Changes In Habitat Structure Research Articles

The effects of fire severity on macroinvertebrate detritivores and leaf litter decomposition.

High severity wildfire events are a feature of forests globally and are likely to be more prevalent with climate change. As a disturbance process, fire has the potential to change important ecological functions, such as decomposition, through its impact on biodiversity. Despite the recognised importance of decomposition in terms of fuel loads and energy flow, little is known about the post-fire effects of fire severity on decomposition by litter-dwelling macroinvertebrate detritivores. We tested the hypotheses that: 1) increasing fire severity is associated with decreased rates of leaf litter decomposition by macroinvertebrate detritivores; and 2) the abundance and biomass of macroinvertebrate detritivores decreases with increasing fire severity, while body size increases. We used a litterbag experiment at long-unburnt, ground-burnt and crown-burnt sites (n = 7 for all treatments) to test the effect of fire severity on: a) macroinvertebrate-driven break-down of litter fuel loads; and b) the size and abundance of macroinvertebrate detritivores three years after fire. Microhabitat conditions differed among fire severity classes. Macroinvertebrate exclusion reduced litter decomposition by 34.7%. Macroinvertebrate detritivores were larger and less abundant following higher severity fires, possibly as a result of fire-induced changes in habitat structure. Opposing effects of fire severity on macroinvertebrate abundance and body size resulted in both similar detritivore biomass and, most interestingly, no differences in leaf litter decomposition under different fire severities. This suggests that the diversity of macroinvertebrates enhances functional resilience of litter decomposition to fire and that litter-breakdown is not inhibited within three years following a high severity fire in this forest type and where recolonisation sources are readily available. We found no support for the hypothesis that high severity fires reduce litter decomposition and therefore increase the likelihood of future fires.

Assessing the distribution of disease‐bearing rodents in human‐modified tropical landscapes

Summary We tested how habitat structure and fragmentation affect the spatial distribution of common murine rodents inhabiting human‐dominated landscapes in South‐East Asia. The spatial distribution patterns observed for each rodent species were then used to assess how changes in habitat structure may potentially affect the risk of several major rodent‐borne diseases. For this analysis, we used an extensive geo‐referenced data base containing details of rodents trapped from seven sites in Thailand, Cambodia and Lao PDR. We also developed land‐cover layers for each site. Results from published studies that screened for five major rodent‐borne pathogens in rodents were used to estimate how these pathogens would likely be impacted by these alterations in habitat structure and composition. Our results confirmed the specialist and/or synanthropic status of several rodent species, although the majority of species studied demonstrated some degree of low level of habitat specialization. Habitat diversity and its alteration (decreasing forest cover, increasing fragmentation, increasing urbanization) were found to favour the presence of synanthropic rodent species such as Rattus tanezumi, known to damage crops and host important rodent‐borne diseases. Synthesis and applications. The five major rodent‐borne pathogens were linked to ongoing changes in habitat structure. In particular, the presence of Bartonella spp. and hantaviruses seemed to be favoured in wooded landscapes affected by ongoing fragmentation and human encroachments. Rodents also pose significant problems for crop production in South‐East Asia. Our results showed that the structure of the landscape affects the likely presence of rodent species considered as agricultural pests. The patchy structure of a landscape can either enhance, such as B. indica, or decrease, such as B. savilei, the presence of rodents that may cause serious damage to crops.

Setting boundaries: environmental and spatial effects on Odonata larvae distribution (Insecta).

Environmental characteristics and spatial distances between sites have been used to explain species distribution in the environment, through Neutral (space) and Niche theory (environment) predictions. We evaluated the effects of spatial and environmental factors on Odonata larvae distribution along the Suiá-Missú River Basin, state of Mato Grosso. We tested the hypotheses that (1) the environment is the main factor structuring the community due to its ecophysiological requirements; and (2) the pattern, if present, is clearer for Zygoptera. Samples were made in 12 sites on the Suiá-Missú River Basin in three seasons (2007/2008), with a total of 1.382 Odonata larvae, comprising 10 families, 51 genera and 100 morphospecies. The Anisoptera were more abundant than Zygoptera, comprising 81% of all specimens. The environment affected Zygoptera (R=0.291; p=0.007) and was the main factor structuring the assembly. Thus, Niche theory was confirmed. The absence of this effect on Anisoptera may be due to the ecophysiological adaptations that enable it to occupy different habitats. Zygoptera larvae are indicators of changes in habitat structure. The effects of environmental variables on larvae ecology emphasize the strong relationship between these organisms and environmental integrity.

Effects of forest fragmentation on the oak–rodent mutualism

Land‐use changes are expected to affect plant–disperser conditional mutualisms through changes in animal behavior. We analyzed the oak–rodent conditional mutualism in Mediterranean fragmented forests at two climatically different locations. We quantified fragmentation effects on seed dispersal effectiveness and assessed if such effects were due to changes in habitat structure and intraspecific competition for acorns in fragmented areas. Fragmentation decreased cover from predators within mouse territories as well as intraspecific competition for acorns. This resulted in lower dispersal effectiveness in small forest fragments. Globally, habitat structure was the main driver in mouse foraging decisions. In small fragments, low shelter availability precluded mouse movements, leading to short mobilization distances and low caching rates. However, as the proportion of cover from predators increased, mice were able to modulate their foraging decisions depending on intraspecific competition for acorns, resulting in higher dispersal quality. In addition to fragmentation effects, delayed breeding in the southern locality caused lower number of rodents during the dispersal season, which reduced acorn mobilization rates. Our study shows that seed dispersal patterns in managed systems can be analyzed as the result of management effects on key environmental factors in dispersers’ foraging decisions.

Wildlife conservation through forestry abandonment: responses of beetle communities to habitat change in the Eastern Alps

Research on changes in biodiversity due to the abandonment of forestry is important in understanding the role of reserves in conservation. The aim of this study was to investigate whether changes have occurred in species richness, abundance and composition of ground, longhorn and bark beetles due to habitat changes as a result of the cessation of forest management. We surveyed ten managed and ten abandoned forest plots in two watersheds located in the north-eastern Italian alpine region, which share a common history of use, climate regimes, stand structure and topography. Ground beetles, and longhorn and bark beetles were collected with pitfall and flight-intercept window traps, respectively, from May to mid-October 2010. The three beetle taxa responded differently to changes in habitat features and management cessation. Differences in individual species responses between the two watersheds may indicate a role of management abandonment through its impact on forest habitat structure. For instance, ground beetle species mainly responded negatively to soil moisture and positively to understorey vegetation cover. Unexpectedly, saproxylic species responded variably, and often negatively, to deadwood features in these forests, but did respond positively to the volume of standing Abies alba trees. The assemblages of carabids and bark beetles differed between the two watersheds. Our results confirmed that 50 years of forest management cessation resulted in changes in the biodiversity of beetles in alpine forests, likely due to their response to changes in habitat structure. Moreover, we expect that where the unplanned abandonment of forestry practices and habitat rewilding are undergoing, like in many marginal areas of Europe, similar habitat structure dynamics and beetle responses are likely to occur spontaneously.

Effects of wildfires on flora, fauna and physico-chemical properties of soil-An overview

Fire is one of the most destructive threats faced by our forests. Fire is good servant but a bad master. The fire season starts in March/April continues up to June. Wildfires destroy not only flora (tree, herbs, grassland, forbs, etc.) and their diversity but also considerable long term negative impact on fauna including wild endangered species. Repeated fires can convert some shrub-lands to grass and fire exclusion converts some grassland to shrub-land and forest. Fires affect animals mainly through effects on their habitat. The extent of fire effects on animal communities generally depends on the extent of change in habitat structure and species composition caused by fire. Fire can also influence a physico-chemical property of soil including texture, color, bulk density, pH, porosity, organic matter, nutrient availability and soil biota. Drought, disease, insect infestation, overgrazing or a combination of these factors mayincrease the impact of fire on an individual plant species or communities. Common effects include plant mortality, increase flowering, seed production and numerous communal affects. Fire affected area showed reduction in species diversity both in flora and fauna. In a social context, fire directly affects people, property and infrastructure, thereby directly affecting the health and livelihood of individuals and communities.

A biological condition gradient model for historical assessment of estuarine habitat structure.

Coastal ecosystems are affected by ever-increasing natural and human pressures. Because the physical, chemical, and biological characteristics unique to estuarine ecosystems control the ways that biological resources respond to ecosystem stressors, we present a flexible and adaptable biological assessment method for estuaries. The biological condition gradient (BCG) is a scientific framework of biological response to increasing anthropogenic stress that is comprehensive and ecosystem based and evaluates environmental conditions and the status of ecosystem services in order to identify, communicate, and prioritize management action. Using existing data, we constructed the first estuarine BCG framework that examines changes in habitat structure through time. Working in a New England (U.S.) estuary with a long history of human influence, we developed an approach to define a reference level, which we described as a "minimally disturbed" range of conditions for the ecosystem, anchored by observations before 1850 AD. Like many estuaries in the U.S., the relative importance of environmental stressors changed over time, but even qualitative descriptions of the biological indicators' status provided useful information for defining condition levels. This BCG demonstrated that stressors rarely acted alone and that declines in one biological indicator influenced the declines of others. By documenting the biological responses to cumulative stressors, the BCG inherently suggests an ecosystem-based approach to management. Additionally, the BCG process initiates thinking over long time scales and can be used to inspire scientists, managers, and the public toward environmental action.

Modelling the effects of habitat on self-thinning, energy equivalence, and optimal habitat structure for juvenile trout

Self-thinning theory predicts that decline in density with increasing individual mass should match the exponent of the metabolism–body mass relationship (∼0.9 in salmonids). However, self-thinning assumes energy equivalence (constant energy available to a cohort as it ages), which may be unrealistic for mobile taxa. I evaluate this assumption using a bioenergetic–stream habitat model to assess the sensitivity of available energy and self-thinning slopes to changes in habitat structure (percent pool). Self-thinning slopes across three age-classes of juvenile trout (young of the year, 1+, and 2+) were sensitive to both modelled habitat structure and density-independent mortality rates. Density-independent overwinter mortality generated self-thinning curves similar to those expected from metabolic allometry, even without habitat limitation (density-dependent mortality). Energy available to sympatric cohorts was unequal under most habitat configurations because of size-based differences in swimming performance that affected habitat availability and interference competition (dominance) that allowed resource monopolization by older cohorts. The optimal habitat structure that maximized abundance of the 2+ age-class (and best approximated energy equivalence) was ∼40% pool, but this value was sensitive to density-independent mortality rate and assumptions about the effect of the pool to riffle ratio on invertebrate prey production.

Effects of livestock grazing and well construction on prairie vegetation structure surrounding shallow natural gas wells.

Short and sparse vegetation near shallow gas wells has generally been attributed to residual effects from well construction, but other mechanisms might also explain these trends. We evaluated effects of distance to shallow gas wells on vegetation and bare ground in mixed-grass prairies in southern Alberta, Canada, from 2010 to 2011. We then tested three hypotheses to explain why we found shorter vegetation and more bare ground near wells, using cattle fecal pat transects from 2012, and our vegetation quadrats. We evaluated whether empirical evidence suggested that observed patterns were driven by (1) higher abundance of crested wheatgrass (Agropyron cristatum) near wells, (2) residual effects of well construction, or (3) attraction of livestock to wells. Crested wheatgrass occurrence was higher near wells, but this did not explain effects of wells on vegetation structure. Correlations between distance to wells and litter depth were the highest near newer wells, providing support for the construction hypothesis. However, effects of distance to wells on other vegetation metrics did not decline as time since well construction increased, suggesting that other mechanisms explained observed edge effects. Cattle abundance was substantially higher near wells, and this effect corresponded with changes in habitat structure. Our results suggest that both residual effects of well construction and cattle behavior may explain effects of shallow gas wells on habitat structure in mixed-grass prairies, and thus, to be effective, mitigation strategies must address both mechanisms.

Response of a dung beetle assemblage along a reforestation gradient in Restinga forest

Scarabaeinae dung beetles are indicator insects used in the evaluation of the ecological effects caused by changes in habitat structure and ecosystem integrity resulting from environmental degradation. We compared dung beetle diversity in conserved restinga forests (coastal tropical moist broadleaf forest) and in reforested areas of various ages during the rainy and dry seasons, on the coast of Paraiba State, Brazil. A total of 3,634 individuals comprising 14 species were collected. In the reforested areas there was a gradual increase in species abundance relative to the area’s age, but in the conserved restinga the abundance of individuals was 10–20 times higher than that recorded in areas of recent reforestation. The highest species richness was found in the conserved restinga and in the oldest reforested area (16 years old) during the rainy season. During the dry season, when environmental conditions do not seem to favor adult survival, most of the species were found in the conserved restinga forest. The dung beetle community structure was related to the increases in habitat heterogeneity in the successional processes of the reforested areas. Our results suggest that reforested areas act as a source of and refuge for dung beetle species.

Giving-up densities and foraging behaviour indicate possible effects of shrub encroachment on arctic ground squirrels

Behavioural responses of prey to predation risk are often mediated by vegetation structure. Erect woody shrubs are increasing in many arctic and alpine environments, and this change in habitat structure has the potential to alter perception of risk and fear for foraging herbivores. To assess the role of shrub cover in determining behavioural responses to foraging under predation risk, we used measurements of giving-up density (GUD) and video recordings of vigilance behaviour of individual Arctic ground squirrels, Urocitellus parryii, across an alpine tundra to shrub ecotone. Dense shrub habitat was associated with higher GUDs, implying that foraging costs were higher in dense shrub than in less shrub-dominated habitats. Foraging strategies differed between habitats, with a negative relationship between visibility and GUD in high-visibility, open-tundra habitats and a positive relationship between visibility and GUD in low-visibility, shrub-dominated habitats, which may be indicative of alternative foraging strategies in different habitats. Squirrels initially made a high investment in vigilance, which was independent of patch residence time. This presumably increases the costs of quitting patches earlier. In shrub-dominated habitat, erect bipedal forms of vigilance were also observed more frequently. Our results indicate that shrub encroachment into northern and alpine tundra may impose costs on foraging arctic ground squirrels and alter foraging strategies.

Altered stand structure and tree allometry reduce carbon storage in evergreen forest fragments in India’s Western Ghats

Tropical forests are among the largest terrestrial reservoirs of carbon, and play an important role in regulating global climate. However, as a result of historic and ongoing deforestation, carbon storage in this biome is increasingly dependent on forests that are fragmented and used by humans, with considerable uncertainty about how such disturbance alters carbon storage potential and cycling. Here, we evaluate differences in above-ground carbon stocks between fragmented and contiguous evergreen forests in the central Western Ghats, India. We also assess differences in the structure, tree allometry and functional composition of forest stands between contiguous and fragmented forests, and explore how these differences influence carbon storage in fragmented forests. Relatively large, well-protected forest fragments currently store 40% less carbon per hectare above ground than contiguous forests. These differences in carbon are related to (i) lower tree density and basal area in fragments, (ii) lower average stand height in fragments, and (iii) compositional shifts favoring species with lower wood densities. Reduced stand height in fragments was associated with intra-specific variation in tree allometry, with trees in fragments being relatively shorter at any given diameter than conspecifics in contiguous forests. Further, the relatively skewed distribution of carbon storage within a few large trees in current-day fragments is added cause for concern: carbon stocks in fragments are likely to decline further in the future, following the eventual death of large trees. Active management and restoration to mitigate ecologically driven changes in habitat structure and species composition might be as important as improved management of resource use and protection from exploitation in order to sustain carbon storage ecosystem services provided by these tropical forest fragments.

Decay of interspecific avian flock networks along a disturbance gradient in Amazonia

Our understanding of how anthropogenic habitat change shapes species interactions is in its infancy. This is in large part because analytical approaches such as network theory have only recently been applied to characterize complex community dynamics. Network models are a powerful tool for quantifying how ecological interactions are affected by habitat modification because they provide metrics that quantify community structure and function. Here, we examine how large-scale habitat alteration has affected ecological interactions among mixed-species flocking birds in Amazonian rainforest. These flocks provide a model system for investigating how habitat heterogeneity influences non-trophic interactions and the subsequent social structure of forest-dependent mixed-species bird flocks. We analyse 21 flock interaction networks throughout a mosaic of primary forest, fragments of varying sizes and secondary forest (SF) at the Biological Dynamics of Forest Fragments Project in central Amazonian Brazil. Habitat type had a strong effect on network structure at the levels of both species and flock. Frequency of associations among species, as summarized by weighted degree, declined with increasing levels of forest fragmentation and SF. At the flock level, clustering coefficients and overall attendance positively correlated with mean vegetation height, indicating a strong effect of habitat structure on flock cohesion and stability. Prior research has shown that trophic interactions are often resilient to large-scale changes in habitat structure because species are ecologically redundant. By contrast, our results suggest that behavioural interactions and the structure of non-trophic networks are highly sensitive to environmental change. Thus, a more nuanced, system-by-system approach may be needed when thinking about the resiliency of ecological networks.

Accounting for habitat when considering climate: has the niche of the Adonis blue butterfly changed in the UK?

The dramatic recovery of three species of grassland specialist butterfly threatened with extinction at their high latitude range limits in the 1980s has been attributed to two factors: increased grazing on calcareous grassland sites and warmer air temperatures. Both result in the warming of soil surface temperatures, favourable to the larvae of these species. We address the influence of both of these factors on the habitat usage of the butterfly Polyommatus bellargus, undergoing recovery at its northern range edge. We test the hypothesis that the larval niche of P. bellargus has become less constrained in the past three decades, whilst controlling for changes in habitat structure. Once habitat change has been accounted for we find no evidence for a broadening of the larval niche of P. bellargus. Further, we show that coincident with the recovery of P. bellargus there have been drastic reductions in average turf height across UK chalk grasslands, but changes in air temperature have been highly variable. We conclude that changes to soil surface temperatures caused by reducing turf heights will have been a more consistent influence than air temperature increases, and so habitat improvements through increased grazing will have been the major driver of recovery in P. bellargus. We consider the need to account for changes in habitat when exploring the impacts of recent climate change on local habitats in thermophilous species, and emphasise the continued importance of habitat management to support such species under variable local climates.

Applying bioacoustic methods for long-term monitoring of a nocturnal wetland bird

Bioacoustic monitoring is becoming more and more popular as a non-invasive method to study populations and communities of vocalizing animals. Acoustic pattern recognition techniques allow for automated identification of species and an estimation of species composition within ecosystems. Here we describe an approach where on the basis of long term acoustic recordings not only the occurrence of a species was documented, but where the number of vocalizing animals was also estimated. This approach allows us to follow up changes in population density and to define breeding sites in a changing environment. We present the results of five years of continuous acoustic monitoring of Eurasian bittern (Botaurus stellaris) in a recent wetland restoration area. Using a setup consisting of four four-channel recorders equipped with cardioid microphones we recorded vocal activity during entire nights. Vocalizations of bitterns were detected on the recordings by spectrogram template matching. On basis of time differences of arrival (TDOA) of the acoustic signals at different recording devices booming bitterns could be mapped using hyperbolic localization. During the study period not only changes in the number of calling birds but also changes in their spatial distribution connected with changes in habitat structure could be documented. This semi-automated approach towards monitoring birds described here could be applied to a wide range of monitoring tasks for animals with long distance vocalizations.

Bird species assemblages across a rural urban gradient around Kolkata, India

Urban development leads to changes in habitat structure and resource base. Bird communities are known to respond sharply to such changes. Our result from study of bird community along urbanization gradient around Kolkata metropolitan city clearly separated the urban bird community from the rural and rural 3 habitats in terms of species diversity and foraging groups. Rural and rural 3 sites had more number of rare species and higher percentage of unique species as compared to the urban habitats. Functional group analysis showed higher abundance of granivores in urban habitats and absence of insectivore and carnivorous species that were found in the rural and rural 3 habitats. The bird species assemblage along the gradient was significantly nested where bird species recorded in urban areas were subset of the species rich rural areas. There was no difference in individual counts between urban and rural habitats, therefore nullifying the hypothesis that rural areas are more species rich because of higher population size. Bird community in the urban areas was less even as compared to the rural areas due to the dominance of omnivorous guild. Bird diversity was negatively correlated to the density of house lots.

Community-level response to habitat structure manipulations: An experimental case study in a tropical ecosystem

Across the globe, environmental change is resulting in novel ecosystems that have altered habitat structure and functioning. Research is needed to understand how changes in habitat structure in these new ecosystems impact community interactions, especially when these manipulations are being proposed to reduce invasive species. We conducted an experiment in Hawaii to determine how changes in habitat structure, represented by leaf litter and understory vegetation, affect the abundance of an invasive generalist predator, the coqui frog (Eleutherodactylus coqui) and its potential prey (invertebrates). This study consisted of four treatments: two vegetation treatments (50% and 100% removal of vegetation with diameter at breast height <5cm) and two leaf litter treatments (50% and 100% removal). Removal of 50% of habitat structure, either vegetation or leaf litter, was not sufficient to produce long-term changes in coqui or invertebrate densities. Only full removal of habitat structure resulted in reduced densities of coqui after four months. The abundance of leaf litter invertebrates and invertebrates flying close to the forest floor was higher in the 100% vegetation removal treatment compared to leaf litter removal treatments, and the abundance of foliage invertebrates was higher in the 100% leaf litter removal treatment compared to vegetation removal treatments. Invertebrate responses were complicated because they not only responded to the loss of habitat but also the reduction of coquis in treatments. Coquis in treatments moved to microhabitats that contained increased prey. Treatments appeared to impact coquis by removing structure needed for diurnal retreats, breeding and foraging. In summary, both the 100% removal of leaf litter or vegetation can reduce coqui densities in relatively small (20m×20m) areas, even when surrounded by intact, invaded forest. This study provides greater understanding of the impact of habitat structure manipulation, a typical management employed to control an invasive frog, in a novel ecosystem.

Mechanisms of Flood-Induced Territory Abandonment in an Obligate Ground-Foraging Bird

Abstract. Large-scale disturbances, by affecting habitat suitability, can influence bird populations and communities. Although we know that disturbances can lead to population decreases and shifts in community structure, our understanding of finer-scaled mechanisms leading to these patterns is limited. We focused on why some territories remain occupied by a species following a large-scale disturbance, while others are abandoned. The Swainson's Warbler (Limnothlypis swainsonii) is especially susceptible to flooding because of its preference for nesting in thick understory vegetation and foraging in leaf litter. In 2008, a major flood inundated a study site where we have studied Swainson's Warblers since 2004. In 2008 and 2009, we resurveyed 42 Swainson's Warbler territories that were occupied between 2005 and 2007 and examined changes in habitat structure and composition and prey abundance influencing territory abandonment. Occupancy declined between the preflood and postflood surveys. Territory abandonmen...

Hard boundaries influence African wild dogs' diet and prey selection

Summary Human‐mediated changes in habitat structure may disturb predator–prey relationships. We investigated the influence of perimeter fences on the diet of a reintroduced population of African wild dogs Lycaon pictus Temminck 1820 in a 316 km2, fenced reserve in South Africa, by tracking radio‐collared individuals during hunting periods to determine dietary composition from observed kills. Nutritional status of impala Aepyceros melampus and kudu Tragelaphus strepsiceros prey, as measured by the percentage of femur marrow fat, was significantly lower than that of unselectively culled individuals. This supports the hypothesis that wild dog predation is at least partially compensatory. Fence‐impeded kills (those for which escape was deemed to be compromised by the fence) comprised 40·5% of kills (n = 316), and 54·1% of all edible biomass consumed. Compared with fence‐unimpeded kills, fence‐impeded kills comprised larger species (32·9 vs. 25·0 kg, W = 25667·0, P ≪ 0·001), older age classes for one prey category (female kudu: Fisher's exact test, P = 0·02, n = 65) and animals in better condition for adult impala males (Mann–Whitney, W = 111·0, P = 0·012, n = 28). Fence‐impeded kills also provided greater catch per unit hunting effort (27·3 vs. 12·2 kg km−1; χ2 = 7·89, P = 0·005), resulting in longer interkill intervals. Movement of the pack towards the fence at the start of each hunting period suggested a decision to exploit the advantage that fences conferred for capturing prey. Synthesis and applications. By enabling coursing predators to capture prey that would otherwise have escaped, fences may reduce the compensatory nature of predation, causing shifts in predator–prey dynamics that could influence the ability of small reserves to support such predators. The establishment of larger conservation areas to reduce perimeter‐to‐area ratios should be encouraged to limit the undesired effects of fences on predator–prey dynamics.

Geologic drivers of late ordovician faunal change in laurentia: investigating links between tectonics, speciation, and biotic invasions.

Geologic process, including tectonics and global climate change, profoundly impact the evolution of life because they have the propensity to facilitate episodes of biogeographic differentiation and influence patterns of speciation. We investigate causal links between a dramatic faunal turnover and two dominant geologic processes operating within Laurentia during the Late Ordovician: the Taconian Orogeny and GICE related global cooling. We utilize a novel approach for elucidating the relationship between biotic and geologic changes using a time-stratigraphic, species-level evolutionary framework for articulated brachiopods from North America. Phylogenetic biogeographic analyses indicate a fundamental shift in speciation mode—from a vicariance to dispersal dominated macroevolutionary regime—across the boundary between the Sandbian to Katian Stages. This boundary also corresponds to the onset of renewed intensification of tectonic activity and mountain building, the development of an upwelling zone that introduced cool, nutrient-rich waters into the epieric seas of eastern Laurentia, and the GICE isotopic excursion. The synchronicity of these dramatic geologic, oceanographic, and macroevolutionary changes supports the influence of geologic events on biological evolution. Together, the renewed tectonic activity and oceanographic changes facilitated fundamental changes in habitat structure in eastern North America that reduced opportunities for isolation and vicariance. They also facilitated regional biotic dispersal of taxa that led to the subsequent establishment of extrabasinal (=invasive) species and may have led to a suppression of speciation within Laurentian faunas. Phylogenetic biogeographic analysis further indicates that the Richmondian Invasion was a multidirectional regional invasion event that involved taxa immigrating into the Cincinnati region from basins located near the continental margins and within the continental interior.