The effects of management on the ground flora of ancient woodland, Brigsteer Park Wood, Cumbria, England

Data from 50 permanent 4 m² quadrats are used to describe changes in the ground flora of an ancient deciduous woodland in response to silvicultural management over an 18 year period. In areas undisturbed since 1969, percentage cover increased due to increased openness of the canopy, but decreased in areas subject to major disturbance due to subsequent canopy closure. Species ‘lost’ altogether from the quadrats in 1969–1987 were largely ruderal and grassland species. Most losses from individual quadrats were also from these species groups and of tree and shrub seedlings and saplings. Species characteristic of woodland shade were little affected by losses or gains.

Changes in the cover of ten abundant shade-tolerant species amplified this picture. Anemone nemorosa and Mercurialis perennis both showed a significant overall increase in mean percentage cover, and an increase in four and two plot groups, respectively. Rubus fruticosus decreased significantly overall, and in all but one of the plot groups. All the other species showed no overall significant change in mean percentage cover, but between one and four significant changes in the plot groups.

Shoot counts of Narcissus pseudonarcissus showed important changes which did not show up in the percentage cover results. Overall, from 1973, there was about a 4% year⁻¹ exponential decline in shoot numbers. Half of the eight plot groups followed this trend. In the one coppiced site, however, shoot numbers increased throughout most of the period.

Difficulties of interpreting these varied results are discussed but it is concluded that coppicing is likely to be effective in maintaining the existing ground flora in perpetuity.     

Trampling effects on coastal dune vegetation in the parker river national wildlife refuge,Massachusetts, USA

Long-term human trampling on coastal dune vegetation was analysed using eight 100 × 100 m study areas ranging in trampling intensity from little or no past trampling pressure to severe trampling pressure. All trampling levels significantly reduced species diversity. Total vegetation cover was significantly reduced only in areas with severe and heavy trampling pressure. Where long-term moderate trampling did not affect total cover, it appears to have favoured Ammophila breviligulata over other more sensitive species. The data suggest that long-term trampling pressure has caused a shift in the horizontal pattern of vegetation, i.e. expanding the width of the foredune plant community, while restricting the interdune community to a narrow strip at the base of the backdune ridge.     

Rehabilitation of degraded Calluna vulgaris (L.) Hull-dominated wet heath by controlled sheep grazing

Many upland areas of the British Isles have seen declines in the area and condition of heather (Calluna vulgaris)-dominated heathland vegetation. To reverse this decline, management regimes must be designed to rehabilitate areas that have seen this decline. As most of this heathland vegetation is primarily managed by grazing, such management has to determine what stocking levels can maintain the vegetation in a desired state. This paper describes how to reverse this decline through suitable grazing management.A degraded ‘wet-heath’ system, previously grazed at 2.1 sheep ha⁻¹, was subject to a range of grazing treatments over a 5-year period. Treatments varied in intensity (0-1.4 sheep ha⁻¹) and timing (summer only, winter only, or year round) of grazing. Grazing levels were maintained at 2.1 sheep ha⁻¹ outside the fenced areas. Vegetation composition remained stable outside the fenced treatments. All the fenced treatments showed an increase in the relative frequency of the evergreen Calluna vulgaris, with the greatest increase being in the ungrazed treatment, and the least in the year round 1.4 sheep ha⁻¹ treatment. This increase was in line with a reduction in heather utilisation to relatively low and sustainable levels. Other species that benefited from reduced grazing included Carex nigra, Deschampsia flexuosa and to a lesser extent Galium saxatile and Erica tetralix, whereas a range of moss species including Hypnum jutlandicum and Rhytidiadelphus loreus were more frequent at higher grazing levels. Though the recovery of heather was similar in the two seasonally grazed treatments, the vegetation showed different overall trajectories. Winter only grazed allowed a substantial increase in the cover of the deciduous Molinia caerulea, whereas this species was kept in check by summer only grazing. A stocking level of between 0.7 and 1.4 sheep ha⁻¹ appears to be appropriate to maintain and even enhance the cover of heather on degraded wet heath. Complete removal is not necessary. Grazing restricted to the winter period is inappropriate in areas where M. caerulea occurs. Setting appropriate stocking levels to maintain the condition of the vegetation must take into account site conditions, especially the presence of species that can affect the utilisation of heather.     

The recent decline of a New Zealand endemic: how and why did populations of Archey's frog Leiopelma archeyi crash over 1996-2001?

Dramatic changes have been documented in New Zealand's vertebrate faunas since human settlement, involving major declines and extinctions, but over recent years few species have declined in numbers so rapidly as the terrestrial Archey's frog Leiopelma archeyi (Anura: Leiopelmatidae). Long-term monitoring over more than 20 years revealed a major population reduction of the species over 1996-2001 and L. archeyi is now classified as Nationally Critical under the New Zealand threat classification system. The decline progressed northwards in the Coromandel ranges, and mostly larger (female) frogs survived. On a 100 m² study plot at Tapu Ridge, annual population estimates averaged 433 frogs (SE ±32) over 1984-1994, declining by 88% to average 53 frogs (SE ±8) over 1996-2002. A mean annual survival rate of 82% for most years declined to 33% over 1994-1997. There is mounting evidence to suggest that disease is the major agent of decline, supported by (1) the rapidity and severity of decline, (2) the progressive (south to north) nature of decline, and (3) finding frogs with chytriodiomycosis from Batrachochytrium dendrobatidis at the time of decline. Surprisingly, sympatric populations of the semi-aquatic Leiopelma hochstetteri have not declined dramatically, nor has a western population of L. archeyi at Whareorino, despite chytridiomycosis occurring in some frogs there. Sustaining and restoring populations of L. archeyi in New Zealand raises major challenges for conservation management.     

The effects of human trampling on the fauna of grassland litter

The effects of trampling on the invertebrate fauna of grassland litter was studied using two levels of treading intensity over a period of 12 months. Changes in the structure of the litter after treatment (fall in total volume, proportion of air space) were measured with a Quantimet Image Analysing Computer. The total volume fell by 81% and the proportion of air space fell from 63% to 38% in the litter samples receiving 10 treads/month. The overall effect of treading on the fauna was a substantial decline in numbers and species, although this did not apply to all groups. At the species level there was considerable variation in sensitivity to treading. The differences in the fauna between the two levels of treading were small and non-significant with the exception of the spiders. The invertebrate fauna of grassland litter appears to be affected by levels of trampling much lower than those required to produce changes in the structure and species frequency of living plants.     

Mercury in fish in the Smallwood Reservoir,Labrador, twenty one years after impoundment

The elevated mercury (Hg) levels in fish flesh found after impoundment of a reservoir, are predicted to decline as the reservoir ages. The length of time required for a return to background levels is dependent on among other things, the trophic status of the fish. Predictions for omnivorous species range between 15 and 20 years while for piscivorous species they vary from 20 to 30 years. Fish in the Smallwood Reservoir, Labrador, Canada, were sampled 6 years after impoundment when hg levels were found to be elevated in most species. Selected of the sites were re-sampled after 16 years and again after 21 years. Mercury in the flesh of omnivorous species such as lake whitefish (Coregonus clupeaformis) had returned to background levels after 16 years as predicted. However, hg in the flesh of piscivores such as northern pike (Esox lucius) and lake trout (Salvelinus namaycush) remained elevated even 21 years after impoundment. While the levels in lake trout have declined somewhat in that time, there is no evidence of decline in the northern pike either within the reservoir or at downstream stations. Models predicting decline in hg levels in piscivorous fish in reservoirs must be re-evaluated in light of this extended data set.     

Evaluation of alternative approaches to rainforest restoration on abandoned pasturelands in tropical North Queensland,Australia

The lag time for natural recruitment of tropical rainforest species in abandoned pastureland is very long, therefore artificial restoration techniques have been employed to accelerate natural seedling recruitment. The objectives of this study were to investigate: (1) the success/failure of establishment 502 seedlings belonging to 15 species from 11 families planted approximately ten years ago; and (2) the influence of different restoration techniques on enhancing natural recruitment during this period. The study was conducted in the wet tropical rainforest region of northeast Queensland, Australia as a completely randomized block design involving five treatments with two replicates. In each plot, 63 tropical rainforest seedlings from one or a combination of species were planted randomly. Two control plots were laid out where no seedlings were planted. Survival, height and diameter data were taken on the seedlings ten years after planting. Each 11×17 m² plot was further divided into 187, 1×1 m² subplots. Within each subplot all seedlings recruited were located and identified. Canopy cover was estimated using belt transects 1 m apart that ran in an east–west direction across the plots. Within each plot the percentage of grass, and the crown cover were estimated using the Braun‐Blanquet cover abundance scale. Survival rate of planted seedlings varied across the treatment plots. The survival rate ranged from 65 to 75 per cent for primary‐promoter species, 85 to 100 per cent in middle‐phase species and 42 to 57 per cent for mature‐phase species. No Pilidiostigma tropicum seedlings survived in any treatment. Fourteen species recruited naturally across the treatment plots. A total of 410 seedlings were naturally recruited from 11 different families in the ten‐year‐old reforested site. The highest natural recruitment (236 seedlings) occurred in Treatment 3, where Omalanthus novo‐guineensis seedlings were planted with eight primary‐promoter species, followed by 99 in Treatment 5 where a group of primary‐promoters, middle phase species and mature‐phase species were planted together, 36 in Treatment 4 (Alphitonia petriei planted with eight primary‐promoter species), 10 in Treatment 2 where only Omalanthus novo‐guineensis seedlings were planted, and 13 in control plots. Grass cover declined with increasing species diversity and increased canopy cover. The results indicate that the diversity of species used in restoration had a major influence on natural recruitment. Copyright © 2004 John Wiley & Sons, Ltd.     

Declines in common, widespread native birds in a mature temperate forest

Common, widespread species are important for ecosystem structure and function. Although such species have declined in some parts of the world, for most ecosystems there is a lack of information about changes in the population status of common species. We studied the abundance of common, widespread forest birds in Nelson Lakes National Park, New Zealand using standardised 5-min bird counts, carried out over a 30-year time span. There was a significant change in the bird community structure during this period. Five native species (bellbird, rifleman, grey warbler, New Zealand tomtit and tui) declined in abundance during the 30 years. All of these declined in abundance at low but not high altitudes, and the decline was substantial for all but New Zealand tomtit and tui. Three other native species increased in abundance (silvereye, yellow-crowned parakeet and New Zealand robin). There was no change in the abundance of introduced blackbirds. We suggest that invasive alien species are the most likely cause of the ongoing declines in common native species. A peak in brushtail possum abundance and the arrival of a new species of Vespula wasp were two large changes in Nelson Lakes forests that occurred during this study. Both are likely to have added to the ongoing impacts of predation by introduced rats and stoats. We suggest that it is necessary to actively manage introduced species in order to maintain populations of widespread, common native bird species in New Zealand.     

Rehabilitation of degraded dry heather [Calluna vulgaris (L.) Hull] moorland by controlled sheep grazing

Many areas of heathland in Europe have seen a decline in the area and condition of Calluna vulgaris (heather)-dominated vegetation, with subsequent declines in the associated faunal interest. Grazing, alongside burning, is still the predominant means of managing heathland vegetation, and, therefore, it is by manipulating this management that cost-effective improvements in vegetation condition can be made. This paper investigates the suitability of different grazing treatments for rehabilitating degraded ‘dry heath’. Treatments varied in the intensity (0-1.9 sheep ha⁻¹ year⁻¹) and timing (summer vs. winter) of sheep grazing. These treatments were compared with the behaviour of vegetation outside the fenced area kept under the previous management (open access all year round). As rabbits were common on the site, fences were erected to prevent access to the sheep grazed plots. Vegetation composition remained stable outside the fenced area, whilst all the fenced treatments showed a decrease in heather utilisation and an increase in the relative frequency of heather over the 5 years of the experiment. The increase was in proportion to the reduction in stocking rate, with only slow increases in relative frequency observed in the high grazing treatments (winter and summer). Other species that benefited from reducing grazing included Empetrum nigrum and Vaccinium myrtillus, whilst declines were observed for Agrostis capillaris and total monocotyledonous species. Only small overall differences were observed between the winter low, summer low and no sheep grazing treatments. However, a difference in response was present between the sheep exclosures and the sheep+rabbit exclosures, indicating that rabbits were having a noticeable effect on heather recovery at this site. On this degraded ‘dry heath’ system, imposing a reduction in stocking density improved the condition of the dwarf shrubs present and reduced the grass component of the vegetation. There was little effect of the timing of grazing, such that a reduction in sheep numbers to 0.8/0.9 sheep ha⁻¹ year⁻¹, to give utilisation levels of below 20%, can achieve the desired result of improving vegetation condition whilst still achieving some economic return from grazing. However, the wide range of ‘sustainable’ stocking densities for different heathland systems highlights the need to base effective management on measured utilisation rather than on stock numbers.     

Increased sheep numbers and the loss of heather moorland in the Peak District,England

The maps of vegetation in the northern Peak District given by Moss (1913) suggest that there were then the equivalent of 154 km² of moorland dominated by heather and bilberry. At present, the same area has the equivalent of only 99 km² of this moorland, a loss of 36%. Sheep numbers in the hill parishes trebled between 1930 and 1976, and the changes in vegetation are consistent with those produced elsewhere, experimentally, by sheep grazing. It is considered therefore that these changes are cause and effect. The repercussions on wildlife of this loss of moorland are largely undocumented, but red grouse stocks seem to have declined to about a third of their 1930s level.     

Vegetation composition in relation to flood frequency in Lillooet River valley,British Columbia

On a 20 km reach of the floodplain of Lillooet River, British Columbia, groupings of plant species were determined by analysing data from one hundred and thirty eight 100 square metre quadrats. Four pioneer species and four forest species groupings were isolated, and shown to be related to both sediment size and flood frequency.Five species were significantly correlated with elevation: mature $\text{Populus trichocarpa}$ (black cottonwood); mature and immature $\text{Thuja plicata}$ (red cedar); and the shrubs $\text{Viburnum pauciflorum}$, $\text{Cornus stolonifera}$ (red-osier dogwood) and $\text{Spirea douglasii}$ (hardhack). Frequency and mean cover data (analysed separately for 82 quadrats in the stable reach and for 56 quadrats in the unstable reach) confirmed the restriction of these species to certain height classes. The indicator species tended to be restricted to higher height classes above datum in the stable reach as compared with the unstable reach.Attempts to predict flood frequency in the unstable reach by standard hydrologic methods failed. Indicator plant species associated with height classes as a surrogate for flood frequency were used to define a developmental model for vegetation on the flood plain.     

Biodiversity gains and losses: Evidence for homogenisation of Scottish alpine vegetation

Alpine areas are important biodiversity reservoirs, but are subject to anthropogenic drivers including climate change, nitrogen deposition and changing land use. Alpine vegetation has been proposed as an indicator of climate change impacts, but this requires long-term data since these communities have high inertia. Most studies have focussed on climate impacts in open, high-alpine summit communities; we investigated responses of closed low- and middle-alpine communities to multiple drivers. Scottish alpine vegetation data collected 1963-1987 was used as a baseline to assess biodiversity change across a range of habitats and a wide geographic spread. Change was assessed over a 20-40 years period using a variety of metrics including α- and β-diversity indices and biodiversity changes were contrasted between habitats and areas. We also examined changes in key species′ distribution and cover. Species richness increased in most habitats, while diversity at the plot scale and β-diversity declined, resulting in increased homogeneity of vegetation. This occurred in closed alpine communities over a 20-40 years period, implying that these communities are considerably more dynamic than previously thought. Key northern and alpine species declined while lowland generalist species increased. This change was consistent with predicted impacts of climate change, but other elements of spatial pattern (decline in lichen richness in high deposition areas) were consistent with effects of nitrogen pollution. Assessment of biodiversity change differed according to the metrics used and we argue that biodiversity targets for conservation management need accurate definition and that multiple measures of biodiversity are required to accurately assess long-term change.     

Status, distribution and long-term changes in the waterbird community wintering in Doñana, south-west Spain

The Guadalquivir Marshes or Doñana wetland complex is the most important wintering site for migratory waterbirds in the Mediterranean region. However, there is a lack of previous information on the status of different species in this area. Using monthly aerial counts conducted from 1978 to 2005, we analysed the size of wintering populations of 21 waterbird species, their distribution within the Guadalquivir Marshes, and their long-term population trends. We used Underhill indices to replace missing values and to correct for flocks of unidentified ducks. Based on long-term means, we identified 16 species whose populations at Doñana exceed 1% of the biogeographical flyway population. For at least 1 month of the year, mean counts were around 10% of the flyway population for six species. The natural, temporary marshes of Doñana National Park were particularly important for Anatidae, ricefields for gulls, white storks and grey herons, fish ponds for flamingos, cormorants and avocets, and salt pans for shelduck. Four Anatidae species have undergone long-term declines and eight non-Anatidae have undergone long-term increases. Population trends were related with trophic guild, migratory status and habitat use. Winter visitors and herbivorous species showed more negative trends than resident, omnivorous-carnivorous species. Those species concentrated in strictly-protected natural marshes have tended to decline. The surface area of ricefields and fish ponds has increased over the study period, and bird species concentrated in these artificial wetlands have tended to increase. This raises questions about the value of waterbirds as flagship or umbrella species for wetland conservation.     

Hunting habitat selection by hen harriers on moorland: Implications for conservation management

We examine habitat use by hunting hen harriers Circus cyaneus at three study sites in Scotland to evaluate whether foraging patterns differ between sexes, sites, and stages of the breeding period. We modelled time spent hunting in focal plots as a function of habitat and nest proximity. Male hunting intensity (time spent hunting per hour of observation and km²) varied between sites and breeding periods, being lower during the nestling than the incubation period. Habitat use patterns were mostly consistent among study sites, which is important for developing species management recommendations applicable over the species’ range. Males avoided improved grassland, and selected areas of mixed heather and rough grass (with an optimum at ca. 50% heather cover). The effect of nest proximity was small. In contrast, females hunted mainly within 300-500 m of the nest, with a small additive effect of vegetation cover, areas of fragmented heather being preferred. Habitat management to benefit foraging harriers will involve creating (or maintaining) mosaics of heather/grassland around nest areas. Additionally, it might be possible to manipulate habitat to reduce conflict in areas where harrier predation on red grouse is important by segregating areas holding highest grouse densities (with high heather cover) from those favoured for harrier foraging (heather-grass mosaics). However, it would be necessary to test whether these manipulations might also influence harrier nest distribution, an effect which could negate any benefits from this strategy.     

Effect of long-term beef manure application on soil test phosphorus,organic carbon,and winter wheat yield

In this study, 24 years (1990–2013) of data from a long-term experiment, in Stillwater, Oklahoma (OK), were used to determine the effect of beef manure on soil test phosphorus (STP), soil organic carbon (SOC), and winter wheat (Triticum aestivum L.) yield. Beef manure was applied every 4 years at a rate of 269 kg nitrogen (N) ha^?1, while inorganic fertilizers were applied annually at 67 kg N ha^?1, 14.6 kg phosphorus (P) ha^?1, and 27.8 kg potassium (K) ha^?1 for N, P, and K, respectively. Averaged across years, application of beef manure, and inorganic P maintained STP above 38 mg kg^?1 of Mehlich-3 extractable P, a level that is far beyond crop requirements. A more rapid decline in SOC was observed in the check plot compared to the manure-treated plot. This study shows that the application of animal manure is a viable option to maintaining SOC levels, while also optimizing grain yield.     

Historical changes in the bird fauna at Coomooboolaroo, northeastern Australia, from the early years of pastoral settlement (1873) to 1999

Across most of northern Australia, the historical record is generally insufficient to serve as a baseline for interpreting the impacts of European settlement on fauna. A notable exception is the pastoral property Coomoobolaroo (454 km²) in central Queensland, where the ornithologist Charles Barnard maintained a detailed record of bird fauna from 1873 to 1933. We re-surveyed the property in 1999, and collated other information on its current avifauna, giving 242 species in total recorded over the period 1873-1999 (of which we had sufficient information to ascribe trends to 200 species). The bird fauna of Coomooboolaroo has undergone substantial change, across both of the periods 1873-1933 and 1934-1999. From 1873 to 1999, 45% of species declined or were lost from the property, compared with 13% of species that either colonised the property or increased. Most of the latter are widespread species or those known to benefit from clearing and land development. This extent of change appears at least as high as that reported for most comparable studies elsewhere in Australia, despite these being conducted at sites that have been subjected to superficially greater environmental degradation. The greatest rates of loss occurred among birds associated with softwood scrub (dry rainforest), grasslands and swamps. Smaller species were more susceptible to decline, but change in status was not significantly associated with foraging style nor different between residents and migrants. Many of the species that have declined at Coomooboolaroo have also declined in many other geographic regions, habitats and land-uses. Change in status at this property can be attributed to diverse factors, including changes in predation pressures; environmental change due to altered fire regimes and/or grazing by livestock; and vegetation clearance at both property and regional scales. The multiplicity and complex interrelationships of such factors renders it difficult to predict assemblage-level change.     

Changes in soil fertility and leaf nutrient concentration at a sugar cane plantation in Papua New Guinea

Abstract

Commercial sugar cane (Saccharum qfficinarum) cultivation in Papua New Guinea started in 1979 at a plantation in the Ramu valley where Udifluvents and Hapluderts are the dominant soil types. The sugar cane is not irrigated and receives only nitrogen (N) fertilizers (±90 kg N ha^‐1 y^‐1). Changes in soil chemical fertility were assessed by comparing soil fertility data from the mid‐1980s and 1990s and by comparing soil fertility data from sugar cane and adjoining natural grassland. Between the mid‐1980s and 1990s the topsoil pH had declined significantly (p<0.001) by 0.3 units and this was accompanied by a decline in cation exchange capacity (CEC) of 34 mmol_c kg^‐1. Total N levels in the topsoils declined (p<0.001) from 2.5 to 1.9 g kg^‐1 and available P from 36 to 27 mg kg^‐1 during the same period. Exchangeable potassium (K) also declined significantly (p<0.05) with 1.3 mmol_c kg^‐1, but changes in exchangeable calcium (Ca) and magnesium (Mg) were not significant. The decline in soil fertility was highest in the topsoil although significant changes occurred up to 0.6 m depth. Total N decreased in the 0–0.15 and 0.15–0.30 m soil horizons, but increased in the lower horizons, possibly because of nitrate leaching. A similar degree of soil fertility decline was observed when soils under sugar cane and adjoining natural grassland were compared. However, the interrow had a slightly lower fertility level in comparison to within sugar cane rows. The decrease in total N, available phosphorus (P) and exchangeable K in the soil coincided with a decrease in the leaf N, P, and K concentrations of the sugar cane over the past 10 years. It was concluded that soil fertility had markedly declined under sugar cane monocropping although levels remained favorable for sugar cane cultivation. For sustainable soil management, nutrient inputs as well as small applications of lime may eventually be needed.     

Evaluation of the rehabilitation procedure of a pyritic mine tailings pond in Avoca,Southeast Ireland

A 32 ha tailings pond used for the disposal of pyritic mine waste was examined after a period of eight years to determine the success of the rehabilitation plan used to revegetate the site. This was achieved by examining both the vegetation cover and the quality of the topsoil in order to determine the effect of the tailings. A number of floristic habitats were identified within the site indicating that succession had occurred since revegetation of the area with metal-tolerant grass species. Four main habitats were investigated: leguminous, grass, gorse and low canopy. The soil layer in Shelton Abbey was 25–30 cm deep and contained levels of nutrients and metals comparable to those found in unpolluted soils. It was followed by a 20–25 cm layer of mixed soil and tailings, followed by the tailings only. The tailings retained elevated concentrations of metals indicating their unsuitability for growth of unadapted plant species. Vegetation from all habitats, analysed both in the summer and winter, contained higher levels of iron only compared with vegetation grown on unpolluted soils. Metals do not appear to be significantly leached from the tailings either into the soil or into surface and ground waters, and have not been accumulated to above normal levels by plant uptake. The rehabilitation protocol used at the site appears to have been successful. However, the site needs to be managed on an on-going basis to ensure the integrity of the bund and revegetated area. © 1998 John Wiley & Sons, Ltd.     

Once-yearly sampling for the detection of trends in biodiversity: The case of Willow Slough, California

The butterfly fauna at Willow Slough, Yolo County, California has been censused for 32 years as part of a participatory citizen-science project, the Fourth of July Butterfly Count. While the utility of a once-a-year census as a monitoring tool is potentially compromised by lack of standardization in counting protocols and variation in observer skill, at Willow Slough these issues have been minimized.We examined the Willow Slough count data for trends in both faunal diversity and the probability of presence of individual species. During the study, the number of species observed at a visit declined by 39%. Regressions of per-visit species counts against time did not detect a statistically significant decline until year 24. In contrast, Fisher’s α, a statistic designed to reduce sample-size bias, detected the decline as early as year 13. Twelve of the 24 species analyzed showed significant declines in probability of occurrence; a further nine exhibited negative but non-significant trends. Butterflies that overwinter as eggs or larvae were more likely to decline than those that overwinter as pupae or adults. Many species in decline at Willow Slough have also been observed less frequently at nearby sites which are monitored year-round, supporting the value of once-a-year monitoring. Although correlations with climatic data have been identified, they are too weak to account for the observed faunal decline. We suspect broader patterns of land use and habitat continuity are implicated in butterfly declines across the region.We conclude that once-a-year sampling, if properly and rigorously done, is in fact useful as a monitoring tool for butterfly faunas, and that Fisher’s α is well suited to early detection of trends in repeated diversity sampling.     

Population declines of a long-lived salamander: a 20+-year study of hellbenders, Cryptobranchus alleganiensis

Accurate assessment of whether long-lived species are stable or declining is challenging. Life history characteristics such as delayed maturity result in relatively slow population responses to perturbations, so data should be collected across a relatively long time span. Because differential effects on age classes can be important, studies should also examine potential changes in the population's age structure. Moreover, multiple populations should be studied to indicate whether changes are regional or are restricted to local populations. We incorporated all three factors (long duration, multiple populations, age structure data) into our study of the conservation status of a long-lived aquatic salamander, the hellbender, Cryptobranchus alleganiensis. Over the 20+ years of this study, populations of hellbenders declined by an average of about 77%. This decline was characterized by a shift in size (age) structure, with a disproportionate decrease in numbers of young individuals. The change in density and age structure was consistent for populations in five rivers and for two subspecies (C. a. alleganiensis and C. a. bishopi), indicating that the decline is not restricted to one or two local populations. For the population with the most extensive data, the decline had clearly begun by the 1980s and there was a significant decrease in body condition over the period of the study. It is not known whether population declines for hellbenders have a single cause or whether each population has experienced independent declines.