Disturbance-sensitive Species Research Articles

Calling up ghosts: acoustic playback of social vocalisations reveals complex communication in a cryptic bat and provides a promising tool for monitoring disturbance-sensitive species

Calling up ghosts: acoustic playback of social vocalisations reveals complex communication in a cryptic bat and provides a promising tool for monitoring disturbance-sensitive species

The rise of hyperabundant native generalists threatens both humans and nature.

In many disturbed terrestrial landscapes, a subset of native generalist vertebrates thrives. The population trends of these disturbance-tolerant species may be driven by multiple factors, including habitat preferences, foraging opportunities (including crop raiding or human refuse), lower mortality when their predators are persecuted (the 'human shield' effect) and reduced competition due to declines of disturbance-sensitive species. A pronounced elevation in the abundance of disturbance-tolerant wildlife can drive numerous cascading impacts on food webs, biodiversity, vegetation structure and people in coupled human-natural systems. There is also concern for increased risk of zoonotic disease transfer to humans and domestic animals from wildlife species with high pathogen loads as their abundance and proximity to humans increases. Here we use field data from 58 landscapes to document a supra-regional phenomenon of the hyperabundance and community dominance of Southeast Asian wild pigs and macaques. These two groups were chosen as prime candidates capable of reaching hyperabundance as they are edge adapted, with gregarious social structure, omnivorous diets, rapid reproduction and high tolerance to human proximity. Compared to intact interior forests, population densities in degraded forests were 148% and 87% higher for wild boar and macaques, respectively. In landscapes with >60% oil palm coverage, wild boar and pig-tailed macaque estimated abundances were 337% and 447% higher than landscapes with <1% oil palm coverage, respectively, suggesting marked demographic benefits accrued by crop raiding on calorie-rich food subsidies. There was extreme community dominance in forest landscapes with >20% oil palm cover where two pig and two macaque species accounted for >80% of independent camera trap detections, leaving <20% for the other 85 mammal species >1 kg considered. Establishing the population trends of pigs and macaques is imperative since they are linked to cascading impacts on the fauna and flora of local forest ecosystems, disease and human health, and economics (i.e., crop losses). The severity of potential negative cascading effects may motivate control efforts to achieve ecosystem integrity, human health and conservation objectives. Our review concludes that the rise of native generalists can be mediated by specific types of degradation, which influences the ecology and conservation of natural areas, creating both positive and detrimental impacts on intact ecosystems and human society.

Short-term effects of camera trap installation on incubation constancy in cranes

Research regarding how birds respond to the installation of cameras at nest sites is limited. We installed cameras at nests of Sandhill Cranes Antigone canadensis ( Linnaeus, 1758 ) and federally endangered Whooping Cranes Grus americana Linnaeus, 1758 in Juneau County, WI, as part of an ongoing study monitoring the reproductive success of Whooping Cranes in WI. The eastern population of Sandhill Cranes has grown, while Whooping Crane population growth has been slow, prompting the need to monitor the reproductive success of cranes on the refuge. We recorded the flight initiation distance during camera installation, the return time after camera installation, as well as measured the distance at which cameras were placed from each nest. We included temperature at camera deployment, age of nest, mode of access, ordinal date, and year in statistical regression models. We found an apparent difference in the observed flight initiation distances between the two species. Sandhill Cranes allowed researchers to approach their nests closer than Whooping Cranes prior to flushing. The post-disturbance return time was influenced by how far away the cameras were placed from the nest and the ambient temperature during camera deploy. Our study may help inform decisions regarding species response to methods and distance when deploying cameras, especially for endangered or disturbance-sensitive species.

Grazing affects vegetation diversity and heterogeneity in California vernal pools.

Disturbance often increases local-scale (α) diversity by suppressing dominant competitors. However, widespread disturbances may also reduce biotic heterogeneity (β diversity) by making the identities and abundances of species more similar among patches. Landscape-scale (γ) diversity may also decline if disturbance-sensitive species are lost. California's vernal pool plant communities are species rich, in part because of two scales of β diversity: (1) within pools, as species composition changes with depth (referred to here as vertical β diversity), and (2) between pools, in response to dispersal limitation and variation in pool attributes (referred to here as horizontal β diversity). We asked how grazing by livestock, a common management practice, affects vernal pool plant diversity at multiple hierarchical spatial scales. In terms of abundance-weighted diversity, grazing increased α both within local pool habitat zones and at the whole-pool scale, as well as γ at the pasture scale without influencing horizontal or vertical β diversity. In terms of species richness, increases in α diversity within habitat zones and within whole pools led to small decreases in horizontal β diversity as species occupancy increased. This had a dampened effect on species richness at the γ (pasture) scale without any loss of disturbance-sensitive species. We conclude that grazing increases species richness and evenness (α) by reducing competitive dominance, without large disruptions to the critical spatial heterogeneity (β) that generates high landscape-level diversity (γ).

Large- and medium-bodied terrestrial mammals of the Upper Berbice region of Guyana

Large mammals are key contributors to forest ecosystems globally, but Neotropical mammal populations are understudied. We employed remotely triggered camera traps and track surveys to assess the mammal community in the newly accessible upper Berbice region of Guyana. In a cumulative 2,821 trap nights between two camps and 14 km of track surveys we recorded 18 species of mammals. Camera trap records showed that Red-Rumped Agouti (Dasyprocta leporina (Linnaeus, 1758)) featured the highest relative abundance at both camps, while Tayra (Eira barbara (Linnaeus, 1758)), Amazonian Brown Brocket Deer (Mazama nemorivaga (F. Cuvier, 1817)), Giant Anteater (Myrmecophaga tridactyla (Linnaeus, 1758)) and Giant Armadillo (Priodontes maximus (Kerr, 1792)) the lowest. We also report na&amp;iuml;ve occupancy estimates. Detections of threatened and disturbance sensitive species indicate that the study site has a high biodiversity value. We provide recommendations for further study in this recently disturbed ecosystem and other understudied regions of Guyana.

Spatiotemporal tourism pattern in a large reindeer (Rangifer tarandus tarandus) range as an important factor in disturbance research and management

Tourism and recreation in protected areas may compromise conservation values if their forms and volumes exceed the area’s tolerance. Disturbance-sensitive species such as wild and semi-domestic reindeer (Rangifer tarandus tarandus) in most mountain areas in Fennoscandia are particularly vulnerable to humans, but disturbance research seldom includes data on the human component of this co-existence. By estimating the visitor volume in space and time and visitor characteristics in the largest national park and wild reindeer range in Norway we analyzed reindeer trail crossing propensity and examined the spatial overlap between humans and GPS-collared female reindeer (n = 98) during summer. The data showed that female reindeer herds used areas with overall less human traffic and recreational infrastructure. Reindeer herds started avoiding crossing hiking trails used by more than 10–15 persons per day and avoided crossing trails when visitor volumes exceeded 30–50 persons per day. During the hunting season, the herds were largely dispersed and crossed over trails independent of visitor volume, indicating a collective flight response to hunters. We discuss how including data on human use can further our understanding of ecological effects in disturbance research and how it can improve management interventions for better co-existence between humans and reindeer.

Restoring tropical forest composition is more difficult, but recovering tree-cover is faster, when neighbouring forests are young

Neighbouring forests constitute biological sources that enable the succession from species-poor systems, such as tree-plantings, to highly diverse forests. However, old forest patches are becoming rare in tropical agricultural landscapes. We were interested in if, and how, spontaneous regeneration under tree-plantings reflects the age and the amount of the neighbouring forest cover. We anticipated that older forests promote a compositionally broader recovery in neighbouring tree-plantings, because older forests likely include disturbance-sensitive species, particularly within least deforested landscapes. We studied twenty-seven restoration sites implemented as tree-plantings in the Brazilian Atlantic Forest. We quantified the effects of age and amount of neighbouring forest cover on structural and compositional characteristics of the regeneration community (dbh < 5 cm). We used two landscape groups (presence, or absence, of forests older than 30 years.) with a similar areal range of forest cover, enabling the disentanglement of forest age from forest amount effects on regeneration community responses. Surprisingly, we found that greater forest cover correlated with denser and more species-rich regeneration communities only when neighbouring forests were young. This pattern was promoted by non-vertebrate dispersed species. Regeneration communities in tree-plantings near to young forests had lower seed-mass and relative abundances of forest-specialists, compared to communities found near old forest patches. Regeneration is likely denser in landscapes of vast young-forest coverage. However, small-seeded and habitat-generalist species, frequently related to disturbance tolerance, tend to be dominant if old-growth forests are far away. This biased seed source appears to preclude the restoration of typical historic tropical forest composition.

CHECKLIST OF THE LICHENS AND ALLIED FUNGI OF FRONTENAC PROVINCIAL PARK, ONTARIO

Frontenac Provincial Park is located on the Frontenac Axis, a southern extension of the Canadian Shield, linking Algonquin Park to the Adirondack Mountains. To better understand the lichen biota of this interesting ecosystem, an inventory was conducted during several field visits from 2016–2019. During these surveys, 280 species of lichens and allied fungi in 115 genera were discovered. Presented is the first published record of Lempholemma cladodes (Tuck.) Zahlbr. in Canada, as well as the first published discoveries of Cladonia petrophila R. C. Harris, Coccocarpia palmicola (Spreng.) Arv. & D. J. Galloway, and Leprocaulon adhaerens (K. Knudsen, Elix & Lendemer) Lendemer & B. P. Hodk. in Ontario. Sixteen species are provincially ranked as critically imperilled (S1, S1S2 or S1S3), sixteen species as imperilled (S2 or S2S3), and nineteen species as vulnerable (S3 or S3S4). Unranked species reported for the second time in Canada are Dermatocarpon muhlenbergii (Ach.) Mull. Arg. and Cladonia atlantica A. Evans. An undescribed species of Lempholemma growing on flooded deciduous tree bases in vernal pools was also discovered. A discussion of Lobaria pulmonaria (L.) Hoffm., a pollution and habitat disturbance sensitive species, is presented. The records of L. pulmonaria discovered in Frontenac quite possibly represent the most southern observations in the province and are of conservation concern. It is recommended that a lichen awareness and education program be created for the park staff and visitors to highlight these rare and sensitive lichens and habitats within the park in the hope that lichens are protected through appropriate management and planning.

Do disturbance-sensitive and habitat-specialized species have a smaller range size? Evidence for a set of common mammals at regional scale

Disturbance-sensitivity and habitat generalism are two important eco-behavioural traits of species. In this paper, we calculated these traits for a set of 21 common mammal species using two proxies (HSrescaled for disturbance-sensitivity, and HHi, for habitat generalism) here obtained synthesizing the numbers and frequency of differently disturbed habitats where a species occurs. Then, we correlated them to their regional range size in Latium (Central Italy). HSrescaled and HHi resulted correlated between them. Moreover both these metrics resulted (or tend to be) positively correlated with the regional range size of species. A GLM model showed that disturbance-sensitivity of the species is more explicative to predict regional range size when compared to generalism. Although with some limitations, this data deserves attention for its implications both in basic and applied ecology. Indeed, (i) our data corroborate the strictly relationship between niche-width and geographic distribution of species at regional scale, and (ii) we obtained eco-behavioural evidence useful for conservation strategies: indeed many of species yet included in list of disturbance-sensitive taxa at landscape scale can be confirmed as indicators of disturbed habitat types.

Seed banks of subtropical grassland patches within an urban matrix in South Africa: reflecting the past and foretelling the future

Urban grasslands often exist as fragmented patches with varying threat levels. These patches are generally inappropriately managed due to limited data on their responses to disturbance and seed bank regenerative potential. This study compared seed banks between non-naturally disturbed and undisturbed patches of South African subtropical grasslands in an urban environment. Standing vegetation was characterised via year-round quadrat and monthly transect sampling. The seed banks were sampled after the two main dispersal periods and assessed for species composition and density. The seed bank species (24) represented a subset (9%) of the standing vegetation, with forbs being the most speciose life form and grasses the most abundant. Disturbance had a moderate impact on seed bank density but significantly affected species composition and ordering. Clustering and ordination analyses separated seed banks based on disturbance history. However, seed banks in disturbed patches maintained the general character of the grassland type. Diagnostic, rare and threatened taxa were absent from seed banks, irrespective of disturbance history. Consequently, restoration will possibly require seed enrichment and species reintroduction rather than exploitation of natural seed banks. Identifying disturbance-sensitive species through seed bank surveys can inform grassland conservation and restoration strategies.

Forest aggregates influence conifer recruitment and height growth in a long-term variable-retention experiment

The practice of aggregated retention is becoming increasingly common in forests managed for multiple objectives (e.g., timber production and maintenance of biodiversity). Undisturbed patches of forest (aggregates) can serve as refugia for disturbance-sensitive species and as dispersal sources for recolonization of adjacent harvested areas. However, few studies have characterized the contributions of aggregates to the natural recruitment or height growth of regenerating trees. In this study, we modeled the density and height of early- and late-seral conifers, including post-harvest recruitment and advanced regeneration (survivors), two decades after aggregated-retention harvest at four sites in the Cascade Mountains of Oregon and Washington. Predictors included distance from edge (0–70 m), edge type (1-ha aggregate vs. intact forest/harvest-unit boundary), and edge exposure (a proxy for heat/moisture stress). For both early- and late-seral species, we observed similar declines in density with distance from aggregate and intact-forest edges. Trends in height growth showed greater variation among sites and seral groups. Height tended to increase with distance from edge, peaking sooner for late-seral advanced regeneration than for early-seral recruitment. In contrast, heights of late-seral recruitment were distinctly shorter and unaffected by distance from edge. Edge exposure did not have a consistent effect on recruitment density or height growth of either seral group. Our results indicate that 1-ha aggregates are functionally equivalent to larger blocks of intact forests in their influences on conifer recruitment and growth. By distributing aggregates across harvest units, managers can accelerate rates of recruitment and promote heterogeneity in the density and height structure of the regenerating forest. Additional research is needed on the sensitivity of regeneration processes to aggregate size, shape, and spatial distribution.

Importance of landscape features and fire refuges on genetic diversity of Thuya occidentalis L., in boreal fire dominated landscapes

The unburned forest remnants of boreal mixed-woods, also known as fire residuals, are essential in providing habitats for disturbance-sensitive species and function as the main source of recolonization of disturbed sites. Forest remnants have been identified as historical or potential reservoirs of genetic diversity in several tree species in fire-prone landscapes. In this study, we investigate the genetic diversity of eastern white cedar (EWC, Thuya occidentalis L.), in forest sites that were affected by different fire regimes. The study area is located in northwestern Quebec, in the Lake Duparquet Research and Teaching Forest (79°10′W–48°30′N). We used 18 polymorphic microsatellite loci to investigate the genetic diversity of eastern white cedar, in forest sites where the fire regime history has been reconstructed to examine the importance of the temporal and spatial continuity of the forest on the genetic diversity of EWC. Three types of landscapes, including; islands within a large lake, fragmented fire refuges (forest patches) and non-fragmented mainland forests were studied. Our results revealed a source-sink dynamic associated with a high level of gene flow. Two of the mainland sites served as the main source of migrants. The level of gene flow in island sites was sufficiently high to counteract the effect of isolation. The fire refuges showed the lowest allelic richness, the highest population differentiation and the fewest number of private alleles. The mean fire-free intervals are much longer in fire-refuges causing environmental isolation through time and higher genetic differentiation. The conservation of large mainland sites should be given careful attention because they maintained high genetic diversity and function as the main source of gene flow. Fire refuges have an intrinsic conservation value in landscapes that are affected by spatially heterogeneous fires because they are important for population persistence through disturbances.

Spider assemblages in floodplain forests along an urbanization gradient

Urban areas have been growing radically worldwide, causing considerable changes in biodiversity of natural habitats. In floodplain forests, we studied the effects of urbanization on ground-dwelling spider assemblages along a rural-suburban—urban gradient in Hungary. We tested three traditional hypotheses (intermediate disturbance hypothesis, habitat specialist hypothesis and hygrophilous species hypothesis) and two novel expectations (shade-preferring species hypothesis, and disturbance sensitive species hypothesis) on spiders. We found that the total number of species was higher in the suburban habitat than in rural and urban ones, supporting the intermediate disturbance hypothesis. We found a decrease in the species richness of forest specialist and shade-preferring species along the urbanization gradient. We found that the number of hygrophilous and disturbance sensitive species was the lowest in the urban habitat. The spider assemblages of the rural and suburban habitats were clearly separated from the assemblages of urban habitats. Based on our findings we emphasize that low and moderate intensity of forest management contributes to the preservation of the local species richness in floodplain forests.

Forest restoration by burning and gap cutting of voluntary set-asides yield distinct immediate effects on saproxylic beetles

Today, the importance of restoring natural forest disturbance regimes and habitat structures for biodiversity is widely recognized. We evaluated the immediate effects of two restoration methods on wood-inhabiting (saproxylic) beetles in boreal forest voluntary set-asides. We used a before-after control-impact experimental set-up in 15 set-asides; each assigned to one of three treatments: (1) restoration burning, (2) gap cutting and (3) no-treatment reference stands. Before treatment, abundance, species richness and assemblage composition of trapped beetles did not differ significantly among treatments. Burning resulted in a significant change in assemblage composition and increased species richness and abundance compared to reference stands. As predicted, saproxylic species known to be fire favoured increased dramatically after burning. The immediate response shows that, initially, fire favoured species are attracted from the surrounding landscape and not produced on site. Gap cutting increased the abundance of cambium consumers but had no significant effect on total species richness or assemblage composition of saproxylic beetles. The stronger effect of burning compared to gap cutting on saproxylic assemblages is probably due to the very specific conditions created by fires that attracts many disturbance-dependent species, but that at the same time disfavour some disturbance-sensitive species. By contrast, gap cutting maintained assemblage composition, increased abundances and is likely to increase species richness in the years to follow, due to elevated level of dead wood. The restoration methods applied in this study may prove particularly useful, partly because of positive effect on saproxylic beetles, but also due to the cost-efficiency of the measures; the voluntary set-asides were already established and the restoration costs fully covered by revenue from the extracted timber.

Short-term effects of three commercial thinning treatments on diversity of understory vascular plants in white spruce plantations of northern New Brunswick

Plantation forestry is increasing in frequency and extent across the landscape, but can negatively impact biodiversity by promoting stand homogeneity and early-seral species dominance. Modifying silvicultural prescriptions in plantations, particularly with respect to creating or retaining more coarse woody debris (CWD), may improve their ability to support biodiversity, by mimicking some aspects of natural disturbance. We used a modified before-after-control-impact design to examine the response of understory vascular plants to four treatments in 25-year-old white spruce plantations of northwestern New Brunswick. Treatments included commercial thinning (CT) with enhanced, moderate, or no debris, as well as an unthinned control. Understory composition was analyzed using complementary methods that summarize biological communities at different resolutions: indicator species analysis, functional group responses, ordination, and biodiversity indices. Understory plants increased in overall richness and abundance after thinning, particularly in no-debris treatments. This was driven by (1) expansion of pre-established clonal forest herbs and (2) invasion of graminoids and long-distance dispersers. Several disturbance-sensitive species were significantly more abundant in unthinned controls. Few compositional differences were observed between the moderate and enhanced debris treatments, perhaps because the effects of CWD creation require longer to detect than those of thinning and ground-layer disturbance (from debris-removal). We recommend (1) continued monitoring of changes in moderate and enhanced treatments to determine the effects of debris-modification and (2) avoiding silvicultural prescriptions that remove branches, tree-tops, and other non-merchantable wood, which appear to facilitate early-seral species, and negatively impact disturbance-sensitive species.

Species- and community-level responses to habitat spatial changes in fragmented rainforests: assessing compensatory dynamics in amphibians and reptiles

The rapid loss and degradation of tropical forests threatens the maintenance of biodiversity across different spatial scales. Nevertheless, the extirpation and population decline of some disturbance-sensitive species may be compensated for by colonization and proliferation of disturbance-adapted species, thus allowing distributions of community-level attributes (e.g., abundance and diversity) to be preserved in human-modified tropical landscapes. To test this poorly assessed hypothesis we evaluated species- and community-level responses of amphibians and reptiles to differences in forest patch (patch size, shape, and distance to water bodies) and landscape metrics (old-growth forest cover, degree of fragmentation, and matrix composition) in the fragmented Lacandona rainforest, Mexico. We found that the abundance of several amphibian and reptile species was strongly associated with forest patch and landscape attributes, being particularly higher in larger patches surrounded by a greater forest cover. Such changes at the species level generated notable changes in reptile communities. In particular, the abundance, diversity, and evenness of reptile communities were strongly related to patch size, patch shape, and matrix composition. Yet, because of compensatory dynamics in amphibians, this group showed weak responses at the community level. Despite such compensatory dynamics, our results indicate that forest loss at the patch and landscape levels represents the main threat to both amphibians and reptiles, thus indicating that to preserve herpetological communities in this biodiversity hotspot, conservation initiatives should be focused on preventing further deforestation.

Arthropod Assemblages Associated with Wild and Cultivated Indigenous Proteas in the Grabouw area, Cape Floristic Region

Control of arthropod pests on indigenous flower crops often has particular challenges. Here we investigate the arthropod species associated with indigenous cultivated Protea species and cultivars in the Cape Floristic Region (CFR), South Africa. Arthropod individuals were collected from various commercial varieties of protea as well as from wild protea plants. Arthropod individuals were recorded directly on plants in the field (for disturbance-sensitive species), as well as from specific plant parts carefully enclosed in plastic bags and taken to the laboratory. Of the arthropod morphospecies recorded, 95.9 % were insects, and the rest mostly mites. A total of 37 % of the individuals could be identified to species level, along with 33 new species records of arthropods on protea plants. Taxonomically, Coleoptera, Lepidoptera, Hymenoptera and Diptera were the most abundant and speciose groups. Structurally complex plants and mixed stands of plant species harboured the most arthropod species. Morphospecies were sorted into guilds, as determined by previous studies. In general, guild structure reflected the complexity of structure of individual plants as well as the mixture of plant species and cultivars, with apparently strong natural enemy activity on complex plants and mixed groups. The free-living, flower visitor guild was the most abundant, with largely beetles contributing to this guild. Endophages were about equal in abundance across all cultivars but less on those with simple structures. From rank abundance curves, a total of 30 % of the arthropod species were categorized as abundant, with the rest (70 %) being rare. Most species were generalists on the various proteas, with some being species or cultivar specialists. A total of 7.26 % species recorded were major pests affecting commercial production of proteas in the CFR. This protea agroecosystem, being composed of plant types being grown in their general native area, resulted in about 93%of the arthropod species being restricted to the Proteaceae, with only 5.6%associated with other South African crops. Even though some of this arthropod assemblage is adverse for protea farming in theCFR, these commercial fields are nevertheless playing a role in biodiversity conservation in the fynbos. The wild proteas supported only intermediate arthropod abundance, suggesting strong, and probably complex, natural regulatory processes at work.

Fine-scale habitat structure complexity determines insectivorous bird diversity in a tropical forest

Habitat complexity in reforested stands has been acknowledged as a key factor that influences habitat use by birds, being especially critical for habitat disturbance-sensitive species such as tropical understory insectivorous birds. Most studies regarding the relationship between forest structure and species diversity were conducted at the landscape scale, but different diversity patterns may emerge at a finer scale (i.e., within a habitat patch). We examined a tropical reforested area (State of Caldas, Colombia), hypothesizing that insectivorous bird richness, abundance, and foraging guild abundance would increase as intra-habitat complexity increases. We established 40 monitoring plots within a reforested area, measured their structural features, and determined their relationships with species richness, total abundance, and foraging guild abundance, using Generalized Additive Models. We found that the increasing variation in basal area, stem diameter, and number of stems was positively correlated with species richness, total abundance, and foraging guild abundance. Relationships between richness or abundance and structural features were not lineal, but showing curvilinear responses and thresholds. Our results show that heterogeneity on basal area, stem diameter, and the number of stems was more correlated to insectivorous bird richness and abundance than the average of those structural features. Promoting structural variation on reforested areas by planting species with different growth rates may contribute to increase the richness and abundance of a tropical vulnerable group of species such as the understory insectivorous birds.

Variation in abundance of nectarivorous birds: does a competitive despot interfere with flower tracking?

Adaptive resource tracking in space and time may be disrupted by the modification of resources and competitors. Major global change drivers (e.g. land-use change) have induced declines in many native species, while facilitating only a few. Given that many resources are predicted to become increasingly scarce under the joint effects of climate and land-use change, disturbance-tolerant species that are able to defend high-value resources may further limit the persistence of disturbance-sensitive species. We sought to determine which nectarivorous birds track variation in flowering and if relationships between nectarivores and flowering are affected by on-transect vegetation structure or the occurrence of a native, hyper-aggressive species, the noisy miner Manorina melanocephala, which has become more prevalent. We measured eucalypt flowering and abundances of nectarivorous birds over the course of a year; we measured vegetation structure on the same forest transects. Nectarivores tracked spatial and some temporal variation in flowering, but this relationship was disrupted by noisy miners. Where present in sufficient numbers, the noisy miner excluded small-bodied nectarivores (<63 g) from fragments, limiting the ability of this numerically dominant component of the avifauna to gain access to flowering resources. Altered patterns of interspecific competition due to vegetation fragmentation and climate-induced degradation may have led to changes in the distribution of small nectarivore species that is a departure from the 'ideal free distribution' model. Interactions between noisy miners and small-bodied nectarivores appear to be best described by the 'ideal despotic distribution' model in which noisy miners exclude smaller competitors and monopolize local resources. Increases in the severity and frequency of extreme climatic events (e.g. long droughts) predicted under climate change may create a boom-bust pattern of availabilities of resources. The apparent insensitivity of noisy miners to such variation in flowering resource availability and the miners' influence on the ability of small nectarivores to access resources may lead to disproportionate declines in smaller-bodied nectarivorous species. Reduced tracking of flowering by nectarivores has the potential to disrupt ecosystem services (e.g. pollination, seed dispersal) and may have long-term consequences for the persistence of fragmented vegetation, adding further pressure on forest-dependent biota.

Decreases by disturbance-dependent tree species in the eastern and central USA

Open pine and oak forest ecosystems and floodplain forests have declined because of fire and flooding suppression. I determined tree species that have contracted in area occupied (where area occupied was ≥0.5 % of total species composition) or decreased in percent composition (i.e., percentage of all stems) during recent surveys (2000–2013) to ≤85 % of area occupied or composition during older surveys (1968–1999). I then identified whether species were associated with frequent fire, flooding, wetlands, postfire conditions, or other disturbances. Of 35 species that decreased in area occupied or composition, 16 species were associated with fire or postfire disturbance and fire-dependent species decreased in composition from 20 to 14 % during tree surveys. Even though species of floodplain forests and wetlands comprise a small percent of overall tree composition, 12 decreasing species were associated with floodplain forests or wetlands. Fire maintains open oak and pine ecosystems and flooding maintains floodplain forests, generally suspending succession. Suppression of fire in upland forests and flooding in floodplain forests has allowed disturbance-sensitive species to remain established and advance successional forests throughout the USA.