Dispersión de Melinis repens (Willd.) Zizka subsp. repens (Poaceae) en Tenerife, Islas Canarias.

Ecophysiology of the invader Pennisetum setaceum and three native grasses in the Canary Islands

Mapping the distribution of invasive species under current and future climate conditions is crucial to implement sustainable and effective conservation strategies. Several studies showed how invasive species may benefit from climate change fostering their invasion rate and, consequently, affecting the native species community. In the Canary Islands and on Tenerife in particular, previous research mostly focused on climate change impacts on the native communities, whereas less attention has been paid on alien species distribution under climate change scenarios. In this study, we modelled the habitat distribution of Pennisetum setaceum, one of the most invasive alien species on Tenerife. In addition, we described the species’ potential distribution shift in the light of two climate change scenarios (RCP2.6, RCP8.5), highlighting the areas that should be prioritized during management and eradication programs. P. setaceum’s suitable areas are located in the coastal area, with higher habitat suitability near cities and below 800 m asl. In both future climate change scenarios, the geographic distribution of P. setaceum suitable areas is characterized by an elevational shift, which is more pronounced in the RCP8.5 scenario. Despite being drought resistant, water supply is crucial for the species’ seed germination, thus supporting future species’ shift to higher elevation and in the north–north–west part of the island, where it could benefit from the combined effect of orographic precipitations and humidity carried by trade winds.

Pluchea ovalis (Pers.) DC. is an invasive alien plant species. It has spread widely on the island of Tenerife since it was first introduced, becoming a major threat to the island’s flora. The aims of this study are to analyze its germination capacity under different environmental conditions (e.g., light and temperature) and determine its effects on soil properties and native plant communities. Germination assays were carried out both in a germination chamber and in a greenhouse. Twelve plots were also established in the field to determine its effect on soil properties and plant species composition. Our results reveal that the germination capacity of Pluchea ovalis decreases under high temperature ranges and increases on flooded substrates. In addition, Pluchea ovalis can modify soil physicochemical properties by increasing soil magnesium content. As its invasive potential has been demonstrated, this study contributes with evidence of its effects on environmental conditions and species composition. Moreover, we recommend its inclusion in the Spanish Alien Invasive Species Catalogue and the development of further studies about its potential distribution and effects in the Canary Islands.

Invasive alien species and planetary and global health policy

Cardiospermum grandiflorum

Control of one invasive plant species allows exotic grasses to become dominant in northern Great Plains grasslands

ABSTRACTUnderstanding the ecological differences between native and invasive species is of considerable scientific and practical interest. We examined such differences between native and invasive inland fish species from the Iberian Peninsula in order to analyse the importance of phylogenetic correction and variability (in addition to central tendency). We collected 26 quantitative and qualitative variables on the ecology, life‐history traits and human use of the 69 inland fish species of the Iberian Peninsula, including native, invasive and migratory species. The taxonomic distribution of invasive fish species deviated significantly from world freshwater richness and in contrast to native species, invasive fish belongs to only five taxonomic orders but to a wide spectrum of families not native to the Iberian Peninsula. Because the life‐history traits were highly dependent on taxonomy, the results, with or without applying phylogenetic methods, differed and after accounting for phylogeny, invasive species displayed higher and wider latitude in general and a different reproductive season mainly among salmonids and cyprinids. Human use was also significantly different between native and invasive fish species and produced more variability in life‐history traits of invasive species and uneven taxonomic distribution because of the high diversity of species introduced. We show that accounting for taxonomy and studying variability in addition to central tendency is important in the comparison of life‐history traits between native and invasive species.

Plant communities developing in abandoned semi-natural areas are being increasingly dominated by invasive exotic species. How these ‘novel residents’ affect re-colonisation by native perennial species, a process generally assumed to be seed limited, remains little explored. We examined the relative roles of dominant exotic grasses and seed dispersal in limiting the richness and abundance of native perennial grasses in an old-field grassland community. We also tested whether native grass recruitment depended on the identity of resident exotic species. A seed addition, single-pulse removal experiment was established in a 20 year old field in the Inland Pampa of Argentina. Seeds of seven native perennial grasses from a nearby relict grassland were sown into intact and disturbed patches dominated by one of four exotic grasses. Species richness and biomass were measured after 2 years from sowing. Seed addition alone had little effect on native grass richness or biomass, with only one sown grass establishing in intact patches. Native grasses successfully colonised disturbed patches dominated by the exotics Lolium multiflorum, Cynodon dactylon or Sorghum halepense. In contrast, patches dominated by Festuca arundinacea repelled sown native grasses, regardless of disturbance treatment. Seed addition increased total plant richness in both disturbed and intact patches but did not affect total aboveground biomass. Our results show that recovery of native grasses during old-field succession is hierarchically constrained by seed arrival and site pre-emption by exotic grasses. Thus, re-establishment of native grass assemblages may only occur at the expense of displacing exotic resident plants. This highlights the importance of niche-limited species assembly in novel, native/exotic plant communities.

Effects of ocean warming on larvae development of Patella tenuis crenata in the Canary Islands

IntroductionInvasive species can cause ecological and economic damage in various areas, including nature reserves. The invasion risks of aquatic invasive vertebrates in nature reserves, however, remain unclear since this group often hides under the water and is frequently neglected in ecological surveys based on traditional methods.MethodsEnvironmental DNA (eDNA) provides a promising alternative way to conduct biodiversity surveys in aquatic ecosystems. Here, we collected aquatic eDNA samples from eight nature reserves in Guangdong Province, China to mainly investigate the diversity of aquatic invasive vertebrates and inform their invasion risks in these nature reserves.Results and discussionWe detected a total of 104 aquatic vertebrate species belonging to three classes (Actinopteri, Amphibia and Reptilia), 12 orders, 32 families, and 71 genera, among which nine were invasive species (8.65% of all aquatic vertebrates detected), i.e., Coptodon zillii, Sarotherodon galilaeus, Oreochromis niloticus, Oreochromis tanganicae, Gambusia affinis, Clarias gariepinus, Chelydra serpentina, Trachemys scripta elegans, and Rana catesbeiana. Surprisingly, 55.56% of these aquatic invasive vertebrates (i.e., five species) were found in at least 75.00% samples, and both C. zillii and S. galilaeus were detected in all samples (100%), suggesting that most invasive species were widely distributed in these nature reserves. In addition, all aquatic invasive vertebrate species ranked very high (top 66 of aquatic vertebrates detected) regarding their relative abundance of sequences, and three of the top 10 species with the highest number of sequences were invasive species (i.e., C. zillii, S. galilaeus, and O. niloticus), suggesting high population size of these invasive vertebrates. Moreover, we also detected 16 endangered/threatened species (15.38% of all vertebrates detected), which demonstrated notable overlaps of geographic distribution with invasive species. The reality of high abundance, wide geographical distribution and overlaps with the endangered/threatened species indicated considerable risks of aquatic invasive vertebrates in nature reserves in Guangdong Province, which calls for urgent needs for effective management. Our study would provide fundamental insights for the formulation of effective management measures to reduce losses caused by invasive species and promote the protection of endangered/threatened species in nature reserves.

Metastrongylid species infecting wild and domestic cats worldwide are increasingly being reported. Between 2017 and 2019, a total of 202 faecal samples of domestic cats from the island of Tenerife (Canary Islands, Spain) were analysed by microscopy and molecular techniques. Morphological analyses showed that 8.91% (18/202) of the faecal samples presented first stage larvae (L1) of metastrongylid species. Total DNA was isolated and tested by PCR targeting a 508 bp fragment of the ITS-2 gene. The nucleotide sequences obtained showed high homology (100%) with the species Oslerus rostratus. This work contributes to the knowledge of the wide distribution of O. rostratus worldwide, being Tenerife (Canary Islands, Spain), close to the African continent, the new geographic location for this metastrongylid species. Further molecular studies involving new geographic areas from the island of Tenerife, as well as neighbouring islands, are needed to provide relevant insight and better understand the epidemiology of O. rostratus and other metastrongylid species in wild and domestic cats from the Canary Islands.

Cynodon dactylonis one of the five most important invasive alien species worldwide. It is the invasive alien species with the broadest distribution range in Uruguay, and its expansion is frequently associated with disturbances. Since natural grasslands are facing processes of productive intensification,C. dactylonrepresents a threat as it could displace native species. However, the mechanisms that explain its invasion success remain unclear. The objective of this study was to analyse interspecific interactions under low nutrient conditions betweenC. dactylonand two species that are native to theCampograsslands in Uruguay. Specifically, we assessed differences in the components of competitive ability effects and responses (or tolerance) as possible mechanisms involved inC. dactyloninvasiveness. We performed a greenhouse experiment in pots with low‐nutrient substrate assessing pair‐wise interactions betweenC. dactylon,Mnesithea selloanaandPaspalum notatumplus control pots consisting of single individual of each species. The invasive species showed greater competitive ability than both native grasses, as it reduced their below and above‐biomass. Conversely, the size ofC. dactylonplants interacting with native species was similar to that of singleC. dactylonplants growing alone (controls). This reveals that the greater competitive ability of the invasive species was due to a greater tolerance to grow with neighbouring plants. The reason underlying this tolerance was a marked increase in biomass allocation towards stolons and leaves, at the expense of roots. Conversely, native species barely changed their shoot‐root allocation pattern when interacting with neighbours. Furthermore,C. dactyloninduced reproductive development solely when interacting with neighbours. Along with the fact that the potential growth rate of the invasive and native species was quite similar, these results suggest that sensitive and rapidly triggered shade avoidance responses could be one mechanism involved in the invasion success ofC. dactylon.

The Canaries: an important biogeographical meeting place

Invasive process of alien species is affected by not only the invaded habitats, but also the surrounding landscape matrix. Understanding the effects of landscape matrix on alien species is of great significance for controlling invasive alien species. We surveyed plant communities along the water-level fluctuating zone (WLFZ) of the Three Gorges Reservoir. Invasive status of alien plant species was evaluated. Totally 10 spatial scales of the surrounding landscape matrix in the scope of 2000 m (including WLFZ) were classified, and 14 landscape indices were applied to analyze the landscape matrix composition and configuration. Using the principal component analysis and correlation analysis, the effects of landscape matrix on the alien invasive plant species and associated scale effect were tested. Results showed that a total of 42 alien invasive plant species were found in the WLFZ, belonging to 17 families and 36 genera. Fuling was a dividing place to differentiate invasive species distribution. The number of the alien invasive species between Fuling and the Three Gorges Dam was found more than that between Fuling and Jiangjin. For the all scales (within 2000 m). The higher the landscape matrix fragmentation was, the more difficult the alien species invading. The higher landscape connectivity was, the easier the alien species invading. The effects of landscape matrix composition and configuration on the invasive plant diversity at large scales (1200-2000 m) was more significant than those at small scales (200-1000 m), in which landscape matrix composition and configuration at 1200-1400 m showed the strongest effect, demonstrating a significant spatial scale effect. Different invasive plant species showed the scale effects of landscape matrix composition and configuration. At all scales, Xanthium strumarium and Bidens frondosa showed weak correlations with landscape indices, but Bidens tripartita and Erigeron canadensis showed strong correlations. Landscape matrix was closely related to invasive plant species, and demonstrated a significant scale effect. The alien invasive plant species could be traced to the landscape matrix at large scales. Grassland and forest patches at the small scales could be used as the 'stepping stone' for the alien species transiting before they arrived at the WLFZ. In order to control alien plants in the WLFZ, land-use management and optimization should be strengthened at different scales of landscape matrix on the basis of enhancement of habitat management. A diversified comprehensive control for alien species should thus be taken into account.

Biodiversity loss caused by invasive species may soon surpass the damage done by habitat destruction and fragmentation. Biological invasions are an important component of human-caused global environmental change. Invasive alien species are now a major focus of global conservation concern. The decisions need to be made on whether benefits derived from the invasive spread of an alien species outweigh the reduced value of ecosystem services, e.g. the loss of grazing land in areas invaded with Lantana camara and Senna occidentalis . It is necessary to consider actions to deal with the current problems caused by invasive species and to reduce the magnitude of the problem in the future. The present catalogue on invasive alien plant species of the northwestern & Western Ethiopia is therefore timely one. It focuses on some species of invasive alien plants in Ethiopia. These include the most serious invasives, such as Alternanthera philoxeroides, Cassia uniflora, Chromolaena odorata, Eichhornia crassipes, Lantana camara, Parthenium hysterophorus , Senna obtusifolia and others. I am confident that this publication will be immense value to foresters, environmentalists, field researchers and conservation managers to pay attention on the ecological impact of invasive aliens both at the species and at the ecosystem levels. Keywords : Biodiversity, invasive species, conservation, environmental change DOI : 10.7176/ALST/74-04 Publication date :May 31 st 2019