Molecular genetic variation following a population crash in the endangered Mauna Kea silversword, Argyroxiphium sandwicense ssp. sandwicense (Asteraceae)

The endangered Mauna Kea silversword, Argyroxiphium sandwicense ssp. sandwicense (Asteraceae), has experienced a severe decline in distribution and abundance because of predation by alien ungulates. The small remnant natural population on the Mauna Kea volcano contains only 46 individuals. By contrast, the Haleakala silversword, A. sandwicense ssp. macrocephalum, consists of a large, vigorous population exceeding 60 000 individuals. Molecular genetic variation in the two populations was assessed using random amplified polymorphic DNA (RAPD) loci. Despite its severe crash in size, the Mauna Kea population did not differ significantly from the Haleakala population in the number of detectably polymorphic loci or in heterozygosity. The lack of substantial reduction in genetic variation, at least as measured with RAPD loci, suggests that the Mauna Kea population may not yet have gone through multiple generations at very small size.     

Population estimates of the Endangered Hawaiʻi ʻĀkepa (Loxops coccineus) in different habitats on windward Mauna Loa

Endangered Hawai‘i ?ākepas (Loxops coccineus) are endemic to Hawai‘i island, where they occur in five spatially distinct populations. Data concerning the status and population trends of these unique Hawaiian honeycreepers are crucial for assessing the effectiveness of recovery and management actions. In 2016, we used point‐transect distance sampling to estimate the abundance of Hawai‘i ?ākepas in portions of Hawai‘i Volcanoes National Park (HAVO) and the Ka?ū Forest Reserve (KFR) on Mauna Loa volcano. We then compiled the survey data from four other populations to provide a global population estimate. In our HAVO and KFR study area, we mapped habitat classes to determine the population densities in each habitat. Densities were highest (1.03 birds/ha) in open‐canopy montane ?ōhi?a (Metrosideros polymorpha) woodland. In contrast, densities of the largest ?ākepa population on Mauna Kea volcano were highest in closed‐canopy ?ōhi?a and koa (Acacia koa) forest where the species is dependent on nest cavities in tall (> 15 m), large (> 50‐cm diameter at breast height) trees. We surveyed potential nesting habitat in HAVO and KFR and found only one cavity in the short‐stature montane ?ōhi?a woodland and five cavities in the tall‐stature forest. Differences in densities between the Mauna Kea and Mauna Loa populations suggest that Hawai‘i ?ākepas may exhibit different foraging and nesting behaviors in the two habitats. The estimated overall population density in the HAVO and KFR study area was 0.52 birds/ha, which equates to 3663 (95% CI 1725–6961) birds in their 11,377‐ha population range. We calculated a global population of 16,428 (95% CI 10,065–25,198) birds, which is similar to an estimate of 13,892 (95% CI 10,315–17,469) birds made in 1986. Our results suggest that populations are stable to increasing in the two largest populations, but the three other populations are smaller (range = 77–1443 birds) and trends for those populations are unknown.     

The diatoms of contemporary and ancient sediments from Lake Waiau,Hawaii, and their geochemical environment

Lake Waiau, a shallow, heart-shaped water body, is located at 3969 m on the summit plateau of Mauna Kea, a now extinct volcano, on the island of Hawaii. Sediment core from the lake bottom contains remnants of diatom populations spanning a period of more than 5000 years. The presence of diatom frustules in conjunction with an analysis of the major chemical constituents of core and modern sediments provided a unique opportunity to assess changes with time in a highly isolated environment.     

High resolution habitat suitability modelling for an endemic restricted-range Hawaiian insect (<Emphasis Type="Italic">Nysius wekiuicola</Emphasis>, Hemiptera: Lygaeidae)

Determining potentially suitable habitat is critical for effective species conservation and management, but can be challenging in remote or sensitive areas. An approach that combines non-intrusive spatial data collection techniques and supporting field data can lead to a better understanding of landscape-scale species distributions. Here we present two habitat suitability models, at 1 and 10 m resolutions, for the endemic wēkiu bug Nysius wekiuicola, a poorly-understood resident scavenging arthropod species present on the summit of Maunakea in Hawai‘i. Our models reveal that the wēkiu bug, restricted almost entirely to portions of cinder cones above 3500 m elevation, has a high degree of habitat specificity and represents a classically rare species. Across the 55 km² study area, 850 ha of potentially suitable habitat were identified at the 10 percentile training threshold, with the core area located at the true summit. Our results show that elevation and surficial mineralogy were the strongest predictors of suitable habitat, with lesser contributions from aspect and slope. Climatic variables also likely influence wēkiu bug distribution patterns, but were not included in our models due to the coarseness of available climate data and high correlation between variables. Relatively minor differences between the two models, in terms of identifying the locations and amount of suitable wēkiu bug habitat, and a higher measure of performance for the 10 m resolution model, suggest that coarser resolution input variables may characterize suitable habitat more efficiently than very fine 1 m resolution data. The suitability models generated as a result of this study will be directly incorporated into conservation management and restoration goals, and can easily be adapted for other arthropod species, leading to a more holistic understanding of metacommunity dynamics at the Maunakea summit.     

A landscape perspective of the Hawaiian rain forest dieback

Abstract. Throughout the 1960s and 1970s there was a rapid decline and canopy dieback in the Metrosideros polymorpha dominated rain forest of Hawai'i. An analysis of air photo sets from 1954, 1965, and 1972, covering the windward slopes of Mauna Kea and Mauna Loa, gave support for an alien disease hypothesis. A total demise of the native forest was predicted for the early 1990s. This prediction as well as the disease hypothesis proved to be wrong. Various searches for a single climatic cause also failed to explain the dieback. The spatial dynamics of the dieback phenomenon were newly analyzed with an additional air photo set from 1977 and by using GIS with spatial statistics. Two juxtaposed and climatically similar landscape matrix samples of ca. 200 km², one each on Mauna Loa and Mauna Kea, were subjected to an analysis of landform heterogeneity and superimposed dieback patterns. The Mauna Loa matrix displays up to 15 000 yr old lava flows, while the Mauna Kea matrix displays up to 250 000 yr old substrates. Initiation of dieback occurred simultaneously on both mountains and was highly correlated with poorly-drained sites. The progression of dieback, however, followed a gradient of decreasing soil moisture, which often terminated at clearly recognizable substrate boundaries in the Mauna Loa matrix and moved over well-drained hill sites in the Mauna Kea matrix. Metrosideros dieback spread across the entire spectrum of volcanic substrates and habitat moisture regimes and developed from a smaller into a larger patch mosaic. By 1977, ca. 50 % of the forest area in both sample matrices had gone into dieback. Thereafter, the dieback came to a halt. The domino-type collapse, which frequently came to a halt at volcanic substrate boundaries, indicates that stands in better drained sites were also predisposed to die. Stands on adjoining substrates often survived. Substrates with dieback stands displayed no other obvious vigor-reducing stresses. The canopy trees on such substrates may have a common history, such as a major disturbance (including dieback) that synchronized stand development in the past. Subsequent weather disturbances and other abiotic/endogenous stresses associated with stand maturation, such as nutrient limitations and stand-level senescence, may reinforce a rhythmic synchrony over several generations of canopy cohorts.     

Life history variation in a temperate plant invader, <Emphasis Type="Italic">Verbascum thapsus</Emphasis> along a tropical elevational gradient in Hawaii

Few studies have examined the life history of temperate plant invaders in the tropics. Temperate invaders that utilize seasonal cues to influence their life histories may be expected to behave differently in the tropics. This study examined variation in life history in an invading temperate weed, Verbascum thapsus, across an elevation gradient (1,690–2,720 m) along the montane and subalpine slopes of Mauna Kea, Hawaii. Over 7,000 seedlings were marked and monitored over a period of 3 years. Germination, survival, growth, and reproduction in V. thapsus varied among sites along the elevational gradient. Compared to plants at lower elevations, those at higher elevation sites (>2,000 m) had lower early seedling survival, higher established rosette survival, higher vegetative growth rates, higher threshold sizes for flowering, and commonly lived more than 3 years before flowering. The abundance of competing vegetation generally decreased with elevation, and this may drive variation in V. thapsus survival and growth. Size-dependent survival appears to play a major role in the selection for smaller size at first flowering and shorter generation time at lower elevations. This pattern is opposite to that reported in temperate mountains where high elevation plants flower sooner and at smaller size, but both patterns appear consistent with general life history theory for biennials. Due to novel biotic and climatic interactions in the tropics, predictions of growth patterns and invasion dynamics for temperate weeds in the tropics can be misleading when based on the plant’s behavior in temperate systems.     

Interactions of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> Cry1Ac toxin in genetically engineered cotton with predatory heteropterans

A number of cotton varieties have been genetically transformed with genes from Bacillus thuringiensis (Bt) to continuously produce Bt endotoxins, offering whole plant and season-long protection against many lepidopteran larvae. Constant whole-plant toxin expression creates a significant opportunity for non-target herbivores to acquire and bio-accumulate the toxin for higher trophic levels. In the present study we investigated movement of Cry1Ac toxin from the transgenic cotton plant through specific predator-prey pairings, using omnivorous predators with common cotton pests as prey: (1) the beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), with the predator Podisus maculiventris (Heteroptera: Pentatomidae); (2) the two-spotted spider mite, Tetranychus urticae (Acarina: Tetranychidae), with the predatory big-eyed bug Geocoris punctipes (Heteroptera: Geocoridae) and (3) with the predatory damsel bug Nabis roseipennis (Heteropera: Nabidae); and (4) the thrips Frankliniella occidentalis (Thysanoptera: Thripidae) with the predatory pirate bug Orius insidiosus (Heteroptera: Anthocoridae). We quantified Cry1Ac toxin in the cotton plants, and in the pests and predators, and the effects of continuous feeding on S. exigua larvae fed either Bt or non-Bt cotton on life history traits of P. maculiventris. All three herbivores were able to convey Cry1Ac toxin to their respective predators. Among the herbivores, T. urticae exhibited 16.8 times more toxin in their bodies than that expressed in Bt-cotton plant, followed by S. exigua (1.05 times), and F. occidentalis immatures and adults (0.63 and 0.73 times, respectively). Of the toxin in the respective herbivorous prey, 4, 40, 17 and 14% of that amount was measured in the predators G. punctipes, P. maculiventris, O. insidiosus, and N. roseipennis, respectively. The predator P. maculiventris exhibited similar life history characteristics (developmental time, survival, longevity, and fecundity) regardless of the prey’s food source. Thus, Cry1Ac toxin is conveyed through non-target herbivores to natural enemies at different levels depending on the herbivore species, but continuous lifetime contact with the toxin by the predator P. maculiventris through its prey had no effect on the predator’s life history. The results found here, supplemented with others already published, suggest that feeding on Cry1Ac contaminated non-target herbivores does not harm predatory heteropterans and, therefore, cultivation of Bt cotton may provide an opportunity for conservation of these predators in cotton ecosystems by reducing insecticide use.     

Unexpectedly low genetic divergences among populations of the threatened bog turtle (<Emphasis Type="Italic">Glyptemys muhlenbergii</Emphasis>)

We used mitochondrial DNA sequence comparisons to assess range-wide population structure and historical patterns of differentiation among populations of the bog turtle (Glyptemys muhlenbergii). This species is one of North America’s smallest and most endangered pond turtles, and is currently found in three largely disjunct groups of populations: in the southern U.S., in the northeast, and in the Finger Lakes and Lake Ontario Plains region of western and central New York State. All the New York sites and most of the northeastern sites were glaciated during the Pleistocene. We surveyed 2793 bases pairs of mitochondrial DNA spanning three genes (cytb, nd4, and d-loop) in 41 individuals from 21 populations throughout most of the bog turtle’s distribution. We found surprisingly low levels of divergence among populations, even in southern populations that have been hypothesized as refugia during times of climate change. Our data suggest populations of bog turtle’s suffered a bottleneck, followed by a rapid post-Pleistocene expansion into northern segments of the species’ range. We discuss historical changes in habitat availability and climate that may have influenced the historical deployment of lineages in this species, and possible life history traits and habitat dynamics that might also contribute to the overall low genetic diversity across its range.     

Conservation of <Emphasis Type="Italic">Hymenocallis coronaria</Emphasis> genetic diversity in the presence of disturbance and a disjunct distribution

Evidence shows that dam construction has affected faunal species distribution and diversity in the southeastern U.S. However, the effects of this perturbation on aquatic flora of the region are heretofore uninvestigated. The objective for this research is to examine the effects of hydroelectric power generation and habitat characteristics on the size and distribution of populations of Hymenocallis coronaria (J. LeConte) Kunth (Amaryllidaceae), an emergent aquatic plant found in the southeastern United States, and to characterize its genetic variability in an effort to target conservation priorities. Multiple linear and logistic regression analyses show that hydropeaking does not have a significant effect on H. coronaria populations located downstream of dams, while other habitat variables associated with the streams are significantly positively related to population size and distribution. Analysis of 24 populations using seven universal cpDNA markers and six nDNA microsatellite markers indicates that the genetic structure for both genomes correlates with the location of a major gap in the species’ range, showing deep divergences in haplotype and population dendrograms between eastern and western regions. An AMOVA confirms that a substantial amount of genetic variation is found among regions, and very little variation is found within regions. The eastern and western regions have diverged for a significant time period, potentially due to the presence of a gene flow barrier in the middle of the species’ range caused by sub-standard habitat. Individual drainage basins contain unique cpDNA haplotypes and should be managed appropriately.     

The ecology and conservation of the coelacanth Latimeria chalumnae

Synopsis Studies on the ecology of the living coelacanth, Latimeria chalumnae, are reviewed and assessed. Early predictions on the life history of the coelacanth have proved to be accurate but recent findings have improved our understanding of its habitat and feeding preferences, diel activity patterns and social behaviour. A history of coelacanth conservation reveals that there has been a sustained concern for the survival of this species which has eventually culminated in several effective conservation actions in recent years. The coelacanth is threatened by a number of socio-economic and biological factors, but international action directed at managing the fishery in the Comoros should ensure that the species survives. Recent observations on living coelacanths in their natural environment have greatly improved our knowledge of the behaviour and relative abundance of adults. Important priorities for future research include studies on the distribution and abundance of juveniles and breeding adults, both off the Comoros and elsewhere. The coelacanth is a highly specialised, precocial fish which occupies a unique place in biology. Co-ordinated international efforts should continue to be made to understand and conserve this remarkable fish.     

Temperature and humidity responses of the arctic-alpine seed bug Nysius groenlandicus

Field observations in Greenland as well as arena choice experiments showed that the arctic-alpine seed bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae) is markedly xerophilous and thermophilous, preferring temperatures around 30 °C. Some variation in thermo-preference was found among individuals from different localities in Greenland. Individuals from an inland locality (Søndre Strømfjord/Kangerlussuaq) had the highest temperature preference. Exposing individuals to rising temperature showed very high thresholds for excessive activity (ca. 41 °C), heat stupor (ca. 51 °C) and death (ca. 52 °C). All stages initially preferred the lowest humidity obtainable but gradually changed to higher humidities. The youngest nymph stages were most tolerant to desiccation. The observed preferences are interpreted as adaptations to a habitat where a warm and dry microclimate allows this obligatorily univoltine species to complete its life cycle within one year. The paper presents some general statistical approaches to analyses of behavioural responses to environmental gradients.     

Genetic structure and mating system in the palila, an endangered Hawaiian honeycreeper, as assessed by DNA fingerprinting

We conducted DNA fingerprinting analyses to ascertain the mating system and population genetic structure of the palila, an endangered Hawaiian honeycreeper, which occupies a fragmented range on the Mauna Kea volcano of the island of Hawai'i. DNA fingerprinting of twelve complete families from the Pu'u La'au population revealed no evidence of extrapair fertilization or intraspecific brood parasitism. Band-sharing coefficients from fingerprints produced with two probes revealed that the large Pu'u La'au population on the southwest slope of Mauna Kea, and a smaller, geographically separate population on the east slope (at Kanakaleonui) had relatively high and virtually identical levels of minisatellite variability (mean S of 0.27 for each population based on combined data of M13 and Jeffreys 33.15 probes). The two populations also had nearly identical allele frequencies based on their mean corrected similarity, S_ij, of 0.98. These data suggest that the two populations have not been fragmented long and/or have sufficient current gene flow to ameliorate any affects of genetic drift. We conclude that present levels of inbreeding are low within both populations, and that proposed translocations of individuals from Pu'u La'au to Kanakaleonui appear appropriate from a genetic standpoint.     

Soil fertility response to <Emphasis Type="Italic">Ulex europaeus</Emphasis> invasion and restoration efforts

Invasive plant species can substantially alter the soil fertility of the ecosystems they invade, and in doing so have the potential to reduce the suitability of the soil for native species. Even after removal of the invader these alterations can inhibit the reestablishment of native species. We evaluated the impact of invasion by the leguminous shrub Ulex europaeus on soil properties on Mauna Kea, HI. We also investigated the effect of efforts to remove U. europaeus and restore native ecosystems in the study area; where the efforts included bulldozing the U. europaeus and planting introduced Cryptomeria japonica to compete with regenerating U. europaeus. Mauna Kea supports a strong rainfall gradient and substantial associated variation in soil properties. We use statistical models to extract the effect of invasion and restoration from the influence of rainfall. We found U. europaeus decreases soil pH, calcium content, base saturation, and labile phosphorus. Restoration efforts over an 11-year period restored the soil’s calcium and phosphorus content to levels comparable to those found in uninvaded soils on Mauna Kea, demonstrating that the effects of U. europaeus on soils are reversible.     

The role of amphibian prey in the diet and growth of giant water bug nymphs in Japanese rice fields

Predatory insects that depend upon particular prey animals are commonly regulated by the prey animal’s abundance. Nymphs of the giant water bug Kirkaldyia (=Lethocerus) deyrolli (Heteroptera: Belostomatidae) are predators regarded as specialists in feeding on tadpoles. We studied the ontogenetic diet shift of aquatic nymphs by quantifying instar abundance and by analyzing captured prey and prey relative abundance during the period of rice irrigation in three localities. We also evaluated the contribution of major prey items (tadpoles, frogs, and Odonata nymphs) on specific growth rates of each nymphal stage in a rearing experiment. First to third-instar nymphs of K. deyrolli fed mainly on tadpoles, regardless of differences in prey availability. Nymphs of subsequent fourth and fifth instar stages shifted from tadpoles to other prey animals within each rice field. A rearing experiment demonstrated that giant water bug nymphs provided with tadpoles had greater specific growth rates at all nymphal stages, except for the final stage, than nymphs fed other prey (frogs and Odonata nymphs). The emergence of young K. deyrolli nymphs seemed to coincide with the period during which tadpoles became abundant in the rice fields. Consumption of tadpoles seems important to allow the nymph to complete its larval development in an unstable temporary habitat. An erratum to this article can be found at     

Locomotion in a sticky terrain

The mirid bug Pameridea roridulae lives mutalistically on the protocarnivorous plant Roridula gorgonias. The latter resembles an effective, three-dimensional flypaper trap which captures numerous flying insects. We have recently shown that P. roridulae bugs are not trapped by the plant, because they are covered with a layer of epicuticular grease, which is considerably thicker than in other insects. The present study demonstrates that the bugs’ morphology and locomotory characteristics also contribute to their specialisation for life on the adhesive plant surface. A structural analysis of the mirid bug’s attachment system, and an experimental study on its attachment ability were carried out. In traction force tests, maximum forces of 8.8 mN were measured on adaxial R. gorgonias leaves, corresponding to 126 times the bug’s body weight. On smooth surfaces, generated forces were only 47 times the bug’s body weight. Compared to closely related mirid bug species avoiding contact with plant adhesive secretion, P. roridulae is distinctly stronger and heavier, and holds its body close to the plant substrate. Two locomotion strategies on the glandular hairy plant surfaces are suggested for mirid bug species from the tribus Dicyphini: (1) avoidance strategy, characterised by the slim body held at a large distance from the plant surface by using long, slender legs, and (2) defense strategy, where trapping of the heavy bugs, situated close to the plant surface, is overcome by generating strong forces during locomotion and by having a thick anti-adhesive epicuticular greasy layer on the bugs’ cuticle.     

Characterization of peroxidase changes in resistant and susceptible warm-season turfgrasses challenged by <Emphasis Type="Italic">Blissus occiduus</Emphasis>

Peroxidases play an important role in plant stress related interactions. This research assessed the role of peroxidases in the defense response of resistant and susceptible buffalograsses [Buchloe dactyloides (Nutt.) Engelm] and zoysiagrasses (Zoysia japonica Steudel) to the western chinch bug, Blissus occiduus Barber. The objectives were: (1) to assess the relationships among protein content, basal peroxidase levels, chinch bug injury, and ploidy levels of chinch bug-resistant and -susceptible buffalograsses; (2) to compare peroxidase activity levels of resistant and susceptible buffalograsses and zoysiagrasses in response to chinch bug feeding; (3) and to analyze extracted proteins from chinch bug-resistant and -susceptible buffalograsses and zoysiagrasses by native gel electrophoresis to obtain information on the peroxidase profiles. Correlation analyses of 28 buffalograss genotypes with varying levels of chinch bug resistance and ploidy levels indicated that buffalograss total protein content was correlated (r = 0.47, P = 0.01) to chinch bug injury, while basal peroxidase levels was not (r = 0.19, P = 0.29), suggesting that the up-regulation of peroxidases in resistant buffalograsses is a direct response to chinch bug feeding. Three of the four chinch bug-resistant buffalograss genotypes evaluated had higher peroxidase activity in the infested plants compared to control plants. Peroxidase activity levels were similar between infested and control plants of the two highly susceptible buffalograss genotypes. Zoysiagrasses had lower peroxidase activity in general when compared to buffalograss control plants, and only ‘Zorro’ consistently showed higher peroxidase activity in the infested plants. Native gel electrophoresis analysis identified differences in the isozyme profiles of infested and control buffalograsses ‘Prestige’ and 196, and the zoysiagrass ‘Zorro’. Results from this study suggest that peroxidases have the potential to be used as markers for selecting chinch bug resistant turfgrasses, and may help explain how plants defend themselves against biotic stresses, such as chinch bugs.     

Fragmentation and genetic differentiation among subpopulations of the endangered Hawaiian mint Haplostachys haplostachya (Lamiaceae)

Haplostachys haplostachya was at one time a prevalent species in the mid-elevation (1650–1800 m) xerophytic shrubland between Mauna Loa and Mauna Kea on Hawaii. Grazing pressure by feral ungulates, destruction of habitat from military activity, and conversion of forest to pastures have fragmented its range to small subpopulations restricted to several cinder cones and portions of the remaining shrubland. Some subpopulations are still extensive, while others are reduced to 20 or fewer individuals. Genetic analyses using random amplified polymorphic DNA (RAPD) markers demonstrate that plants in subpopulations with a large number of individuals maintain levels of genetic variation similar to the entire population, whereas plants in a small subpopulation at Pu'u Leilani (14 individuals remaining) have reduced levels of variation. Of the 122 loci identified, 54 (44%) were polymorphic. Two large populations showed variation at 45 and 49 loci, but the Pu'u Leilani plants showed variation at only 37 loci. The mean expected heterozygosity ( H ) in this subpopulation was also lower (0.137 vs. 0.163 and 0.154) and genetic differentiation ( G _ST) was higher (0.167 vs. 0.018 and 0.052) than in other subpopulations. An examination of variation indicates that although plants of the three subpopulations are genetically similar, there is evidence of genetic restructuring among the subpopulations. The impact of these results towards conservation efforts of this and other endangered species is discussed.     

The consequences of predator control for brown hares (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) on UK farmland

The brown hare Lepus europaeus is a valued game species but also a species of conservation concern owing to its severe decline in abundance on farmland throughout Europe during the twentieth century. Changes in the farmland habitat and predation have both been cited as causative factors. Their relative roles have been unclear, but most conservation action has focused on improving habitat. We analyse data from a sequence of three unique studies (one experiment and two demonstrations) covering the period 1985–2006 in which control of several common predator species was undertaken to increase densities of wild game on farmland in England. Across the three studies, regression modelling of the proportional change in hare numbers between successive years showed that—after site, year differences and harvesting were accounted for—predator control was a significant determinant of hare population change. Where habitat improvement also took place, hares reached autumn densities that were exceptional for the UK and which could sustain substantial harvests. When predation control was stopped, hare densities fell, even where habitat improvements remained in place. This analysis demonstrates that even where farmland habitat is greatly improved, uncontrolled predation prevents hares making full use of its carrying capacity. This helps explain the mixed—and at best modest—success of agri-environment schemes in the UK and elsewhere in Europe to increase hare densities. Game-shooting estates, on which effective predator control takes place, probably have a special significance within the landscape as source areas for brown hares.     

Phytogeochemical,geographical and vulnerability study of the Paleosubtropical element <Emphasis Type="Italic">Notholaena marantae</Emphasis> subsp. <Emphasis Type="Italic">marantae</Emphasis> (Sinopteridaceae) at the western edge of its range

Serpentine outcrops are distinct from their background geological context, as they are often isolated from one another, and provide a home to a significant number of rare or endemic taxa. The aim of this study was to assess the Portuguese populations of one such taxon, Notholaena marantae subsp. marantae, including information on its biogeography, habitat, geographical range and conservation status. A detailed study was also made of the endemic association Notholaenetum marantae, a member of the Phagnalo saxatilis-Cheilanthion maderensis alliance, a type of vegetation included in the EU Habitats Directive 92/43/ECC. The distribution of Notholaena marantae was highly fragmented, with two sites accounting for over 50% of the total number of individuals recorded. The presence of N. marantae is associated with that of ultramafic rocks, which show specific geochemical features. The conservation status of the species is a cause for concern. We propose that the species be considered ‘vulnerable’ according to the criteria of the IUCN (2001), and that areas where its populations grow be protected. This study confirms the endemic status of N. marantae subsp. marantae in Portugal and the importance of the conservation of its serpentine habitats.