Replicating Life Cycle of Early‐Maturing Species in the Timing of Restoration Seeding Improves Establishment and Community Diversity

Tallgrass prairie is among the most endangered ecosystems in North America. High‐diversity restorations protect remnant habitat and expand native communities. Excluding land acquisition, the most expensive step in restoration is procuring seed. Given this cost, managers want to maximize seedling establishment. Native species that flower and ripen early in the growing season are included in a diverse seeding mix but as a group they have not successfully established. For early‐maturing species, the practice of storing seeds in a cold room from harvest until sowing in the dormant season effectively eliminates exposure to the summer conditions seeds would naturally have in the wild. In this study, we compared the effect of summer sowing timing and winter sowing timing on establishment in field conditions. In August 2004 and December 2004, we broadcast a seed mix of seven early‐maturing species: Antennaria plantaginifolia (L.) Richardson. (Pussy toes), Arabis lyrata L. (Sand cress), Carex swanii (Fernald) Mack. (Downy green sedge), Hymenopappus scabiosaeus L'Hér. (Old plainsman), Lupinus perennis L. ssp. perennis var. occidentalis S. Watson. (Wild lupine), Phlox bifida Beck. (Sand phlox) and Hesperostipa spartea (Trin.) Barkworth. (Porcupine grass). We collected data on establishment and reproductive success at 12 time points from June 2005 until October 2008. Species established one growing season sooner when planted at the summer sowing time, and diversity in the summer sowing plots was higher after 4 years. Quicker establishment may have benefits such as providing early competition from weeds that may outweigh additional effort required to ensure timely planting.     

Non‐continuous reproductive phenology of animal‐dispersed species in young forest restoration plantings

Tree species that produce resources for fauna are recommended for forest restoration plantings to attract pollinators and seed dispersers; however, information regarding the flowering and fruiting of these species during early growth stages is scarce. We evaluated the reproductive phenology of animal‐dispersed tree species widely used in Atlantic Forest restoration. We marked 16 animal‐dispersed tree species in 3‐ to 8‐year‐old forest restoration plantings in Itu‐São Paulo, southeast Brazil. We noted the age of the first reproductive event, flowering and fruiting seasonality, percentage of trees that reached reproductive stages, and intensity of bud, flower, and fruit production for each species. Flowering and fruiting are seasonal for most species; only two, Cecropia pachystachya and Ficus guaranitica, exhibited continuous flowering and fruiting throughout the year; we also identified Schinus terebinthifolia and Dendropanax cuneatus fruiting in the dry season during resource scarcity. Therefore, we recommend all as framework species, that is, species that are animal‐dispersed with early flowering and fruiting potential, for forest restoration. Further, we recommend identifying and planting similar animal‐dispersed tree species that produce fruits constantly or in the dry season to maximize fauna resource availability throughout the year in tropical forest restoration plantings. Abstract in Portuguese is available with online material     

Divergent selection on flowering phenology but not on floral morphology between two closely related orchids

Closely related species often differ in traits that influence reproductive success, suggesting that divergent selection on such traits contribute to the maintenance of species boundaries. Gymnadenia conopsea ss. and Gymnadenia densiflora are two closely related, perennial orchid species that differ in (a) floral traits important for pollination, including flowering phenology, floral display, and spur length, and (b) dominant pollinators. If plant–pollinator interactions contribute to the maintenance of trait differences between these two taxa, we expect current divergent selection on flowering phenology and floral morphology between the two species. We quantified phenotypic selection via female fitness in one year on flowering start, three floral display traits (plant height, number of flowers, and corolla size) and spur length, in six populations of G. conopsea s.s. and in four populations of G. densiflora. There was indication of divergent selection on flowering start in the expected direction, with selection for earlier flowering in two populations of the early‐flowering G. conopsea s.s. and for later flowering in one population of the late‐flowering G. densiflora. No divergent selection on floral morphology was detected, and there was no significant stabilizing selection on any trait in the two species. The results suggest ongoing adaptive differentiation of flowering phenology, strengthening this premating reproductive barrier between the two species. Synthesis: This study is among the first to test whether divergent selection on floral traits contribute to the maintenance of species differences between closely related plants. Phenological isolation confers a substantial potential for reproductive isolation, and divergent selection on flowering time can thus greatly influence reproductive isolation and adaptive differentiation.     

Traits,neighbors, and species performance in prairie restoration

Questions: Are traits related to the performance of plant species in restoration? Are the relationships between traits and performance consistent across the functional groups of annual forbs, perennial forbs and grasses? Do the relationships between traits and performance depend on neighboring functional groups? Location: A former agricultural field, being restored to native upland prairie, in the Willamette Valley of western Oregon, USA. Methods: Twenty‐eight native species, representing three functional groups, were sown in seven different combinations. Eleven functional traits were measured from plants in the laboratory and in the field. Correlations between individual traits and performance variables were measured and regression techniques used to determine which sets of traits were most strongly related to performance. Results: Sets of traits explained up to 56% of variation in cover, and up to 48% of variation in establishment frequency. The relationships between traits and performance were influenced by functional group identity; the functional group identity of neighboring species also influenced species' cover and the relationships between traits and cover. Species' establishment rate in monoculture was the trait most strongly correlated to both establishment and cover in mixtures. In multi‐trait models, annual forb functional group identity was strongly related to establishment in mixtures, and height, leaf weight ratio at 7 d and seed mass were strongly related to cover. Conclusions: Multiple‐trait models should be a useful way of predicting the performance of species prior to sowing in restoration. The functional group identity of each species and the other species being sown may need to be taken into account when making predictions.     

The influence of seed addition and cutting regime on the success of grassland restoration on former arable land

Questions: Can seed addition enhance the success of establishing species‐rich grassland on former arable land? Are sowing date and cutting regime important in determining success? Location: Aberdeen and Elgin, northeast Scotland, United Kingdom. Methods: A field experiment was conducted at two sites to assess the effect of seed addition, sowing date and cutting regime on the vegetation developing on former arable land, the aim being to compare the success of different treatments at producing a species‐rich grassland. Results: Sowing a seed mix resulted in the establishment of vegetation very distinct from the species‐poor vegetation dominated by perennial grasses which otherwise developed, though establishment success of the sown grassland species was highly variable between sites. Where establishment of the sown species was poor, sowing date had no significant effect on species composition, whereas the cutting regime was very important. Cutting the vegetation significantly increased both the number and abundance of sown species compared with the uncut control. Conversely, where establishment had been good, the cutting regime in the first year had little effect on species composition. Cutting the vegetation at least twice a year appeared to be the most effective management over the length of the experiment. Conclusions: Sowing a seed mixture significantly reduced the abundance and number of naturally colonising species, effectively controlling problem weed species such as Senecio jacobaea and Cirsium vulgare, highlighting the agronomic value of sowing seed mixtures on fallow farmland. The sowing of a seed mix on former arable land has demonstrated that it is feasible to create vegetation similar in character to that of species‐rich grasslands.     

Sowing density effects and patterns of colonization in a prairie restoration

A cost‐effective approach in plant restorations could be to increase sowing density for species known to be challenging to establish, while reducing sowing density for species that easily colonize on their own. Sowing need not occur evenly across the site for rapidly dispersing species. We explored these issues using a prairie restoration experiment on a high‐school campus with three treatments: plots sown only to grasses (G plots), to grasses and forbs (GF1), and to grasses and forbs with forbs sown at twice the density (GF2). In year 2, GF1 and GF2 plots had higher diversity than G plots, as expected, but GF2 treatments did not have twice the sown forb cover. However, high forb sowing density increased forb richness, probably by reducing stochastic factors in establishment. Cover of nonsown species was highest in G plots and lowest in GF2 plots, suggesting suppressive effects of native forbs on weedy species. Colonization of G plots by two sown forbs (Coreopsis tinctoria and Rudbeckia hirta) was apparent after 2.5 years, providing evidence that these species are self‐sustaining. Colonization was greater in edges than in the central areas of G plots. Through construction of establishment kernels, we infer that the mean establishment distance was shorter for R. hirta (6.7 m) compared to C. tinctoria (21.1 m). Our results lead us to advocate for restoration practices that consider not only seed sowing but also subsequent dispersal of sown species. Furthermore, we conclude that restoration research is particularly amenable for outdoor education and university‐high school collaborations.     

Establishment of Native Semidesert Grasses into Existing Stands of Eragrostis lehmanniana in Southeastern Arizona

The semidesert grassland in southern Arizona has changed from a native grassland to a scattered Prosopis juliflora var. velutina (mesquite) woodland with an understory of African Eragrostis lehmanniana (Lehmann lovegrass) on many sites. To determine native grass restoration potential, seven species were direct seeded into E. lehmanniana stands that were left alive, burned, sprayed with an herbicide and then either left standing, or mowed. Initial native grass establishment was limited in the live standing treatment but was successful for all other treatments when either June or August sowing was followed by consistent summer precipitation and soil water availability. Four species, Bothriochloa barbinodis (cane beardgrass), Bouteloua curtipendula (sideoats grama), Digitaria californica (Arizona cottontop), and Leptochloa dubia (green spangletop) initially established most successfully, while only Muhlenbergia porteri (bush muhly) had consistently limited or no establishment. E. lehmanniana establishment from the seed bank was increased by canopy removal associated with burning. Densities of native grasses one year after successful initial establishment were much lower than that of E. lehmanniana. A possible revegetation strategy would be to spray emergent E. lehmanniana seedlings and surviving plants with an herbicide during the summer rainy season after spring burning. Native grasses could then be established by sowing in early August of that year or June and August of subsequent years until consistent precipitation produces a native grass stand.     

An intraspecific application of the leaf‐height‐seed ecology strategy scheme to forest herbs along a latitudinal gradient

We applied the leaf‐height‐seed (LHS) ecology strategy scheme (a combination of three ecologically important traits: specific leaf area (SLA), seed mass and plant height) intraspecifically to two widespread European forest herbs along a latitudinal gradient. The aims of this study were to quantify LHS trait variation, disentangle the environmental factors affecting these traits and compare the within‐species LHS trait relationships with latitude to previously established cross‐species comparisons. We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900–2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two‐fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three‐factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring‐flowering Anemone was affected more by temperature, whereas early‐summer flowering Milium was affected more by local and other latitude‐related factors. Finally, previously reported cross‐species correlations between LHS traits and latitude were generally unsupported by our within‐species approach.     

Mass effects,clonality, and phenology but not seed traits predict species success in colonizing restored grasslands

Preserved grasslands commonly host species‐rich plant communities but a large part of the grasslands were plowed up in the past. Their restoration often requires a long time and initial restoration measures might trigger ecosystem recovery, which is then followed by spontaneous colonization. We evaluate the establishment success of target grassland species, which were not sown but established spontaneously in the restored grasslands of Bílé Karpaty Mts., SE Czech Republic. According to their key functional traits and incidence in the landscape (mass effect; acquired from the results of a grid mapping project in the region), we examined the frequency of species and their mean cover in 82 restored grasslands. The best predictor of species frequency in the grasslands was their mass effect, followed by a high capacity for clonal growth and late phenology. Seed dispersal traits (seed mass, terminal velocity, epizoochory ranking index) and plant height had no significant effect. Specific leaf area was positively correlated with mass effect. Species having a high cover in the restored grasslands had a high capacity for clonal growth. In the preparation of seed mixtures, we should therefore consider that nonclonal species relying on regeneration from seeds will be generally less able to reproduce and should be promoted by artificial sowing. At the same time, species common in the landscape, which spread well clonally, and those with a late phenology, might be expected to colonize restored meadows on their own, so that sowing them is not necessary.     

Functionally Similar Species Confer Greater Resistance to Invasion: Implications for Grassland Restoration

Plant community functional composition can be manipulated in restored ecosystems to reduce the establishment potential of invading species. This study was designed to compare invasion resistance among communities with species functionally similar or dissimilar to yellow starthistle (Centaurea solstitialis), a late‐season annual. A field experiment was conducted in the Central Valley of California with six experimental plant communities that included (1) six early‐season native annual forbs (AF); (2) five late‐season native perennials and one summer annual forb (NP); (3) a combination of three early‐season native annual forbs and three late‐season native perennials (FP); (4) six early‐season non‐native annual grasses (AG); (5) monoculture of the late‐season native perennial grass Elymus glaucus (EG); and (6) monoculture of the late‐season native perennial Grindelia camporum (GC). Following establishment, C. solstitialis seed was added to half of the plots, and a monoculture of C. solstitialis (CS) was established as a control. Over a 5‐year period, the AF and AG communities were ineffective at preventing C. solstitialis invasion. Centaurea solstitialis cover remained less than 10% in the FP and NP communities, except in year 1. By the fourth year, E. glaucus cover was greater than 50% in NP and FP communities and had spread to all other communities (e.g., 27% cover in CS in year 5). Communities containing E. glaucus, which is functionally similar to C. solstitialis, better resisted invasion than communities lacking a functional analog. In contrast, G. camporum, which is also functionally similar to C. solstitialis, failed to survive. Consequently, species selection for restored communities must consider not only functional similarity to the invader but also establishment success, competitiveness, and survivorship.     

Experimental Restoration of Disturbed Cliff-Edge Forests in Bruce Peninsula National Park, Ontario, Canada

Abstract Restoration of degraded natural vegetation in parks is often complicated by the need to maintain public access. We tested whether the natural canopy species, Thuja occidentalis, can be restored to degraded cliff edges in Bruce Peninsula National Park, Ontario, Canada without reductions in visitor numbers. Eighty 10‐year‐old and 80 4‐year‐old container‐grown saplings and 1,400 seeds were planted and monitored for 4 years. Eight treatments were applied that tested for effects of planting site (distance from cliff edge and pathways) and supportive measures (soil, water, cages, or signs) on survival, growth, and damage. No trees became successfully established from seed. Younger trees showed faster initial establishment and growth, but 4‐year survival was the same for both age groups (39%). Supplemental soil improved the health of planted trees, and both soil and water slightly improved their survival. Cages did not affect survival and growth but decreased damage to 4‐year‐old trees and increased it for 10‐year‐olds. Signs had no effect on any measured variable. Trees planted away from the cliff edge and from pathways had the greatest establishment success, 4‐year survival, and general health. Relative visitor density, as estimated from spot counts of visitors, had the largest effect on restoration success; the results suggest a threshold of visitor density above which restoration may be impossible. Planting location, especially with respect to shade, was also important. The planting of 4‐year‐old trees without supportive measures is suggested as the most cost‐effective restoration technique at this site. The results indicate that restoration of open woodland habitats is possible without total visitor exclusion but that some restrictions on visitor numbers or activities are necessary.     

Widespread resistance of Mediterranean island ecosystems to the establishment of three alien species

Although some invasive plants are cosmopolitan, not all ecosystems are invaded to the same degree. Yet there is little experimental work on how ecosystem resistance to invasion at the establishment phase differs among ecosystems. We conducted two field sowing experiments in two consecutive years to examine establishment of the deciduous tree Ailanthus altissima, the succulent subshrub Carpobrotus spp. and the annual geophyte Oxalis pes‐caprae in coastal dunes, shrublands and oldfields in more than 200 sites across six Mediterranean Basin islands differing in climatic conditions and local species richness. Establishment success (i.e. percentage of plots with at least one seedling) and rates (i.e. seedling to sown seed ratio) were low, especially for Ailanthus even when accounting for differences in seed viability. Oxalis was capable of producing a new cohort of seedlings the year following planting. By contrast, all Ailanthus seedlings and half the Carpobrotus seedlings died following the first summer. Differences in establishment success and rates among ecosystems were species‐, island‐ and year‐dependent. Differences in precipitation and mean temperature were associated with differences in establishment rates across sites. Establishment rates tended to be positively correlated with cumulative precipitation and negatively with mean T^a. Unexpectedly, native species richness was not a good predictor of seedling establishment, except for higher Oxalis establishment success in species rich habitats. By conducting field sowing tests at multiple sites across a region we found that except for Oxalis, Mediterranean island ecosystems are quite resistant to invader establishment. These results suggest that differences in the degree of invasion between ecosystems and islands might be more dependent upon the influence of invasion event factors (e.g. propagule pressure) or factors acting at a later life‐history stages rather than differences in the resistance imposed by ecosystems to invader recruitment. Moreover, our results support the notion that in Mediterranean ecosystems invasions are highly idiosyncratic events and strongly dependent on water availability conditions.     

Fishing pressure and species traits affect stream fish invasions both directly and indirectly

Aim

We sought to identify direct and indirect effects of factors contributing to establishment and spread of 272 stream fish species.

Location

Two hundred and ninety‐seven watersheds in the eastern United States.

Methods

We modelled two variables: (1) whether a species had become established outside its native range (establishment) and (2) the number of watersheds in which species established outside their native range (spread). We estimated these variables by comparing historical distributions to a rich data set of contemporary sampling. We calculated metrics of human use (indexing propagule pressure), and gathered species trait data from an open‐access database. We then used piecewise path analysis to estimate direct and indirect effects of human use, native range size and species traits on the two metrics of species introductions.

Results

We identified a hierarchical causal structure in which native range size and fishing pressure were important direct determinants of introductions. Species traits had some direct effects, but played a more indirect role. Native range size was significantly affected by thermal tolerance and diet breadth. Likewise, fishing pressure was significantly affected by life history strategy: larger‐bodied, longer‐living and more fecund species were positively associated with fishing pressure.

Main conclusions

Functional traits can confer an advantage to some species during the establishment phase, but human use is important for subsequent dispersal throughout the non‐native range. However, human use is non‐random, and is largely a function of species traits. Considering both direct and indirect effects of traits across stages of the invasion process can help to elucidate the full role of traits in species invasions.

     

Pollinator‐mediated assemblage processes in California wildflowers

Community assembly is the result of multiple ecological and evolutionary forces that influence species coexistence. For flowering plants, pollinators are often essential for plant reproduction and establishment, and pollinator‐mediated interactions may influence plant community composition. Here, we use null models and community phylogenetic analyses of co‐occurrence patterns to determine the role of pollinator‐mediated processes in structuring plant communities dominated by congeners. We surveyed three species‐rich genera (Limnanthes, Mimulus and Clarkia) with centres of diversity in the Sierra Nevada of California. Each genus contains species that co‐flower and share pollinators, and each has a robust phylogeny. Within each genus, we surveyed 44–48 communities at three spatial scales, measured floral and vegetative traits and tested for segregation or aggregation of: (i) species, (ii) floral traits (which are likely to be influenced by pollinators), and (iii) vegetative traits (which are likely affected by other environmental factors). We detected both aggregation and segregation of floral traits that were uncorrelated with vegetative trait patterns; we infer that pollinators have shaped the community assembly although the mechanisms may be varied (competition, facilitation, or filtering). We also found that mating system differences may play an important role in allowing species co‐occurrence. Together, it appears that pollinators influence community assemblage in these three clades.     

Species properties and recovery from disturbance: Forest herbs buried by volcanic tephra

Question: How do forest herb species differ from each other in their spatial and temporal dynamics during recovery from volcanic disturbance, and how are dynamics related to species traits? Location: Northeast of Mount St. Helens, Washington, USA. Methods: Following deposition of volcanic tephra in 1980, we measured herb density and cover in permanent 1‐m² plots during 1980‐2005 in three old‐growth forests with differing tephra depths. For 26 species, we calculated the frequency of plots with residuals (individuals that survived the eruption) versus re‐establishment on the tephra, timing of establishment, turnover, influence of nearby conspecific plants, importance of three components of cover increase, and relationship of flowering frequency to succession. Results: Tephra depth affected species behavior. Deep tephra produced fewer residuals, a greater increase in shoot size, and more shoot turnover; favored species that established late; and allowed establishment of early seral herbs. Nearby presence of conspecifics increased permanence of first establishment and rate of plot occupancy. Most species spread significantly in deep tephra but not in shallow tephra. Among species, frequency of flowering increased with fewer residuals, later establishment, and higher turnover. Species behavior seldom differed among growth forms based on leaf longevity and vegetative spread. Conclusion: Population dynamics at the small‐plot scale differed from those of the entire population. The timing and permanency of establishment and mechanism of expansion differed among species and with tephra depth. There was some consistency among species with similar habitat breadth and degree of flowering, but little consistency associated with the usual growth form classification.     

Effects of Connectivity and Regional Dynamics on Restoration of Small Mammal Communities in Midwestern Grasslands

Grasslands are among the most imperiled North American ecosystems. State Acres for Wildlife Enhancement (SAFE) is a national conservation program that converts agricultural fields into grasslands mainly to improve habitat for high priority wildlife species. To provide a broader assessment of the contribution of the SAFE program to biodiversity in the Midwest region of North America, we evaluated local and landscape constraints to restoration of small mammal communities. We livetrapped small mammals during three summers (2009–2011) on plots that were recently seeded, seeded 1–4 years prior to sampling, or established references (>10 years old). Restoration trajectories for small mammal communities included a shift over time from dominance by the habitat generalist Peromyscus maniculatus (deer mouse) to communities dominated by grassland Microtus species (prairie voles and meadow voles). Vole abundance during the first year following restoration depended on spatial connectivity provided by linear habitats (roadside ditches and grass waterways) within 300 m of the restored grassland. Patch size and seeding type (cool‐season versus warm‐season grasses) were not predictors of early restoration success. In 2011, voles experienced a severe regional decline consistent with multi‐year population cycles. During the crash, most remaining voles occurred on restored SAFE grasslands, but not on established grasslands. This surprising outcome suggests young restoration plots could function as refuges for voles during population declines in agricultural landscapes.     

Seasonality,species richness and poor dispersion mediate intraspecific trait variability in stonefly community responses along an elevational gradient

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Reduced abundance and earlier collection of bumble bee workers under intensive cultivation of a mass‐flowering prairie crop

One of the most commonly seeded crops in Canada is canola, a cultivar of oilseed rape (Brassica napus). As a mass‐flowering crop grown intensively throughout the Canadian Prairies, canola has the potential to influence pollinator success across tens of thousands of square kilometers of cropland. Bumble bees (Bombus sp.) are efficient pollinators of many types of native and crop plants. We measured the influence of this mass‐flowering crop on the abundance and phenology of bumble bees, and on another species of social bee (a sweat bee; Halictus rubicundus), by continuously deploying traps at different levels of canola cultivation intensity, spanning the start and end of canola bloom. Queen bumble bees were more abundant in areas with more canola cover, indicating that this crop is attractive to queens. However, bumble bee workers were significantly fewer in these locations later in the season, suggesting reduced colony success. The median collection dates of workers of three bumble bee species were earlier near canola fields, suggesting a dynamic response of colonies to the increased floral resources. Different species experienced this shift to different extents. The sweat bee was not affected by canola cultivation intensity. Our findings suggest that mass‐flowering crops such as canola are attractive to bumble bee queens and therefore may lead to higher rates of colony establishment, but also that colonies established near this crop may be less successful. We propose that the effect on bumble bees can be mitigated by spacing the crop more evenly with respect to alternate floral resources.     

Restoration of species‐rich flood‐plain meadows from abandoned arable fields in NE France

Abstract. Attempts to restore species‐rich flood‐plain meadows from abandoned arable fields in the valley of the river Meuse, NE France, were studied. The study area was sown with a commercial seed mixture, composed of Phleumpratense, Festuca pratensis, Lolium perenne and Trifolium repens. The above‐ground vegetation in the study area 1, 2 and 3 yr after restoration was compared to (1) the vegetation present during the previous 5‐yr fallow stage and (2) target flood‐plain meadows. Before restoration, the above‐ground fallow vegetation was dominated by ruderal and annual species, while only very few meadow species were present. Sowing led to tall, dense vegetation, mainly dominated by the sown species. Ruderal and annual species had decreased 3 yr after restoration, but target species were still poorly represented. Species richness was significantly lower in the sown site than in the semi‐natural target meadows and the vegetation had a different composition. Analysis of the soil seed bank of the restored meadow showed that only a few meadow species were present and that it was dominated by a few ruderal species. Three years after sowing, the vegetation of our experimental site is moving slowly towards the target communities but impoverished seed sources seem to limit the success of this restoration operation and will lead to under‐saturated communities.     

Recovery of the Bird Community after a Mine Spill and Landscape Restoration of a Mediterranean River

In Mediterranean areas, river systems are key for maintaining regional biodiversity by providing a high diversity of habitats. We studied bird community recovery for 9 years (2001–2009) during landscape restoration and Guadiamar Green Corridor establishment in the area affected by the Aznalcóllar mine spill (SW Spain, 1998). One year following plant restoration (3 years after the spill), values for α‐ and β‐bird species diversity were high, sooner than reported for similar restoration processes elsewhere. Species richness, ecological diversity, and abundance increased only slightly in the following 8 years. Overlap between communities in sequential years, measured by similarity indexes, increased throughout the study period to about 70% during final survey years, and most breeding bird species present before the accident again inhabit the area. Only 5 years after the mine accident, bird communities in the restored site were similar in species richness, abundance, and diversity to an unaffected reference site; redundancy analysis demonstrated that bird communities were also similar between the reference river and the Guadiamar. Despite the severity of the mine accident, our results suggest a swift recovery of the bird community. We attribute this success to the rapid restoration of habitat availability and the resilience of the birds. This long‐term study contributes to our limited knowledge of bird species response to habitat restoration following toxic spills in Mediterranean habitats.