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Tree plantations are an important cause of plant invasions worldwide, being a serious concern for biodiversity conservation. Pinus and Eucalyptus are the two most important genera for the forestry industry worldwide, with Eucalyptus globulus and Pinus radiata among the most widespread and invasive. In this study we analyse the establishment of wildlings of these two species in native eucalypt forests (karri and jarrah forests) of SW Australia, a global biodiversity hotspot. We selected boundaries between plantations and adjoining native forests (26 for E. globulus and 25 for P. radiata ) and established in each a plot 100 m long (aligned to outer edge of forest) × 100 m or 50 m deep into the native forest (for boundaries with P. radiata and E. globulus plantations, respectively), that was thoroughly searched for wildlings. Eucalyptus globulus wildlings were only found in 3 of the 26 boundaries studied, 6 individuals in total, all within first 10 m from the forest edge. Pinus radiata wildlings were found in all boundaries and at all distances inspected. Wildling density was greater in jarrah forest compared to karri forest (mean 70.7 and 24.7 wildlings ha −1 ; respectively); it was negatively correlated with understorey cover (r = −0.501, F = 7.72, p = 0.011) and the density of older wildlings (20 + years) was positively correlated with time since plantation establishment (r = 0.512; F = 8.16; P = 0.009). Invasion of native eucalypt forests by alien E. globulus does not seem currently of concern in SW Australia. The scheduled short rotations (8–10 years), which means that trees are mostly harvested before reaching their full reproductive potential, lower dispersal ability than P. radiata and the customary establishment of cleared margins around plantations (10 m wide on average) all contribute to reduce the propagule pressure in native forests and with it the invasion potential. Nevertheless, attention should be paid to abandoned plantations left unharvested for longer, which may increase the invasion risks. In contrast, P. radiata plantations do constitute a threat to native vegetation for the invasion capacity of this species, as indicated by the presence of wildlings in all native forests studied, together with the relatively high density of old trees with high reproductive capacity in the forests interior. Awareness about wilding pine spread is urgently needed in SW Australia, in order to minimise the risks. [ABSTRACT FROM AUTHOR]

Plantations of alien tree species may pose environmental risks associated to their spontaneous spread in areas of introduction. Eucalyptus globulus Labill. is one of the most used species in forestry and has been reported as invasive in many areas around the world. Fire has been suggested to enhance E. globulus recruitment but no study to date has compared burnt vs. unburnt sites for seedling emergence and survival, and little is known about the mechanisms that could favour recruitment after fire. A better understanding of the effect of fire on the invasive potential of E. globulus is essential for improved management of this species in the areas of introduction. In this study, we analyse the effect of fire on the emergence and establishment of E. globulus seedlings in the field, in the most common habitats adjacent to plantations in NW Spain, and explore the underlying mechanisms that could explain the patterns observed by means of greenhouse experiments. Fire enhanced seedling recruitment in the forested habitats studied, due to a positive effect on both seedling emergence and survival. Seedling emergence was 42.5 and 7.0 times higher in burnt vs. unburnt sites in native forests and pine plantations, respectively. Final seedling establishment was 2% in burnt vs. nil in unburnt native forests, and 2.5 times higher in burnt vs. unburnt pine plantations. In shrublands, however, final seedling establishment was similar in burnt and unburnt sites. The positive effect in forested habitats seems to be mainly related to the destruction of litter, which played an important role as a physical barrier to seedling emergence, and to the increase in light availability, which has a positive effect on seedling survival and can result from litter consumption or the burning/scorching of the canopies. Our results demonstrate that fire can increase the invasion risk posed by E. globulus to the native vegetation next to plantations, especially in native oak forests, which had been shown to be rather resistant to E. globulus seedling establishment in the absence of fire. This increased seedling recruitment in burnt areas together with the high fire-proneness of eucalypts could lead to positive feedbacks that may favour eucalypt expansion, further increasing the vulnerability of the native vegetation to colonization by this alien tree. [ABSTRACT FROM AUTHOR]

Effective fire prevention requires a better understanding of the patterns and causes of fire ignition. In this study, we focus on the interacting factors known to influence fire ignition risk, such as the type of vegetation, topographical features and the wildland-urban interface (WUI; i.e. where urban development meet or intermingle with wildland). We also analyze the human activities and motivations related to fires and whether they differ depending on the type of vegetation and the location within/outside WUI. There were significant interactions between topography, type of vegetation and location within/outside WUI. The risk of ignition was in general higher at lower elevations, and this tendency was more marked in forested land covers (all plantations and open woodlands), with the noticeable exception of native forests. North-facing sites had lower fire ignition risk outside the WUI, especially in native forests, while southern aspects showed higher fire ignition risk, especially in open shrublands. However, this effect of the aspect was only significant outside WUI areas. In relation to causes, there were also interactions between human activities/motivations related to fires, the type of vegetation and the location within/outside WUI. All forestry plantations appeared clustered in relation to fire causes, especially in the WUI, with high incidence of deliberately caused fires related to violent or mentally ill people and rekindle fires. In contrast, native forests, despite structural similarities with forestry plantations, showed more similarity with agricultural areas and open woodlands in relation to fire causes. In shrublands, there was a relatively high incidence of fires related to ranching, especially outside the WUI. This pattern of interactions depicts a complex scenario in relation to fire ignition risk and prompts to the importance of taking this complexity into account in order to adjust fire management measures for improved effectiveness. [ABSTRACT FROM AUTHOR]

Wildland-urban interfaces (WUIs) are areas where urban settlements and wildland vegetation intermingle, making the interaction between human activities and wildlife especially intense. Their relevance is increasing worldwide as they are expanding and are associated with fire risk. The WUI may affect the fire risk associated with the type of vegetation (land cover/land use; LULC), a well-known risk factor, due to differences in the type and intensity of human activities in different LULCs within and outside WUIs. No previous studies analyse this interaction between the effects of the WUI and the LULC, despite its importance for understanding the patterns of fire risk, an essential prerequisite to undertake management decisions that can influence fire regimes. The aim of this study is to assess the effect of the WUI on fire ignition risk and the area burned, and the interaction between its effect and that of the LULC. We used a database of 26,838 wildfires recorded in 2006–2011 in NW Spain and compared fire patterns in relation to WUI and LULC with a random model, using a Montecarlo approach. There was a clear effect of the WUI on the risk of both fire ignition and spread (higher ignition risk but lower risk of spread in WUIs). The risk of fire was also affected by LULC and, interestingly, the pattern among LULCs differed between WUI and non-WUI areas. This interaction WUI × LULC was particularly important for forestry plantations, which showed the highest increase in ignition risk in WUI compared to non-WUI areas. Native forests and agricultural areas had the lowest ignition risk. Agricultural areas showed the smallest difference in fire size between WUI and non-WUI areas, while shrublands showed much larger fires outside WUIs. Deliberate fires were larger in general than those with other causes, especially outside the WUI. The differences found between LULCs in fire risk, both in WUI and non-WUI areas, have interesting implications for fire management. Promotion of land covers with low fire risk should be considered as a low cost alternative to the usual fire prevention measures based on fuel load reduction, which require the continuous clearing of vegetation. In this regard, the low fire risk in native forests should be taken into account. Native forests naturally colonize many areas in the study region and require low or no management, in contrast with agricultural areas, also with low fire risk but requiring continuous management in order to avoid colonization by natural vegetation. [ABSTRACT FROM AUTHOR]

The degree of ecological integration of an exotic species depends on the emergence of new interactions with the host community, either antagonistic or mutualistic, such as pollination. This will determine the impact of the new species on the host community (positive or negative, direct or indirect) as well as the capacity of the new species to sustain biodiversity. Eucalypts are the most widely planted trees in the world and depend on pollination by animals for seed production. Blue gum ( Eucalyptus globulus ), one of the most commonly used and a dominant tree in NW of Spain, where this study has been conducted, is pollinated mainly by birds in its native range. In Europe pollination is mainly insect mediated, there are no specialized nectar-feeding birds and ornithophily (plant adaptation for bird pollination) is extremely rare (only recognized for one species, a Tertiary relict). Nevertheless, opportunistic nectar-feeding has been occasionally observed for some European songbirds. In this study, we determine the prevalence and strength of the interaction between eucalypts and birds by analyzing the occurrence and abundance of pollen in birds captured in mist nets in mixed landscapes with eucalypt plantations. Eucalypts represented the most important flower resource for the flower-visiting bird community. Eucalypt pollen was present in 171 individuals belonging to 19 bird species (out of the 485 birds captured in 33 species) and represented 98.2% of all pollen recorded. The large pollen loads found are indicative of frequent eucalypt flower use by the bird community. This study provides a good example of the ecological integration of a widely planted forestry species. The frequency of eucalypt pollen in birds points to the widespread use of this novel resource by birds and to the high ecological relevance of this interaction. The establishment of this novel interaction may favor seed production and, with it, population regeneration and spread of this exotic tree. [ABSTRACT FROM AUTHOR]

Highlights: [•] I studied bird communities in shrublands, oak forests, eucalypt and pine plantations. [•] Bird diversity and abundance was lowest in eucalypt plantations. [•] Native forests reached the highest bird abundance and diversity. [•] Pine plantations harbored a diverse and abundant avifauna similar to oak forests. [•] Pine plantations but not eucalypt plantations may enhance connectivity for forests. [Copyright &y& Elsevier]

Highlights: [•] Eucalyptus globulus spread from plantations into surrounding habitats was studied. [•] Native forests had lower invasibility than shrublands and pine plantations. [•] Strongly leptokurtic seed dispersal curve: 98.6% of seeds recorded within 15m. [•] A safety belt around plantations could reduce eucalypt spread. [•] Safety belts covered by native forest vegetation would be more effective. [ABSTRACT FROM AUTHOR]

Abstract: The extension of native forests has been reduced worldwide and their distribution is increasingly fragmented. In contrast, tree plantations have expanded, and currently constitute an important element of the matrix of semi-natural habitats surrounding native forest fragments. The objective of this study is to evaluate the suitability of tree plantations to harbor epiphytic lichen flora typical of native forests, thus increasing landscape connectivity. We focus especially on Eucalyptus globulus plantations, which have dramatically expanded in the last decades in the study area (NW Spain). We surveyed epiphytic lichen diversity and composition of species and functional groups in the most common forested habitats in the area: eucalypt plantations of three ages (young, intermediate and mature), pine plantations (Pinus pinaster) and native oak (Quercus robur) forests. Lichen diversity and abundance was highest in oak forests and pine plantations and lowest in eucalypt plantations, particularly in young plantations. Oak forests were associated with the most shade tolerant and hygrophytic species, whereas those requiring more light and the most xerophytic were associated with eucalypt plantations. Oaks and pines were associated with species requiring acidic substrates, whereas eucalypts were associated with lichens of basic substrates and eutrophicated sites. In eucalypt plantations, there was a higher predominance of sexual reproduction and crustose lichens in younger eucalypts and of asexual reproduction and foliose lichens in the older eucalypts. Native forests had a very distinctive species composition. They had the highest percentage of unique species and were associated with the species of higher conservation concern (e.g. cyanolichens and members of the Lobarion community). The low abundance and diversity together with the differences in species composition show that eucalypt plantations are a poor habitat for lichens and can hardly provide connectivity among oak forests patches. Pine plantations harbor higher lichen abundance and diversity but differ markedly with oak forests in composition, in both species and functional types. Thus they cannot provide connectivity to the lichen flora typical of native oak forests, especially for the most vulnerable. [Copyright &y& Elsevier]

Abstract: Plantation forestry contributes to the economic growth of many regions, but may also produce ecological impacts (e.g. on biodiversity) that can be reduced with proper management. We assessed the value of eucalypt plantations to favor habitat connectivity at the landscape scale by determining their ability to provide habitat for species associated with the natural vegetation. For this purpose, we compared diversity and composition of understory vegetation in low-management eucalypt plantations in young, intermediate (ready for harvest) and mature stages with pine plantations, native forests and shrublands. We estimated the true species richness with Chao2 estimators and compared among habitats the average species richness (at two different local scales: per plot and per site), Shannon indices and biovolume of herbs, shrubs and trees in the understory using ANOVAs or GLZs, depending on data distributions. Differences among habitats in understory species composition and functional types were compared with PERMANOVA, and were graphically represented using NMDS ordinations. At local scales, diversity tended to be higher in native communities (native forests and shrublands) and lower in plantations (lowest in intermediate eucalypt plantations). Diversity across all study sites was again lowest in eucalypt plantations in intermediate age, but was relatively high in other plantations, due to a high species turnover in young and mature eucalypt plantations. Eucalypt plantations were similar to shrublands in understory species composition and functional types when young, becoming more distant to them when older, and more similar to pine plantations and native forests. Native forests were the most distinctive community, with pine plantations being the most similar to them. Native forests harbored the rarest species and were also associated with seed dispersal by vertebrates (internally). Ant- and wind dispersal were the most common in shrublands and eucalypt plantations. Given the prevalence of eucalypt plantations in some regions, determining (and improving, if feasible) their ability to harbor biodiversity of native communities becomes a crucial goal, in order to increase landscape connectivity and favor species persistence at regional scales. In the study region, eucalypt plantations provide habitat for species typical of shrublands when young but do not contribute significantly to the maintenance of the understory biodiversity associated with native forests. Considering the distinctiveness of native forests, we favor protection and, where feasible, restoration of native forests over managing eucalypt plantations for biodiversity to best improve conservation outcomes. [Copyright &y& Elsevier]

• Pinus pinaster has not spread widely into terrestrial vegetation in the Perth region Australia. • Spread into wetlands near plantations is however serious, and is promoted by fire. • Pinus pinaster wildings commonly establish after plantation clearing and/or burning. • Feeding activities of black cockatoos are likely to reduce seed dispersal of pine seed. Pinus pinaster is a common plantation species in many Mediterranean-climate regions of the world and has become invasive in several of these, but little is known about its invasive potential, with no studies regarding its invasion potential and patterns being carried out in Australia. It has been widely planted over many decades in the Perth region of southwest Australia. Here we used plots to measure the density, size and approximate age of P. pinaster wildings in native vegetation adjacent to pine plantations and in areas of cleared plantations. Results demonstrated that densities of P. pinaster wildings were highest at edges and varied widely with vegetation type, being much greater in dense, wetland vegetation compared to more open sclerophyllous woodlands, which was contrary to that experienced in other regions. Wilding regeneration following clearing was also highly variable. Local populations of black cockatoos, which fell cones to ground for feeding, are likely to have contributed to low levels of spread into native bushland by curtailing wind dispersal of seeds from tree canopies, as well as providing an ample seed source for regeneration of wildings at cleared sites. Wildfires, which can lead to mass regeneration of P. pinaster elsewhere, did not promote spread of wildings into adjoining bushland, but did enhance wilding densities in wetland vegetation within the plantation matrix. [ABSTRACT FROM AUTHOR]

• We study lichen communities at age stages in Eucalyptus globulus and Pinus pinaster. • Tree species, age and their interaction affected lichen abundance and richness. • Native P. pinaster is more suitable for lichens than exotic E. globulus. • Pines had more lichen abundance and diversity than eucalypts in all ages. We explore the patterns of epiphytic lichen community richness and composition (both taxonomical and functional) on the trunks of the two most important species used for forestry in NW Spain (the non-native Eucalyptus globulus , and Pinus pinaster , a native species in the Iberian Peninsula) across a chronosequence of age classes. We recorded a total of 56 lichen taxa in 30 genera across all sites. Lichen abundance and species richness was significantly affected by tree species (eucalypt vs. pine plantations) by age and by the interaction between them. Pines had more lichen abundance and diversity than eucalypts in all ages, with 2–17 times more lichen cover and 2.5–6.5 times higher average species richness, depending on the age. The taxonomical and functional composition of the epiphytic community was also affected by the tree species, the age and its interaction. The colonization pattern in both eucalypts and pines was typical of an additive system, with an ongoing increase of species and epiphytic cover, where early colonizers persist and new species are added later on without replacing the existing species. This study demonstrates that plantations of the native species P. pinaster provides a more suitable habitat for lichens than those of the exotic E. globulus in the study region, not only as a consequence of longer rotation cycles but for the higher rate of lichen colonization and expansion in their trunks, as these differences were observed in all ages. [ABSTRACT FROM AUTHOR]