We tested the hypotheses that reproductive interference between 2 congeneric damselfly species influences their local population densities and the female morph ratios in one of the species. Nehalennia irene has 2 female types (andromorph and gynomorph), whereas N. gracilis exhibits only one female type. Andromorphic N. irene females not only resemble conspecific males in body coloration, but also resemble heterospecific females of N. gracilis. We predicted male N. irene to be most attracted to gynomorphs of N. irene and male N. gracilis to be least attracted to them. Further, if N. gracilis males harass andromorphic N. irene females excessively, then they may reduce andromorph frequencies of N. irene locally. Our results indicate hybridization to be prevented by a “lock-and-key” mechanism, but male N. irene often attempt mating with female N. gracilis. Contrary to prediction, andromorph frequency in N. irene did not depend on whether N. irene populations were in sympatry or allopatry with N.gracilis. As predicted, N. irene males attempted tandem formation most frequently with conspecific gynomorphs, while N. gracilis males made most heterospecific tandem attempts on N. irene andromorphs. Collectively, our results suggest that N. gracilis females may be frequently harassed by N. irene males, and that this may help explain the relative rarity of N. gracilis.

Nomenclature: Walker, 1953.

Distylous polymorphisms represent a useful model system for studying the functioning of flower morphology because floral morphs have reciprocal flower developmental pathways and co-occur in the same environment such that they share the same pollinators. Distylous plants typically display both reciprocal herkogamy and a heteromorphic incompatibility system, which allows mating only between morphs. In this paper, we document morphspecific patterns in floral morphology and pollen receipt of Palicourea padifolia, a hummingbird-pollinated shrub. Floral traits typically associated with the functioning of distyly, reciprocal herkogamy, and population morph ratios of flowering individuals from 10 populations were measured and quantified. Pollen receipt on stigmas of the same measured flowers was then used to determine the effectiveness of distyly in promoting disassortative pollen transfer. Pollen of long-styled flowers was more effective in reaching legitimate stigmas, while short-styled morphs were more successful in the reception of legitimate pollen across populations. Variation in pollen receipt across populations was not explained by reciprocal herkogamy, which typically promotes legitimate pollination. Natural pollination resulting in a higher proportion of legitimate pollen in short-styled flowers increased with stigma–anther separation (promotion of outcross pollination) and width of corolla entrance (avoidance of self-pollination).

Nomenclature: Taylor, 1989; 1993; 1997; Burger & Taylor, 1993.

This paper reports the use of thin sections to improve precision and accuracy when ageing seedlings of Nothofagus pumilio. We compare 2 methods for determining the number of rings on 85 basal disks from seedlings: (1) ring counts of wood disks viewed with reflected light and (2) ring counts of thin sections viewed with transmitted light. Samples included 14 to 53 rings. Comparison of ring counts from the 2 methods revealed discrepancies of 1 to 12 y for 85% of the seedlings. Two sources of error were identified. In 70 of 85 samples, up to 12 incomplete rings explained differences between ring counts of 2 radii on the same wood disk. Secondly, the small radii, large number of rings, and diffuse porous nature of the wood resulted in frequent errors when visually detecting rings on wood disks. One to 3 false rings were detected in 15 seedlings. Narrow and suppressed rings in 57 samples resulted in under-estimates of 1 to 12 y for ring counts on wood disks relative to thin sections. High variation in the incidence of narrow rings limited our attempt to visually crossdate ring-width patterns among seedlings. However, counts of thin sections allowed us to identify false and incomplete rings, improving precision and accuracy when estimating seedling age. For studies of slow-growing seedlings that require high-resolution age estimates, we recommend the preparation and dating of thin sections as outlined in this paper.

Nomenclature: Muñoz-Schick, 1980.

This study analyzes the recovery of Pinus pinea in forested areas that have burned in the last 30 years. The main objectives of the study were (i) to analyze the success of the regeneration of P. pinea in areas with the presence or absence of surviving adult trees and (ii) to investigate whether or not the post-fire response of P. pinea may affect its present distribution. We analyzed the survival of adult P. pinea trees and the regeneration of P. pinea seedlings in 8 areas burned by wildfires in Catalonia (northeast Spain) between 1979 and 2001. This study shows that the inability of seedlings to establish after fire, together with the short seed dispersal distance of this species and the low level of seedling survival, renders the natural regeneration of P. pinea in burned areas difficult. A comparison of the presence of P. pinea in plots located in burned and unburned areas throughout its distribution area in Catalonia indicates that its presence at the regional level is clearly reduced after fire. Moreover, in the areas where it persists, tree density and cover are smaller than in unburned areas. This decrease of P. pinea forests is exacerbated by the increase in surface area burned by forest fires during recent decades in the Mediterranean basin and by decreasing profits associated with this species as a consequence of the falling value of its pine kernel.

Nomenclature: Bolós et al., 1990.

Overlapping moult and reproduction might be crucial for long-distance migratory birds, which are time-constrained to complete these energy-demanding functions before the onset of migration. However, proximate factors modulating the potential trade-off between moult and breeding, such as haemoparasite infection and stress, have not been studied in wild avian populations. We investigated the occurrence of moult-breeding overlap in females of a Spanish population of pied flycatchers (Ficedula hypoleuca) and its association with female age, haemoparasite prevalences, physiological stress, and condition at initial (incubation phase or beginning of the nestling period) and final breeding stages (days 11–12 of the nestling period). Late-breeding females were more likely to show a moult–breeding overlap than early-breeding females. Female age was not associated with moult status when taking into account laying date and study year. A higher proportion of females infected by Haemoproteus at initial breeding stages showed a moult–breeding overlap. Haemoproteus prevalences at final breeding stages did not differ according to moult status. Females with a moult–breeding overlap also showed better condition and lower stress levels (HSP60 levels) at the end of the season. A higher proportion of moulting females returned to the breeding grounds in the following season compared with non-moulting ones. Conversely, moulting females showed reduced hatching success and numbers of hatchlings and fledglings. Overlapping moult and breeding might be the expression of a shift in resource allocation between present and future reproduction, towards increased self-maintenance and reduced reproductive investment.

Nomenclature: Cramp, Perrins & Brooks, 1993.

Historical low-severity fire regimes are well characterized in ponderosa pine and mixed-conifer forests at many sites in the western United States, but not in the southern interior of British Columbia, Canada. We reconstructed a history of low-severity fires (1750–1950) near the northern limit of ponderosa pine and demonstrated that local-scale spatial variation in fire frequency varied with topography and that the intra-ring position of fire scars (a proxy for fire seasonality) varied somewhat with topography but more strongly by tree species. Fires were significantly more frequent on the south than the north aspect (14 versus 24 y mean plot fire intervals, respectively), likely due to differences in fuel type and condition. Frequency did not vary with elevation, although our range of elevation is likely too narrow to detect such variation (227 m). Ring-boundary scars were 5.6 times more likely on Douglas-fir than ponderosa pine, 1.8 times more likely on north than south aspects, and 1.6 times more likely at low than high elevation. Our results confirm the importance of understanding the effect of interspecific variation and topography on cambial phenology and hence intra-ring position before inferring historical fire seasonality from fire scars.

Nomenclature: Canadian Biodiversity Information Facility, 2005.

The relationships between grey-sided vole (Clethrionomys rufocanus) densities, levels of invertebrate herbivory on Northern willow (Salix glauca) leaves, and chemical quality of the willows was studied on 8 islands and 2 mainland sites with contrasting vole densities in northernmost Norway. These variables were measured at each of the study sites to determine the degree and nature of the effects of browsing-induced alterations in plant quality on subsequent invertebrate herbivory. The level of invertebrate herbivory was positively correlated with vole density, as were the number of leaves per shoot, leaf size, and leaf nitrogen content, while leaf C/N ratios were negatively correlated with vole density. The level of herbivory increased from > 1% on the vole-free island to < 4% on the island with the highest vole density. The plant character that explained most of the variance in the level of invertebrate herbivory was leaf size. Since the vole densities have been altered by human intervention and their numbers are largely governed by predation rather than food quality, the positive correlation between vole densities and level of invertebrate herbivory is probably due to a facilitative effect of voles on invertebrate herbivores, mediated through changes in plant chemistry. We suggest that voles affect susceptibility of willows to invertebrate herbivory both directly by winter browsing and indirectly by reducing the abundance of competing plants.

Nomenclature: Nilsson, 1986.

Stone's sheep (Ovis dalli stonei) are susceptible to anthropogenic disturbances, but few data have been available to help minimize impacts. We used the movements of individuals to define use and availability, and resource-selection functions (RSF) and the information-theoretic approach to examine seasonal habitat selection and interannual variation in selection of attributes by groups of Stone's sheep. Movement rates of Stone's sheep followed consistent yearly patterns, with highest rates occurring in summer and fall. Models that contained vegetation, topography, and risk of predation best explained resource selection. Topographic features ranked better, however, than components of vegetation or risk of predation from grizzly bears (Ursus arctos) and wolves (Canis lupus) at explaining habitat selection. Selection strategies were variable among groups of Stone's sheep and between years within groups even though consistencies in selection for steep slopes, ridge-like topography, south aspects, and upper elevations were common. This research provides the first comprehensive analysis of habitat selection by Stone's sheep, which show strong fidelity to seasonal ranges but also exhibit behavioural plasticity in selection of attributes within those ranges.

Nomenclature: Hultén, 1974; Nowak & Paradiso, 1983.

The restoration of cutaway peatlands provides an opportunity to return the carbon (C) sink function and to examine the influence of climate on peat formation and C accumulation. We studied CO₂ exchange dynamics in 2002 and 2003 at a rewetted cutaway peatland located within the temperate maritime climatic zone. Gross photosynthesis (P_G), ecosystem respiration (R_TOT), and net ecosystem exchange (NEE) were observed in a range of microsites representing a hydroseral succession gradient: Typha latifolia – Phalaris arundinacea, Eriophorum angustifolium – Carex rostrata, and Juncus effusus – Holcus lanatus vegetation communities and areas of bare (unvegetated) peat. Annual rainfall was 26% higher in 2002 and 4% lower in 2003 than the long-term average and influenced water table position at all microsites. Observed instantaneous CO₂ fluxes varied temporally and spatially at all microsites. Modelled P_G was strongly dependent on irradiation (Photosynthetically Active Radiation) and the Vascular Green Area index (VGA). R_TOT was influenced by the soil temperature at 5 cm depth (T_5cm) and the water table position. All microsites were net sources of CO₂ in both years of the study, and higher losses (with the exception of Juncus / Holcus) were observed in 2003 at all microsites. In general, losses followed the trend Juncus / Holcus > Phalaris > Typha > bare peat > Eriophorum– Carex in 2002 and Phalaris > Juncus– Holcus > Typha > Eriophorum / Carex > bare peat in 2003. Losses ranged from −163 to −651 g CO₂– C·m⁻²·y⁻¹ in 2002 and −308 to −760 g CO₂ – C·m⁻²·y⁻¹ in 2003. Considerable wintertime losses were observed at all microsites. The results from this study suggest that these peatlands are vulnerable to interannual variations in climatic inputs and that future predictions of climatic change may make restoration of the C sink function in cutaway peatlands in the temperate maritime climatic zone a considerable challenge in the years ahead.

Nomenclature: Moore, 1982.

We examined the influence of tree- and stand-level conditions on lichen diversity on 143 ash trees, varying in age from 11 to 140 y, in 5 deciduous stands in southern Sweden. The number of lichen species per tree varied from 2 to 30 and was primarily explained by tree trunk diameter and to a lesser extent by tree age, crown cover, lichen cover, and stand identity. The positive relationship between species richness and lichen cover seems compatible with a random placement of species and suggests that similar factors affect both lichen growth and establishment. Species richness did not increase on trees above 65 y of age, while species composition changed with tree age. Together with the positive linear effect of trunk diameter, these results suggest a slight overall positive effect of area, but that species richness over time depends more on species turnover. In addition, we examined if lichens occurring on trees of different ages differed in life history traits, e.g., spore size, thallus height, and pH preference. The results indicate that lichens that most frequently occurred on old trees had larger spores and thicker thalli than other species, suggesting that lichen species' response to tree age can be understood to some extent from their life history traits. However, in this respect lichen ecology is still in its infancy.

Nomenclature: Santesson et al., 2004.

Sponge assemblages were examined simultaneously in 2 shallow habitats (consolidated rocks and boulder tops) in May and November 2002 in Mazatlán Bay. Important differences were found between the assemblages in the 2 habitats, despite them being only 40–50 m apart. Total (35) and exclusive (25) species richness were higher on boulders than on consolidated rocks (22 and 12, respectively), and only 10 species occurred in both habitats simultaneously. Non-metric multidimensional scaling (nMDS) in combination with analysis cluster revealed a disjunct pattern in the distribution of sponges between habitats. These analyses also showed that the structure of these assemblages varied less over time in consolidated rocks (60% similarity between times) than in the boulders (40% similarity). In fact, the number of species was less variable on consolidated rocks (from 15 to 16 species from May to November) than on boulders (from 12 to 32). The patterns presented here show that the sponge assemblages were not homogeneous in rocky habitats but varied over small spatial scales. The assemblages were more stable on consolidated rocks (the most stable habitat), but diversity was higher in the unstable habitat than on consolidated rocks. However, although the habitat type played an important role in explaining these differences, variables covarying with depth, such as water movement and habitat stability, constituted major environmental factors responsible for the differences observed in sponge assemblage structure between habitats.

Nomenclature: Hooper & van Soest, 2002.

The intraspecific occupancy–abundance relationship is a widely used descriptor of species distributions, with potential value to conservation and pest management for predicting species abundance from occurrence data. Six traditional and commonly used models for the description of this relationship include the Poisson, exponential, metapopulation, fractal, negative binomial, and improved negative binomial models. However, these models deviate systematically from empirical data. We present a model (the “droopy-tail” model or DTM) that improves estimates of occupancy at coarse scales by taking the percolation effect of scale on the occupancy–abundance relationship into account. The DTM is a fundamental departure from previous models because the slope of the scaling curve limits to negative infinity (rather than to zero) at coarse scales in addition to providing a good fit to empirical data at all spatial scales.

Interspersion of dense coniferous stands that offer cover and more open mixedwood stands providing food resources has been recommended for the management of white-tailed deer (Odocoileus virginianus) wintering yards in northeastern North America. On Anticosti Island, at the northeastern limit of this deer's distribution range, previous studies have shown continuous decline of deciduous browse. As native balsam fir (Abies balsamea) stands progressively shift to white spruce (Picea glauca), the persistence of the deer population will increasingly depends on its capacity to use white spruce stands. To provide insights into deer responses to long-term changes in their habitat, we investigated resource use along a gradient of expected habitat quality for deer. Stand use increased with the proportion of balsam fir, reaching an asymptote when > 40% of the stand's basal area was composed of fir. Stand use does not appear to be related to snow interception since sinking depth was lower in white spruce forests. Deer using white spruce stands mainly consumed balsam fir (72%), whereas spruce represented only 17% of their diet. The consumption of arboreal lichens increased from 6% in January to 21% in March. The observed patterns of habitat use and the composition of the winter diet confirm the dependence of deer on balsam fir in winter and give additional support to the hypothesis that litterfall from balsam fir provides an alternate food source sustaining high deer density in a boreal forest without predators.

Nomenclature: Anonymous, 2005.

Animal-pollinated angiosperm plants that respond positively to nectar removal by replenishment invest energy that can entail a reproductive cost. Here we use nectar removal manipulation to investigate whether nectar removal increases total nectar production in Moussonia deppeana (Gesneriaceae) and to see if this leads to lower seed production. We found that flowers strongly respond to increased nectar removal by producing 2–4 times as much additional nectar. Other nectar removal treatments had little effect on nectar production and rule out alternative explanations at the flower level. Compared with open-pollinated flowers, hand cross-pollination yielded similar seed production in flowers with experimentally increased nectar removal. Although flower-level effects of nectar replenishment on seed production were not detected in M. deppeana, costs of nectar replenishment need further study as tradeoffs between nectar production and seed production could be expressed at the plant level and/or as long-term effects.

Nomenclature: Wiehler, 1975; 1982.

In this study we assessed the seedling assemblages of a large fragment of the Atlantic forest to test 2 hypotheses: (1) seedling abundance and richness are lower in the forest edge (0–200 m) than in the forest interior (>250 m); and (2) large-seeded seedlings (seeds >1.5 cm) are the main group affected by edge creation. The study was car ried out at the Coimbra forest, an old, 3500-ha fragment surrounded by sugar cane plantations in northeast Brazil. The seedling survey was based on 200-m-long transects along which 420 plots of 1-m² were set up per habitat and per season (dry and rainy). Within the plots, all shrub, tree, palm, and liana species seedlings ≤ 50 cm tall were counted and classified to morphospecies level. A total of 13 208 seedlings were recorded in the whole survey. At plot level, forest edge and interior showed similar scores for both average seedling density (4.7–11.2 seedlings·m⁻²) and richness (2.8–5.1 species·m⁻²) irrespective of season. At community level, however, scores for total species richness were 4.8–17.9% lower in forest edge plots than in those of the forest interior, depending on the estimator used. Moreover, large-seeded species accounted for 2.3–2.7% of all species recorded in forest edge plots, yet this group reached 13.1–14.9% in forest interior plots. As a consequence, the forest edge housed between 166 and 262 large-seeded seedlings·ha⁻¹, whereas the forest interior housed 5 952–6 047 large-seeded seedlings·ha⁻¹. Our results suggest that old forest edges hold biased and impoverished assemblages of seedlings, particularly in terms of large-seeded trees.