichen section includes spot test chemical characteristics. The comments are fun to read and provide insight about the general look of species, their biology and look-alikes. The range maps and elevation charts give a broad sense of distributions. This book is accessible to amateur botanists and is an especially good starting place for those interested in learning about biotic soil crusts. The photographs allow the reader to develop an eye for these inconspicuous organisms, and the habitat descriptions suggest places to examine more closely which may have been overlooked. I have enjoyed using it in the field and often bring it with me when I travel through new dryland habitats.