Woodland Matrix Research Articles

Life history changes in the eastern collared lizard in response to varying demographic phases and management policies

AbstractBy 1980 eastern collared lizards (Crotaphutus collaris collaris) had experienced massive local extinction on glades (open, rocky areas imbedded in a woodland matrix) in the Ozarks, a highland region in central North America. Lizards were translocated to the Peck Ranch Conservation Area in Missouri on three restored glades starting in 1984, and went through three demographic phases: (1) an isolate phase with initial growth followed by decline in population size and no colonization of nearby glades; (2) a colonizing phase of high dispersal and population growth that started with the onset of prescribed woodland burning, and (3) a stable metapopulation phase. We used mark/recapture information on over 1500 lizards with high sample coverage to estimate life history parameters. Life history was homogeneous within each phase, but differed significantly between phases. Changes occurred in less than a generation, indicating plasticity in life history. The isolate phase was characterized by low juvenile survivorship, high adult survivorship, long generation times, an old age structure, and almost no dispersal. The colonization phase had increased yearling survival, decreased adult survival, shorter generation times, a younger age structure, and much dispersal. The stable metapopulation phase was intermediate between these two extremes. These transitions indicated trade‐offs among different life history parameters. These plastic life history attributes show that species cannot be regarded as static units, resulting in not a life history, but rather a set of feasible life histories. Ignoring this set of feasible life histories can result in poor conservation decisions.

Land-use legacy and tree age in continuous woodlands: weak effects on overall ground beetle assemblages, but strong effects on two threatened species

In woodlands, land use legacy, but also present habitat management can influence biodiversity and ecosystem functions in various ways. However, little is known about how former and current land use interact in woodlands with different habitat continuity and tree age. The aim of this study was to investigate the impact of both habitat continuity and tree age on ground beetles. We performed a field study in the nature reserve “Luneburger Heide” (Germany). The study area comprised ancient woodland embedded in a matrix of recent woodland. We defined four woodland types by combining ancient and recent woodland with young and old trees and analysed five replicate plots within each of the resulting four woodland types. Habitat continuity, tree age as well as the combination of both of these factors had no significant impact on ground beetle species diversity, abundance, biomass, and evenness with most woodland species occurring on near to all of the four types of woodland plots. Four species, however, showed a significant preference for one of the specified woodland types studied. Our findings provide evidence that all woodland-inhabiting ground beetles of this region are able to colonize new habitats in the continuous woodland matrix, at least, up until a distance of 2.3 km. We call for a heterogeneous woodland management and increasing habitat connectivity to protect both species with a preference for ancient woodland sites and/or old trees and those species which prefer early successional stages.

Vegetation change and conservation status of Coastal Upland Swamps

SummaryCoastal Upland Swamp communities are characterized by high biodiversity and provide habitat for a range of threatened flora and fauna. In this research project, we are monitoring swamp vegetation dynamics over decadal timescales and relating observed changes to environmental factors. We have also modelled potential effects of climate change on swamp distributions. We found that swamp communities are spatially dynamic, both internally and in relation to the woodland matrix. Transitions between communities depended on initial states. In addition, these water‐dependent communities appeared highly sensitive to projected climate change and their ‘Endangered’ status makes their active management a high priority. Improved understanding of dynamics at the community and landscape scale facilitates horizon scanning and improves our capacity to plan effective management interventions now and under future management and climate change scenarios.

Role of Termite Mounds on the Distribution of Spiders in Miombo Woodland of South-Western Burundi

Summary Miombo woodlands are characterized by numerous termitaria that are suitable for studying the relationship between spiders and termites. In the Rumonge miombo woodland (south-western Burundi), we sampled spiders on 14 termite mounds and in the surrounding woodland matrix with pitfall traps, to assess the mounds' effect on the distribution of spiders. Of the 24 traps per sampling site, six were placed on the mound itself and six at intervals of 5 m, 10 m and 20 m from it. Among the 39 species recorded, mainly ground-dwelling wandering spiders, only Cyphonisia cf. kissi, Langelurillus sp. and Andromma sp. seem to be associated with termitaria. Spiders are more frequently trapped in the woodland matrix than on the mounds. This could be related to the stability of the woodland matrix, which is protected against fires, clearing, etc. by local authorities. Being complex habitats, as compared to the woodland matrix, the vegetation structure of termitaria seems to have a restrictive influence on ground-dwe...

Looking Backwards into a Mediterranean Edge Environment: Landscape Changes in El Congost Valley (Catalonia), 1850-2005

Abstract We examine the evolution from the mid-nineteenth century to the present of the cultural landscape in two Catalan townships that jointly constitute an edge environment between Mediterranean plain and mountain. This environmental edge has changed over time, from a border between an agricultural plain confronting an area of forestry and livestock-raising in the mid-nineteenth century, to a limit of the Barcelona Metropolitan Region confronting two 'natural' protected sites in the present. Over a century and a half land use changes in this area have brought about the two main, but superficially 'opposed' dynamics that characterise landscape evolution throughout Catalonia and great parts of Europe today: intensification and abandonment. The most salient ecological impact of both processes has been the loss of landscape mosaics. In the plain those mosaics interwove cereal cropping with vineyards and olive orchards together with patches of woodland, scrubland and pastureland into an agricultural land matrix. In the mountains, a woodland matrix of holm oaks and pines became cleared through timber and firewood extraction, and the pruning of branches for charcoal making, creating a mixture of open forest articulated by grazing areas, cropland and scrub. Both sides of the edge interlinked, and jointly played a key role as ecological connectors to maintain biodiversity. From the 1960s onwards the ecological dynamics attendant upon the abandonment of the prevailing integrated management of forests, livestock breeding and cropland has led to a significant loss of these landscape mosaics. In spite of the transformation of much of this area into natural protected sites, the growth of a uniform and continuous reforested woodland canopy, directly confronted with urban sprawl, is endangering its richness in terms of species - such as Mediterranean orchids, whose habitats are disappearing.

Genetic restoration in the eastern collared lizard under prescribed woodland burning

Eastern collared lizards of the Ozarks live in glades--open, rocky habitats embedded in a woodland matrix. Past fire suppression had made the woodlands a barrier to dispersal, leading to habitat destruction, fragmentation and local extinction. Reintroduced populations of lizards were subjected to 10 years of habitat fragmentation under continued fire suppression followed by twelve years of landscape restoration with prescribed burns. Prior to prescribed burning, genetic diversity decreased within glades and differentiation increased among glades. With woodland burning, genetic diversity within glades first decreased during an expanding colonization phase, but then increased as a dynamically stable metapopulation was established. Population differentiation among glades also stabilized in the metapopulation under weak isolation-by-distance. This study is one of the first to examine the genetic changes in a species of conservation concern throughout all the stages of decline and recovery and shows the importance of landscape-level restoration for maintaining the genetic integrity of populations. This study also demonstrates how mark-recapture and genetic data together can yield detailed insight into metapopulation dynamics that would be impossible from just one type of data alone.

The transition from isolated patches to a metapopulation in the eastern collared lizard in response to prescribed fires

Habitat fragmentation often arises from human-induced alterations to the matrix that reduce or eliminate dispersal between habitat patches. Elimination of dispersal increases local extinction and decreases recolonization. These phenomena were observed in the eastern collared lizard (Crotaphytus collaris collaris), which lives in the mid-continental highland region of the Ozarks (Missouri, USA) on glades: habitats of exposed bedrock that form desert-like habitats imbedded in a woodland matrix. With the onset of woodland fire suppression, glade habitats degenerated and the woodland matrix was altered to create a strong barrier to dispersal. By 1980, lizard populations in the Ozarks were rapidly going extinct. In response to this decline, some glades were restored by clearing and burning. Starting in 1984, collared lizard populations were translocated onto these restored habitats. The translocated populations persisted but did not colonize nearby glades or disperse among one another. In 1994 prescribed woodland fires were initiated, which unleashed much dispersal and colonizing behavior. Dispersal was highly nonrandom by both intrinsic variables (age, gender) and extrinsic variables (overall demography, glade population sizes, glade areas, landscape features), resulting in different classes of lizards being dominant in creating demographic cohesiveness among glades, colonizing new glades on a mountain, and colonizing new mountain systems. A dramatic transition was documented from isolated fragments, to a nonequilibrium colonizing metapopulation, and finally to a stable metapopulation. This transition is characterized by the convergence of rates of extinction and recolonization and a major alteration of dispersal probabilities and pattern in going from the nonequilibrium to stable metapopulation states.

Influence of habitat fragments on bird assemblages in Cork Oak woodlands

Capsule Fragments of olive groves and riparian galleries have a positive influence on bird assemblages in Cork Oak woodlands. Aims Assess the impact of fragments of olive groves and riparian vegetation on the birds of the matrix of Cork Oak woodland. Methods Bird point counts at increasing distances (0, 50, 150, 250 and 350 m) from 15 olive groves and 13 sectors of riparian vegetation embedded in a matrix of Cork Oak woodland to determine species assemblages and species abundance. Results A total of 72 bird species were recorded during the spring, and 61 in winter. The diversity of the bird assemblages of the Cork Oak matrix was somewhat greater near fragments. The density of six out of the 17 most abundant bird species varied due to the presence of olive groves or riparian vegetation. Of those, five were more abundant near the fragments and only one was less abundant. These effects could be mostly predicted from the species' density in the fragments of olive groves and riparian vegetation and depended on the season. Conclusions In Mediterranean landscapes dominated by Cork Oak woodlands, the maintenance of the existing networks of olive grove fragments and riparian galleries has a positive effect on the bird assemblages of the woodland matrix. The increase in abundance of birds near olive groves and riparian galleries is probably due to the additional fruit resources provided by the fragments, especially in winter. We conclude that active maintenance of the existing fragments should be included in the management of this valuable agricultural–silvicultural–pastoral system.

EASTERN COLLARED LIZARD

The foreground shows a glade on Stegall Mountain that was colonized by collared lizards after prescribed woodland fires were initiated. Thorny Mountain is in the background, showing the glades imbedded in the woodland matrix. The Thorny Mountain glades were colonized by lizards from Stegall Mountain after the fire management area was expanded to include Thorny Mountain and the valley between Stegall and Thorny Mountains. Photograph by Alan Templeton. The eastern collared lizard (Crotaphytus collaris collaris) lives on Ozark glades habitats of exposed bedrock imbedded in a woodland matrix. Effective fire suppression began in the 1940s in the Stegall and Thorny Mountain region of the Ozarks. The unburned woodlands became a barrier to lizard dispersal between glades, leading to extinction by 1980. Starting in 1984 we translocated lizards onto restored glades. The translocated populations persisted, but did not disperse. In 1994 woodland fires were initiated, which unleashed much dispersal. The populations underwent a dramatic transition from isolated fragments, to a nonequilibrium colonizing metapopulation, and finally to a stable metapopulation. A collared lizard hatchling. Hatchlings have a low probability of dispersal during the colonizing phase, but once a stable metapopulation has been established, ~50% of the hatchlings disperse, and they disperse long distances. All dispersal between mountains was mediated by hatchlings. This photograph also illustrates the main capture technique of noosing lizards with a dental floss noose tied to a fishing pole. Photograph by Jennifer L. Neuwald. A gravid adult collared lizard female. Female shave bright orange stripes and spots induced by hormonal changes after their eggs are fertilized. Adult females have the lowest probabilities of dispersal and the lowest dispersal distances. Photograph by Alan Templeton. Adult male collared lizards. About 25% of adult males disperse once a stable metapopulation has been established, and they disperse long distances, although they always remain on the same mountain. A male showing the more typical male coloration. This male lizard has more yellow coloration. The increase in the frequency of these yellowish males was associated with the founding of populations on Thorny Mountain by a small number of lizards dispersing from Stegall Mountain. Photographs by Alan Templeton. An adult male/female pair of collared lizards. Both males and females are territorial, but male territories typically include several female territories. Territories are aggressively defended, particularly by males against other males. Photograph by Alan Templeton. These photographs illustrate the article “The transition from isolated patches to a metapopulation in the eastern collared lizard in response to prescribed fires” by Alan R. Templeton, Hilary Brazeal, and Jennifer L. Neuwald, tentatively scheduled to appear in Ecology 92(9), September 2011. [doi: 10.1890/10-1994.1].

Large termitaria act as refugia for tall trees, deadwood and cavity-using birds in a miombo woodland

Landscape heterogeneity can play an important role in providing refugia and sustaining biodiversity in disturbed landscapes. Large Macrotermes (Isoptera) termite mounds in miombo woodlands form nutrient rich islands that sustain a different suite of woody plant species relative to the woodland matrix. We investigated the role of termitaria in providing habitat for cavity-using birds in miombo woodlands that had been greatly impacted by elephants and fire, by comparing the availability of habitat favored by cavity-using birds (tall trees, trees with deadwood, and cavities) on and off mounds, and then testing its effect on species richness and abundance of cavity-using birds. We surveyed 48 termitaria paired with 48 woodland matrix sites in the breeding season; and 54 matrix-termitarium pairs in the non-breeding season in Chizarira National Park, Zimbabwe. Generalized linear mixed-effects models showed that termitaria harboured significantly higher densities (ha−1) of habitat components considered important for cavity nesting birds. Density of trees >6 m in height and incidence of trees with deadwood was nearly 10 times greater on mounds than in the matrix, and the density of cavities was nine times higher on mounds compared to the matrix. A model selection procedure showed that termitaria provided refugia for cavity-using birds and contributed to the resilience of bird communities through high on-mound densities of trees with deadwood. Large termitaria thus appear to play an important role in maintaining functionally important components of the avifauna in heavily impacted Miombo woodlands.

Competitive responses of seedlings and understory plants in longleaf pine woodlands: separating canopy influences above and below ground

A trenching study was used to investigate above- and below-ground competition in a longleaf pine ( Pinus palustris P. Mill.) woodland. Trenched and nontrenched plots were replicated in the woodland matrix, at gap edges, and in gap centers representing a range of overstory stocking. One-half of each plot received a herbicide treatment to remove the understory. We monitored pine survival and growth, understory productivity, light level (gap fraction), and soil resources. The overstory facilitated pine seedling survival. Pine seedling growth was reduced as overstory stocking increased. Reduced growth of seedlings was also observed in gaps when the understory was left intact. Understory plants competed with seedlings by filling the root gaps that developed as a result of overstory disturbance. Hardwood growth increased in gaps, owing to decreased belowground competition with adult pines, while growth of herbaceous plants and pine seedlings increased with light availability. Large overstory gaps are not required to initiate regeneration in longleaf pine woodlands. Retaining overstory dispersed throughout the stand but variable in density, through single-tree selection approaches, may be an alternative to gap-based approaches. This approach would allow for the fuel continuity needed to sustain the frequent fire required to maintain the diversity characteristic of this type of woodland.

Elephant- and human-induced changes to dung beetle (Coleoptera: Scarabaeidae) assemblages in the Maputaland Centre of Endemism

High African elephant stocking rates in nature reserves in southern Africa have been shown to have significant impacts on vegetation structure and diversity. However, the direct and indirect effects of elephants on fauna, particularly invertebrates, remain poorly known. The Maputaland Centre of Endemism, an area of southern Mozambique and northern KwaZulu-Natal in South Africa, is undergoing rapid rates of habitat conversion. Sand Forest, the rarest vegetation type in the Centre, is threatened by human disturbance outside of protected areas and by elephant browsing pressure in Tembe Elephant Park, one of the few protected areas for Sand Forest. Here we examine the effects of elephant- and human-induced disturbance to Sand Forest on a functionally important component of invertebrate diversity, i.e. the dung beetle fauna. The dung beetle assemblage associated with elephant-disturbed Sand Forest was transitional between undisturbed Sand Forest and Mixed Woodland, whereas that associated with human disturbance was markedly different to either habitat type. Differences are attributed to a change in habitat structure under both disturbance types, as well as to changes in the quality and distribution of dung under human disturbance. Therefore, grazing impacts by elephant not only affect plant diversity, but also implement changes in invertebrate fauna. The maintenance of the integrity of the Sand Forest–Mixed Woodland matrix is considered critical for biodiversity conservation in the Maputaland Centre of Endemism. Management of elephant populations, as well as the protection of sufficient Sand Forest inside conservation areas must, therefore, necessarily form part of the conservation strategy for the Centre.

White-Tailed Deer Use of Clearings Relative to Forage Availability

Use of woodland clearings by white-tailed deer (Odocoileus virginianus) may be in response to increased availability of forage within open patches or increased ability of deer to locate predators. We tested predictions, based upon the forage-maturation hypothesis, that white-tailed deer used areas with the greatest availability of high-quality forage, and that habitat use changed seasonally depending upon availability and quality of major types of forage in their diet. We tested those predictions in subtropical thorn woodland in South Texas, United States. Treatments included (1) areas with continuous woody cover as controls, (2) clearings with high availability of forbs and shrub sprouts, (3) clearings with low availability of shrub sprouts, (4) clearings with low availability of forbs, and (5) clearings with low availability of forbs and shrub sprouts. Intensity of use by deer during summer and autumn increased with increasing biomass of shrub sprouts and then declined with increasing shrub biomass as areas became dominated by mature shrubs with less accessible, usable forage. During spring, intensity of deer use increased in clearings with increases in forage availability and quality, indicated by an index to carrying capacity, then declined as vegetation matured. Responses of white-tailed deer to clearings supported the forage-maturation hypothesis in which herbivore responses to clearings resulted, in part, from the presence of shrub sprouts of high nutritional quality, particularly during summer and autumn when forage availability was low. Maintenance of clearings that are interspersed in a woodland matrix and maintaining high levels of immature shrub sprouts may alter the spatial distribution of white-tailed deer on the landscape.

Landscape structure and breeding bird distribution in a sub-Mediterranean agro-ecosystem

Richness, abundance and distribution of birds were investigated in the Aulella watershed,a mountainous area of 300 km2, located in the extreme northwestern corner of Tuscany, Italy in spring and summer, 1995. The study area encompasses five vegetation types (from Mediterranean maqui to upland beech forest) and three main land use categories (woodlands, mixed cultivated + urban areas, montane prairies). The recent history of land abandonment in the study area has produced a rapid expansion of shrubland and woodland, reducing cultivated areas to small patches interspersed in a woodland matrix. Richness, abundance and distribution of birds recorded at 414 points, randomly selected along secondary roads, and located using a Global Positioning System (GPS), were compared with topography, vegetation type and land use in a Geographic Information Systems (GIS) with a grid cell resolution of 200 × 200 m. Bird richness (55 species in all) and abundance are correlated: (a) negatively with the increasing altitude and increasing distance from cultivated areas; (b) positively with the increasing distance from woodlands and mountain prairies. Slope orientation appears to have a negligible effect on bird assemblages. Bird richness and abundance are significantly correlated with vegetation type. Cultivated areas support the highest bird richness and abundance that increase with patch size of the cultivated areas. Local extinction and/or reduction in within-species abundance of birds are expected to continue if the process of land abandonment continues.

Woodland/Grassland Boundary Changes in the Middle Niobrara Valley of Nebraska Identified by δ 13 C Values of Soil Origanic Matter

-Recent studies document that woodland species are expanding out of the middle Niobrara River canyon and into the adjoining Sandhills Prairie. Stable carbon isotope ratios of soil and root samples from valley contours are used to contrast the past vs. present configuration of grassland and woodland boundaries. Carbon isotope ratios for samples obtained beneath the canopies of known-age ponderosa pine (Pinus ponderosa Laws.) trees are used to provide evidence of the time associated with community change. Carbon isotope differences between root and bulk soil samples indicate that in the past woodlands were more narrowly restricted to the lower slopes of the Niobrara canyon and its short tributary streams. Analysis of samples collected beneath aged ponderosa pines suggest that isolated patches of woodland vegetation existed within a grassland matrix on the upper canyon slopes prior to European settlement. These patches now occur within the expanded woodland matrix.

Multi-model habitat suitability index analysis in the Red River Valley

Recent developments in habitat modeling have led to a situation where landscape architects, planners and wildlife biologists can study proposed landscape modifications and configurations simultaneously upon multiple species. Proposed development of the M.B. Johnson nature interpretive area in Clay County Minnesota illustrates this multi-model process. Nineteen species were studied: Blackcapped Chickadee (Parus atricapillus), Gray Partridge (Perdix perdix), Yellow warbler (Dendroica magna), Downy Woodpecker (Picoides pubescens), Beaver (Castor canadensis), Muskrat (Ondatra zibethicus), Wood Duck (Aix sponsa), Gray Squirrel (Sciurus carolinensis), Fox Squirrel (Sciurus niger), Pileated Woodpecker (Dryocopus pileatus), Mink (Mustela vison), Pine Warbler (Dendroica pinus), Yellow-headed Blackbird (Xanthocephalus xanthocephalus), Red-winged Black-bird Agelaius phoeniceus), Great Blue Heron (Adrea herodias), Ruffed Grouse (Bonasa umbellus), Veery (Catharus fuscescens) and Belted Kingfisher (Megaceryle alcyon). Landscape iterations were examined to increase species diversity as measured by fauna richness number, Simn's Index and Shannon-Weiner Index. In addition, aesthetic values, hydrological constraints, cost criteria and time-benefit criteria affected the development of the landscape. The modeling process led to the creation of a prairie-scape matrix, shrubland patches, cropland patches, wetland patch and additional woodland matrix features. The multi-modeling procedure is described as a decision tool, as a form giver, as an indicator of goal achievement, as a time saver, as a communication device and as a temporary technology. In addition, the multi-modeling procedure is described within a human behavioral context and within the political arena.

Vegetational Changes in the San Antonio Prairie Associated with Grazing, Retirement from Grazing, and Abandonment from Cultivation

INTRODUCTION The San Antonio Prairie as represented in Figure 1, is located in southeast-central Texas. The prairie is about 100 mi. long and ranges between 1 and 6 mi. in width. The boundaries are irregular and the area appears as a broken belt of grassland. The larger discontinuities are caused by the major rivers which flow through the general region in a southeasterly direction. The vegetation bordering the larger streams and their tributaries is woodland composed principally of species of Quercus, Celtis and Ulmus. The San Antonio Prairie is completely surrounded by oak-hickory forest and is one of several small prairies appearing in this woodland matrix. The Blackland Prairie lies to the north and the Fayette Prairie to the south. Much of the land within the San Antonio Prairic is used for a variety of agricultural crops, principally cotton, corn and small grains. Many sites which have not been cultivated have been grazed by domestic livestock, or used consistently since settlement for native hay production. Most of the grazed pastures are relatively small in size. The general practice is to graze small dairy herds yearlong without pasture deferment or rotation. This practice is altered on some ranches where beef herds constitute the major enterprise. Supplemental feeding of concentrates is practiced in some instances during the dry-feed season, which results in more uniform use of all the vegetation. Certain areas are grazed during part of the year and are deferred the remainder of the time. This diversity of land use has introduced many changes in the native vegetation making it quite variable in character. Tall grasses are most apparent in the hay meadows and similar areas that have re-(eived relatively light use. The grazed pastures