Laurifolia Research Articles

Diversity hotspots of the laurel forest on Tenerife, Canary Islands: a phylogeographic study of Laurus and Ixanthus.

Macaronesian laurel forest is among the worldwide hotspots of threatened biodiversity. With increasing evidence that woodland composition on the Canary Islands changed dramatically during the last few thousand years, the aim of this study was to find evidence for substantial recent population dynamics of two representative species from laurel forest. Amplified fragment length polymorphism (AFLP) was used to evaluate fine-scaled genetic variation of the paradigmatic tree Laurus novocanariensis (Lauraceae) and a long-lived herbaceous gentian from core laurel forest, Ixanthus viscosus (Gentianaceae), on Tenerife. Bioclimatic variables were analysed to study the respective climate niches. A chloroplast DNA screening was performed to evaluate additional genetic variation. Genetic diversity of the laurel tree showed severe geographic partitioning. On Tenerife, fine-scaled Bayesian clustering of genetic variation revealed a western and an eastern gene pool, separated by a zone of high admixture and with a third major gene pool. Compared with genetic clusters found on the other Canary Islands, the East-West differentiation on Tenerife seems to be more recent than differentiation between islands. This is substantiated by the finding of extremly low levels of chloroplast DNA-based polymorphisms. Ixanthus showed no geographic structuring of genetic variation. Genetic data from Tenerife indicate contemporary gene flow and dispersal on a micro/local scale rather than reflecting an old and relic woodland history. In particular for Laurus, it is shown that this species occupies a broad bioclimatic niche. This is not correlated with its respective distribution of genetic variation, therefore indicating its large potential for contemporary rapid and effective colonization. Ixanthus is more specialized to humid conditions and is mostly found in the natural Monteverde húmedo vegetation types, but even for this species indications for long-term persistence in the respective bioclimatically differentiated regions was not find.

A Comparative Study of Long‐Term Effects on Fire‐Affected Volcanic Soils in Two Different Ecosystems in the Canary Islands

AbstractVolcanic soils have unique properties that can be specifically affected by fire. In this work, we use a chronosequence approach to investigate the long‐term effects of wildfires on the surface and topsoil (0–30 cm) of volcanic soils in two different ecosystems: the Canary pine forest (dry and fire‐adapted) and the laurel forest or monteverde (subhumid and not prone to fire). Redundancy analysis and partial Kendall's correlation were used to analyse the relationship between soil characteristics and the wildfire chronosequences, controlling most significant environmental variables. No long‐term effects of fire were observed on the pine forest topsoil, but strongly persistent erosion‐related features were found on the soil surface, suggesting that chronic erosion might occur as a result of increased wildfire frequency. The soils of the monteverde were affected over the long term by severe losses of organic matter including highly humified and complexed forms. Organic losses appeared to be mainly due to erosion and associated with decreases in water‐holding capacity and in the levels of organo‐complexed metals and bioavailable nutrients such as boron or zinc. Fire also led to decreased bioavailability of some nutrients (e.g. phosphorus) and increased release of other elements (e.g. silicon), most likely by exposing surfaces of short‐range‐order minerals. Better management is needed to reduce irreversible effects of severe wildfires on these soils. Copyright © 2015 John Wiley & Sons, Ltd.

Are there any widespread endemic flowering plant species in Macaronesia? Phylogeography of Ranunculus cortusifolius.

Oceanic island endemics typically exhibit very restricted distributions. In Macaronesia, only one endemic angiosperm species, Ranunculus cortusifolius, has a distribution spanning the archipelagos of the Azores, Madeira, and Canaries. Earlier work suggested possible differences between archipelagos and the multiple origins of the species. This paper tests the hypothesis that R. cortusifolius is a single widespread Macaronesian endemic species with a single origin. Chloroplast (matK-trnK, psbJ-petA) and ITS sequences were generated from across the distribution of R. cortusifolius. Relationships were investigated using Bayesian inference and divergence times estimated using BEAST. Infraspecific variation was investigated using statistical parsimony. The general mixed Yule-coalescent model (GMYC) was further used to identify putative species boundaries based on maternally inherited plastid data. The hypothesis of multiple independent origins of R. cortusifolius is rejected. Divergence of the R. cortusifolius lineage from a western Mediterranean sister group in the late Miocene is inferred. Distinct genotypes were resolved within R. cortusifolius that are endemic to the Azores, Madeira, and the Canaries. Four to five putative species were delimited by different versions of the GMYC model. Ranunculus cortusifolius is the result of a single colonization of Macaronesia. The large distances between archipelagos have been effective barriers to dispersal, promoting allopatric diversification at the molecular level with diversification also evident within the Canaries. Isolation has not been accompanied by marked morphological diversification, which may be explained by the typical association of R. cortusifolius with stable and climatically buffered laurel forest communities.

A new species of Tremella from Macaronesia

Tremella laurisilvae, a species new to science with a parasitic strategy on Biscogniauxia species, is described from the evergreen laurel forests of Macaronesia. The basidiocarps are macroscopically differentiated by finger-like lobes and brown-orange colour. Micromorphological differences with phylogenetically related species are evaluated and its phylogenetic placement in Tremellomycetes is inferred from ITS rDNA sequences. A detailed description, plate with photographs and a key to species from Europe and Macaronesia are provided.

Palaeo-islands as refugia and sources of genetic diversity within volcanic archipelagos: the case of the widespread endemic Canarina canariensis (Campanulaceae).

Geographical isolation by oceanic barriers and climatic stability has been postulated as some of the main factors driving diversification within volcanic archipelagos. However, few studies have focused on the effect that catastrophic volcanic events have had on patterns of within-island differentiation in geological time. This study employed data from the chloroplast (cpDNA haplotypes) and the nuclear (AFLPs) genomes to examine the patterns of genetic variation in Canarina canariensis, an iconic plant species associated with the endemic laurel forest of the Canary Islands. We found a strong geographical population structure, with a first divergence around 0.8Ma that has Tenerife as its central axis and divides Canarian populations into eastern and western clades. Genetic diversity was greatest in the geologically stable 'palaeo-islands' of Anaga, Teno and Roque del Conde; these areas were also inferred as the ancestral location of migrant alleles towards other disturbed areas within Tenerife or the nearby islands using a Bayesian approach to phylogeographical clustering. Oceanic barriers, in contrast, appear to have played a lesser role in structuring genetic variation, with intra-island levels of genetic diversity larger than those between-islands. We argue that volcanic eruptions and landslides after the merging of the palaeo-islands 3.5Ma played key roles in generating genetic boundaries within Tenerife, with the palaeo-islands acting as refugia against extinction, and as cradles and sources of genetic diversity to other areas within the archipelago.

Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests.

The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data.

Establishment of laurel forest vegetation in adjacent secondary forest in central Japan

Distributions of lucidophyllous species are limited due to the fragmentation of laurel forest. On Komayama Hill in central Japan, we evaluated the colonization of typical lucidophyllous vascular plants from a 350-year-old laurel forest into adjacent abandoned secondary forest for conservation and restoration purposes. A total of 14 consecutive subplots were established along the vegetation border between the two forests (length, 30 m; width, 5 m), extending 70 m into the secondary forest; 18 quadrats of old-growth forest were surveyed. Edge effects of old-growth forest were found to play an important role in re-establishing lucidophyllous saplings and seedlings in the secondary forest. In particular, the abundances of the four dominant canopy species of the old-growth forest significantly decreased with increasing distance. Hence, they are expected to colonize further into the secondary forest and, ultimately, to dominate the canopy. However, the number of lucidophyllous species did not change with distance. Species such as Ficus nipponica, Damnacanthus indicus, Ilex integra, and Lemmaphyllum microphyllum were near-completely or completely limited to the old-growth forest. They are known to be negatively affected by forest fragmentation and were observed to be struggling to colonize the exterior of the old-growth forest even after 60 years of abandonment. Their absence highlighted the limited colonization capacities of some old-growth forest species and underlined the time required for habitat restoration following human disturbance. We conclude that it is important to consider the population dynamics of dominant canopy species and the colonization of these interior species when assessing the habitat expansion of lucidophyllous species and hence the restoration of degraded lands.

Species turnover during secondary succession in a laurel forest stand 60 years after clearcutting

Aim of study: The present study was designed to evaluate the effects of clearcutting and recovery of a laurel forest stand, 50 years after felling.Area of study: Laurel forest stand in Agua García, Tenerife (Canary Islands)Material and methods: Structural stand parameters were measured in a large patch of laurel forest.Main results: The results revealed that Erica arborea and Ilex canariensis have acted as pioneer species in the broad sense of the term, while Morella faya has remained abundant throughout the study. Persea indica became increasingly dominant throughout succession, as indicated by several different structural parameters.Research highlights: Recovery of the laurel forest after clearcutting has been possible in some areas without any further forest management, as indicated by the species composition and forest structure.Key words: Canary Islands; Ecological Restoration; Laurel forest; Succession.

The Laurisilva as a cultural heritage: proposal for the protection of the relict of laurel forest near Ponte Renaro

The name Laurisilva was introduced by Humboldt to indicate mixed broadleaved evergreen forests, with a consistent presence of Lauraceae, widespread in the subtropical-humid zone of South America; similar vegetation was successively described for SE-Asia, China, Japan, SW-Pacific Islands and S. Africa; besides, remnants of laurophyllous forests occur in the Canary Islands and Madeira. In the Mediterranean basin only one species of Lauraceae occurs: the endemic Laurus nobilis. The discontinuous distribution of L. nobilis can be interpreted as the relict of an ancient continuous presence from the Iberian Peninsula to Caucasus, fragmented during the salinity crisis of Messinian and the cold phases of Pleistocene. Very few occurrences of L. nobilis in the natural vegetation are recorded along the Tyrrhenian coast of Italy and in Sicily. In the Castelporziano area near Rome L. nobilis is relatively frequent in mixed (evergreen-deciduous) stands: the Lauro-Carpinetum betuli a plant community with peculiar ecological requirements, well distinct from the surrounding oak forests (Quercus cerris, Q. frainetto, Q. ilex). The area of Valle Renaro, where the laurel forest occupies large areas of natural appearance is proposed as a wildlife sanctuary, to preserve a valuable record of this rare relic vegetation. The structure of the forest and the particular microclimatic and edaphic conditions are discussed. The population of L. nobilis in Valle Renaro is witnessing the palaeogeographic vicissitudes of an area that along a millenary history became, as well, an important cultural heritage.

The Cultural Theory of Laurel Forest and Japanese Scholars’ Culture Researching to Southwest China Minority

The Cultural Theory of Laurel Forest and Japanese Scholars’ Culture Researching to Southwest China Minority

Edaphic heterogeneity related to below-canopy water and solute fluxes in a Canarian laurel forest

Aim To study the differences in the edaphic properties between stemflow infiltration areas around different tree species and between these and other areas of the forest.

Seedling survival patterns in Macaronesian laurel forest: a long-term study in Tenerife (Canary Islands)

Seedling dynamics of the Macaronesian laurel forest have been monitored for the first time in a long-term study to determine whether the survival of the seedling community is affected by slope aspect and forest structure. More than 4000 seedlings were monitored monthly from 2000 to 2003 in well-preserved laurel forest stands on Tenerife, Canary Islands. Trees and seedling bank species composition differed between windward and leeward slopes. On both slopes, differences in species composition between the canopy and the seedling bank suggest future shifts in canopy species composition towards a more advanced successional stage. Surprisingly, seedling survival was higher on the drier leeward than on the wetter windward slope. This seems to be related to environmental and structural differences of the forest stand between slope aspects (e.g. larger trees, higher canopy cover and tree density and lower light penetration in windward plots). Analysed species have long-lived seedling banks with survival rates of 12 per cent and 5 per cent in the long term (12 years) for leeward and windward slopes, respectively, with significant differences among species. This result reflects the high regeneration potential of the forest in well-preserved stands, indicating that no management interventions are required to ensure the regeneration of this endemic forest.

Genetic, morphological, and dietary changes associated with novel habitat colonisation in the Canary Island endemic grasshopper Acrostira bellamyi

1. The large flightless grasshopper Acrostira bellamyi Uvarov, endemic to the island of La Gomera (Canary Islands), inhabits two different environments: the xeric euphorb shrubland, as is typical for congeneric Canarian species, and the humid laurel forest, a novel habitat for the genus.2. We investigate genetic, morphological, and ecological variation among individuals of A. bellamyi from the two habitats. DNA sequence data were used to evaluate whether grasshoppers from the two environments represent distinct lineages. Morphological and trophic analyses were performed to assess phenotypic differentiation between the two different habitats.3. Population genetic analyses support the hypothesis that the euphorb shrubland is the ancestral habitat for this species. Female laurel forest specimens are larger than those inhabiting the euphorb shrubland, and some external body parts exhibit significant morphometric differences between the two populations. Diet of shrubland individuals is completely different from that of laurel forest individuals. Although in each habitat they consume the most abundant plants, individuals are able to select food plants, which appear to be explained by their nutrient content.4. Our results suggest that A. bellamyi has colonised laurel forest from shrubland, and that this habitat shift has resulted in genetic, morphological, and ecological changes, perhaps as an adaptation to this new habitat.

Labile carbon pools and biological activity in volcanic soils of the Canary Islands .

It is important to assess the mineralisation of soil organic carbon (SOC) to predict the short-term response of biosphere carbon reservoirs to changing environmental conditions. We investigated the labile (easily-mineralisable) SOC in volcanic soils, where the bioavailability of SOC is typically affected by physico-chemical stabilisation mechanisms that are characteristic of these soils. Ten soils were selected that represent the most typical soil types (mainly Andosols) and natural habitats (xerophytic scrubland, laurel forest and pine forest) in the Canary Islands, a volcanic archipelago. Over two years we measured several physico-chemical SOC fractions with different degrees of bioavailability: water-soluble carbon in fresh soil samples (WSC) and in the saturated extract (WSC<sub>se</sub>), hot water-extractable carbon (HWC), potassium sulphate-extractable carbon (PSC), microbial biomass carbon (MBC), particulate organic carbon (POC), humic substances carbon (HSC), and total organic carbon (TOC), and performed CO<sub>2</sub> emission incubation assays. We related these measurements to the potential C inputs of plant litter and roots and to the activity of certain hydrolytic enzymes (CM-cellulase, β-D-glucosidase, and dehydrogenase) that are involved in carbon turnover. In vitro carbon mineralisation measurements from short assays (ten days) were fitted with simple first-order kinetics to investigate SOC. This procedure was simple and allowed us to obtain estimates both for potentially mineralisable SOC and for the heterogeneity of the substrates that were consumed during incubation. The investigated volcanic soils had large labile SOC concentrations in which simple carbohydrates predominated and that were mainly derived from roots and aboveground non-woody residues. Among the analysed physico-chemical SOC fractions, HWC (3.1 g kg<sup>-1</sup> on average at 0-30 cm depth in Andosols) was the most correlated with C<sub>0</sub> (1.2 g kg<sup>-1</sup>) and therefore best represents potentially mineralisable SOC. PSC (0.77 g kg<sup>-1</sup>), which represents an SOC pool of low bioavailability, was protected by its adsorption to allophane in silandic Andosols.

Evolutive and regressive soil sequences for characterization of soils in laurel forest (Tenerife, Canary Islands) .

Soil degradation processes have achieved the recognition of a global environmental problem in recent years. It has been suggested by various international forums and organizations that in order to adequately establish methods to combat land degradation, it is necessary to evaluate this degradation locally and at a detailed scale. The evaluation of soil degradation of natural ecosystems at a detailed scale requires the definition of standards to which to compare this degradation. To define these standards and properly handle the processes that give rise to variations in soil quality and degradation, it is necessary to establish in some detail the pedogenic processes that have or have not taken place in a particular area and which lead to the formation of a mature soil. A mature soil should be considered as standard in these situations and, therefore, a non-degraded soil. This paper presents the possible evolutive and regressive sequences of soil, and provides some examples of using this methodology to evaluate the degradation of the same in the Monteverde of the island of Tenerife. It also presents some physical, chemical and mineralogical properties of climacic mature soils, degraded soils and low quality soils, and examines their similarities and differences in this bioclimatic environment and on different parent materials. Thus it is observed that the main processes of degradation in these areas are related to plant cover modifications that lead to the decreasing protection of the soil surface, which results in the long term, in the onset of degradation processes such as water erosion, biological degradation, loss of andic properties, compaction and sealing and crusting surface, loss of water retention capacity, illuviation, etc. Climacic soils that can be found in areas of steep lava flows are Leptosols, while gently sloping areas are Cambisols and Andosols. On pyroclastic materials there are vitric Andosols and andic Andosols according to their degree of evolution. The most characteristic regressive processes are illuviation/leaching, resulting in Luvisols, Lixisols and Alisols; and water erosion, causing the presence of secondary Leptosols.

Understanding the formation of Mediterranean-African-Asian disjunctions: evidence for Miocene climate-driven vicariance and recent long-distance dispersal in the Tertiary relict Smilax aspera (Smilacaceae).

Tethyan plant disjunctions, including Mediterranean-African-Asian disjunctions, are thought to be vicariant, but their temporal origin and underlying causes remain largely unknown. To address this issue, we reconstructed the evolutionary history of Smilax aspera, a hypothesized component of the European Tertiary laurel forest flora. Thirty-eight populations and herbarium specimens representing 57 locations across the species range were sequenced at seven plastid regions and the nuclear ribosomal internal transcribed spacer region. Time-calibrated phylogenetic and phylogeographic inferences were used to trace ancestral areas and biogeographical events. The deep intraspecific split between Mediterranean and African-Asian lineages is attributable to range fragmentation of a southern Tethyan ancestor, as colder and more arid climates developed shortly after the mid-Miocene. In the Mediterranean, climate-induced vicariance has shaped regional population structure since the Late Miocene/Early Pliocene. At around the same time, East African and South Asian lineages split by vicariance, with one shared haplotype reflecting long-distance dispersal. Our results support the idea that geographic range formation and divergence of Tertiary relict species are more or less gradual (mostly vicariant) processes over long time spans, rather than point events in history. They also highlight the importance of the Mediterranean Basin as a centre of intraspecific divergence for Tertiary relict plants.

Bryophyte conservation on a North Atlantic hotspot: threatened bryophytes in Madeira and Selvagens Archipelagos (Portugal)

On oceanic islands, the evolution of plants and animals with particular characteristics is favoured due to their isolation, populations normally comprising a large number of unique, endemic species. The Madeira and Selvagens archipelagos are considered biodiversity hotspots, containing an especially rich bryoflora. Due to its characteristically small size, this taxonomic group does not get much attention in conservation programmes. However, these plants are an important component of terrestrial ecosystems, representing a major part of biodiversity and playing a vital role in the ecosystem's functioning. As such, the development of the first Red List for Madeira and Selvagens Archipelagos has the potential to guide conservation efforts focused on taxa and habitats where threatened species and endemics are better represented. By applying the International Union for Conservation of Nature and Natural Resources (IUCN) criteria, recently revised to apply to small islands, it was possible to obtain the percentage of threatened taxa present in the archipelagos (23.6%), and for each habitat type. It was verified that high mountain habitats and the Laurel forest represent areas that host higher percentages of threatened taxa (29.5% and 22.2%). An important result of the present Red List is the identification of hotspots for bryophyte diversity, supporting the definition of reserves/microreserves. The information obtained can also be linked up with the Red Lists of other taxonomic groups to work towards the definition of a more holistic conservation strategy.

A new species in the lichen genus Vahliella from the Canary Islands, including a key to Vahliellaceae, Pannariaceae, and Coccocarpiaceae in Macaronesia

Vahliella isidioidea, found on consolidated soil in the laurel forest from the Canary Islands is described as new to science. A description of the species is given together with notes on its chemistry, distribution, ecology and taxonomy. Possible related lichen taxa are discussed briefly and a key to the Macaronesian species of Vahliella and morphologically related species is also provided.

A new endemic Ramalina species from the Canary Islands (Ascomycota, Lecanorales)

Ramalina alisiosae (Ramalinaceae), found on trees in the laurel forests of the Canary Islands is described as new to science. A description of the species is given together with notes on its chemistry, distribution, ecology, and taxonomy. Bayesian and Maximum Likelihood analyses of ITS sequences showed a close relation of the new species with R. implectens and R. farinacea. Morphological and anatomical differences with these related lichen taxa are discussed.

Tertiary relict laurophyll vegetation in the Madonie mountains (Sicily)

:Laurel woodlands in the Madonie mountains (Sicily) are characterized by the presence of Laurus nobilis, Rhamnus lojaconoi and Vitis vinifera subsp. sylvestris. The results of a phytosociological study are presented, and a new endemic association, Rhamno lojaconoi–Lauretum nobilis, is described. Present Mediterranean laurel communities are the result of an adaptive response by Tertiary laurel forest to the peculiar microclimatic conditions that characterize the refugia where they persist. These refugia have been recently considered as a priority habitat under the Directive 92/43/EEC, and their plant communities are very vulnerable. Protection measures of the studied laurel populations are necessary, with particular reference to the bulking up of R. lojaconoi through in situ and ex situ propagation. A multivariate analysis of 63 relevés from all the Sicilian laurel communities described so far and additional 65 relevés from all over southern Europe and the Mediterranean basin bears out the autonomy of the new association, showing at the same time some floristic affinities between Sicilian, southern Italian, Spanish and Iberian associations. Their syntaxonomic treatment is discussed.