Woodland Structure Research Articles

Floristic Composition, Structure, and Species Associations of Dry Miombo Woodland in Tanzania

For the majority of forest reserves in Tanzania, biodiversity is poorly documented. This study was conducted to assess species richness (woody species), diversity, and forest structure and to examine relationships between species occurrence and topographic and edaphic factors in the Gangalamtumba Village Land Forest Reserve, a dry Miombo woodland area in Tanzania. A total of 35 nested circular plots with radii of 5, 15, and 20 m were used to collect data on woody species and soil samples across the 6,065 ha community-managed forest reserve. Stumps were measured 20 cm above ground. A total of 88 species belonging to 29 families were identified. Generally forest structure parameters and diversity indices indicated the forest to be in a good condition and have high species richness and diversity. Vegetation analysis revealed four communities of which two were dominated by the family Caesalpiniaceae, indicating large variation of site conditions and possible disturbances in the study area. The high level of diversity of woody species and the high basal area and volume indicate that the forest is in good condition, but the effect of anthropogenic activities is evident and stresses the need for proper management to maintain or enhance the present species diversity.

Woodland structure, rather than tree identity, determines the breeding habitat of Willow Warblers Phylloscopus trochilus in the northwest of England

Capsule Woodland structure, rather than tree species, is the most important determinant of breeding habitat selection by Willow Warblers in North West England.Aims To examine how habitat characteristics predict the occurrence of male Willow Warbler territories.Methods Woodland structure (trunk density, trunk diameter, canopy cover and understory cover), tree species and food abundance were compared between woodland areas within and outside of male territories at a site in the UK.Results Territories contained higher trunk numbers, had a narrow range of trunk diameters, and intermediate canopy cover. Food abundance did not differ with occupancy. Willow and alder were the most common trees within territories, in contrast to birch which has been found in previous studies. The habitat structure matches young woodlands, where birches often grow. However, at the study site the birches were large and mature, and therefore unsuitable. Moreover, woodland structure variables were better predictors of occupancy than any particular tree genera.Conclusion The results indicate that vegetation structure, but not tree species or food availability, influence breeding habitat selection by Willow Warblers. The preferred structure is similar to coppice woodlands; therefore, the Willow Warbler decline may be linked to the loss of this traditional management across south England.

Diversity and structure of woody vegetation across areas with different soils in Gonarezhou National Park, Zimbabwe

Despite the importance of edaphic factors in influencing woody vegetation diversity and structure in savannas, there is still limited research on the topic across most savanna ecosystems. Here we investigate the differences and/or similarities of woody vegetation diversity and structure across areas with different edaphic factors (i.e. soil group) in Gonarezhou National Park, Zimbabwe. We stratified our study area into two strata based on soil group, namely siallitic soil in northern Gonarezhou and regosol soil in central Gonarezhou. Data were collected from 96 sample plots between March and April in 2011. Our results showed significantly higher woody species diversity in siallitic soil stratum compared to regosol soil stratum. In contrast, there were no significant differences in woody vegetation structure between the two study strata. Our results suggest that soil variations play an important role in influencing woody vegetation diversity more than woody vegetation structure in Gonarezhou. Future studies should investigate the role of soils on a specific woodland type's composition and structure, and also determine the interactive effects between soils and other environmental determinants in Gonarezhou and similar protected areas in savanna ecosystems.

Evaluating Restoration Baselines for Historically Fire-Protected Woodlands within a Northeastern Illinois Prairie Peninsula Landscape

The forests and woodlands of the Prairie Peninsula region in the Midwestern USA have been heavily impacted by human influences over the past ∼150 years. Current composition, structure, and dynamics in forest communities across the region lie outside the historical range of variability. However, areas along major waterways were afforded greater fire protection historically than the landscape as a whole (and are common locations for modern natural areas), and historical and modern conditions may be more analogous in these locations. This study assessed composition and structure of woodlands in a series of natural areas along the Des Plaines River in Lake County, Illinois, and related current conditions to historical baselines for the locality and region. Modern composition and structure in even these fire-protected habitats appear to lie outside the historical range of variability. High canopy cover, stem density, and dominance by sugar maple (Acer saccharum Marsh.) and European buckthorn (Rhamnus cathartica L.) are especially inconsistent with historical conditions. Current structure suggests a continued trajectory toward homogenized, closed-canopy ecosystems with increased dominance by mesophytic and invasive species and decreased importance of historically-dominant oak (Quercus spp.) species. Community-specific management strategies focused on modifying canopy structure and composition will be necessary to shift these communities toward conditions of increased light availability, structural complexity, and biological diversity. Strategies to achieve these goals are currently not well established, especially those that could be applied in urban natural areas. Implementation of multiple approaches in an adaptive management framework would aid in developing best management practices for wooded ecosystems in the region.

Soil development mediated by traditional practices shape the stand structure of Spanish juniper woodland

Aim of study: Assessing the effect of soil development on the stand structure of a Spanish juniper forest traditionally shaped by livestock browsing and wood extraction. Area of study: Berlanga de Duero (Soria, Castilla y León), Spain.Material and Methods: A stand inventory served to record stand structure. Tree age, height, DBH, basal area, and overbark volume were determined in each plot. Results were pooled considering two well-differentiated degrees of soil evolution. One-way ANOVAs (and Tukey’s test) and regressions between growth parameters were performed to assess significant differences between growth performances on both types of soils. Research highlights: Deeper soils yielded significant higher plant density and stand stock figures than stony shallower profiles despite the intense past livestock activity in the area; and single tree-size was also significantly greater. Non-significant differences were found for merchantable junipers age (≈120-160 years). Wood extraction and livestock browsing should be limited on shallower soils to allow soil and forest evolution; as well as to preserve the genetic pool better adapted to hardest growing conditions.Keywords: livestock browsing; forest development; Juniperus thurifera L.; soil evolution; stand stock.

English

Miombo woodlands is one of the major forest vegetation types covering about two thirds of the country forest land and form an integral part of the rural landscape in Tanzania, also they play crucial role in providing wide range of ecosystem services including carbon sequestration. This study aimed at assessing the effects of degradation on the structure and carbon stocks of miombo woodlands. Data were collected from 50 rectangular plots measuring 40×20 m. Stump diameter, diameter at breast height, tree height and species local and botanical names were recorded. Analysis was done by using R software and excel spread sheet. Results showed total harvesting of 10.53 m3ha-1 as compared to standing volume of 32.6 ± 2.3 m3ha-1 with basal area of 4.73 ± 0.5 m2ha-1. Estimated annual harvesting was found to be 6.63 ± 3.0 m3 ha-1 which exceeds mean miombo annual increment of 4.35 m3 ha-1 year1, this is indicator for unsustainable utilization which could results into woodland change. Harvesting resulted into total loss of 4.1±0.9 tCha-1 equivalent to 15.05 ± 3.3 tCO2eha,-1 new harvesting presenting 9.91 tCO2e ha-1 and old 5.14 tCO2eha-1. Managing the miombo woodlands carbon stocks for emissions and climate change mitigation in Tanzania and elsewhere requires rigorous effort to reduce anthropogenic degradation.   Key words: Carbon emissions, climate change, Miombo woodlands, degradation.

Socialist and postsocialist land-use legacies determine farm woodland composition and structure: lessons from Eastern Germany

European agroecosystems host a variety of farm woodlands that act as primary determinants of biodiversity and ecosystem services. While woodland areas have been in decline worldwide, they have regionally increased, for example, in Eastern Germany. This study performs a quantitative and spatially explicit assessment of differences in species richness, diversity, and evenness as well as forest physiognomy and structure among Eastern German farm woodlands established during (1) the presocialist era (until 1945), (2) the socialist era (1945–1990), and (3) the postsocialist era (after 1990). Aerial imagery was used to allocate woodlands to one of the three eras, after which a forest inventory of 120 woodlands was performed. The results show substantial differences in forest composition and structure. Presocialist-era woodlands are composed of native (mean 96 %), deciduous (mean 94 %) tree species. Mean diameters and species richness values are high. Typical socialist woodland species are nonnative (mean 35 %) and/or coniferous (mean 51 %). Stands have a uniform, even-aged stand structure. Species richness/diversity indices are generally low. Postsocialist woodlands exhibit a high degree of variability. Percentages of nonnative (7 %) and coniferous (10 %) individuals are low. The findings suggest that socialist and postsocialist farmland and forest policies translated into distinct land-use legacies in the newly established farm woodlands, which differ considerably from the composition and structure of presocialist woodlands. We argue that forest conservation planning should actively consider land-use legacies, which are of particular relevance in the landscapes of Central and Eastern Europe, as these have undergone multiple, abrupt, and severe land-use transitions.

Climatic influence upon early to mid-Holocene fire regimes within temperate woodlands: a multi-proxy reconstruction from the New Forest, southern England

A combined pollen, charcoal and climatic record is presented from Cranes Moor, southern England, covering the period c. 10 500–5850 cal a BP. It is shown that the occurrence of burning is closely related to natural processes, including prevailing climatic conditions and vegetation composition. These burning events are often linked to an increase in the summer moisture deficit, implying that the timing of burning events is linked to periods of warmer/drier climate during the Holocene Thermal Maximum (c. 11 000–5000 cal a BP). These events play an important role in the vegetation composition and succession around the site. The nature of the burning recorded at the site shows strong similarities with other records from northern Europe. This study throws caution on suggestions that fire in the Holocene record from areas such as the British Isles is linked only to human activity, and enhances the possibility that natural fire incidence played an important role in natural woodland structure dynamics.

Fragmentation patterns of evergreen oak woodlands in Southwestern Iberia: Identifying key spatial indicators

Mediterranean evergreen oak woodlands (composed of Quercus suber L. and Quercus rotundifolia Lam.) are becoming increasingly fragmented in the human-modified landscapes of Southwestern Portugal and Spain. Previous studies have largely neglected to assess the spatial changes of oak woodlands in relation to their surrounding landscape matrix, and to characterize and quantify woodland boundaries and edges. The present study aims to fill this gap by analyzing fragmentation patterns of oak woodlands over a 50-year period (1958–2007) in three landscapes. Using archived aerial imagery from 1958, 1995 and 2007, for two consecutive periods (1958–1995 and 1995–2007), we calculated a set of landscape metrics to compare woodland fragmentation over time. Our results indicated a continuous woodland fragmentation characterized by their edge dynamics. From 1958 to 2007, the replacement of open farmland by shrubland and by new afforestation areas in the oak woodland landscape surrounding matrix, led to the highest values for edge contrast length trends of 5.0 and 12.3, respectively. Linear discriminant analysis was performed to delineate fragmented woodland structures and identify metric variables that characterize woodland spatial configuration. The edge contrast length with open farmland showed a strong correlation with F1 (correlations ranging between 0.55 and 0.98) and may be used as a proxy for oak woodland mixedness in landscape matrix. The edge dynamics of oak woodlands may result in different patterns of oak recruitment and therefore, its study may be helpful in highlighting future baselines for the sustainable management of oak woodlands.

English

Sustainable management of plant-herbivore systems requires an understanding of their long-term dynamics through modeling approaches. A preliminary simulation model was developed using STELLA to predict the impacts of elephants and fire on the structure of semi-arid miombo woodlands of north-western Zimbabwe. Elephants alone at a density of 0.27 km-2 will convert the woodland into coppice in 120 years due to resulting massive declines of large trees. The same result is achieved in only 10 years if elephant density is at 2 km-2. The pattern remains similar with simultaneous application of fire once every 4.7 years with elephants at 0.27 km-2. When elephants are culled at 30% whenever their densities reach 1 km-2, the woodland does not degenerate into coppice despite fire occurrence once every 4.7 years. Therefore, elephants alone can degrade and maintain semi-arid miombo woodland into coppice, largely due to their damaging impacts on mature canopy trees and fire acts to speed up the process by suppression of an already low recruitment. Fire alone has a lesser influence on woodland structure than elephants because of low fuel loads due to heavy grazing and low grass production as a result of low rainfall and inherently poor soils in the area. A maximum elephant density of 0.1 km-2 is recom-mended to achieve equilibrium in the area. Key words: Zimbabwe, Sengwa, STELLA, elephants, fire, miombo woodlands, simulation model.

Model highlights likely long‐term influences of mesobrowsers versus those of elephants on woodland dynamics

AbstractThe potential long‐term influences of mesobrowsers versus those of savannah elephants on woodland dynamics have not been explored. This may be a critical omission especially in southern African savannahs, where efforts to preserve existing woodlands are typically directed at elephant management. We describe a simple browse–browser model, parameterized from an extensive review of the literature and our own data, including quantitative assessment of impala impact, from the study site, iMfolozi Park, South Africa. As there is a paucity of species‐specific demographic data on savannah woody species, we modelled, in a novel approach, functional groups of plant species typical of Acacia woodlands. Outputs suggest that over the long term (100 years), low‐to‐moderate densities of impala will have a similar impact on woodland structure, in terms of density of adult trees, as low‐to‐moderate densities of elephant. Further, the outputs highlight the apparently strong synergistic effect impala and elephant impacts combined have on woodland dynamics, suggesting that reduction or removal of either impala or elephant will radically reduce long‐term destruction of savannah woodlands. Recorded changes in adult tree numbers in iMfolozi broadly supported the model's outputs.

Fire History, Woodland Structure, and Mortality in a Piñon-Juniper Woodland in the Colorado National Monument

The Colorado National Monument (COLM), on the northeastern edge of the Uncompahgre Plateau, supports a persistent Piñon (Pinus edulis Engelm.) — juniper (Juniperus osteosperma (Torr.) Little) woodland, which has not been disturbed by large stand-replacing fires since modern fire records began. We examined the fire history of large (> 100 ha) stand-replacing fires, documented tree population structures, and characterized tree density, quadratic mean diameter (QMD), relative composition, and cumulative mortality using 431 -0.1-haplots distributed over 1600 ha of the Monument. We found no evidence of large stand-replacing fires (charred wood or truncated stand structures) in the study area. Stand ages inferred from size structures suggest that large stand-replacing fires have been absent for possibly a millennia. Tree population structures show a more stable stand structure for juniper; Piñon pine population structures show a more recent and sustained regeneration pulse. Cumulative mortality of Piñon pines was 18%, peaking at 47% in trees 20 – 24.5 cm diameter. Spatial patterns of juniper density, QMD, and mortality were more homogeneous than those of Piñon pine. Results suggest temporal dynamics and spatial patterns of the COLM woodland are more influenced by drought and small fires (< 10 ha) than large fires (> 100 ha). This study provides important baseline data for changes that may be brought about by climate change in coming decades. It also stresses the importance of controlling cheatgrass (Bromus tectorum) and other invasive species to increase resistance of these persistent Piñon-juniper woodlands to future fires.

Dynamics and Conservation Management of a Wooded Landscape under High Herbivore Pressure

We present the use of a spatially explicit model of woodland dynamics (LANDIS-II) to examine the impacts of herbivory in the New Forest National Park, UK, in relation to its management for biodiversity conservation. The model was parameterized using spatial data and the results of two field surveys and then was tested with results from a third survey. Field survey results indicated that regeneration by tree species was found to be widespread but to occur at low density, despite heavy browsing pressure. The model was found to accurately predict the abundance and richness of tree species. Over the duration of the simulations (300 yr), woodland area increased in all scenarios, with or without herbivory. While the increase in woodland area was most pronounced under a scenario of no herbivory, values increased by more than 70% even in the presence of heavy browsing pressure. Model projections provided little evidence for the conversion of woodland areas to either grassland or heathland; changes in woodland structure and composition were consistent with traditional successional theory. These results highlight the need for multiple types of intervention when managing successional landscape mosaics and demonstrate the value of landscape-scale modelling for evaluating the role of herbivory in conservation management.

Classification and mapping of the composition and structure of dry woodland and savanna in the eastern Okavango Delta

The dry woodland and savanna regions of the Okavango Delta form a transition zone between the Okavango Swamps and the Kalahari Desert and have been largely overlooked in terms of vegetation classification and mapping. This study focused on the species composition and height structure of this vegetation, with the aim of identifying vegetation classes and providing a vegetation map accompanied by quantitative data. Two hundred and fifty-six plots (50 m × 50 m) were sampled and species cover abundance, total cover and structural composition were recorded. The plots were classified using agglomerative, hierarchical cluster analysis using group means and Bray-Curtis similarity and groups described using indicator species analysis. In total, 23 woody species and 28 grass species were recorded. Acacia erioloba and Colophospermum mopane were the most common woody species, whilst Urochloa mossambicensis, Panicum maximum, Dactyloctenium gigantiumand Eragrostis lehmanniana were the most widespread grasses. Eleven vegetation types were identified, with the most widespread being Short mixed mopane woodland, Tall mopane woodland and Tall mixed mopane woodland, covering 288.73 km2 (28%), 209.14 km2 (20%) and 173.30 km2 (17%) of the area, respectively. Despite their extensive area, these three vegetation types were the least species-rich, whilst Palm thornveld, Short mixed broadleaf woodland and Open mixed Acacia woodland were the most taxonomically variable. By contrast, Closed mixed Acacia woodland and Closed Acacia–Combretum woodland had the most limited distribution, accounting for less than 1% of the mapped area each.Conservation implications: The dry woodland and savanna vegetation of the Okavango Delta comprises a much wider suite of plant communities than the Acacia-dominated and Mopane-dominated classifications often used. This classification provided a more detailed understanding of this vegetation and essential background information for monitoring, management and research.

Impact of landscape fragmentation on a specialised woodland bat, Rhinolophus hipposideros

For habitat specialists, fragmentation has major consequences as it means less suitable habitat for the species to live in. In a fragmented landscape, we would expect larger, but spatially more clustered, foraging ranges. We studied the impact of landscape fragmentation on the foraging range and habitat exploitation of a specialised forest bat by radiotracking 16 female lesser horseshoe bats Rhinolophus hipposideros in a landscape with connected woodland structures and in a highly fragmented landscape in Carinthia, Austria.Contrary to our expectations, spatial foraging behaviour was not influenced by fragmentation. No differences in the behaviour of the bats between the sites were evident for the foraging ranges (minimum convex polygon, MCP), the core foraging areas (50% kernel), nor the mean or the maximum distances from the roost. However, in the highly fragmented landscape, the foraging activity of individuals was spatially more clustered and the overall MCP of all bats of a colony was greater compared to the less fragmented landscape.Woodland was the most important foraging habitat for the lesser horseshoe bats at both study sites. Habitat selection at the individual MCPs was evident only at the site with low fragmentation. However, in the core foraging areas, woodland was significantly selected over all other habitat types at both study sites.We conclude that (1) conservation measures for colonies of lesser horseshoe bats should be undertaken within 2.5km of the nursery roost, (2) woodland is the key foraging habitat particularly in the vicinity of the roost, and (3) any loss of woodland near the colonial roosts are likely to negatively influence the colony, since these bats do not seem to be able to adapt their spatial foraging behaviour in a degraded landscape. The inflexible spatial behaviour of this specialised bat highlights the need to compensate for any habitat loss within the foraging range of a bat colony.

Structural characterization and analysis of the regeneration of woodlands dominated by Juniperus oxycedrus L. in west-central Spain

This work addresses the structural characterization of Juniperus oxycedrus-dominated woodlands in west-central Spain, as well as the analysis of the regeneration of this species in the presence of other species (mainly Quercus ilex) as a function of different environmental and land-use factors. The two densest populations of the species were sampled and different physiographic and land-use parameters were obtained. First, a structural characterization, specifically focused on regeneration, was carried out, based on the count of individuals and their classification according to their size (seedlings, saplings, or adults) and position (either beyond or below the canopy). The use of Generalized Linear Models (GLM) and Regression Trees permitted the identification and analysis of environmental and land-use variables significantly related to regeneration. Juniper woodlands in this part of Spain generally show a remarkable level of regeneration, although some significant differences were detected between the two existing populations. Of the factors studied, time since regeneration started, elevation, and soil rock surface cover influence J. oxycedrus regeneration at most of the individual classes considered, indicating the significance of these variables in this species regeneration. Canopy cover and depth of the organic layer and zone also affect several of the recruitment classes. Furthermore, radiation, the time elapsed since regeneration started, elevation, and aspect affect stand structure to a significant extent. The results of this study enlarge the knowledge on J. oxycedrus regeneration and woodland structure, providing helpful information for the conservation of these protected habitats.

Describing Habitat Occupation by Woodland Birds with Territory Mapping and Remotely Sensed Data: An Example Using the Marsh Tit (Poecile palustris)

Abstract. Changes in the structure of woodlands and forests, caused by shifts in management, stand maturity, and composition, have been implicated in the population decline of some bird species in Europe and North America. One such species is the Marsh Tit (Poecile palustris). We investigated relationships between Marsh Tit occupation (derived from territory mapping) and vegetation structure, tree species composition, and proximity to woodland edge in a British woodland, using a combination of 5 years of occupation data and high-resolution (0.5 and 1 m), large-scale (155 ha) habitat models derived from remote sensing. The results demonstrated that Marsh Tit occupation was linked to vegetation characteristics through the woodland's full vertical profile and related significantly and positively with overstory height, tree canopy closure, and the coverage of understory vegetation below the overstory. Marsh Tit occupation was lower within 50 m of the woodland perimeter, where habitat structure was less favora...

A tale of two villages: assessing the dynamics of fuelwood supply in communal landscapes in South Africa

SUMMARYFuelwood is the dominant source of energy used by most rural households in southern Africa to meet daily domestic energy requirements. Due to limited financial resources, most rural households are unable to make the transition to electricity thus they remain dependant on the woodlands surrounding their settlements as a source of cheap energy. Unsustainable fuelwood harvesting due to increasing demand as a result of growing human populations may result in environmental degradation particularly in the high-density, communal savannah woodlands of South Africa. Evaluating the sustainability of current fuelwood harvesting patterns requires an understanding of the environmental impacts of past logging practices to establish patterns of woodland degradation. This study evaluates impacts of fuelwood harvesting from 1992–2009 on the woodland structure and species composition surrounding two rural villages located within the Kruger to Canyons Biosphere Reserve (Mpumalanga Province, South Africa). Both villages (Welverdiend and Athol) were of similar spatial extent and exhibited similar socioeconomic characteristics. The total wood stock in the communal woodlands of both villages declined overall (with greater losses seen in Welverdiend) and, in Welverdiend, there were also changes in the woodland structure and species diversity of the species commonly harvested for fuelwood over this period. The woodlands in Welverdiend have become degraded and no longer produce fuelwood of preferred species and stem size in sufficient quantity or quality. The absence of similar negative impacts in Athol suggests more sustainable harvesting regimes exist there because of the lower human population and lower fuelwood extraction pressure. The Welverdiend community has annexed neighbouring unoccupied private land in a social response to fuelwood scarcity. Athol residents behaved similarly during drought periods. The potential for future conflict with neighbouring conservation areas within the Kruger to Canyons Biosphere is high if current land uses and fuelwood extraction patterns are maintained.

Floristic diversity, regeneration status, and vegetation structure of woodlands in Metema Area, Amhara National Regional State, Northwestern Ethiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state, Ethiopia Our objective was to describe plant species composition, diversity, regeneration status, and population structure by a selective approach with a systematic sampling design. A total of 74 quadrats (each for 25 m × 25 m, spaced at intervals of 150–200 m) were sampled along established transect lines following the homogeneity of the vegetation. Vegetation data including cover-abundance, height, diameter at breast height (DBH), and numbers of seedlings and saplings of woody species were analyzed using Excel spreadsheet, Shannon Weiner diversity index, and PAST version 1.62. A total of 87 vascular plant species of 74 genera and 36 families were recorded. The dominant family was Fabaceae represented by 16 (18.39 %) species of 13 genera. Shannon Weiner diversity and evenness were 3.67 and 0.82, respectively, which showed that the area was endowed with rich floral diversity evenly distributed. The vegetation structure, as quantified by cumulative diameter class frequency distribution, plotted as an interrupted inverted-J-shape pattern with a sharp decrease in the 2nd diameter class. This indicated poor vegetation structure. The diameter classes frequency distributions of selected species plotted in four general patterns i.e., interrupted Inverted-J-shape, J-shape, Bell-shape and Irregular-shape. In conclusion, although the area showed high floral diversity and evenness, woody species including Sterculea setigera, Boswellia papyrifera, and Pterocarpus lucens showed lowest recruitment of seedlings and saplings.

Influence of time since fire on pinyon–juniper woodland structure

Although development of pinyon–juniper woodlands is understood to require decades after stand-replacing fire, data describing relationships between many key structural elements and time since fire (TSF) are lacking. In this study, we sampled live trees, seedlings, shrubs, snags, and downed logs on 13 sites that together comprised a 370-year fire chronosequence. We analyzed individual relationships between structural attributes and TSF. We also developed an additive index of structural complexity and analyzed its relationship with TSF. Live juniper and total tree density were positively and linearly related to TSF (R2=0.76 and 0.49, respectively). Pinyon tree density and TSF were not significantly related. No live trees (⩾1.37m height) were found on sites burned less than 30years before sampling, although seedlings were found as early as 6years TSF. Live pinyon tree biomass, live juniper biomass, and total tree biomass followed “s-shaped” functions (4-parameter Weibull; R2=0.32, 0.62, and 0.96, respectively), with total biomass maximizing at 65Mgha−1 around 250years since fire. Seedling densities and shrub cover were not significantly related to TSF. Juniper snag density showed a significant negative relationship with TSF (R2=0.54) and total snag density followed a “u-shaped” function depending on TSF (2nd-order polynomial; R2=0.47). Pinyon snag density and TSF were not significantly related. Density of rotten logs was positively and linearly related to TSF (R2=0.46) whereas sound logs and TSF were not statistically related. Structural complexity showed a positive linear relationship with TSF (R2=0.46). These results indicate that although individual structural elements show various relationships with TSF, structural complexity increases as sites approach persistent woodland conditions. Findings from this study provide resource professionals with information that can help in developing and assessing management approaches intended to emulate natural structural patterns.