Long-term hay meadow management maintains the target community despite local-scale species turnover

Hay meadows, which are managed using a low-intensity regime, are characterized by highly diverse vegetation but have declined significantly since the mid twentieth century. Remaining species-rich meadows are often protected by statutory designations and conservation management agreements. However, long-term studies of change in the composition of meadow vegetation, and investigations of the success of conservation over the long-term are rare. Fourteen sites, which had a long history of being managed for field dried hay, were resurveyed after 25 years and redundancy analysis was undertaken to investigate changes in community composition. Investigations of the effect of soil conditions, site size and spatial distribution of the meadow sites were carried out. Although overall community composition had changed significantly, the suite of species representative of the meadow community had been maintained, and species usually associated with more intensively managed grasslands had declined. However, there were losses of particular species of conservation importance such as Alchemilla glabra and Conopodium majus, and losses and gains of species varied from site to site. There was a significant increase in the homogeneity of the meadow vegetation between the two survey years. Comparisons of indicators of soil conditions suggested that there had been no significant change for the community as a whole but analyses of the species showing the most change indicated a decrease in soil fertility. Low-intensity management has been successful in maintaining the meadow community but consideration of changes in key species and losses at the site level is needed. More research is needed to establish whether fragmentation is starting to have an impact on diversity.     

The interpretation of fen carr pollen diagrams: pollen–vegetation relationships within the fen carr

Sediments deposited in fen carr environments are frequently used in pollen-based reconstructions of vegetation history, although few studies of modern pollen–vegetation relationships in fen carr have been undertaken to aid the interpretation of fossil assemblages. It is often assumed that the wetland pollen signal will reflect the overall composition of the fen carr system although, given the closed canopy context, it may actually be dominated by local vegetation elements. This paper seeks to determine whether the vegetation heterogeneity within a modern fen carr is reflected in the pollen signal of the wetland taxa. Vegetation composition was recorded around a series of moss polster sample points at Calthorpe and Wheatfen, two areas of fen carr in the Norfolk Broadland, UK. The spatial interrelationship between the wetland components of the vegetation and their palynological equivalents in the moss polster pollen assemblages is explored through trend surfaces and a correlation based statistical test (the Mantel Test). The representation of the major vegetation components in the pollen record is highly variable. Values for Alnus glutinosa, a dominant canopy species, range from 5.3% to 73% of total land pollen (TLP) at Calthorpe and 2.5–61% TLP at Wheatfen. In part, this variation reflects the enhanced input of pollen from dry land sources close to the wetland edge although the variation recorded at points equidistant from the dry land margin suggests that other processes are also influential. The strongest positive associations in the Mantel Test are for under-storey and ground flora elements that are poorly represented in the pollen record. Taxa for which there is no association include those with few vegetation occurrences and those for which a large proportion of the pollen appears to have been derived from outside the study areas. We conclude that modern pollen samples collected from fen carr broadly reflect the vegetation composition of the study areas. However, the input of pollen from fen carr species is spatially inconsistent. Differences between the sample points can be attributed to the distribution and pollination biology of the under-storey and ground flora elements and the structure of the vegetation around sites. The results caution against assuming that changes in the pollen representation of wetland taxa, in fossil sequences constructed from fen carr deposits, necessarily reflect changes in the overall composition of the community.     

Recent vegetation changes at the high‐latitude tree line ecotone are controlled by geomorphological disturbance,productivity and diversity

Aim We test how productivity, disturbance rate, plant functional composition and species richness gradients control changes in the composition of high‐latitude vegetation during recent climatic warming. Location Northern Fennoscandia, Europe. Methods We resampled tree line ecotone vegetation sites sampled 26 years earlier. To quantify compositional changes, we used generalized linear models to test relationships between compositional changes and environmental gradients. Results Compositional changes in species abundances are positively related to the normalized difference vegetation index (NDVI)‐based estimate of productivity gradient and to geomorphological disturbance. Competitive species in fertile sites show the greatest changes in abundance, opposed to negligible changes in infertile sites. Change in species richness is negatively related to initial richness, whereas geomorphological disturbance has positive effects on change in richness. Few lowland species have moved towards higher elevations. Main conclusions The sensitivity of vegetation to climate change depends on a complex interplay between productivity, physical and biotic disturbances, plant functional composition and richness. Our results suggest that vegetation on productive sites, such as herb‐rich deciduous forests at low altitudes, is more sensitive to climate warming than alpine tundra vegetation where grazing may have strong buffering effects. Geomorphological disturbance promotes vegetation change under climatic warming, whereas high diversity has a stabilizing effect.     

Vegetation composition dynamics in peatlands used as buffer areas in forested catchments in southern and central Finland

Peatland buffer areas are important means in reducing sediment and nutrient loading from discharge waters in a variety of landscapes; however, use of natural mires as buffer areas may induce unwanted changes in the plant species composition. Vegetation composition dynamics were studied at one rewetted peatland and two natural peatlands used as buffer areas in forested catchments in southern and central Finland. In addition to the sediment and nutrient loads from the upstream catchments, the buffer areas received nitrogen and phosphorus from two artificial additions made in 2003?C2005 and 2008 in order to simulate loads caused by forestry operations. The first vegetation inventory was done in the year of buffer construction (1996 or 2000), the second inventory 4?C5?years after the first one, and the third inventory after 9?C13?years. The vegetation composition changed significantly at all three buffer areas. Grasses and sedges, as well as herbs were generally favored by the use of peatlands as buffer areas, and at the species level, the coverages of Menyanthes trifoliata and Calamagrostis purpurea increased the most. At the two natural sites, the change in vegetation composition was more apparent in the upstream parts of the buffer areas, probably because they received more sediments and nutrients than the lower parts. Also, the vegetation changed significantly more in the lawn-level surfaces than in the hummocks. As the vegetation composition in natural peatlands used as buffer areas is likely to undergo significant changes, the use of endangered mire site types should be avoided.     

Ecological indicators of Tuber aestivum habitats in temperate European beech forests

Although Tuber aestivum is widely distributed across Europe, little is known about its biology and ecology. We assess the vegetation composition of wild T. aestivum sites and use this information to characterise suitable habitats in Fagus sylvatica, Carpinus betulus and Ostrya carpinifolia (FCO) forests. Plant species composition at 16 naturally colonised T. aestivum sites in southwestern Germany and Switzerland was compared with that of 232 reference sites in Swiss FCO forest communities. The vegetation composition of truffle sites exhibits a high proportion of herb and shrub species that are indicators of a warm and dry climate, alkaline soil, and open tree canopy and thus typically occur in thermophilous FCO communities on calcareous bedrock. We conclude that T. aestivum is associated with a set of key species in addition to known host species. Based on their floristic composition, we identified FCO forest communities with high and low suitability for T. aestivum.     

Dynamics of hydrophilic phytocenoses in the littoral of the Rybinsk Reservoir

The dynamics of overgrowths of the most common phytocenoses of higher aquatic vegetation was studied in the littoral of the Rybink Reservoir from 1986 to 2008. Long-term changes in the floristic composition of phytocenoes have been observed at geobotanical sites.     

Post-drainage changes in vegetation composition and carbon balance in Lakkasuo mire,Central Finland

The post-drainage changes in vegetation composition and carbon balance were studied on four site types (from minero- to ombrotrophic conditions) in Lakkasuo mire, central Finland, by directly comparing undrained and drained parts (30 years ago) of the mire. Drainage had drastically changed the species composition of the sites, especially at the minerotrophic sites, where almost all Sphagna had been replaced by forest mosses. On the ombrotrophic sites much of the mire vegetation still remained 30 years after drainage. Drainage had decreased the C stores in ground vegetation on the minerotrophic sites but increased them on the ombrotrophic sites. The changes were, however, very small compared to the changes in the tree stand, where the C stores had increased at all sites (increasing with nutrient level). The change in peat C balance over the 30-year post-drainage period was negative on the most nutrient-rich site, and positive on the others, increasing with lower nutrient levels. The decrease in the peat C balance on the most nutrient-rich site was compensated by the greater increase in the tree stand C stores and the changes in the total C balance (peat+tree stand+ground vegetation) remained positive on all sites. This revised version was published online in June 2006 with corrections to the Cover Date.     

Sawgrass (Cladium jamaicense) responses as early indicators of low-level phosphorus enrichment in the Florida Everglades

Anthropogenic phosphorus (P) inputs to the Florida Everglades have produced dramatic changes in the wetland vegetation of this otherwise oligotrophic system. While the proliferation of undesirable plant species in response to enrichment has been well documented, nutrient-related changes in the physiological and morphological attributes of existing vegetation, prior to any shifts in species composition or changes in the spatial extent of certain taxa, have yet to be adequately characterized. In this experiment, three sawgrass-dominated areas were enriched with P for 3 years at rates of 0.4 g P/m²/year (HP), 0.1 g P/m²/year (LP), or 0 g P/m²/year (controls) to assess potential impacts of P-enriched discharges from stormwater treatment areas into the Everglades. Elevated concentrations of TP in rhizomes and leaves and reduced ratios of leaf N:P were detected in HP plants within ~1 year at most sites. Live leaf densities, plant heights, and plant densities of the HP groups were generally higher than LP and control groups after 2 years, a pattern that was evident even after major fire events. Total aboveground biomass was significantly elevated in both HP and LP treatments at two of the three sites after 3 years. No change in species composition was detected during the study. Planned hydrologic restoration measures will increase P loads into parts of the Everglades that have not previously experienced anthropogenic P enrichment. Monitoring native vegetation such as sawgrass can be a sensitive and relatively robust means of detecting unintended P enrichment in these areas prior to shifts in vegetation community composition or changes in area cover of key species.     

Forest cover and heterogeneous pastures shape the diversity of predatory rove beetles in tropical riparian habitats

In tropical landscapes, forest remnants have been reduced to narrow strips of vegetation along rivers and streams surrounded by agricultural land that affects biodiversity, depending on the habitat and landscape characteristics. To assess the effect of riparian forest loss on the diversity of Staphylininae predatory rove beetles, we considered two habitat conditions (river sites with riparian vegetation and sites with heterogeneous pastures) within two micro-basin types (with >70% and <40% forest cover) in a tropical montane cloud forest landscape, Mexico. Beetles were collected using baited pitfall traps during the rainy season of 2014. No differences were found between micro-basin types and, although species richness (⁰D) was similar between habitat conditions, when the diversity of common (¹D) and dominant (²D) species was considered, sites with heterogeneous pastures were almost twice as diverse as those with riparian vegetation. All diversity measurements were greater in sites with heterogeneous pastures of either micro-basin type. Air temperature and canopy cover were the environmental variables that best explained the variation in beetle species composition. The greatest environmental differences related to species composition were detected between habitat conditions and were more evident in sites with heterogeneous pastures and low forest cover in the surroundings. The results suggest that replacing riparian vegetation with heterogeneous pastures, within micro-basins that lost between 30% and 60% of their forest cover, does not significantly reduce the diversity of predatory rove beetle but rather modifies the beetle composition. Effective formulation of management strategies to mitigate the impact of land use modification therefore requires an understanding of the interaction between vegetation remnants and landscape characteristics.     

Taxon specific response of carabids (Coleoptera,Carabidae) and other soil invertebrate taxa on invasive plant Amorpha fruticosa in wetlands

False indigo (Amorpha fruticosa L.) is an invasive exotic plant introduced to Europe in the early eighteenth century. Its spread has been rapid, particularly in disturbed wetland habitats, where it forms dense impermeable monospecific stands and modifies habitat conditions. The impact of A. fruticosa on native plant communities has been well analyzed, however knowledge concerning the possible effects on soil invertebrates and particularly carabid beetles is completely lacking. This study analyzed the impact of an A. fruticosa invasion on carabid beetles and other soil invertebrates. Soil fauna was sampled by pitfall traps at natural habitats, initially colonized by A. fruticosa, and habitats largely invaded by A. fruticosa. In total 2,613 carabid beetles belonging to 50 species and 72,166 soil invertebrates were collected. The invasion of A. fruticosa strongly affected the carabid beetle species composition, which clearly differed between all studied sites. Widespread euritopic carabid beetle species showed positive responses to A. fruticosa invasion, while the activity density of open habitat species strongly declined. Mean individual biomass was significantly higher at invaded sites due to increased incidence of large carabids (genus Carabus Linné, 1758). Carabid beetle activity density and abundance of soil invertebrates were considerably higher at invaded sites than in natural sites. Conversely, the impact of A. fruticosa on carabid beetle species richness and diversity was less pronounced, most likely due to immigration from adjacent habitats. Changes in carabid beetle species composition and abundance of soil invertebrates were most likely due to changes in vegetation structure and microclimate. The results suggest that A. fruticosa invasion considerably affected carabid beetles, an insect group that is only indirectly related to plant composition. Therefore, severe future changes can be expected in invertebrate groups that are closely related to plant composition, since A. fruticosa cannot be completely removed from the habitat and covers relatively large areas.     

罕山土壤微生物群落组成对植被类型的响应

选取分布在中国东北部地区的阔叶林-针叶林-亚高山草甸这一明显的植被垂直带谱来研究植被类型对土壤微生物群落组成的影响。选取5种植被类型-山杨(Populus davidiana)(1250—1300 m),山杨(P.davidiana)与白桦(Betula platyphylla)的混交林(1370—1550 m),白桦(B.platyphylla)(1550—1720 m),落叶松(Larix principis-rupprechtii)(1840—1890 m),亚高山草甸(1900—1951 m),采用磷脂脂肪酸(Phopholipid Fatty Acids,PLFAs)分析方法测定不同植被类型下的土壤微生物群落组成。分别采用主成分分析(Principal Components Analysis,PCA)以及冗余分析(Redundancy Analysis,RDA)来解释单种特征PLFAs的分异以及土壤理化指标与微生物PLFAs指标间的相关性。结果表明不同植被类型下土壤有机碳(SOC)对土壤微生物PLFAs总量,各类群(真菌(f)、细菌(b)、革兰氏阳性菌(G+)、革兰氏阴性菌(G-))生物量以及群落结构影响显著;土壤微生物PLFAs总量及各类群的生物量随土层加深总体上表现降低趋势,G+/G-和f/b分别随土层加深总体上表现升高趋势。不同植被类型下,阔叶混交林土壤PLFAs总量及各类群生物量总体上最高;针叶林比阔叶林下的f/b和G+/G-高;亚高山草甸下低的p H值对有机碳的可利用性有一定的抑制作用,导致f/b和G+/G-的值相对较高。总之,不同植被类型下SOC对土壤微生物群落组成的影响最为显著,而较低的p H对有机碳的可利用性有一定的抑制作用;真菌对植被类型的变化比细菌更敏感,而细菌更易受可利用性养分和p H变异的影响,这对预测不同林型下的土壤微生物群落组成有重要的启示作用。     

Effects of Mesolithic hunter-gatherers on local vegetation in a non-uniform glacio-isostatic land uplift area, northern Sweden

The oldest early Mesolithic settlements found so far (i.e. 8600 b.p.) in the interior of northern Sweden, in the province of Norrbotten, have been discovered through the application of a model simulating glacio-isostatic land uplift. The objective of this study was to investigate, through pollen and charred particle analyses, vegetation composition and the influence of man on vegetation and fire pattern in the vicinity of two of these early settlements. Early Holocene vegetation was characterised by Betula, Hippophaë and Salix-species, but no initial impact by hunter-gatherers on vegetation was detected. Subsequently Betula and Pinus became dominant but abrupt changes in the tree layer followed, Poaceae, Hippophaë and Salix-species increased, and Humulus occurred. These changes, which were synchronous with dates of archaeological findings at the settlements, indicated local vegetation changes caused by man. The relationship between these changes and fire was, however, subtle. Eventually Pinus forests became dominant and human impact on vegetation became less apparent. It is concluded that the impact of early Mesolithic hunter-gatherers on vegetation was detectable, but that their effect on fire pattern was difficult to evaluate. Further, we show that the glacio-isostatic land uplift must be considered in the search for Mesolithic settlements in areas previously covered by the Weichselian Ice, and that the process has influenced the biological archives through re-deposition of material.     

Riparian bird density decline in response to biocontrol of <Emphasis Type="Italic">Tamarix</Emphasis> from riparian ecosystems along the Dolores River in SW Colorado,USA

Biocontrol of invasive tamarisk (Tamarix spp.) in the arid Southwest using the introduced tamarisk beetle (Diorhabda elongata) has been hypothesized to negatively affect some breeding bird species, but no studies to date have documented the effects of beetle-induced defoliation on riparian bird abundance. We assessed the effects of tamarisk defoliation by monitoring defoliation rates, changes in vegetation composition, and changes in density of six obligate riparian breeding bird species at two sites along the Dolores River in Colorado following the arrival of tamarisk beetles. We conducted bird point counts from 2010 to 2014 and modeled bird density as a function of native vegetation density and extent of defoliation using hierarchical distance sampling. Maximum annual defoliation decreased throughout the study period, peaking at 32–37% in 2009–2010 and dropping to 0.5–15% from 2011–2014. Stem density of both tamarisk and native plants declined throughout the study period until 2014. Density of all bird species declined throughout most of the study, with Song Sparrow disappearing from the study sites after 2011. Blue Grosbeak, Yellow-breasted Chat, and Yellow Warbler densities were negatively related to defoliation in the previous year, while Lazuli Bunting exhibited a positive relationship with defoliation. These findings corroborate earlier predictions of species expected to be sensitive to defoliation as a result of nest site selection. Tamarisk defoliation thus had short-term negative impacts on riparian bird species; active restoration may be needed to encourage the regrowth of native riparian vegetation, which in the longer-term may result in increased riparian bird density.     

Seed banks of managed and degraded grasslands in the Krkonoše Mts., Czech Republic

Grassland seed banks are traditionally considered a source of new species in degraded communities. However, many recent studies have shown that the potential of the seed bank to restore many communities is rather limited. Two principal reasons for these limitations, loss of species from the seed bank or inability of the species to create any seed bank, are, however, usually not distinguished. This study aims to assess the role of seed bank composition and heterogeneity in the restoration of species-rich plant communities. It was carried out in mountain grasslands in the eastern part of the Krkono?e Mountains, Czech Republic. The composition of vegetation and seed bank were recorded and their relationship was assessedin 1.5m × 1.5 m plots placed in non-degraded and degraded parts of seven grasslands. Vegetation at currently managed sites is not degraded; degraded parts were without management (dominated byHolcus mollis, Bistorta major orRumex alpinus). The degree of heterogeneity of seed bank and vegetation was tested as the relationship between subplot similarity, distance, and degradation stage. Degradation had significant effects on composition of both aboveground vegetation and seed bank and increased heterogeneity both in the vegetation and in the seed bank. Species absent from the vegetation of degraded plots were also absent from the seed bank of both degraded and non-degraded plots, indicating that the absence of species from the seed bank is not due to their loss during the degradation process but rather due to the low number of seeds in the seed bank already in the non-degraded communities. Furthermore, the seed bank of the degraded communities largely results from the present vegetation of these communities. This supports the limited role of the seed bank in these communities. Restoration of these sites is thus impossible unless management will include methods with which seeds will arrive at the degraded sites.     

Site fertility drives temporal turnover of vegetation at high latitudes

Experimental evidence shows that site fertility is a key modulator underlying plant community changes under climate change. Communities on fertile sites, with species having fast dynamics, have been found to react more strongly to climate change than communities on infertile sites with slow dynamics. However, it is still unclear whether this generally applies to high‐latitude plant communities in natural environments at broad spatial scales. We tested a hypothesis that vegetation of fertile sites experiences greater changes over several decades and thus would be more responsive under contemporary climate change compared to infertile sites that are expected to show more resistance. We resurveyed understorey communities (vascular plants, bryophytes, and lichens) of four infertile and four fertile forest sites along a latitudinal bioclimatic gradient. Sites had remained outside direct human disturbance. We analyzed the magnitude of temporal community turnover, changes in the abundances of plant morphological groups and strategy classes, and changes in species diversity. In agreement with our hypothesis, temporal turnover of communities was consistently greater on fertile sites compared to infertile sites. However, our results suggest that the larger turnover of fertile communities is not primarily related to the direct effects of climatic warming. Furthermore, community changes in both fertile and infertile sites showed remarkable variation in terms of shares of plant functional groups and strategy classes and measures of species diversity. This further emphasizes the essential role of baseline environmental conditions and nonclimatic drivers underlying vegetation changes. Our results show that site fertility is a key determinant of the overall rate of high‐latitude vegetation changes but the composition of plant communities in different ecological contexts is variously impacted by nonclimatic drivers over time.     

Latitudinal variations in the composition and structure of vegetation in the northwestern Tatar Strait

The pattern of the latitudinal distribution of the floristic composition and structure of the submerged vegetation cover in the western Tatar Strait (within Khabarovsk Krai) is studied using the published data and original materials. Irregularities of the floristic composition have been found within limited areas of bays in this region, where they do not form any distinct borders or gradients. In the vegetation cover, vice versa, borders and gradients have been shown to form various combinations. The specific biomasses of most of the dominant species are significantly increasing, whereas the width and depth of the vegetation belt decreases from the south to the north. Their regression lines intersect at the latitude of 50° N (Cape Syurkum). Discrete coenotic variations are manifested most clearly as well at this point, where the dominance of Saccharina japonica, observed south of the cape, changes for S. cichorioides north of it. This allows establishing the phytocoenotic border here. The revealed features correspond to the direction of the temperature gradient, as well as to the variations in topical conditions and the level of hydrodynamic load along the coast.     

Effects of Invasive-Plant Management on Nitrogen-Removal Services in Freshwater Tidal Marshes

Establishing relationships between biodiversity and ecosystem function is an ongoing endeavor in contemporary ecosystem and community ecology, with important practical implications for conservation and the maintenance of ecosystem services. Removal of invasive plant species to conserve native diversity is a common management objective in many ecosystems, including wetlands. However, substantial changes in plant community composition have the potential to alter sediment characteristics and ecosystem services, including permanent removal of nitrogen from these systems via microbial denitrification. A balanced assessment of costs associated with keeping and removing invasive plants is needed to manage simultaneously for biodiversity and pollution targets. We monitored small-scale removals of Phragmites australis over four years to determine their effects on potential denitrification rates relative to three untreated Phragmites sites and adjacent sites dominated by native Typha angustifolia. Sediment ammonium increased following the removal of vegetation from treated sites, likely as a result of decreases in both plant uptake and nitrification. Denitrification potentials were lower in removal sites relative to untreated Phragmites sites, a pattern that persisted at least two years following removal as native plant species began to re-colonize treated sites. These results suggest the potential for a trade-off between invasive-plant management and nitrogen-removal services. A balanced assessment of costs associated with keeping versus removing invasive plants is needed to adequately manage simultaneously for biodiversity and pollution targets.     

The needle mycobiome of Picea glauca – A dynamic system reflecting surrounding environment and tree phenological traits

Fungi play a crucial role in terrestrial Arctic ecosystems as symbionts of vascular plants and nutrient recyclers in soil, with many species persistently or temporarily inhabiting the phyllosphere of the vegetation.In this study we apply high-throughput sequencing to investigate the mycobiome of 172 samples of fresh (current year) and aged (3 year old) needles of Picea glauca from three sites over a distance of 500 km in Alaska (USA). We analysed Illumina-generated ITS2 sequences to relate mycobiome data with phenotypic tree traits, measures of genetic variation and climate variables obtained from long-term monitoring of the sites.Alpha-diversity declined with increasing environmental stress/climate harshness. Fungal communities differed in richness and taxonomic composition between sites, with a pronounced difference in the relative abundance of OTUs assigned to species of the rust genus Chrysomyxa, plant pathogens which seem to have been in an outbreak at two sites at the time of sampling.Beside climate parameters, needle age was the second strongest explanatory variable of the mycobiome composition, whereas we found no effect of tree genetic variation, indicating that environmental and tree trait specific variables mainly determined individual white spruce mycobiomes at Alaska's treelines.     

Species composition of coastal dune vegetation in Scotland has proved resistant to climate change over a third of a century

Climate change is expected to have an impact on plant communities as increased temperatures are expected to drive individual species' distributions polewards. The results of a revisitation study after c. 34 years of 89 coastal sites in Scotland, UK, were examined to assess the degree of shifts in species composition that could be accounted for by climate change. There was little evidence for either species retreat northwards or for plots to become more dominated by species with a more southern distribution. At a few sites where significant change occurred, the changes were accounted for by the invasion, or in one instance the removal, of woody species. Also, the vegetation types that showed the most sensitivity to change were all early successional types and changes were primarily the result of succession rather than climate‐driven changes. Dune vegetation appears resistant to climate change impacts on the vegetation, either as the vegetation is inherently resistant to change, management prevents increased dominance of more southerly species or because of dispersal limitation to geographically isolated sites.     

Determinants of Tree Assemblage Composition at the Mesoscale within a Subtropical Eucalypt Forest

A variety of environmental processes, including topography, edaphic and disturbance factors can influence vegetation composition. The relative influence of these patterns has been known to vary with scale, however, few studies have focused on environmental drivers of composition at the mesoscale. This study examined the relative importance of topography, catchment flow and soil in influencing tree assemblages in Karawatha Forest Park; a South-East Queensland subtropical eucalypt forest embedded in an urban matrix that is part of the Terrestrial Ecosystem Research Network South-East Queensland Peri-urban SuperSite. Thirty-three LTER plots were surveyed at the mesoscale (909 ha), where all woody stems ≥1.3 m high rooted within plots were sampled. Vegetation was divided into three cohorts: small (≥1–10 cm DBH), intermediate (≥10–30 cm DBH), and large (≥30 cm DBH). Plot slope, aspect, elevation, catchment area and location and soil chemistry and structure were also measured. Ordinations and smooth surface modelling were used to determine drivers of vegetation assemblage in each cohort. Vegetation composition was highly variable among plots at the mesoscale (plots systematically placed at 500 m intervals). Elevation was strongly related to woody vegetation composition across all cohorts (R²: 0.69–0.75). Other topographic variables that explained a substantial amount of variation in composition were catchment area (R²: 0.43–0.45) and slope (R²: 0.23–0.61). Soil chemistry (R²: 0.09–0.75) was also associated with woody vegetation composition. While species composition differed substantially between cohorts, the environmental variables explaining composition did not. These results demonstrate the overriding importance of elevation and other topographic features in discriminating tree assemblage patterns irrespective of tree size. The importance of soil characteristics to tree assemblages was also influenced by topography, where ridge top sites were typically drier and had lower soil nutrient levels than riparian areas.