Vascular plant diversity and climate change in the alpine zone of the Snowy Mountains,Australia

This study examines vascular plant species richness along an altitudinal gradient in alpine Australia. Vascular plant composition and soil temperature records were obtained for five summits (from 1729 m to 2114 m a.s.l.) using sampling protocols from the Global Observation Research Initiative in Alpine Environments program. Species richness was examined against altitude, aspect and climatic variables at different spatial scales (10 × 10 cm quadrats, 1 m² quadrats, clusters of 4 * 1 m² quadrats, for the summit area above a line 5 m altitudinally below the summit (the −5 m isoline), for the extended summit down to the −10 m isoline). About 75 taxa (70 species, 5 graminoid genera) were recorded, 9 of which are endemic to the small alpine area of ∼100 km². There were significant linear relationships between species richness and altitude and climatic variables for the top to −5 isolines on the summits. However, there was no consistent pattern for species richness at other spatial scales, altitude, aspect or climatic variables. The proportion of species for the whole summits with localised distributions (local endemics) increased with altitude. Predicted increasing temperatures and reduced snowcover is likely to result in an increase in species richness as shrubs, herbs and introduced weeds become more common at higher altitude. Because Australian alpine areas occur in narrow altitudinal bands with no nival zone, there are no higher altitudinal refuges available for alpine species. Therefore many of these species are likely to be at risk of extinction from climate change.     

Plant species richness and diversity along an altitudinal gradient in the Sierra Nevada, Mexico

This article presents an analysis of plant species richness and diversity and its association with climatic and soil variables along a 1300‐m elevation gradient on the Cerro Tláloc Mountain in the northern Sierra Nevada in Mexico. Two 1000‐m² tree sampling plots were created at each of 21 selected sampling sites, as well as two 250‐m² plots for shrubs and six 9‐m² plots for herbaceous plants. Species richness and diversity were estimated for each plant life form, and beta diversity between sites was estimated along the gradient. The relationship between species richness and diversity and environmental variables was modelled using simple linear correlation and regression trees. Species richness and diversity showed a unimodal pattern with a bias towards high values in the lower half of the elevation gradient under study. This response was consistent for all three life forms. Beta diversity increased steadily along the elevation gradient, being lower between contiguous sites at intermediate elevations and high – the species replacement rate was nearly 100%– between sites at the extremes of the gradient. Few species were adapted to the full spectrum of environmental variation along the elevation gradient studied. The regression tree suggests that differences in species richness are mainly influenced by elevation (temperature and humidity) and soil variables, namely A₂ permanent wilting point, organic matter and horizon field capacity and A₁ horizon Mg²⁺.     

Seedling establishment of two shrubby plants native to the Sierra Nevada mountain range

The Sierra Nevada mountain range near the Mediterranean Sea is an unique environment known for the variety of endemic species. Nevertheless, an alpine ski station situated on the mountain has dramatically affected the landscape, leaving some areas barren. In an effort to restore the vegetation cover, laboratory experiments were conducted with seeds of Genista versicolor Boiss and Reseda complicata Bory, two shrubby plants native to Sierra Nevada. Using different concentrations of two plant growth regulators, Ethrel and N⁶-benzyladenine, seeds from both species were planted in soil sampled from the alpine ski resort. Surprisingly, both Ethrel and N⁶-benzyladenine significantly improved seedling establishment. Consequently, seedling pre-treatment with definite plant growth regulators could be a useful approach to revegetation of the Sierra Nevada mountain range.     

MATING SYSTEM IN NATURAL POPULATIONS OF JEFFREY PINE

The mating system and allozyme variation at 20 loci in three Klamath Mountains and two Sierra Nevada populations of Jeffrey pine (Pinus jeffreyi Grev. & Balf.) were investigated. On average, multilocus estimates of the proportion of viable progeny due to outcrossing (t_m) were high in all populations (mean t_m = 0.935, range 0.881 to 0.971). Despite differences in stand structure, t_m did not differ (P > 0.05) between the Klamath (mean t_m = 0.933) and Sierra Nevada (mean t_m = 0.937) populations. At all but one locus in one population and at two in another, genotype frequencies fit (P > 0.05) Hardy-Weinberg expectations. Mean estimates of observed heterozygosity in Klamath (0.182) and Sierra Nevada (0.327) populations were comparable to values reported for other conifers.     

Evaluating Sierra Nevada Yellow-Legged Frog Distribution Using Environmental DNA

Genetic tools that identify species from trace DNA samples could supplement traditional survey methods to clarify distributional limits of rare species. For species with legal habitat protection, elevational limits of distributions are used to determine where management actions may affect endangered species. The endangered Sierra Nevada yellow-legged frog (Rana sierrae) generally is found down to 1,370 m, but in the Plumas National Forest, California, USA, there are a number of historical records below this elevation, resulting in protections extending to 1,067 m. This species is phenotypically similar to the foothill yellow-legged frog (R. boylii), with which it occasionally hybridizes. We used a combination of genetic methods to investigate the fine-scale distribution of the Sierra Nevada yellow-legged frog in the Plumas National Forest. We collected and analyzed environmental DNA (eDNA) samples from all accessible lower elevation sites with records of Sierra Nevada yellow-legged frog (n = 17) and swabbed 220 individuals for genetic identification from 2016–2018 to clarify the distribution of this endangered species. We created a climatic suitability model using the validated Sierra Nevada yellow-legged frog records and current (1970–2000) climate models to assess additional highly suitable localities for Sierra Nevada yellow-legged frog presence using eDNA capture. We did not confirm detection of Sierra Nevada yellow-legged frog eDNA at any historical sites and identified all swabbed individuals from below 1,370 m (n = 144) as foothill yellow-legged frogs. We located a new Sierra Nevada yellow-legged frog site (at 1,919 m) during surveys guided by the climatic suitability model. It does not appear after extensive eDNA and genetic sampling that the Sierra Nevada yellow-legged frog occurs below 1,370 m in this portion of their range at present. Our results show that eDNA sampling can be used as an effective management tool to evaluate historical locations and previously unknown suitable localities for current presence of a species of interest. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.     

Past and future demographic dynamics of alpine species: limited genetic consequences despite dramatic range contraction in a plant from the Spanish Sierra Nevada

Anthropogenic global climate change is expected to cause severe range contractions among alpine plants. Alpine areas in the Mediterranean region are of special concern because of the high abundance of endemic species with narrow ranges. This study combined species distribution models, population structure analyses and Bayesian skyline plots to trace the past and future distribution and diversity of Linaria glacialis, an endangered narrow endemic species that inhabits summits of Sierra Nevada (Spain). The results showed that: (i) the habitat of this alpine‐Mediterranean species in Sierra Nevada suffered little changes during glacial and interglacial stages of late Quaternary; (ii) climatic oscillations in the last millennium (Medieval Warm Period and Little Ice Age) moderately affected the demographic trends of L. glacialis; (iii) future warming conditions will cause severe range contractions; and (iv) genetic diversity will not diminish at the same pace as the distribution range. As a consequence of the low population structure of this species, genetic impoverishment in the alpine zones of Sierra Nevada should be limited during range contraction. We conclude that maintenance of large effective population sizes via high mutation rates and high levels of gene flow may promote the resilience of alpine plant species when confronted with global warming.     

Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest

Questions: What influence does mechanical mastication and other fuel treatments have on: (1) canopy and forest floor response variables that influence understory plant development; (2) initial understory vegetation cover, diversity, and composition; and (3) shrub and non‐native species density in a second‐growth ponderosa pine forest. Location: Challenge Experimental Forest, northern Sierra Nevada, California, USA. Methods: We compared the effects of mastication only, mastication with supplemental treatments (tilling and prescribed fire), hand removal, and a control on initial understory vegetation response using a randomized complete block experimental design. Each block (n=4) contained all five treatments and understory vegetation was surveyed within 0.04‐ha plots for each treatment. Results: While mastication alone and hand removal dramatically reduced the midstory vegetation, these treatments had little effect on understory richness compared with control. Prescribed fire after mastication increased native species richness by 150% (+6.0 species m²) compared with control. However, this also increased non‐native species richness (+0.8 species m²) and shrub seedling density (+24.7 stems m²). Mastication followed by tilling resulted in increased non‐native forb density (+0.7 stems m²). Conclusions: Mechanical mastication and hand removal treatments aided in reducing midstory fuels but did not increase understory plant diversity. The subsequent treatment of prescribed burning not only further reduced fire hazard, but also exposed mineral soil, which likely promoted native plant diversity. Some potential drawbacks to this treatment include an increase of non‐native species and stimulation of shrub seed germination, which could alter ecosystem functions and compromise fire hazard reduction in the long‐term.     

Species Richness,Spatial Variation,and Abundance of the Soil Seed Bank of a Secondary Tropical Rain Forest1

Despite the importance of the soil seed bank in tropical forest regeneration, little is known about spatial variability in species composition and abundance of seeds stored in the soil. To develop sampling methods for comparative studies, we examined species richness, spatial variation, and abundance of germinants from the soil seed bank in a 16 year old secondary, tropical wet forest at La Selva Biological Station, Costa Rica. Surface soil (10 cm deep, 4.7 cm diameter) was collected at the intersection points of a gridded 1 ha plot (10 × 10-m grid, 121 samples) and in a nested 100 m² subplot (2 × 2-m grid, 36 samples). The 1 ha plot had a density of 4535 seeds/m² with 34 species observed. Based on a series of 100 randomized species accumulation curves, a Michaelis-Menten fit predicted a mean species richness of 36.3 species; the number of observed species was close to the predicted asymptote. A nonparametric, first-order jackknife species richness estimator predicted a species richness of 37.0 species. Eighty-five and 95 percent of the observed species richness is contained, on average, within 41 and 74 pooled samples, respectively. Within the 100 m² nested subplot, a density of 5476 seeds/m² was observed, comprising 26 species with an estimated species richness (Michaelis-Menten fit) of 29.1 species. The jackknife species richness estimator predicted a species richness of 36.7 species. For species richness and abundance of both plots, spatial autocorrelation statistics (Moran's I) were not significantly different from zero at lag distances from 2 to 100 m, indicating a random distribution at these spatial scales. For this site, accurate estimates of species composition depend upon the number of samples collected as well as the spatial distribution of sampling effort. Many small samples distributed over a large area provide greater accuracy and precision for estimating species richness of the soil seed bank.     

EFFECTS OF ISLAND GROUPS,DEPTH, AND EXPOSURE TO OCEAN WAVES ON SUBTIDAL MACROALGAL ASSEMBLAGES IN THE RECHERCHE ARCHIPELAGO,WESTERN AUSTRALIA1

Temperate Australia has a speciose highly endemic algal flora. This study explored the influence of geographical isolation between islands, depth and exposure to ocean swells on the diversity of macroalgae in the Recherche Archipelago (Western Australia). Macroalgae were harvested (0.25‐m² quadrats) from sites at two exposures (sheltered and exposed to wave energy), three depths (<10, 10–20, and 21–28 m), and two island groups (three islands within Esperance Bay and three islands outside the bay). A total of 220 species were collected. Species richness and biomass were significantly different at the smallest spatial scale (0.25 m²), and density of overstory species decreased with depth. Results from analysis of similarity tests suggested that macroalgal assemblages differed with depth, exposure and to a lesser extent with island group. Assemblage differences were often associated with particular overstory or understory taxa and not the entire assemblage composition. Average species richness·0.25 m^?2 ranged from 13 to 29 species, typically with a few species contributing more than 50% of average biomass. Species richness was maintained by species turnover at the 0.25‐m² spatial scale. Our results suggest that richness in temperate Australia is maintained by turnover of broadly distributed species. More dominant species in assemblages were associated with differences in depth and exposure to ocean swells. Our findings support the hypothesis of a geographical transition of dominant species from kelp‐dominated in the west to a fucalean‐dominated assemblage in the Recherche Archipelago and east of the Great Australian Bight.     

Dataset of Passerine bird communities in a Mediterranean high mountain (Sierra Nevada,Spain)

In this data paper, a dataset of passerine bird communities is described in Sierra Nevada, a Mediterranean high mountain located in southern Spain. The dataset includes occurrence data from bird surveys conducted in four representative ecosystem types of Sierra Nevada from 2008 to 2015. For each visit, bird species numbers as well as distance to the transect line were recorded. A total of 27847 occurrence records were compiled with accompanying measurements on distance to the transect and animal counts. All records are of species in the order Passeriformes. Records of 16 different families and 44 genera were collected. Some of the taxa in the dataset are included in the European Red List. This dataset belongs to the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.     

Genetic diversity and differentiation in narrow versus widespread taxa of Helianthemum (Cistaceae) in a hotspot: The role of geographic range,habitat, and reproductive traits

Unraveling the relationships between ecological, functional traits and genetic diversity of narrow endemic plants provide opportunities for understanding how evolutionary processes operate over local spatial scales and ultimately how diversity is created and maintained. To explore these aspects in Sierra Nevada, the core of the Mediterranean Betic‐Rifean hotspot, we have analyzed nuclear DNA microsatellite diversity and a set of biological and environmental factors (physicochemical soil parameters, floral traits, and community composition) in two strictly endemic taxa from dolomite outcrops of Sierra Nevada (Helianthemum pannosum and H. apenninum subsp. estevei) and two congeneric widespread taxa (H. cinereum subsp. rotundifolium and H. apenninum subsp. apenninum) that further belong to two different lineages (subgenera) of Helianthemum. We obtained rather unexpected results contrasting with the theory: (a) The narrow endemic taxa showed higher values of genetic diversity as well as higher average values of pollen production per flower and pollen‐to‐ovule ratio than their widespread relatives; and (b) the two taxa of subg. Helianthemum, with larger corollas, approach herkogamy and higher pollen production than the two taxa of subg. Plectolobum, displayed lower genetic diversity and higher values of inbreeding. Altogether, these results disclose how genetic diversity may be affected simultaneously by a large number of intrinsic and extrinsic factors, especially in Pleistocene glacial refugia in mountains where the spatial context harbors a great ecological heterogeneity. On the other hand, differences in mating system and the significant effect of the substrate profile, both being highly diverse in the genus Helianthemum, in the genetic variability illustrate about the importance of these two factors in the diversification and species differentiation of this paradigmatic genus in the Mediterranean and open the field to formulate and test new hypotheses of local adaptation, trait evolution, and habitat diversification.     

Prioritizing conservation areas and vulnerability analyses of the genus Pinus L. (Pinaceae) in Mexico

Mexico hosts the highest species richness of pines (Pinus, Pinaceae) worldwide; however, the priority areas for their conservation in the country are unknown. In this study, the ecological niche of the 50 native pine species was modeled. Then, through a multi-criteria analysis, the priority areas for the conservation of the genus Pinus were identified according to the spatial patterns of richness, geographic rareness, irreplaceability, the level of vulnerability of their habitat and the status of legal protection. The results revealed that the regions with high species richness differed from those with high endemism. Also, most pine species have undergone processes of habitat degradation, having been the endemic species the most affected. The priority areas covered regions with high species richness, high endemism, and highly degraded forests, located at mountainous portions of the Baja California Peninsula, the Sierra Madre Occidental, the Sierra Madre Oriental, the Trans-Mexican Volcanic Belt, and the Sierra Madre del Sur. A low proportion of priority areas overlapped with protected areas or terrestrial regions considered priorities for biological conservation. These results suggest that conservation efforts for this genus should be focused beyond regions with high species richness and current protected areas. Besides, the priority areas identified in this study can be the basis to create biological corridors and new protected areas, which could contribute significantly to the conservation of this genus in Mexico.     

Elevational patterns in the vascular flora of a highly diverse region in southern Mexico

We examined general and family-specific patterns of vascular plant richness along a large elevational gradient (0?C3,670?m a.s.l.), assessed the continuity of these patterns and analysed their potential underlying causes in a high diversity region of the Sierra Madre del Sur, Oaxaca, Mexico. We used a vascular plant database constructed previously. The gradient was divided into 18 200-m elevation belts. To examine elevational patterns of richness, we used both observed and estimated (interpolated) species richness, as well as genus and family observed richness, for each belt. A generalised linear model (GLM) was used to assess the effect of altitude on area-corrected species richness (standard area?=?100?km²), and a numerical classification of the elevational belts based on species richness was performed. Overall, richness at the three taxonomic levels decreased with elevation, but some individual families departed from this pattern. A sharp drop in species richness was observed at 1,800?m, and the dendrogram separated two elevational floristic groups at this elevation. The GLM revealed a significant negative effect of elevation on species richness. Despite this overall decreasing pattern for vascular plants along this extensive gradient, an examination of some family-specific patterns revealed the existence of other elevation?Cdiversity relationships, indicating taxon-specific responses to elevation. The most noticeable discontinuity in species richness, at ca. 1,800?m, is likely related to a critical temperature isocline.     

Drought ecohydrology alters the structure and function of benthic invertebrate communities in mountain streams

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Contrasting ectomycorrhizal fungal communities on the roots of co-occurring oaks (Quercus spp.) in a California woodland

Plant host species is considered an important factor influencing ectomycorrhizal (EM) communities. To gain insights into the role of host species in structuring EM communities, EM communities on sympatric oak (Quercus) species were compared in the Sierra Nevada foothills of California. Using molecular methods (polymerase chain reaction, cloning, restriction fragment length polymorphism and DNA sequencing), EM fungi on roots of deciduous Quercus douglasii and evergreen Quercus wislizeni trees were identified from 64 soil cores. The total EM species richness was 140, of which 40 taxa were detected on both oak hosts. Greater diversity and frequency of EM fungi with epigeous fruiting habit were found on Q. wislizeni, while taxa in the Ascomycota were more frequent and diverse on Q. douglasii. Using ordination, it was determined that both soil extractable phosphorus and oak host species explained a significant proportion of the variation in EM species distribution. These results indicate that plant host species can be an important factor influencing EM fungal community composition, even within congeneric trees.     

Macroinvertebrate community succession in Wolf Point Creek, Glacier Bay National Park, Alaska

• 1 Macroinvertebrate community development in Wolf Point Creek in Glacier Bay National Park, Alaska formed by ice recession was investigated from 1991 to 1994 as part of a long‐term study of colonization now exceeding 20 years. Chironomidae, the first taxon to colonize the stream, still dominated the community comprising 75–95% by number, but species succession was apparent.
• 2 Species richness in August increased from five species in 1978 to 11 in 1991 and 16 in 1994.
• 3 Diamesa species, abundant in 1978 at densities exceeding 2 750 m^‐2, were not collected in 1994, while Pagastia partica dominated the community with densities exceeding 10 000 m^‐2.
• 4 Sixteen taxa, never previously collected, colonized the stream between 1991 and 1994 including representatives of Coleoptera, Muscidae, Trichoptera, and the first noninsect taxon, Oligochaeta. Colonization by new taxa was associated with an increase in summer water temperature and the development of riparian vegetation.
• 5 Inter‐specific competition is suggested as a possible factor in species succession and is incorporated into a taxa richness model of community development in postglacial streams incorporating stable and unstable channels.

     

Pronophiline butterflies (Satyridae) of the Sierra Nevada de Santa Marta, Colombia

Abstract. The twenty-four species of Pronophilini known from the Sierra Nevada de Santa Marta, a small, isolated and very high north Colombian mountain range, are listed. The ecology of the tribe in northern South America, where these butterflies are exclusively montane, is described. The evolutionary relationships of the thirteen endemic species are analysed. Three new genera, three new species, and four new subspecies are described. Four new synonymies are established, the status of three taxa revised, six new combinations made, lished, the status of three taxa and one original combination re-instated.     

Spatial variability of epifaunal communities in the North Sea in relation to sampling effort

Benthic epifauna was sampled in six areas from the German Bight towards the Norwegian Sea using a 2-m standard beam trawl. Nine replicates were taken in each area and year from 1999 to 2006. This data set (60–67 replicates per area) was used to describe the spatial variability in local species composition and to assess the effect of increasing sampling effort on species richness and community structure. Our results confirmed the importance of the 50-m depth contour for the separation of benthic fauna in the North Sea. Low species richness, sparse sessile fauna and high abundances of scavenging species such as Asterias rubens, Liocarcinus holsatus, Astropecten irregularis and Ophiura albida were characteristic of the low-water area south of the 50-m contour. Differences in community structure were less conspicuous in deeper waters north of the 50-m contour, but distribution patterns and abundances of single species such as Echinus elegans, Hyalinoecia tubicola, Ophiothrix fragilis, Scaphander lignarius as well as several hermit crabs resulted in well-defined epifaunal communities. One replicate caught 17–28% of the species found in 60–67 samples and was sufficient to separate the community in the German Bight from those in the central and northern North Sea by using multidimensional scaling. Nine replicates sampled a proportion of 53–60% and provided additional information on the spatial variability of community structure in the central and northern North Sea. Our study indicates that appropriate replication enhances the quality of the data and can partly overcome the constraints of sampling with a 2-m beam trawl. This might be helpful for future monitoring programmes.     

Ants on a mountain: spatial, environmental and habitat associations along an altitudinal transect in a centre of endemism

Mountains are biodiversity hotspots and provide spatially compressed versions of regional and continental variation. They might be the most cost effective way to measure the environmental associations of regional biotic communities and their response to global climate change. We investigated spatial variation in epigeal ant diversity along a north–south elevational transect over the Soutpansberg Mountain in South Africa, to see to what extent these patterns can be related to spatial (regional) and environmental (local) variables and how restricted taxa are to altitudinal zones and vegetation types. A total of 40,294 ants, comprising 78 species were caught. Ant richness peaked at the lowest elevation of the southern aspect but had a hump-shaped pattern along the northern slope. Species richness, abundance and assemblage structure were associated with temperature and the proportion of bare ground. Local environment and spatially structured environmental variables comprised more than two-thirds of the variation explained in species richness, abundance and assemblage structure, while space alone (regional processes) was responsible for <10%. Species on the northern aspect were more specific to particular vegetation types, whereas the southern aspect’s species were more generalist. Lower elevation species’ distributions were more restricted. The significance of temperature as an explanatory variable of ant diversity across the mountain could provide a predictive surrogate for future changes. The effect of CO₂-induced bush encroachment on the southern aspect could have indirect impacts complicating prediction, but ant species on the northern aspect should move uphill at a rate proportional to their thermal tolerance and the regional increases in temperature. Two species are identified that might be at risk of local extinction.     

Shifts in fisher (Pekania pennanti) diet in response to climate-induced tree mortality in California assessed with DNA metabarcoding

A recent climate-induced tree mortality event in California, USA has led to dramatic landscape-level changes in the southern Sierra Nevada. Wide-spread conifer mortality was documented in habitat occupied by fisher (Pekania pennanti), a mature-forest associated species of conservation concern in this region. We analyzed fisher scats collected on the Sierra National Forest from the pre-tree-mortality period (PreTM, 2011 – 2013) and post-tree-mortality period (PostTM, 2017 – 2018). We used DNA metabarcoding to successfully identify taxa and summarized diet composition for 109 PreTM and 102 PostTM fisher scats. We observed 48 different diet items (33 assigned to species and 15 to genus). Mammals, birds, and plants of the Ribes genus (gooseberries and currents) comprised the highest proportions of diet items, although scats also contained DNA from reptiles, insects, arachnids, snails, and fungi. The frequency of occurrence of mammalian prey items was lower in PostTM (49.0%) versus PreTM scats (81.7%) with a reduction in the occurrence of two tree squirrels (Douglas squirrel and Humboldt’s flying squirrel). A higher proportion of scats collected PostTM (46.1%) contained DNA from Ribes spp. versus scats collected PreTM (19.3%). Our data reveal potential cascading effects of climate-induced tree mortality on fisher diet in the southern Sierra Nevada. Flexibility in fisher diet, however, may allow resilience to ecological change though future studies should consider the behavioral, energetic, demographic or fitness consequences from a shift away from medium-sized mammalian prey to plants.