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Arbuscular mycorrhizal (AM) fungi are the most abundant plant symbiont and a major pathway of carbon sequestration in soils. However, their basic biology, including their activity throughout a 24-h day : night cycle, remains unknown. We employed the in situ Soil Ecosystem Observatory to quantify the rates of diurnal growth, dieback and net productivity of extra-radical AM fungi. AM fungal hyphae showed significantly different rates of growth and dieback over a period of 24 h and paralleled the circadian-driven photosynthetic oscillations observed in plants. The greatest rates (and incidences) of growth and dieback occurred between noon and 18:00 h. Growth and dieback events often occurred simultaneously and were tightly coupled with soil temperature and moisture, suggesting a rapid acclimation of the external phase of AM fungi to the immediate environment. Changes in the environmental conditions and variability of the mycorrhizosphere may alter the diurnal patterns of productivity of AM fungi, thereby modifying soil carbon sequestration, nutrient cycling and host plant success.

Herbivory is poorly characterized in the endangered California sage scrub ecosystem, because previous studies were conducted only in winter and spring. To better understand vertebrate herbivore impacts, we first examined if and when vertebrate herbivores influence Artemisia californica seedling survivorship by examining differences in mortality between caged and uncaged seedlings. Then, we examined: (1) vertebrate herbivore preference of common sage scrub shrub species, and (2) which vertebrate species constitute important herbivores in the ecosystem. We found that mortality for uncaged A. californica seedlings was twice that of caged seedlings, and occurred in the summer and early fall, when previous studies in the system were not conducted. Short leaved shrubs, Artemisia californica and Eriogonum fasciculatum, were more susceptible to herbivory than broader leaved Salvia apiana and Eriodictyon trichocalyx. However, susceptibility likely depends on the herbivore assemblage, as the three main herbivore species [Sylvilagus audubonii (desert cottontail), Zonotrichia leucophrys (white-crowned sparrow; a bird, not a mammal), and Otospermophilus beecheyi (California gray squirrel)] all had different shrub preferences. Our results contrast with previous studies that suggests that native vertebrate herbivores facilitate shrub seedling survivorship by highlighting that late-season vertebrate herbivory may negatively affect shrub seedling survivorship. We demonstrate the complex but understudied role herbivores play in the sage scrub ecosystem, and highlight that further study of these key ecological interactions is warranted. [ABSTRACT FROM AUTHOR]

Seeds of native plants are needed for rangeland restoration in the Intermountain West. Many of these plants are rarely cultivated and relatively little is known about the cultural practices required for their seed production. Irrigation trials were conducted over multiple years for two perennial Eriogonum species, Eriogonum umbellatum Torr. and Eriogonum heracleoides Nutt. The two species grown at the Oregon State University Malheur Experiment Station, Ontario, Ore., received 0, 100, or 200 mm·year-1 of drip irrigation. Seed yield responses to irrigation were evaluated by linear and quadratic regression against 1) applied water; 2) applied water plus spring precipitation; 3) applied water plus winter and spring precipitation; and 4) applied water plus fall, winter, and spring precipitation. In general, seed yields responded quadratically to irrigation. For E. umbellatum, over 11 years, highest seed yields averaged 260 kg·ha-1 and ranged from 207 to 508 kg·ha-1. For E. heracleoides, over 6 years, highest yields averaged 353 kg·ha-1 and ranged from 168 to 588 kg·ha-1. Adding spring precipitation to applied water improved the accuracy of estimated water requirements for maximum seed production of E. umbellatum. For E. heracleoides, adding precipitation to applied water did not improve the accuracy of estimated water requirements for maximum seed production. Averaged over 11 years, seed yield of E. umbellatum was maximized by 209 mm·year-1 of spring precipitation plus irrigation. Averaged over 6 years, seed yield of E. heracleoides was maximized by 126 mm·year-1 of applied water. Both species required relatively small amounts of irrigation to help assure seed yield, and the irrigation needed for E. umbellatum could be adjusted by taking spring precipitation into account. [ABSTRACT FROM AUTHOR]

The relative roles of chance colonization and subsequent gene flow in the development of insular endemic biotas have been extensively studied in remote oceanic archipelagos, but are less well characterized on nearshore island systems. The current study investigated patterns of colonization and divergence between and within two wild buckwheat species (Polygonaceae), Eriogonum arborescens and E. giganteum, endemic to the California Channel Islands to determine whether geographical isolation is driving diversification. Using plastid and nuclear sequence data and microsatellite allele frequencies, we determined that gene flow in these Eriogonum spp. is restricted by isolation. The data suggest that successful colonization of and gene flow among the islands are infrequent. Colonization appears to have followed a stepping-stone model that is consistent with a north-to-south pattern across the islands. This colonization pattern coupled with relatively little post-colonization inter-island gene flow, particularly among southern islands, has generated a pattern of more divergent lineages on the isolated southern islands. These results run counter to the general expectation that all islands close to a continental source should receive a high level of gene flow. Finally, management recommendations focused on protecting the lineages from loss of private alleles and the erosion of the remaining genetic diversity are offered. [ABSTRACT FROM AUTHOR]

A biography of James L. Reveal, botanist's botanist is presented. His interest in botany started when he was growing up in California assn attended Utah State as an undergraduate.In 1964 he was then hired by the New York Botanical Garden to collect plants for the Intermountain Flora but his primary research interest with the genus Eriogonum. He also wrote a book Gentle Conquest :The Botanical Discovery of North America (Reveal 1992).

For plant species important in ecological restoration, seed transfer zones have been developed to maximize the probability that sown seed will germinate, establish, persist, and reproduce without negatively impacting the genetic composition of remnant plant populations. However, empirically based seed transfer zones have not been developed for most species. In their absence, maps based on ecological or climatic variables have been suggested as proxies. In the United States, these maps typically include the Environmental Protection Agency's Levels III and IV Ecoregion maps and the US Forest Service's Provisional Seed Zones. Maps of different spatial scales represent a compromise between economic and ecological considerations; those that delineate larger seed transfer zones are less costly to implement but impose more risk of poor adaptation to local conditions. To test the relative suitability of each map in delineating seed transfer zones, we conducted common garden experiments using five forb species found throughout the Great Basin and measured variation in traits thought to influence plant performance. We distinguished between environmentally and genetically controlled variation in measured traits and assessed how well this variation was explained by different candidate seed transfer zones. We found significant, population-level variation in all species for most measured traits. All tested seed transfer zones significantly explained some of this variation, but the proportion explained generally decreased with increasing zone size. Results suggest the intersection of Provisional Seed Zones and Level III Ecoregions was the best proxy for formal seed transfer zones developed based on common garden studies. This spatial scale captured 80% of the variation among source populations on average, and represents a viable compromise between ecological and economic considerations. [ABSTRACT FROM AUTHOR]

Analyses of flower-visitor interaction networks allow application of community-level information to conservation problems, but management recommendations that ensue from such analyses are not well characterized. Results of modularity analyses, which detect groups of species (modules) that interact more with each other than with species outside their module, may be particularly applicable to management concerns., We conducted modularity analyses of networks surrounding a rare endemic annual plant, Eriogonum visheri, at Badlands National Park, USA, in 2010 and 2011. Plant species visited were determined by pollen on insect bodies and by flower species upon which insects were captured. Roles within modules (network hub, module hub, connector and peripheral, in decreasing order of network structural importance) were determined for each species., Relationships demonstrated by the modularity analysis, in concert with knowledge of pollen species carried by insects, allowed us to infer effects of two invasive species on E. visheri. Sharing a module increased risk of interspecific pollen transfer to E. visheri. Control of invasive Salsola tragus, which shared a module with E. visheri, is therefore a prudent management objective, but lack of control of invasive Melilotus officinalis, which occupied a different module, is unlikely to negatively affect pollination of E. visheri. Eriogonum pauciflorum may occupy a key position in this network, supporting insects from the E. visheri module when E. visheri is less abundant., Year-to-year variation in species' roles suggests management decisions must be based on observations over several years. Information on pollen deposition on stigmas would greatly strengthen inferences made from the modularity analysis., Synthesis and applications: Assessing the consequences of pollination, whether at the community or individual level, is inherently time-consuming. A trade-off exists: rather than an estimate of fitness effects, the network approach provides a broad understanding of the relationships among insect visitors and other plant species that may affect the focal rare plant. Knowledge of such relationships allows managers to detect, target and prioritize control of only the important subset of invasive species present and identify other species that may augment a rare species' population stability, such as E. pauciflorum in our study. [ABSTRACT FROM AUTHOR]

Native plant and beneficial insect associations are relatively unstudied yet are important in native habitat restoration programs aimed at improving conservation biological control in perennial crops such as wine grapes. Beneficial insects (predators, parasitoids, pollinators) attracted to 10 species of flowering native wild buckwheat ( Eriogonum spp.) in central Washington were identified and counted on transparent sticky traps. Combining all categories of beneficial insects, the mean number per trap ranged from 48.5 ( Eriogonum umbellatum) to 167.7 ( Eriogonum elatum). Three Eriogonum spp. ( E. elatum, Eriogonum compositum, and Eriogonum niveum) attracted significantly more beneficial insects than the lowest-ranked species. E. niveum attracted greatest numbers of bees and parasitic wasps, and E. elatum was highly attractive to predatory true bugs and beneficial flies. Blooming periods of Eriogonum spp. extended from mid April to the end of September. This study demonstrates the attraction of beneficial insects to native flowering buckwheats and suggests their potential as a component of habitat restoration strategies to improve and sustain conservation biological control in Washington viticulture. [ABSTRACT FROM AUTHOR]

Abstract: Detailed soil and surficial geologic data are needed for ecological interpretations, yet are often absent or incomplete in published studies of arid land ecology or biogeography. Clear, edaphic habitat definitions are needed for gypsophilic plants including the Las Vegas buckwheat, E. corymbosum var. nilesii (LVB), a rare shrub endemic to the Mojave Desert. As a case study, we use soil profile data and high resolution (1:3000 scale) surficial geologic maps to identify likely edaphic controls of LVB habitat, potential habitat, and non-habitat distributions. We confirm gypsiferous substrates lacking hard, physical surface crusts as a boundary condition in most, but not all population clusters, but find that fine-grained, carbonate-rich soil lacking gypsum is also viable habitat, as is shallow (<1m) sandy alluvium overlying gypsiferous sediments. Deep (>1m), coarse-grained alluvium and/or surfaces with tightly interlocking desert pavement exclude LVB. Our results challenge the view of this target species as a true gypsophile, however, it remains unclear whether carbonate-rich habitats represent ideal conditions or refugia. This study underscores the important merits of surficial geologic mapping and soil morphological description for ecological research, conservation, restoration, and land management in arid environments, especially gypsum soils, worldwide. [Copyright &y& Elsevier]

In this article, the author offers information on Eriogonum deflexum, a member of the Polygonaceae family. He mentions that the deflexum is an herbaceous plant and also known as skeleton weeds. He reflects on several characteristics features of the plant including its inflorescences, leaf and flowering stems. He further presents several articles which he has used as references to gather knowledge on deflexum species.

The article investigates the life stages of Leptothrips fasciculatus (Crawford), a tubuliferan thrips that has primarily been collected as adults from the shrub Eriogonum fasciculatum Bentham. Adults and immature stages of the thrips were observed and collected. Eggs were located, and first- and second-instar larvae were plentiful, inside flowers and within the involucres that surround flower clusters. Mature second-instars and non-feeding fourth- and fifth-instars were found in leaf litter and soil beneath plants. Adults and larve were noted to be feeding on pollen and other flower parts but not on prey.

In semi-arid ecosystems, heterogeneous resources can lead to variable seedling recruitment. Existing vegetation can influence seedling establishment by modifying the resource and physical environment. We asked how a native legume, Lupinus argenteus, modifies microenvironments in unburned and burned sagebrush steppe, and if L. argenteus presence facilitates seedling establishment of native species and the non-native annual grass, Bromus tectorum. Field treatments examined mechanisms by which L. argenteus likely influences establishment: (1) live L. argenteus; (2) dead L. argenteus; (3) no L. argenteus; (4) no L. argenteus with L. argenteus litter; (5) no L. argenteus with inert litter; and (6) mock L. argenteus. Response variables included soil nitrogen, moisture, temperature, solar radiation, and seedling establishment of the natives Elymus multisetus and Eriogonum umbellatum, and non-native B. tectorum. In both unburned and burned communities, there was higher spring soil moisture, increased shade and reduced maximum temperatures under L. argenteus canopies. Adult L. argenteus resulted in greater amounts of soil nitrogen (N) only in burned sagebrush steppe, but L. argenteus litter increased soil N under both unburned and burned conditions. Although L. argenteus negatively affected emergence and survival of B. tectorum overall, its presence increased B. tectorum biomass and reproduction in unburned plots. However, L. argenteus had positive facilitative effects on size and survival of E. multisetus in both unburned and burned plots. Our study indicates that L. argenteus can facilitate seedling establishment in semi-arid systems, but net effects depend on the species examined, traits measured, and level of abiotic stress. [ABSTRACT FROM AUTHOR]

* Premise of the study: Microsatellite primers were designed for Eriogonum giganteum var. formosum, an endemic shrub of San Clemente Island, to investigate population structure, genetic diversity, and demographic history. * Methods and Results: Twelve polymorphic microsatellite loci were isolated from the California Channel Island endemic Eriogonum and were screened for variability. The primers amplified one to eight alleles in the target taxon. Many primers also amplified in conspecific and congeneric (E. arborescens, E. fasciculatum, E. grande, E. latifolium, and E. parvifolium) taxa and in the closely related Chorizanthe valida. The total number of alleles per locus for all taxa screened ranged from three to 24. * Conclusions: These primers will be useful for conservation genetic and evolutionary studies within the California Channel Island endemic Eriogonum. [ABSTRACT FROM AUTHOR]

This research examined plant area covered (plant cover) for six plant species on an existing modular extensive green roof in a semiarid climate. Species evaluated were Antennaria parvifolia Nutt., Bouteloua gracilis (Kunth) Lag., Delosperma cooperi (Hook. f.) L. Bol., Eriogonum umbellatum Torr. aureum 'Psdowns', Opuntiafragilis Nutt., and Sedum lanceolatum Torr. Many methods for measuring plant cover are subjective and based on semiquantitative measurements. This study compared digital image analysis data (DIA) with manually collected converted two-dimensional data (C2D) for plants grown on an extensive green roof. For each plant in the study, digital images and manual two-dimensional measurements were taken on four dates (at 6-week intervals) in 2008 and on four dates (at 6-week intervals) in 2009. Additionally, comparisons between DIA data and final biomass, and C2D and final biomass, were performed. Plant cover increased for all six species during the 2008 growing season. However, E. umbellatum aureum 'Psdowns' had a low overwintering rate (12.5%) and was removed from analysis in 2009. in the spring of 2009, four of the five remaining species exhibited decreased plant cover as a result of winter dieback; the one exception was O. fragilis, in terms of plant cover, both quantification methods (C2D and DIA) revealed that B. gracilis and D. cooperi had more plant cover than A. parvifolia, O.fragilis, and S. lanceolatum by the end of the study. Thus, five of the six species evaluated in this study are appropriate for use in extensive green roof applications in semiarid regions. High levels of correlation were found between the DIA and C2D data sets (r = 0.77) averaged over the five species on all eight data collection dates. The groundcover species (A. parvifolia, D. cooperi, and S. lanceolatum) had a higher correlation on average (r = 0.83) than the upright (B. gracilis, r = 0.70) and decumbent (O.fragilis, r = 0.65) species. Additionally, DIA and final biomass correlations showed parallel trends with groundcovers averaging r = 0.83, upright r = 0.64, and decumbent r = 0.41. Therefore, using DIA to evaluate plant cover and biomass accumulation is especially appropriate for groundcover species. [ABSTRACT FROM AUTHOR]

The article offers information on a study of ecosystem processes recovery in annual grasslands on Santa Cruz Island, California. In the examination of the influence of shrub colonization on nutrient cycling using the native shrubs Artemisia californica and Eriogonum arborescens, Artemisia increased nitrogen pools while Eriogonum depressed nitrogen pools. It also reveals in the determination of shrub effects that Eriogonum colonization is harmful while Artemisia favors grasses over the shrub.

The article presents a study on the taxonomic designation of Eriogonum corymbosum var. nilesii. Accordingly, related Eriogonum species in the subgenus Eusycla was examined to assess the genetic affiliations of E. corymbosum var. nilesii that are located in Clark County, Nevada and compares its AFLP files and chloroplast DNA sequences with related Eriogonum species from Colorado, Utah, and Arizona. Furthermore, genetic component supports the morphological findings on its taxonomic distinctness.

The subfamily Eriogonoideae (Polygonaceae) comprises 31 genera of which 20 are part of the radiation of Eriogonum and allied genera in North America. The eleven remaining genera are all woody, and include species that are vines, trees and shrubs. They are distributed in North, Central and South America, the Antilles and West Africa, and in most cases the number of species is not known, even less their relationships. Brunnichia is a woody vine native to the southeastern United States. In the past some authors have recognized species of Brunnichia as occurring in West Africa. Alternately, others recognized two genera, Brunnichia corresponding only to the American species and Afrobrunnichia to the African species. In this study two accessions of Afrobrunnichia erecta from Gabon and Ghana, representatives of Podopterus, Brunnichia ovata, and several other species of Polygonaceae are analyzed using three chioroplast genes (rbcL, matK, ndhF) and the nuclear ribosomal internal transcribed spacer (ITS). Maximum parsimony and maximum likelihood analyses strongly support Afrobrunnichia as sister to the remaining genera of Eriogonoideae; Brunnichia and Antigonon are strongly supported as sister genera. Based on these results, Afrobrunnichia is supported as a separate genus from Brunnichia. Podoplerus is placed sister to Coccoloba. [ABSTRACT FROM AUTHOR]

Abstract: The unique physical and chemical properties of gypsum soils have been used to explain species distribution across landscapes, however, past research on gypsophiles often has not encompassed broad analysis of soil–landscape–plant interaction and thus may have incorrectly labeled many species as gypsophiles. We use the example of the two reported gypsophiles, Arctomecon californica Torrey & Frémont and Eriogonum corymbosum Bentham var. nilesii Reveal found in the southern Mojave Desert, USA, to test the hypothesis that both species are gypsophiles and then draw conclusions from our work to evaluate past studies of gypsum soils, their landscapes and gypsophiles. Results from detailed pedologic analyses indicate that site characteristics affecting potential soil water content (topgraphic relief, soil particle size, depth to horizons perching water, and soil chemistry and mineralogy) differentiate habitat types and suggest surface differences affecting soil water content are more important for species success than sub-surface factors. Results suggest that gypsum is but one part of the explanation for A. californica and E. corymbosum habitat differentiation and in fact neither species are gypsophiles. While few soils across all habitats had abundant gypsum, gypsum was of very low abundance at most sites and not limited to one habitat type. Foliar chemistry data also indicate neither species accumulates sulfur; the hypothesis that these species are gypsophiles is thus rejected. This research demostrates the complicated nature of determining the influence of soil and landscape on habitat differentiation and the necessity of detailed field-pedologic analysis when defining species limiting soil-landscape constraints. [Copyright &y& Elsevier]

El artículo enfoca en el género de plantas herbáceas Eriogonum y una de sus especies Eriogonum jamesii (var. undulatum). Se indican las características morfológicas y anatómicas de este arbusto, se cita su distribución geográfica general y se describe su escasa presencia y posible vulnerabilidad a extinción en la zona del Bajío de México y alrededores.

The article focuses on the recognition of the subfamilies Eriogonoideae and Polygonoideae as monophyletic family. These groups were analyzed using three chloroplast regions and increased taxon sampling of Eriogonoideae does not support this delimitation. The second intron and portions of the flanking exons of the nuclear gene LEAFY were used to explore phylogenetic utility in Polygonaceae.

Plant roots may be linked by shared or common mycorrhizal networks (CMNs) that constitute pathways for the transfer of resources among plants. The potential for water transfer by such networks was examined by manipulating CMNs independently of plant roots in order to isolate the role(s) of ectomycorrhizal (EM) and arbuscular mycorrhizal fungal (AMF) networks in the plant water balance during drought (soil water potential –5.9 MPa). Fluorescent tracer dyes and deuterium-enriched water were used to follow the pathways of water transfer from coastal live oak seedlings (Quercus agrifolia Nee; colonized by EM and AMF) conducting hydraulic lift (HL) into the roots of water-stressed seedlings connected only by EM (Q. agrifolia) or AMF networks (Q. agrifolia, Eriogonum fasciculatum Benth., Salvia mellifera Greene, Keckiella antirrhinoides Benth). When connected to donor plants by hyphal linkages, deuterium was detected in the transpiration flux of receiver oak plants, and dye-labelled extraradical hyphae, rhizomorphs, mantles, and Hartig nets were observed in receiver EM oak roots, and in AMF hyphae of Salvia. Hyphal labelling was scarce in Eriogonum and Keckiella since these species are less dependent on AMF. The observed patterns of dye distribution also indicated that only a small percentage of mycorrhizal roots and extraradical hyphae were involved with water transfer among plants. Our results suggest that the movement of water by CMNs is potentially important to plant survival during drought, and that the functional ecophysiological traits of individual mycorrhizal fungi may be a component of this mechanism. [ABSTRACT FROM PUBLISHER]

The article discusses the propagation of Anaphalis margaritacea, Eriophyllum lanatum and Eriogonum umbellatum for seed production at J. Herbert Stone Nursery in Oregon. Respectively, the three are native forb seed known as western pearly everlasting, common woolly sunflower and sulphur-flower buckwheat. The process of field preparation, sowing, culturing, harvesting, and seed processing and storage is elaborated. The species can be grown in agricultural settings.

An alpine fellfield community on granite substrate (elevation 3750 m) near the University of California Barcroft Laboratory in the White Mountains of eastern California was studied during the 2000 growing season to determine whether classic perennial life forms can be treated as plant functional groups. A series of 1-m² quadrat samples were measured to determine common species. The four species with greatest cover were Penstemon heterodoxus var. heterodoxus, Trifolium andersonii var. beatleyae, Poa glauca subsp. rupicola, and Eriogonum ovalifolium var. nivale. These and four additional common perennial species were selected for ecophysiological studies representing four distinct ecological life forms: chamaephytes, cushion plants (including mat formers), herbaceous dicot perennials, and graminoid perennials. Summer midday leaf temperatures for species with foliage held close to ground surface were up to 20°C higher than air temperatures, whereas on upright species, leaves away from the ground surface closely matched ambient temperatures. For the eight species, peak values of mean maximum photosynthetic rates ranged from 11.5-25.5 μmol CO2 m-2 s-1, typical of published values, although chamaephytes in the study showed higher rates comparable to herbaceous perennials. Water-use efficiency, as estimated by a ratio of internal to ambient CO2, was relatively high (ci:ca ratios of 0.43-0.59) compared to published data. During the stressful end of the growing season, neither predawn nor midday shoot water potentials ever reached low levels, presenting conflicting evidence for the role of soil moisture as a limiting factor. Overall, the data on plant functional attributes showed no strong patterns of differences between categories of life forms in the feIlfield community, suggesting that classical life forms in this habitat do not represent plant functional groups. [ABSTRACT FROM AUTHOR]

Spatial pattern of a biotic population may change over time as its component individuals grow or die out, but whether this is the case for desert annual plants is largely unknown. Here we examined seasonal changes in spatial patterns of two annuals, Eriogonum abertianum and Haplopappus gracilis, in initial (winter) and final (summer) densities. The density was measured as the number of individuals from 384 permanent quadrats (each 0.5 m × 0.5 m) in the Chihuahuan Desert near Portal, Arizona, USA. We used three probability distributions (binomial, Poisson, and negative binomial or NB) that represent three basic spatial patterns (regular, random, and clumped) to fit the observed frequency distributions of densities of the two annuals. Both species showed clear clumped patterns as characterized by the NB and had similar inverse J-shaped frequency distribution curves in two density categories. Also, both species displayed a reduced degree of aggregation from winter to summer after the spring drought (massive die-off), as indicated by the increased k-parameter of the NB and decreased values of another NB parameter p, variance/mean ratio, Lloyd’s Index of Patchiness, and David and Moore’s Index of Clumping. Further, we hypothesized that while the NB (i.e., Poisson-logarithmic) well fits the distribution of individuals per quadrat, its components, the Poisson and logarithmic, may describe the distributions of clumps per quadrat and of individuals per clump, respectively. We thus obtained the means and variances for (1) individuals per quadrat, (2) clumps per quadrat, and (3) individuals per clump. The results showed that the decrease of the density from winter to summer for each plant resulted from the decrease of individuals per clump, rather than from the decrease of clumps per quadrat. The great similarities between the two annuals indicate that our observed temporal changes in spatial patterns may be common among desert annual plants. [ABSTRACT FROM AUTHOR]

Question: What changes in species composition and cover have occurred in chaparral as a function of fire history across an ecoregion? Location: San Diego County, California, USA. Methods: Stands in which 40 mid-elevation chaparral vegetation plots (each 400 m² in area) were located in the 1930s were resurveyed in 2001. We stratified the stands into Infrequently versus Frequently burned (0-1 versus 2 or more fires recorded in the 91-yr period), and Immature versus Mature (≤31 yr versus >31 yr since last fire), resulting in four groups. Ten stands were randomly selected from each of these groups for survey. Results: There were no major shifts in life form composition, e.g., live oak trees were not invading chaparral that had experienced little or no fire, nor were subshrubs or herbaceous species replacing shrubs in areas that had experienced more frequent fires. However, there was a notable increase in the frequency of the subshrub Eriogonum fasciculatum across all fire history groups. In the mature stands with infrequent fire, average cover of resprouting shrubs increased (from 72 to 91%) and cover of obligate seeding shrubs (species with firecued germination) decreased (from 21 to 6%) significantly. Mature stands with frequent fire showed a significant decrease in resprouter cover (from 87 to 80%) and increase in obligate seeders (from 10 to 16%). Conclusions: While the tremendous changes in land use in southern California have been predicted to cause shifts in chaparral composition, these shifts are difficult to detect because species longevity and fire cycles are on the order of decades to a century. In this study, the expected trends could only be detected in groups that were mature at the time of the second survey. [ABSTRACT FROM AUTHOR]

Copyright of Brittonia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brittonia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of his research was to describe the organization of genetic variation in the federally endangered plant taxon Eriogonum ovalifolium var. vineum using allozymes. Such information can help prioritize sites and management choices for capturing and maintaining genetic variation and can reduce the number of populations necessary to commit to conservation, thus reducing costs and conflicts with competing land uses. Information on genetic diversity patterns also provides insight into evolutionary and demographic history of a taxon which can provide means to assess future risk of erosion of diversity. Similar to other Eriogonum ovalifolium varieties, E. ovalifolium var. vineum is diverse at both the taxon (proportion of polymorphic loci [P] = 0.55 and alleles per locus [A] = 5.45 [SD = 2.5]) and population (P = 0.56 [SD = 0.11] and A = 2.68 [SD = 0.35]) levels. Gene diversity (He) within populations averaged 0.19 (SD = 0.03). We found some evidence for limited clonal reproduction within populations. Populations were moderately differentiated from one another (θS = 0.14) and showed moderate deviations from Hardy-Weinberg equilibrium within populations (f = 0.14 and F = 0.19). Mean Nei's genetic distance (D) among all pairs of populations was 0.02. Populations with high levels of multiple measures of genetic diversity, high levels of differentiation, and low levels of apparent inbreeding are suggested as conservation priorities. [ABSTRACT FROM AUTHOR]