Restoration Of Plant Communities Research Articles

Non-trophic interactions in deserts: Facilitation, interference, and an endangered lizard species

Research on plant–animal interactions has been focused on direct consumer interactions (i.e. plants as resources), but non-trophic interactions including providing shelter or interference with movement can also affect the fine-scale distribution of animals. In particular, non-trophic interactions that are positive could support threatened animal populations. Positive interactions have been used in the restoration of plant communities, but have not yet been extended to the management of animal habitat. In this study, we tested the hypothesis that non-trophic interactions influence the occurrence of an endangered lizard species in an arid shrub-annual system. At a location known to have a population of blunt-nosed leopard lizards (Gambelia sila), we geotagged 700 shrubs, measured shrub morphometric traits, collected biomass samples, and surveyed for lizard presence using scat detection dogs over two years. Relative to 2014, in 2013 plant productivity was high and lizard scats were found more frequently in areas with low invasive grass cover (i.e. residual dry matter, RDM). In 2014, plant productivity was low because of an extreme drought year, and lizard scats were more frequently observed under shrub canopies, particularly those with relatively dense cover. These findings support the novel theory that positive non-trophic interactions are a critical form of plant–animal interactions in addition to consumption. Dominant shrubs can act as a foundation species by functioning as a basal node in structuring both plant and animal communities through a network of interactions. Managing dominant plants, in addition to habitat, is therefore important for conserving animal species in arid ecosystems.

Analysis of soil seed bank patterns in an oxbow system of a disconnected floodplain

Soil seed banks have a high potential for vegetation re-establishment in restoration projects. We studied the soil seed bank in an oxbow system of a disconnected floodplain of the Danube River in Southern Germany. The aim of the study was to analyze if floodplain target species were still present in the seed bank after more than 150 years of embankment and disconnection from fluvial dynamics. In this context we investigated seed density, seed bank species richness and species composition in four broad habitat types with and without water-level fluctuations during the time of embankment (permanent water, fluctuating water, reed bed, hardwood floodplain forest). In addition, the similarity between seed bank and above-ground vegetation in these habitat types was studied in order to predict the success of future restoration measures. In total, 124 vascular plant species were determined in the seed bank samples. More than 50 % (66 species) were target species typical for floodplain habitats and 26 of these target species were lost or very rare in the above-ground vegetation. The four habitat types differed significantly in mean seed density and mean species richness. Mean species richness and the number of target species in the seed bank as well as the mean seed density were greatest in the habitats with fluctuating water level whereas mean seed density was much lower in the parts with more or less stable conditions like permanently standing water and hardwood floodplain forest. Sørensen similarity between seed bank and above-ground vegetation was very low in habitats with more or less stable water levels and desirable floodplain target species were very rare or completely absent. Our results indicate that the soil seed bank can be an important seed reservoir for the ecological restoration of floodplain plant communities especially for habitats with unstable environmental conditions during the period of disconnection. Restoration of water level dynamics is important to maintain the seed bank of populations of floodplain target species.

Fragmentation affects plant community composition over time

Habitat fragmentation can lead to major changes in community composition, but little is known about the dynamics of these changes, or how community trajectories are affected by the initial state of habitat maturity. We use four landscape‐scale experiments from different biogeographic regions to understand how plant community composition responds to fragmentation over decades. Within each experiment, we consider first whether plant communities in the most‐fragmented treatments diverge in composition from plant communities in the least‐fragmented treatments. Second, because communities embedded in different fragments may become more similar to one another over time (biotic homogenization), we asked whether beta diversity – compositional variation across space – declines among fragments over time. Third, we assessed whether fragmentation alters the degree to which temporal change in fragmented landscapes is due to ordered species losses and gains (nestedness) versus species replacements (turnover). For each of these three questions, we contrasted patterns of compositional change in mature communities following fragmentation (disassembly; n = 2 experiments) with patterns in newly‐developing plant communities in fragments cleared of vegetation (assembly; n = 2 experiments).In the two studies where communities were disassembling, community composition in the most‐fragmented habitats diverged from that in least‐fragmented habitats. Beta diversity within a fragmentation treatment did not change over time at any of the four sites. In all four experiments, temporal patterns of compositional change were due mostly to species turnover, although nestedness played a role in the least‐fragmented sites in two of the studies. Overall, the impacts on community composition varied among landscape experiments, and divergence may have been affected by the maturity of the plant community. Future comparisons across ecosystems that account for species identities (vs simply richness) will be critical for predicting the effects of fragmentation, managing mature plant communities in remnants, and restoring plant communities where habitat has been lost.

The missing link in grassland restoration: arbuscular mycorrhizal fungi inoculation increases plant diversity and accelerates succession

Summary Because soil microbial communities are often altered by anthropogenic disturbance, successful plant community restoration may require the restoration of beneficial soil microbes, such as arbuscular mycorrhizal (AM) fungi. Recent evidence suggests that later successional grassland species are more strongly affected by AM fungi relative to early successional plants and that late successional plants consistently benefit from some AM fungi but not other AM fungal species. Many of these late successional species are also often missing in restorations despite being heavily seeded. To assess the effects of AM fungal composition within grassland restorations, we inoculated plots with six different AM fungal community treatments including one of four different AM fungal species isolated from a prairie, a mixture of all four fungal species, and a non‐inoculated control. AM fungi were introduced by planting 16 different inoculated nurse plants into replicated plots. We also seeded the restoration with a diverse, 54 species prairie seed mixture. We found that AM fungal inoculation drove plant community composition; plots inoculated with certain AM fungal treatments were dominated by desirable prairie plants, whereas plots inoculated with other AM fungal species and the non‐inoculated control were dominated by non‐desirable plants including weeds and exotic species. Specifically, we found that many early successional species established well regardless of AM fungal inoculation, whereas the establishment and growth of many late successional species was strongly dependent on the presence of specific AM fungal species. Many conservative late successional species did not occur without inoculation. Overall, total plant community richness, diversity, and Floristic Quality Index were all significantly improved with AM fungal inoculation, whereas we observed that non‐desirable plant abundance was significantly greater in the non‐inoculated plots. Synthesis and applications. Our results suggest that the lack of late successional establishment reported in many previous restorations may be due to ineffective arbuscular mycorrhizal fungal communities at these sites. We conclude that the reintroduction of arbuscular mycorrhizal fungi from reference prairie environments could improve restoration outcomes by promoting plant diversity and richness, especially for desirable later successional plant species, while simultaneously inhibiting less desirable weedy plants.

Does restored plant diversity play a role in the reproductive functionality of Banksia populations?

AbstractVegetation structure and plant species diversity of restoration sites are predicted to directly affect pollinator attraction, with potential impacts on gene flow, reproduction, genetic diversity of future generations, and ultimately restoration success. We compared Banksia attenuata R.Br. (Proteaceae) in a low species diversity restoration site and an adjacent natural remnant. We assessed fecundity genetic diversity in adult plants and their offspring, mating system parameters and pollen dispersal using paternity assignment. Results were compared to an earlier study of reproductive functionality within a high species diversity restoration site that was restored in a similar manner, enabling us to investigate any association between plant species diversity and fecundity. Seed set data indicated no significant differences between restored and adjacent natural sites; however, seed set data between restoration sites was significantly different (2.08 ± 0.39 and 6.89 ± 1.12, respectively). The mean number of fruits (follicles) per inflorescence was not significantly different between restoration sites. Genetic diversity of adult plants and their offspring were comparable in all sites. Higher allelic richness and genetic differentiation in one restored site reflected sourcing beyond local provenance. Low correlated paternity indicated high levels of multiple siring of seeds and paternity assignment demonstrated strong genetic connectivity between sites. Reproductive functionality, as measured by fecundity and genetic diversity in the offspring of B. attenuata, is resilient to low species diversity within a restored plant community. We consider our results in the context of establishing seed production areas (SPAs) that maximize the quantity and genetic quality of Banksia seeds for restoration.

Effects of temperature, moisture and soil type on seedling emergence and mortality of riparian plant species

Restoration of riparian plant communities on bare soil requires germination of seeds and establishment of seedlings. However, species that are present in the soil seed bank do not always establish in the vegetation. Temperature, moisture conditions and soil type could play a major role in the establishment of riparian plant communities, through impacting seedling emergence.We studied the effects of temperature, combinations of temperature and moisture conditions, and soil type on seedling emergence and mortality of perennial reeds (Typha latifolia and Phragmites australis) and annual or biannual pioneer species (Senecio congestus, Rumex maritimus and Chenopodium rubrum). The responses to the environmental conditions were species-specific and resulted in context-dependent differences in proportions of species emerging from the soil seed bank. Typha latifolia and S. congestus preferred wet or very wet conditions, C. rubrum and R. maritimus preferred dry to very dry conditions. Phragmites australis was able to establish under all conditions. Both cold and very dry conditions resulted in low emergence and survival, which was not fully compensated for when conditions became favorable again. Senecio congestus, R. maritimus and C. rubrum benefitted from secondary seedling emergence when, after a very dry period, the weather became very wet again, while T. latifolia and P. australis remained absent.When the conditions remained wet, more seedlings emerged from sand than from clay. However, when the soil was drying out, fewer seedlings emerged from sand than from clay.We propose that using information on plant species-specific responses to abiotic environmental conditions during germination, emergence and establishment can help to restore different target riparian plant communities.

Greenup and evapotranspiration following the Minute 319 pulse flow to Mexico: An analysis using Landsat 8 Normalized Difference Vegetation Index (NDVI) data

In the southwestern U.S., many riparian ecosystems have been altered by dams, water diversions, and other anthropogenic activities. This is particularly true of the Colorado River, where numerous dams and agricultural diversions have affected this water course, especially south of the U.S.–Mexico border. In the spring of 2014, 130 million cubic meters of water was released to the lower Colorado River Delta in Mexico. To understand the impact of this pulse flow release on vegetation in the delta’s riparian corridor, we analyzed a modified form of Landsat 8 Operational Land Imager (OLI) Normalized Difference Vegetation Index (NDVI*) data. We assessed greenup during the growing period and estimated actual evapotranspiration (ETa) for the period prior to (yr. 2013) and following (i.e., yr. 2014 and 2015) the pulse flow. We found a significant increase in NDVI* from 2013 to 2014 (P<0.05) and a decrease from 2014 to 2015; however, 2015 levels were still significantly higher than in 2013. ETa was also higher in 2014 vs. 2013, with an estimated 74.5 million cubic meters in 2013 and 88.9 in 2014. The most intense greening occurred in the zone of inundation but also extended into the non-flooded part of the riparian zone, indicating replenishment of groundwater. These findings suggest the peak response by vegetation to the flow lasted about one year, followed by a decrease in NDVI*. As a long term solution to the declining condition of vegetation, additional pulse releases are likely needed for restoration and survival of riparian plant communities in the Colorado River Delta.

Understanding the ecology of tree-seedling growth in dry tropical environment: a management perspective

The dry tropical forests are among the most vulnerable ecosystems of the world and, however, are relatively understudied. These forests provide various ecosystem services, and are progressively being converted into patches of dry scrubs, savanna and marginal cropland systems, due to various anthropogenic perturbations. Soils of these regions are relatively nutrient poor with a patchy nutrient and water distribution pattern. Therefore, the variability in these natural resources imposed by the present climate change scenario may affect the forest plant community of dry tropics via its impact on seedling growth and recruitment. Seedlings are considered as the most sensitive stage of plant lifecycle, and therefore, understanding of seedling regeneration may help in restoration of forest ecosystems. Seedling growth is majorly regulated by various naturally occurring resources (such as light, water, nutrient, etc.) and disturbances (such as defoliation, grass competition, fire, etc.). Therefore, efforts on the regeneration of these forest systems are highly necessitated. In the present study, we critically reviewed the studies on seedling survival and growth under different resource and disturbance regimes with a special focus to dry tropical environment. We found that water, light, nutrients, herbivory, and grass competition majorly regulates recruitments, growth, and establishment of the tree seedling in dry tropical environment. Most of the studies are limited to observe the effect of one or two factors over the seedling survival and growth. However, the resources and disturbances may have an interactive effect over seedling growth. Therefore, studies encompassing the interactions of various growth factors (resources and disturbances) under different climatic conditions are urgently needed for the successful regeneration of tree seedlings and for the restoration of plant community. Moreover, it will improve our ability to manage the tropical vegetation under changing climatic scenario.

Phylogenetic diversity reveals hidden patterns related to population source and species pools during restoration

Summary A phylogenetic perspective of community assembly can reveal new insights into how variation within dominant species interacts with the local species pool to influence the structure of restored plant communities. Many studies have examined the effect of dominant species in structuring plant communities, but few have investigated their effect on phylogenetic diversity (PD). We established grassland in a post‐agricultural field using two population sources (cultivars and local ecotypes) of three dominant grasses (Sorghastrum nutans, Andropogon gerardii and Schizachyrium scoparium) with three unique pools of subordinate species that varied in PD but not taxonomic or life‐form diversity. We tested the effect of the population source treatment on two metrics of community PD (net relatedness index [NRI] and nearest taxon index [NTI]) during the first 4 years of restoration. The NRI measures the overall pairwise phylogenetic distance between all pairs of taxa in a community. By contrast, NTI measures the pairwise distance between closely related taxa in a community. Population sources had a transitory effect on community phylogenetic structure over time. Local ecotypes decreased the abundance of closely related eudicots, monocots (low +NRI and +NTI values) and volunteer species (−NTI) more than cultivars. However, population sources did not affect ecologically conservative species (i.e. species with intermediate‐to‐poor ecological tolerance and a high degree of fidelity to prairie habitats). Thus, cultivars might have a positive effect on community phylogenetic diversity more than local ecotypes by decreasing the abundance of a phylogenetically diverse community of less closely related volunteer species. Differences in PD of seed mixes were maintained in the community of high‐fidelity species, but did not affect PD of the unsown (volunteer) species in the assembling community. Synthesis and applications. This is the first experiment to show consequences of using different seed sources on phylogenetic diversity (PD) in grassland restoration. Phylogenetics can reveal the effects of population sources on the abundance of volunteer species not evident through traditional analyses of species diversity. The PD of seed mixes or establishing communities, or other assessments of phylogenetic relationships, by restoration practitioners is recommended as a metric to allow consequences of the evolutionary patterns among species to be included in conservation planning. Increased accessibility of phylogenetic tools will allow the application of PD in restoration monitoring.

Postfire Drill-Seeding of Great Basin Plants: Effects of Contrasting Drills on Seeded and Nonseeded Species

Objectives of postfire seeding in the Great Basin include reestablishment of perennial cover, suppression of exotic annual weeds, and restoration of diverse plant communities. Nonconventional seeding techniques may be required when seeding mixes of grasses, forbs, and shrubs containing seeds of different sizes. We conducted an operational-scale experiment to test the effectiveness of two rangeland drills (conventional and minimum-till) for seeding native plant mixes following wildfire in Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) communities. Both drills were configured to place small and large seeds in alternate rows. We hypothesized that the minimum-till drill’s advanced features would improve establishment compared with the conventional drill. We also hypothesized that the minimum-till drill would cause less damage to residual perennials, whereas the conventional drill would have a greater impact on annual weeds. The experiment was replicated at three burned sites and monitored for 2 yr at each site. Seeded plant establishment was lowest at a low-precipitation site that became dominated by exotic annuals. Another site had high perennial grass establishment, which effectively suppressed exotic annuals, while a third site attained high diversity of seeded species and life forms but became invaded by exotic annuals in plant interspaces. Small-seeded species generally established better with the minimum-till drill equipped with imprinter wheels than the conventional drill with drag-chains. However, large-seeded species frequently established better with the conventional drill despite its lack of depth bands and press wheels. Soil disturbance associated with the conventional drill had a negative effect on residual perennials and exotic annuals at some sites. Results indicate that different drill features are advantageous in different ways, but that either of the tested drills, if properly used, can be effective for seeding native plant mixes provided site conditions are otherwise favorable for seedling establishment.

Phylogenetic Relatedness Influences Plant Interspecific Interactions Across Stress Levels in Coastal Ecosystems: a Meta-Analysis

Positive and negative interactions can occur simultaneously between plant species. According to the stress gradient hypothesis (SGH), species interactions shift towards more facilitative interactions or reductions in competition with increasing stress, whereas debate continues over whether evolutionary history influences the strength of species interactions. However, few studies have investigated the effects of phylogenetic relatedness (i.e., the sum of branch lengths separating species on a phylogeny) on the outcomes of interspecific interactions across stress levels. Therefore, we conducted a Bayesian meta-analysis on data collected from publications on plant interactions within coastal ecosystems in order to investigate the effects of phylogenetic relatedness on interspecific interactions across different stress levels. These analyses showed the effect sizes of species interactions on survival and growth to increase with stress increment, supporting the SGH in coastal ecosystems. However, phylogenetic relatedness did not lead to these differences of interspecific interactions between low and high stress. We found that species interactions affecting plant survival were not significantly influenced by phylogenetic relatedness; however, when evolutionary relationships of target and neighbor species were more phylogenetically distant, their interactions were more likely to facilitate growth of target species. Furthermore, the effect of the interaction between phylogenetic distance and stress on species interactions was negative. This suggests the observed net effects of phylogenetically distant neighbor species on target species were not due to true facilitation but reductions in competition when moving from low stress to high stress environments. According to these results, phylogenetic relatedness should be considered in choosing species for restoration of coastal ecosystem plant communities. Specifically, increasing the phylogenetic breadth of the assemblage is more likely to include species that have evolved to reduce stress on surrounding species through modification of the environment.

Facilitating the restoration of aquatic plant communities in a Ramsar wetland

Human activities such as land clearing and intensive land use around water bodies, particularly wetlands, have a detrimental impact on water quality and quantity, aquatic plant communities, and associated wetland fauna. Lake Alexandrina and Lake Albert are internationally significant Ramsar wetlands located at the terminus of the Murray River, Australia's longest river system. Agriculture, water regulation, and extraction and droughts have had a detrimental impact on native plant communities in the lakes. We studied the influence of young (<1–3 years) and old (8–11 years) plantings of a native sedge (bulrush), Schoenoplectus tabernaemontani, to facilitate the establishment of aquatic plant communities in comparison with remnant and control sites. We also measured how planting structure (height, stand width, and stem density) changed with age in comparison with remnant sites. Results suggest that as plantings age they get substantially wider and have a greater maximum height, although do not reach similar stand widths by 11 years when compared to remnant areas. However, old plantings do not differ from remnant habitats in relation to aquatic plant species richness, counts of aquatic plants, and community composition. Young plantings have substantially less abundant and diverse plant communities, but are developing on a similar trajectory to old plantings. It is likely that planting sedges along lake shorelines causes a breakwater effect that facilitates the recolonization of wetland plants between the planted area and the water's edge. Management agencies should consider restoring native sedges to increase aquatic biodiversity, and potentially reduce erosion.

Genetic differentiation and regional adaptation among seed origins used for grassland restoration: lessons from a multispecies transplant experiment

Summary One of the key questions in ecosystem restoration is the choice of seed material for restoring plant communities. More and more scientists and practitioners are currently advocating the use of regional seed sources, based on the argument that plants are often adapted to local or regional environmental conditions, and thus, regional seed sources should provide the best restoration success. However, there is still substantial debate about this approach, partly because of a lack of solid empirical data. We conducted a multispecies transplant experiment in which we compared the performance of eight seed origins of seven plant species frequently used in grassland restoration in four common gardens across Germany. We found that, on average, plants of regional origins produced 10% more inflorescences and 7% more biomass than those of foreign origins. There were substantial differences among species in the strength of these effects, but in the majority of the study species fitness decreased with increasing geographical distance of seed origins or with increasing climatic differences between plant origins and experimental sites. In addition to these effects on plant fitness, increasing geographical or climatic distances of origin were often also correlated with increasing differences in plant phenology. Since phenology is important for biotic interactions, especially with pollinators and seed predators, using foreign seed sources may have cascading effects on local ecosystems. Synthesis and applications. Genetic differentiation is widespread in grassland species and often shows the patterns of regional adaptation. Our study thus supports the use of regional seed sources in restoration. Moreover, using non‐regional seed sources in grassland restoration may not only decrease the performance of plants, but it will likely also affect their biotic interactions.

Primary succession on re-created coastal wetland leads to successful restoration of coastal halophyte vegetation

Understanding the causes of patterns in plant distribution is especially important when we want to create new terrain for vegetation development for conservation purposes. In Škocjan Inlet Nature Reserve it was carefully planned for new mudflats and islets to be created along a microaltitudinal gradient, aiming to achieve the spontaneous development of at least three target habitat types (mudflats not covered by seawater at low tide, Mediterranean glasswort swards and Mediterranean saltmarsh scrubs, including the transitional forms between them) through the primary succession pathways. Thus, this study was actually projected as a field experiment, on the one hand, and as a practical conservation measure, to recover a degraded area, on another. Vegetation cover on the newly constructed mudflats changed by 92% over 6 years of succession. In general, un-vegetated mudflats decreased from 71% to 26%. In contrast to this, Mediterranean glasswort swards increased from 6.5% to 28.2%, whereas saltmarsh scrub had the longest positive trend, constantly gaining area from 2008 (0.6%) to 2012 (28.9%). Detailed mapping showed rather deterministic successional pathways, which make restoration plans for halophyte communities more predictable. The study shows that this “ecological experiment” might have concrete implications for the restoration or re-creation of halophyte plant communities along sedimentary seacoasts—in general, all priority habitats in the European Union. The approach of creating artificial terrain within coastal protected areas is especially important in the light of the climate change-driven rise in sea level, often in conjunction with the “coastal squeeze” phenomenon.

Restoration effects influenced by plant species and landscape context in Young-il region, Southeast Korea: Structural and compositional assessment on restored forest

Despite it has been mentioned that the successful restoration in landscape level was achieved in the Young-il soil erosion control project, quantitative evaluation of restored plant communities (Alnus firma as introduced species and Pinus thunbergii as native species) was hardly founded. Light availability, litter and woody debris cover, and forest structure and composition were determined for 500 m2 band-quadrat in three forest types. Abiotic factors of Q. serrata stands, as reference forest, and A. firma stands were similar but not for P. thunbergii stands. There were no significant difference on mean stem density (stems ha-1, H = 3.6, p = 0.162), and the mean basal area of each stand had marginal significance (m2 ha-1, H = 5.7, p = 0.058) among stands as total basal area was higher with the order of A. firma (21.4 m2 ha-1), P. thunbergii (19.8 m2 ha-1) and Q. serrata (16.2 m2 ha-1). Restoration of vegetation structure was more effective in fast-growing and N-fixing A. firma, as introduced species plantation. However, result of MRPP, NMS ordination and ISPAN for herbaceous layer, not for tree and shrub species composition, indicated that restoration of ground vegetation was likely influenced highly from local environment. Propagule availability from landscape context such as connectedness to natural vegetation and management practices in restored isolated stands are available explanations for restoration effects and gaps between restored plantations and secondary oak forest.

Efficient use of seed banks of fallow pastures in floodplain area for the restoration of wetland plant communities

Efficient use of seed banks of fallow pastures in floodplain area for the restoration of wetland plant communities

Liverworts to the rescue: an investigation of their efficacy as mycorrhizal inoculum for vascular plants

Summary Pezoloma ericae (D.J. Read) Baral, a widespread mycorrhizal fungus of plants in the Ericales, is known to form intracellular associations with several families of leafy liverworts (Schistochilaceae, Lepidoziaceae, Cephaloziaceae, Cephaloziellaceae) in vitro. The ecological significance of this link between vascular and non‐vascular plants is unknown. Fungal symbionts were isolated from rhizoids of the leafy liverworts Cephalozia connivens (Dicks.) Lindb. and C. bicuspidata (L.) Dum. (Cephaloziaceae), as well as from the hair roots of two dominant ericoid mycorrhiza‐forming species of European heathlands, Erica tetralix (L.) and Calluna vulgaris (L.). Using pure cultures of P. ericae, we resynthesized liverwort–fungus associations to use colonized liverworts as inoculum which was applied to substrates supporting the growth of heather seedlings and cuttings. Effects were quantified using germination, rooting, plant colonization, plant survival under waterlogging stress and growth in height in experimental systems with and without liverworts and/or fungi. Fungal symbionts growing from liverwort rhizoids readily colonized the hair roots of ericaceous plants to form typical ericoid mycorrhizas. The presence of inoculum‐bearing liverworts led to significant increases in plant growth. Erica tetralix was more responsive to inoculation than C. vulgaris. Ericaceous cuttings rooted and survived more successfully when they were coplanted with previously colonized liverwort stems. We demonstrate, under realistic ecological circumstances, that liverworts can deliver mycorrhizal inoculum and improve the establishment of vascular plants. We propose that by providing sources of mycorrhizal inoculum, symbiotic non‐vascular plants can contribute to the restoration of plant communities dominated by Ericales plants. This research leads to broader knowledge about the function of ericoid mycorrhizas in ecosystems.

Drivers of the composition and diversity of carabid functional traits in UK coniferous plantations

Functional diversity (FD) is increasingly used as a metric to evaluate the impact of forest management strategies on ecosystem functioning. Management interventions that aim to maximise FD require knowledge of multiple environmental drivers of FD, which have not been studied to date in temperate coniferous production forests. We quantified the relative importance of abiotic (forest management) and biotic (ground vegetation community) drivers of carabid FD and trait distribution in 44 coniferous plantation forest stands across the UK. Carabid FD declined with canopy cover and carabid body length correlated negatively with the percentage of open semi-natural area surrounding a plot. We conclude that forest management could enhance carabid FD through initiatives that emulate natural disturbance regimes through gap creation. We found that neither functional nor taxonomic metrics of vegetation diversity correlated with carabid FD, suggesting that restoration of plant communities, a major goal of forest restoration efforts, will not necessarily enhance carabid FD in coniferous plantations.

Characteristics of soil freeze–thaw cycles and their effects on water enrichment in the rhizosphere

The freeze–thaw process can lead to water enrichment in freezing layers of soil, and may have beneficial effects on vegetation restoration efforts in sandy land habitats. This study determined the characteristics of soil water migration in dunes and interdune areas during freeze–thaw process, and discussed its potential application to the restoration and recovery of sandy land plant communities. In this research, the mobile sand dunes and interdune lowlands were chosen as the study objects in Horqin Sandy Land, north China. We investigated the soil temperature and moisture content on depths of 20cm, 50cm, 100cm and 150cm during soil freeze–thaw period (from September 20, 2010 to April 9, 2011), and determined the migrated water during freezing–thawing processes on soil of sand dunes and interdune lowlands, and discussed its potential application on plant recovery processes. Results showed that the soil freeze–thaw process occurred mostly at a depth of 0–100cm, and the longest period of soil that remained frozen is 104days at a depth of 20cm and the shortest period is 39days at a depth of 100cm in sand dunes. The number of freeze–thaw cycles was not different between sand dune and interdune area over winter. Most freeze–thaw cycles occurred in the thawing process, and mostly at a depth of 0–50cm. The freeze–thaw cycles of interdune areas only occurred in the thawing process, but the freeze–thaw cycles of sand dunes occurred both in the process of freezing and thawing. More water of the interdune areas apparently migrated than did in the sand dunes. The range of soil water storage content at depths of 0 to 100cm increased to 92.4mm on interdune, and 10.8mm on sand dunes during the freeze–thaw process. A negative correlation was found between soil temperature and moisture at depths of 100cm and 150cm, and while a positive correlation existed at depths of 20cm and 50cm. The freeze–thaw process can lead to water enrichment in freezing layer of soil on sand dunes and interdune. Soil texture affected the quantity of soil water migrating during the freeze/thaw process, and more water migrated in interdune areas than in sand dune habitat.

Restoring native understory to a woodland invaded by Euonymus fortunei: multiple factors affect success

Invasive species are capable of causing change in native plant communities, but invasion is often associated with other anthropogenic impacts on natural areas, such as habitat fragmentation and associated dispersal limitation for native species. Consequently, invasive species removal alone may not always be sufficient to meet restoration objectives. We tested if invasion and dispersal limitation interact to limit plant community restoration within a forest fragment invaded by Euonymus fortunei. Removal of Euonymus alone did not lead to the recolonization of native plant species. However, planting seedlings increased total native cover in invaded, Euonymus removal, and uninvaded control treatments. The consistent establishment of native plant seedlings across all treatments indicates that Euonymus invasion may have limited ability to displace established plants. In contrast, plant species that we added as seed were unable to establish in invaded plots, indicating that Euonymus invasion limits recruitment of native plant species from seed. Over the course of our experiment, a number of setbacks and surprises occurred, including high levels of herbivory, a windstorm, and extreme drought, all of which likely limited restoration success. Overall, our results indicate that Euonymus may contribute to native species declines, but other factors are important. Thus, invasive species removal alone may not be sufficient to reestablish a diverse native plant community. Instead, impacts on natural areas may need to be mitigated along with invasive species removal for restoration to be successful.