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.     

Elephants,termites and mound thermoregulation in a progressively warmer world

Context

With global change, microclimates become important refuges for temperature-sensitive, range-restricted organisms. In African savannas, woody vegetation on Macrotermes mounds create widely-dispersed microclimates significantly cooler than the surrounding matrix, which buffer against elevated temperatures at the finer scale of mounds, allowing species to persist at the landscape scale. Termite colonies cultivate symbiotic fungi to digest lignin, but the fungi require temperatures between 29 and 32 °C, which termites strive to maintain. Mound-associated vegetation is a hot-spot for elephant herbivory, so removal of woody species cover by elephants could influence mound-associated microclimates, impacting temperature regulation by termites.

Objectives

We explored the interaction between two prominent ecosystem engineers (termites and elephants) to ascertain whether elephant removal of mound woody cover affects (1) external mound-associated microclimate and (2) internal mound temperature.

Methods

We surveyed 44 mounds from three sites in Kruger National Park, South Africa, during an El Niño/Southern Oscillation-induced drought and heatwave, recording whether sub-canopy, external, mound-surface and internal mound temperatures varied with vegetation removal by elephant.

Results

Elephant damage to mound-associated vegetation reduces the fine-scale microclimate effect provided by vegetation on Macrotermes mounds. Despite this, termites were able to regulate internal mound temperatures, whereas internal temperatures of abandoned mounds increased with elevated surface temperatures.

Conclusions

Termites can persist despite loss of mound-associated microclimates, but the loss likely increases energetic costs of mound thermoregulation. Since mound vegetation buffers against drought, loss of widely-dispersed, fine-scale microclimates could increase as megaherbivores remain constrained to protected areas, impacting climate-sensitive organisms and ecosystem function at a range of scales.

     

Effects of multiple fires on tree invasion in montane grasslands

There is circumstantial evidence that grasslands on the Bunya Mountains were once maintained by Aboriginal burning, and with lack of fire under European management are being colonised by trees. To assess the efficacy of burning for maintaining grasslands, 119 fires were lit between 1996 and 2006. The total area of unburnt grasslands decreased by 27%, while grasslands burnt at least once decreased by 1%. The density of invading trees was recorded from fixed plots on 23 grasslands burnt between one and six times. Cassinia was virtually eliminated and the density of the Rainforest species guild slowly but continually declined. Acacia irrorata exhibited a humped response, with initial increases resulting from vegetative resprouting and gradual decline with persistent burning. Phyllodinous Acacia and Woodland trees were the least fire sensitive guilds, having stable or increased density with repeated burning. Multi-factor regression modelling detected no significant relationships between changes in woody plant density and the interval between fires, fire intensity, the initial density of large trees, an index of soil moisture, or the cumulative number of fires for any species guild. The survivorship of both Cassinia and Rainforest guilds was significantly lower with summer burning than winter burning, but a seasonal effect of burning was not evident for other guilds. The findings suggest that regardless of fire conditions, frequent burning will reduce the number of adult trees, maintain resprouts in an immature state, facilitate further fire and reduce the rate of grassland loss. Woodland species are especially resilient to fire, and burning to maintain grassy ecosystems will be most successful where the main colonisers are rainforest species and burning is conducted in summer. The findings suggest that the montane grasslands of the Bunya Mountains were maintained by anthropogenic burning and active fire management will prolong their existence.     

Early forest dynamics in stand-replacing fire patches in the northern Sierra Nevada, California, USA

There is considerable concern over the occurrence of stand-replacing fire in forest types historically associated with low- to moderate-severity fire. The concern is largely over whether contemporary levels of stand-replacing fire are outside the historical range of variability, and what natural forest recovery is in these forest types following stand-replacing fire. In this study we quantified shrub characteristics and tree regeneration patterns in stand-replacing patches for five fires in the northern Sierra Nevada. These fires occurred between 1999 and 2008, and our field measurements were conducted in 2010. We analyzed tree regeneration patterns at two scales: patch level, in which field observations and spatial data were aggregated for a given stand-replacing patch, and plot level. Although tree regeneration densities varied considerably across sampled fires, over 50 % of the patches and approximately 80 % all plots had no tree regeneration. The percentage of patches, and to a greater extent plots, without pine regeneration was even higher, 72 and 87 %, respectively. Hardwood regeneration was present on a higher proportion of plots than either the pine or non-pine conifer groups. Shrub cover was generally high, with approximately 60 % of both patches and individual plots exceeding 60 % cover. Patch characteristics (size, perimeter-to-area ratio, distance-to-edge) appeared to have little effect on observed tree regeneration patterns. Conifer regeneration was higher in areas with post-fire management activities (salvage harvesting, planting). Our results indicate that the natural return of pine/mixed-conifer forests is uncertain in many areas affected by stand-replacing fire.     

Distribution of the red imported fire ant,shape Solenopsis invicta,in road and powerline habitats

For early-successional species, road and powerline cuts through forests provide refugia and source populations for invading adjacent forest gaps. Within an 800 km² forest matrix in South Carolina, we determined if width, disturbance frequency or linear features of road and powerline cuts influenced the mound distribution of the red imported fire ant, Solenopsis invicta Buren. For each of five linear habitat types, differing in width and disturbance frequency, we mapped all mounds located within ten 500 m segments. Mean mound density was lowest in narrow, infrequently-disturbed closed-canopy dirt road habitats (8.8 mounds/ha). For types with an opening in the forest canopy (i.e., open dirt road, gravel road, paved road and powerline cut), mean mound density was highest in narrow habitats where disturbance was intermediate (open dirt roads, 86.5 mounds/ha). It was lowest in wide habitats where disturbance was infrequent (powerline cuts, 27.6 mounds/ha). Mean mound size was greater in infrequently-disturbed powerline cuts than in frequently-disturbed paved roads. Mounds were located significantly closer to road or forest edges than expected by random. In all types except dirt roads, mounds were more common toward northern edges, and more so as the orientation of the linear habitat changed from north/south to east/west. These data suggest that narrow, disturbed habitats are more suitable for fire ant establishment and success than wider ones, and that the distribution of fire ants in linear habitats is not as uniform as it has been shown to be in pastures. A decrease in roadside disturbance and an increase in shade, especially along the northern edge, may result in lower fire ant mound density in these linear habitats.     

Land Cover Type and Fire in Portugal: Do Fires Burn Land Cover Selectively?

The purpose of this study is to investigate if, or under what conditions, fires select given land cover types for burning. If fires burn unselectively then the land cover composition (the proportional area of various land cover types) of individual fires should approximate the land cover composition available in their neighborhood. In this study we test this hypothesis by performing statistical analyses of a data set consisting of paired vectors with the proportions of land cover types present in burned areas and in their respective surroundings. The statistical methods employed (a permutation technique and the C_max statistic) are commonly used in resource selection studies where data is subject to a unit-sum constraint. The results of the analysis of 506 fires that burned in Portugal in 1991 indicate that fires are selective, with small fires exhibiting stronger land cover preferences than large fires. According to the results of a multiple comparison analysis performed for small fires, there is a marked preference for shrubland followed by other forest cover types, while agriculture is clearly avoided. A similar analysis is performed to test if fire selectivity is related to the ecological region where it occurs. The results obtained in this study contribute to the discussion on the relative importance of fuels as a drivers of fire spread.     

Post-fire resource redistribution and fertility island dynamics in shrub encroached desert grasslands: a modeling approach

A common form of land degradation in desert grasslands is associated with the relatively rapid encroachment of woody plants, a process that has important implications on ecosystem structure and function, as well as on the soil hydrological and biogeochemical properties. Until recently this grassland to shrubland transition was thought to be highly irreversible. However recent studies have shown that at the early stages of shrub encroachment in desert grasslands, there exists a very dynamic shrub–grass transition state with enough grass connectivity between the shrub islands to allow for fire spread. In this state fire could play a major role in determining the dominance of grasses and their recovery from the effects of overgrazing. Using a spatially explicit cellular automata model, we show how the patch-scale feedbacks between fires and soil erosion affects resource redistribution and vegetation dynamics in a mixed grass–shrub plant community at landscape to regional scales. The results of this study indicate that at its early stages, the grassland-to-shrubland transition can be reversible and that the feedbacks between fire and soil erosion processes may play a major role in determining the reversibility of the system.     

Community structure of dung beetles in Amazonian savannas: role of fire disturbance,vegetation and landscape structure

Understanding the relative influence of environmental and spatial variables in driving variation in species diversity and composition is an important and growing area of ecological research. We examined how fire, local vegetation structure and landscape configuration interact to influence dung beetle communities in Amazonian savannas, using both hierarchical partitioning and variance partitioning techniques to quantify independent effects. We captured a total of 3,334 dung beetles from 15 species at 22 savanna plots in 2003. The species accumulation curve was close to reaching an asymptote at a regional scale, but curves were variable at the plot level where total abundance ranged from 17 to 410 individuals. Most plots were dominated by just three species that accounted for 87.7% of all individuals sampled. Hierarchical partitioning revealed the strong independent and positive effect of percentage forest cover in the surrounding landscape on total dung beetle abundance and species richness, and richness of uncommon species and the tunneler guild. Forest cover also had a negative effect on community evenness. None of the variables that related to fire affected community metrics. The minimal direct influence of fire was supported by variance partitioning: partialling out the influence of spatial position and vegetation removed all of the individual explanation attributable to fire, whereas 8% of the variance was explained by vegetation and 28% was explained by spatial variables (when partialling out effects of the other two variables). Space-fire and vegetation-fire joint effects explained 14 and 10% of the dung beetle community variability, respectively. These results suggest that much of the variation in dung beetle assemblages in savannas can be attributed to the spatial location of sites, forest cover (which increased the occurrence of uncommon species), and the indirect effects of fires on vegetation (that was also dependent on spatial location). Our study also highlights the utility of partitioning techniques for examining the importance of environment variables such as fire that can be strongly influenced by spatial location.     

Fire-driven dynamic mosaics in the Great Victoria Desert,Australia – I. Fire geometry

The dominant ground cover in the Great Victoria Desert is porcupine grass or spinifex, a fire-prone perennial grass that grows in hummocks or tussocks. Lightning sets hundreds of wildfires annually in inland arid Australia, generating an ever changing spatial-temporal patchwork of habitats that differ in their state of post-fire recovery. The spatial configuration of this patchwork is determined by the size, shape, frequency and inter-spatial relationships of fires, and is likely to play a vital role in the maintenance of the desert biota. Chronosequences of satellite imagery spanning the years 1972–1991 are used to extract and describe the geometry of over 800 fires from fire scars. In the imagery study area, an average of 43 fires occur annually, fire size frequency distributions are roughly log-normal with mild right skew, with average area of 28 km², burning between 2 and 5% of the burnable landscape each year. Average fire return interval is estimated to be at least 20 years. These empirical findings are an important prerequisite for developing a more sophisticated understanding of the dynamics of the fire cycle in this ecosystem.     

Fire-induced changes in northern Patagonian landscapes

In northern Patagonia, Argentina we quantify changes in fire frequency along a gradient from mesic Nothofagus dombeyi forest to xeric woodlands of Austrocedrus chilensis at the steppe ecotone, and we examine patterns of vegetation change coincident with the changes in fire regimes across a range of spatial scales. At a regional scale changes in land cover types are documented by comparing 1:250000 scale cover type maps from 1913 and 1985. Changes in landscape structure are analyzed by comparing vegetation patterns on 1:24000 scale aerial photographs taken in 1940 and 1970. Fire frequency peaked in the late nineteenth-century due to widespread burning and clearing of forests by European settlers late in the century. Subsequently, fire frequency declined dramatically about 1910 due to the cessation of intentional fires and has remained low due to increasingly effective fire exclusion. At a regional scale there has been a dramatic increase during the twentieth century in the proportion of forest cover relative to areas mapped as recent burns or shrublands in 1913. Remnant forest patches that survived the widespread late-nineteenth century burning have coalesced to form more continuous forest covers, and formerly continuous areas of shrublands have become dissected by forest. Under reduced fire frequency there has been a shift in dominance from short-lived resprouting species (mostly shrubs) towards longer-lived species and obligate seed-dispersers such as Austrocedrus chilensis and Nothofagus dombeyi. Due to limited seed dispersal of these tree species, the spatial configuration of remnant forest patches plays a key role in subsequent changes in landscape pattern.     

Consequences of Landscape Heterogeneity on Grassland Diversity and Productivity in the Espinal Agroforestry System of Central Chile

The current land use system in the anthropogenic savannas (Espinales) of the Mediterranean climate region of Chile, has resulted in considerable heterogeneity at the landscape level which is associated with different covers of the legume tree, Acacia caven. The effects of landscape heterogeneity on the diversity and productivity of herbaceous plant communities were studied in 29 plots of 1000 m², with a wide range of woody cover. A detrended correspondence analysis of the species × plots matrix explained 73% of the total variation and revealed the existence of two trends of variation in floristic composition: one associated with physiographic position (hillsides and flatlands) and the other related to the number of years since the last cutting, or coppicing, of A. caven. Despite the great majority of the original herbaceous species having disappeared as a result of the prevailing land use system, some native species have been able to survive especially on hillside areas with low grazing intensity. Woody cover was a good indicator of spatial heterogeneity and land use history. It was also correlated with stocking rate, above-ground biomass of herbaceous vegetation, and soil fertility (organic matter, nitrogen and phosphorus concentration), both on hillsides and flatlands. The relationship between woody cover and herbaceous plant species richness was significant and unimodal in flat land areas, and linear, and marginally significant, on hillsides. The consequences of land use changes on the conservation of the ecological and productive values of grasslands are analyzed.     

Comparison of establishment methods for extensive green roofs in southern Sweden

The most common technique for establishment of thin extensive green roofs in Sweden has been using prefabricated vegetation mats. Our study investigated (1) how the establishment of green roofs in Sweden was influenced by the establishment method (prefabricated vegetation mat, plug-plant, shoot), substrate composition and species mixture, and (2) whether on-site construction was a possible alternative. The establishment of the vegetation, which in all cases consisted of succulent species, was recorded using the quadrate point intercept method in fixed plots and the success measured as frequency cover.Prefabricated vegetation mats had higher succulent plant cover than on-site constructed roofs. There was no difference in succulent plant cover between plots established using plug-plants compared to shoots. Shoot-established plots had more moss than the other establishment methods. The commercial substrate ‘Roof soil’ had significantly higher succulent plant cover than the other substrates, which might be related to a higher nutrient content. The organic content of the non-commercial substrates was rapidly decomposed. The standard species mixture produced a higher cover than both the mix developed for northern conditions and the mix with an increased proportion of big leaved species. The total cover of the plots was mainly dependent on the cover of two species: Sedum album (L.) and Sedum acre (L.). Few species managed to establish spontaneously but the establishment of woody species highlighted the need for proper maintenance.     

Historical influences dominate the composition of regenerating plant communities in abandoned citrus groves in north-central Florida

The question of what determines plant community composition is fundamental to the study of plant community ecology. We examined the relative roles of historical land use, landscape context, and the biophysical environment as determinants of plant community composition in regenerating citrus groves in north-central Florida. Results were interpreted in light of plant functional traits. Herbaceous and woody plants responded differently to broad-scale variables; herbs correlated most strongly with surrounding land cover at a scale of 8 km, while the only significant determinant of woody species distributions was local land use history. There were significant correlations between herbaceous species and spatial context, habitat isolation, environmental variables, and historical variables. Partial Mantel tests indicated that each variable provided a unique contribution in explaining some of the variation in the herbaceous dataset. The correlation between woody plants and local historical variables remained significant even with other effects corrected for. In the herbaceous community, species composition was linked to functional traits much as expected from classical theory. While spatial influences in our study system are important for both woody and herbaceous plants, the primary determinant of plant community composition in regenerating citrus groves is historical land use. Our results suggest that the fine-scale mechanisms of local competition, tolerance and facilitation invoked by many classical studies may ultimately be less important than land use history in understanding current plant community composition in regenerating agricultural areas.     

Factors driving natural regeneration beneath a planted urban forest

Cities around the world are investing in urban forest plantings as a form of green infrastructure. The aim is that these plantations will develop into naturally-regenerating native forest stands. However, woody plant recruitment is often cited as the most limiting factor to creating self-sustaining urban forests. As such, there is interest in site treatments that promote recruitment of native woody species and simultaneously suppress woody non-native recruitment. We tested how three, common site treatments—compost, nurse shrubs, and tree species composition (six-species vs. two-species)—affected woody plant recruitment in 54 experimental plots beneath a large-scale tree planting within a high-traffic urban park. We identified naturally regenerating seedling and sapling species and measured their abundance six-years after the site was planted. This enabled us to examine initial recruitment dynamics (i.e. seedlings) and gain a better understanding of seedling success as they transition to the midstory (i.e. saplings). Seedling and sapling recruitment (native and total) was greater in areas with higher canopy cover. The combination of the nurse shrub treatment with compost and species composition (six-species) treatments increased seedling recruitment by 47% and 156%, respectively; however, the nurse shrub treatment by itself decreased seedling recruitment by 5% and native seedling recruitment by 35%. The compost treatment alone had no effect on the total number of recruits but resulted in 76% more non-native seedlings. The sizes of these treatment effects were strongly dependent on whether the forest plantings were in open areas, versus areas with existing tree canopy, the latter condition facilitating recruitment. Our findings therefore suggest that combinations of site treatments, paired with broad canopy tree species, may be most effective for promoting regeneration of native species resulting in more self-sustaining urban forests.     

扬州市公园绿地木本地被植物种类及应用调查

对扬州市公园绿地木本地被植物种类及应用进行调查与分析.结果表明:扬州公园绿地中应用的木本地被植物共计88种,其中低矮灌木54种,匍匐灌木6种,木质藤本类21种,地被竹7种.该文介绍了公园绿地木本地被植物的观赏特性及主要应用方式,并提出优化公园绿地木本植物应用的几点对策,以期为扬州城市绿地建设提供参考依据.     

Urban epiphytes: Bromeliad diversity in a green cover gradient across a Neotropical streetscape

The Neotropical region is undergoing high levels of urban expansion and harbors the greatest diversity of vascular epiphytes globally. In cities, it could be expected that the density of woody vegetation positively predicts epiphyte communities by providing substrate, resources for pollinators, and buffering microclimatic conditions. However, there is a dearth of knowledge regarding how urbanization intensity affects the diversity of vascular epiphytes. In this study, we assessed the relationship between a woody cover gradient and bromeliad species richness and community composition across a streetscape of the Neotropical city of Xalapa (Mexico). We recorded bromeliads in nine street segments and one peri-urban green space. These sites represent a gradient of woody cover ranging from 10.5% to ∼87% in a 100 m buffer, and 100% in the peri-urban green space. We recorded 824 individuals of 14 species (all from the Tillandsioideae subfamily). The most abundant species was Tillandsia recurvata and the most frequent ones were T. juncea and T. schiedeana. Results show that bromeliad species richness was positively related to the woody cover, as expected. Interestingly, community composition did not associate with the percentage of woody cover. These results suggest that additional factors such as microclimatic conditions and seed availability and/or dispersal may be key modulators on the establishment of bromeliad species. Nevertheless, wooded streets do show potential for harboring diverse bromeliad communities.     

Grassland fragmentation and its influence on woody plant cover in the southern Great Plains,USA

Context

Woodland and agricultural expansion are major causes of grassland fragmentation. Fire and rainfall play important roles in maintaining grasslands, however, fire activity has been reduced in fragmented landscapes.

Objectives

Quantify the degree to which basic landscape fragmentation metrics could be used as drivers of woody cover potential.

Methods

Woody plant percent cover was calculated between 2004 and 2008 at?>?2000 sites. At each site, we calculated these fragmentation metrics for grassland cover type (classified by the National Land Cover Database); # patches, landscape proportion, edge density, largest patch index, effective mesh size and patch cohesion index within 3 circular areas (10 km², 360 km² and 3600 km²) surrounding the sampling site. A quantile regression was performed to identify which metrics were useful at predicting the 25th, 50th, 75th or 95th quantile of woody cover distribution.

Results

Grassland proportion and edge density were significant predictors of the woody plant potential (75th and 95th quantile). Woody cover potential was positively associated with edge density suggesting that fragmented areas (i.e., areas with high number of edges) maintained higher woody cover, while grassland proportion was negatively associated with woody plant potential.

Conclusion

We propose that in addition to a lack of fire, fragmented landscapes may facilitate further woodland expansion by reducing natural land and restricting grasslands to smaller, less connected patches, which can maintain higher woody cover. Given current trends in woodland expansion, special attention should be given to areas that are found within a fragmented landscape and climatically prone to woodland expansion.

     

Rural depopulation and recent landscape changes in a Mediterranean region: Consequences to the breeding avifauna

We studied the vegetational and avifaunistic changes following rural depopulation in an area covering 2,600 ha north of Montpellier (Southern France). The study area is covered by a mosaic of Mediterranean habitats that includes cultivation, grasslands, shrublands, and woodlands and is representative of the natural features present and of the human usage practiced so far in this part of the Mediterranean. We sampled the vegetation and the bird fauna in the same 193 census plots in 1978 and in 1992. At both the habitat and landscape scales the cover of woody plants increased significantly. Open habitats tend to disappear. As a consequence the abundance of open-habitat bird species decreased significantly whereas the abundance of forest birds increased significantly. These changes favor a pool of forest species widespread in western Europe and reduce habitat availability for open habitat and shrubland species. Many of the latter are Mediterranean species whose distribution in Western Europe could become reduced under current landscape dynamics. Our observation of more woodlands and their typical birds and of less open habitats and their associated avifauna is not consistent with the traditional worry shown by the public and the managers about the regression of forests and woodlands in the Northern Mediterranean as a consequence of fire.     

Factors associated with crown damage following recurring mixed-severity wildfires and post-fire management in southwestern Oregon

Wildfires and post-fire logging and planting have a lasting influence on the quantity and arrangement of live and dead vegetation, which can, in turn, affect the behavior of future fires. In 2002, the Biscuit Fire re-burned 38,000 ha of mixed-conifer/evergreen hardwood forest in southwestern Oregon that had burned heterogeneously during the 1987 Silver Fire and then was subject, in part, to post-fire logging and planting. We measured vegetation cover and crown damage from at temporal sequence (1987, 2000, and 2002) of digital aerial photo-plots (plot size = 6.25 ha) within managed and unmanaged portions of the twice-burned landscape. We estimated the strength and nature of relationships between crown damage in the two fires while also accounting for the influence of several vegetation, topographic, weather, and management variables. On average, unmanaged plots within the reburn area had 58% of their live crown cover scorched or consumed by the Biscuit Fire (median = 64%). The level of re-burn crown damage was strongly related to the level of crown damage during the Silver Fire. Typically, the areas that burned severely in the Silver Fire succeeded to a mix of shrubs and tree regeneration (i.e. shrub-stratum vegetation), which then experienced high levels of Biscuit Fire damage. In contrast, the level of tree-stratum damage in the Biscuit Fire was largely independent of Silver Fire damage. Within plots that were salvage-logged then planted after the Silver Fire, on average 98% of the vegetation cover was damaged by the Biscuit Fire (median = 100%). Within the plots that experienced complete crown damage in the Silver Fire but were left unmanaged, on average 91% of the vegetation cover was damaged by the Biscuit Fire (median = 95%). Our findings suggest that in productive fire-prone landscapes, a post-fire mosaic of young regenerating vegetation can influence the pattern of crown damage in future wildfires.     

Environmental,historical, and contextual determinants of vegetation cover: a landscape perspective

We formulated and tested models of relationships among determinants of vegetation cover in two agroforested landscapes of eastern North America (Haut Saint-Laurent, Quebec, Canada) that differed by the spatial arrangement of their geomorphic features and intensity of agricultural activities. Our landscape model compared the woody plots of each landscape in terms of the relative influence of environmental attributes, land use history (1958 – 1997), and spatial context (i.e., proximity of similar or contrasting land cover). Our vegetation model evaluated the relative contribution of the same sets of variables to the distributions of herbs, trees, and shrubs. Relationships were assessed using partial Mantel tests and path analyses. Significant environmental and contextual differences were found between the vegetation plots of the two landscapes, but disturbance history was similar. Our vegetation model confirms the dominant effect of historical factors on vegetation patterns. Whereas land-use history overrides environmental and contextual control for trees, herbaceous and shrub species are more sensitive to environmental conditions. Context is determinant only for understory species in older, less-disturbed plots. Results are discussed in relevance to vegetation dynamics in a landscape perspective that integrates interactions between environmental and human influences.