Erica Arborea Research Articles

Spatial and temporal patterns in structure and diversity of Mediterranean forest of Quercus pyrenaica in relation to fire

The main objective of this work is to analyze the spatial and temporal response of Q. pyrenaica community to fire. In order to do so, an ecological characterization of 15 forests in different succession stages (5 Initial: 0–20 years, 5 Medium: 20–60 years and 5 Mature: over 60 years), paying special attention to structural and diversity features, was carried out. The results show that temporal changes are very important, and particularly affect the structure and relative abundance of the vegetation. The main differences consist in the change from a homogenous structure, with high cover and overlayering of woody species, at Initial stage, to a more pluristratified, complex and organized structure, with lower cover and overlayering of woody species at Mature stage. The changes in abundances showed a decrease in shrubby species, such as the Erica australis, Genista florida and Erica arborea at Initial stage, and the incorporation of tree species, such as Crataegus monogyna, Acer pseudoplatanus and Alnus glutinosa at Mature stage. However, there are no significative differences between stages for specific richness and diversity values. Spatial heterogeneity is high and similar in all three defined stages.

Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain)

The ecophysiologic role of fog in the evergreen heath-laurel 'laurisilva' cloud forests of the Canary Islands has not been unequivocally demonstrated, although it is generally assumed that fog water is important for the survival and the distribution of this relict paleoecosystem of the North Atlantic Macaronesian archipelagos. To determine the role of fog in this ecosystem, we combined direct transpiration measurements of heath-laurel tree species, obtained with Granier's heat dissipation probes, with micrometeorological and artificial fog collection measurements carried out in a 43.7-ha watershed located in the Garajonay National Park (La Gomera, Canary Islands, Spain) over a 10-month period. Median ambient temperature spanned from 7 to 15 degrees C under foggy conditions whereas higher values, ranging from 9 to 21 degrees C, were registered during fog-free periods. Additionally, during the periods when fog water was collected, global solar radiation values were linearly related (r2=0.831) to those under fog-free conditions, such that there was a 75+/-1% reduction in median radiation in response to fog. Fog events greatly reduced median diurnal tree transpiration, with rates about 30 times lower than that during fog-free conditions and approximating the nighttime rates in both species studied (the needle-like leaf Erica arborea L. and the broadleaf Myrica faya Ait.). This large decrease in transpiration in response to fog was independent of the time of the day, tree size and species and micrometeorological status, both when expressed on a median basis and in cumulative terms for the entire 10-month measuring period. We conclude that, in contrast to the turbulent deposition of fog water droplets on the heath-laurel species, which may be regarded as a localized hydrological phenomenon that is important for high-altitude wind-exposed E. arborea trees, the cooler, wetter and shaded microenvironment provided by the cloud immersion belt represents a large-scale effect that is crucial for reducing the transpirational water loss of trees that have profligate water use, such as those of the 'laurisilva'.

Facilitated establishment of Quercus ilex in shrub-dominated communities within a Mediterranean ecosystem: do mycorrhizal partners matter?

Positive plant-plant interaction is a widespread phenomenon, especially in harsh environments, which can contribute to secondary successions. Here, we investigated whether Arbutus unedo positively influences Quercus ilex establishment in shrub communities by abiotic and/or biotic interactions in a Mediterranean forest ecosystem, where we previously showed that A. unedo and Q. ilex share numerous species of mycorrhizal fungi. In a first field experiment, patterns of Q. ilex survivorship were documented. During the summer following germination, a majority of seedlings survived in A. unedo chaparral (AU), whereas most of them died in previous succession stages dominated by Erica arborea (EA). These results showed that survival of the Q. ilex seedling is succession stage dependent, probably due to the differential effects of the summer drought. In a second experiment, Q. ilex seedlings were used as bait plants to investigate the mycorrhizal inoculum in EA and AU. Morphotyping and molecular typing revealed 2.5 times higher colonization in AU than in EA, with more diverse fungi. Our results demonstrate that A. unedo facilitates mycorrhization of Q. ilex by hosting compatible ectomycorrhizal symbionts and positively influences seedling survival by buffering abiotic conditions. A comprehensive understanding of facilitation should thus include investigations of the soil biological patterns.

Influence of different plant species on water repellency in Mediterranean heathland soils

Abstract It is established that soil hydrophobicity reduces soil infiltration rates, and enhances runoff flow and soil erosion. Water repellency has been studied with special interest in coniferous and eucalyptus forests, particularly after burning, but the number of studies concerning Mediterranean heathlands is still very low. In this paper, we study the occurrence and persistence of water repellency in soil samples collected under different plant species susceptible to induce soil hydrophobicity ( Erica arborea , Erica australis , Calluna vulgaris , Quercus lusitanica and Rhododendron ponticum ) in a natural protected area in southern Spain. Great attention has been paid to the relationships between soil water repellency and environmental factors as organic matter content and soil acidity. The largest hydrophobicity was measured in soil samples collected under E. australis , E. arborea and C. vulgaris . For these species, the organic matter content and pH showed positive and negative correlations with the persistence of water repellency, respectively. The hydrophobicity originated by humic substances in the soil seems to be the only explanation for slight soil water repellency under Q. lusitanica or R. ponticum . The patchy patterns of occurrence and persistence of soil water repellency is governed by the spatial distribution of the studied species and modulated by other factors. Soil surface water repellent layers reduce the infiltration rates and limit the water storage capacity. However, the macropore flow can be enhanced on non-repellent layers, cracks or roots such us the wetting's front shown. The vegetation effects on soil hydrology should be considered for afforestation works and flooding control.

Short-term effects of clear-cutting on the biomass and richness of epiphytic bryophytes in managed subtropical cloud forests

• Managed laurel forests in the Canary Islands have undergone clear-cutting with rotation periods of less than 30 y. Forest owners have recently requested a drastic reduction in the cutting interval. The effects of this new harvesting cycle on organisms like epiphytic bryophytes are not well known. • This study investigates how time since last clear-cut, host species and characteristics of tree zones influence the biomass, cover and richness of epiphyte bryophytes in managed laurel forests in La Palma, Canary Islands. Four forest ages (8, 15, 25 and 60 y) and three host tree species (Erica arborea, Laurus novocanariensis and Myricafaya) were studied. • Biomass, cover and richness of bryophytes increased through the chronosequence, both at the level of each plot and overall for L. novocanariensis. Most of the biomass (53%) and richness (81%) was concentrated in one of the tree species (L. novocanariensis), in plots for which 60 y had elapsed since the last clear-cutting. Trunks supported greater bryophyte biomass and richness than canopies, even in the oldest plots. • Our results suggest that the current rotation periods used to manage laurel forests are insufficiently long to allow for complete reestablishment of epiphytic bryophyte assemblages.

Epiphytic bryophytes in Canarian subtropical montane cloud forests: the importance of the time since disturbance and host identity

The aim of this study was to determine the short- and medium-term effects of forestry practices on epiphytic bryophyte communities growing on whole trees of three host species ( Erica arborea L., Laurus novocanariensis Rivas-Mart., Lousa, Fern. Prieto, E. Días, J.C. Costa & C. Aguilar, Myrica faya Aiton) in subtropical montane cloud forests on La Palma (Canary Islands, Spain). Specifically, we investigated differences in temporal and spatial shifts of species composition and richness of phylogenetic groupings among host species. The most common harvest method in the study area is clear-cutting. Four different postharvest successional stages (8, 15, 25, and 60 years after harvest) were studied. Temporal bryophyte species turnover varied according to host species. Most of the later-successional bryophytes with narrower ecological requirements had low abundances on L. novocanariensis; this host experienced a gradual increase of epiphytic richness along the chronosequence. Temporal changes for E. arborea and M. faya were different; they showed increasing richness during the second period (15–25 years) followed by a drop in richness during the last period (25–60 years), and early-successional species dominated throughout the chronosequence. We conclude that the protection of “old-growth stands” containing trees of selected species can contribute to the survival of epiphytic bryophytes in managed cloud-forest landscapes.

Antioxidant phenolic compounds from the leaves of Erica Arborea (Ericaceae)

Reversed-phase HPLC analyses of the methanol extract of the leaves of Erica arborea afforded a novel phenylpropanoid glucoside, named ericarborin, together with five flavonoids, dihydromyricetin 3-O-α-L-rhamnopyranoside, quercetin 3-O-β-D-glucopyranoside, quercetin 3-O-α-L-rhamnopyranoside, apigenin 7-O-β-D-glucopyranoside and apigenin 7-O-β-D-(6-O-acetyl-glucopyranoside). While the structure of ericarborin was determined by extensive 1D and 2D NMR analyses, the structures of all known flavonoids were determined by direct comparison of their spectroscopic data with respective literature data. The antioxidant properties of these compounds were assessed by the DPPH assay. The chemotaxonomic significance of these phenolic compounds has been discussed.

Fog Water Collection in a Subtropical Elfin Laurel Forest of the Garajonay National Park (Canary Islands): A Combined Approach Using Artificial Fog Catchers and a Physically Based Impaction Model

AbstractFog precipitation has long been assumed as an additional water source in the relic laurel ecosystems of the Canary Islands, located at 500–1400 m MSL. However, to what extent fog water can contribute to the laurel forest water balance is not yet clear. Combining data from artificial fog catchers and a physically based impaction model, the authors evaluated the potential contribution of fog water captured by needle-leafed Erica arborea L. trees in a selected watershed of the Garajonay National Park (La Gomera Island) for a 2-yr period (February 2003–January 2005). Fog water collection was measured with artificial catchers at four micrometeorological stations placed at 1145, 1185, 1230, and 1270 m MSL. Average fog water collection was only significant at the highest measurement site (one order of magnitude greater than at lower altitudes), totaling 496 L m−2 yr−1 during the 2-yr period. The average fog water yield in the first and second annual periods ranged between 0.2–5.0 and 0.1–2.1 L m−2 day−1, respectively. Rainfall exhibited seasonality, distinguishing between rainy and dry seasons, while fog water collection was distributed more evenly throughout the year. Regarding fog water captured by the vegetation, the impaction model predicted a significant amount of fog water potentially collected by a single E. arborea tree, on the order of 1810–2090 L yr−1. Taking tree population density into account, the yearly average water contribution to the soil surface by wind-driven fogs was 251–281 mm, whereas annual rainfall was 635 and 1088 mm, respectively. The hourly course of micrometeorological variables shows a 58% reduction in global radiation under foggy conditions and a concomitant 3°–6°C mean temperature decrease compared to fog-free periods. Thus, limiting evapotranspiration may also be a relevant effect of fog in this subtropical elfin cloud forest.

Experimental study of laminar flames obtained by the homogenization of three forest fuels

This work aims to improve the understanding of the parameters involved in the burning of vegetative fuels. As the role of the surface-to-volume ratio is already known, we focused on the influence of other parameters. Three Mediterranean species ( Pinus pinaster, Erica arborea and Cistus monspeliensis) were crushed in order to decrease the surface-to-volume ratio effects. The burning of these fuel samples produces unsteady, axisymmetric, non-premixed, laminar flames. The thermal properties and the mass loss of the crushed fuels, the distribution of temperature inside the sample and in the flame, the gases released by the fuels and the flame geometry were investigated. Thanks to these experimental data, the influence of the different fuel properties was underlined. We observed that the mass burning rate of the samples mainly controls the flame dynamics. However, the combustion kinetics in the flame depends on the degradation gases released by the fuels: the reaction zone is shifted and the flame height is changed. It appears that the composition of the degradation gases has to be taken into account to improve forest fire modeling.

Tricetin 4′-O-α-L-rhamnopyranoside: A new flavonoid from the aerial parts of Erica arborea

Reversed-phase preparative HPLC purification of the methanol (MeOH) extract of the aerial parts of Erica arborea resulted in the isolation of a new flavonoid glycoside, tricetin 4′-O-α-L-rhamnopyranoside, together with the known flavonoid, isorhamnetin 3-O-α-L-rhamnopyranoside. The structures of these compounds were determined by spectroscopic means. The antioxidant properties of these compounds were assessed by the DPPH assay.

Valuation of anti-inflammatory and antinociceptive activities of Erica species native to Turkey

Erica L. species (Ericaceae) have been popularly used as antirheumatic, diuretic, astringent and treatment of urinary infections. In order to evaluate this information, anti-inflammatory and antinociceptive activities of different extracts prepared with methanol, chloroform, ethyl acetate, n-butanol and water from the aerial parts of Erica arborea L., Erica manipuliflora Salisb., Erica bocquetii (Peşmen) P.F. Stevens and Erica sicula Guss. subsp. libanotica (C.&W. Barbey) P.F. Stevens (Ericaceae) of Turkish origin were investigated by using in vivo methods. For the anti-inflammatory activity, carrageenan-induced hind paw edema model, PGE 2-induced hind paw edema model, and 12- O-tetradecanoyl-13-acetate (TPA)-induced mouse ear edema model and for the antinociceptive activity p-benzoquinone-induced writhing test in mice were employed. The ethyl acetate extracts of Erica arborea (EAE), Erica bocquetii (EBE) and Erica manipuliflora (EME) exhibited notable inhibition against carrageenan-induced (24.1–32.3%, 23.8–36.1%, 29.2–35.1%, respectively) and PGE 2-induced (21.2–37.7%, 6.8–29.7%, and 6.2–34.1%, respectively) hind paw edema as well as TPA-induced mouse ear edema models in mice, while the ethyl acetate extract of Erica sicula subsp. libanotica (ESE) (10.7–29.7%) displayed potent anti-inflammatory activity only on the PGE 2-induced hind paw edema model. However, the remaining extracts were found to be inactive against inflammatory models. Same extracts, i.e., EAE, EBE and EME were also found to exhibit remarkable antinociceptive activity in p-benzoquinone-induced abdominal constriction test at a dose of 100 mg/kg (46.5%, 27.7% and 36.3%, respectively).

Physiological response of eight Mediterranean maquis species to low air temperatures during winter

We analyzed the physiological response of the Mediterranean evergreen species (Arbutus unedo L., Cistus incanus L., Erica arborea L., Erica multiflora L., Phillyrea latifolia L., Pistacia lentiscus L., Quercus ilex L., and Rosmarinus officinalis L.) to winter low air temperatures. In occasion of two cold events, in February 2005 (T min = 1.8 °C), and January 2006 (T min = 3.1 °C and minimum T air = -0.40 °C during the nights preceding the measurements), R. officinalis, C. incanus, and E. multiflora had the highest net photosynthetic rate (P N) decrease (73 %, mean value) with respect to the winter P N maximum, followed by A. unedo (62 %), P. latifolia and P. lentiscus (54 %, mean value), E. arborea (49 %), and Q. ilex (44 %). Among the considered species, Q. ilex was able to maintain P N near the maximum for 150 min during the day, A. unedo, P. lentiscus, E. arborea, P. latifolia, E. multiflora, and R. officinalis for 60 min, and C. incanus for 30 min. The calculated mean winter daily P N ranged from 7.9±0.6 (Q. ilex) to 2.8±0.5 (R. officinalis) µmol(CO2) m-2 s-1. During the study period, chlorophyll (Chl) content decreased by 36 % on an average in the two cold events, and the carotenoid (Car) to Chl ratio increased by 133 % in Q. ilex, having the highest value in January 2006. Principal component analysis underlined the highest cold resistance of Q. ilex by high P N and high Car/Chl ratio. On the contrary, R. officinalis and C. incanus had the lowest cold resistance by the highest P N decrease and the lowest Car/Chl (C. incanus). Thus, winter stress could be an additional limitation to Mediterranean evergreen species production, and the capacity of the species to maintain P N near 90-100 % during winter is determinant for biomass accumulation.

An alternative method to estimate zero flow temperature differences for Granier's thermal dissipation technique

Calibration of the Granier thermal dissipation technique for measuring stem sap flow in trees requires determination of the temperature difference (DeltaT) between a heated and an unheated probe when sap flow is zero (DeltaT(max)). Classically, DeltaT(max) has been estimated from the maximum predawn DeltaT, assuming that sap flow is negligible at nighttime. However, because sap flow may continue during the night, the maximum predawn DeltaT value may underestimate the true DeltaT(max). No alternative method has yet been proposed to estimate DeltaT(max) when sap flow is non-zero at night. A sensitivity analysis is presented showing that errors in DeltaT(max) may amplify through sap flux density computations in Granier's approach, such that small amounts of undetected nighttime sap flow may lead to large diurnal sap flux density errors, hence the need for a correct estimate of DeltaT(max). By rearranging Granier's original formula, an optimization method to compute DeltaT(max) from simultaneous measurements of diurnal DeltaT and micrometeorological variables, without assuming that sap flow is negligible at night, is presented. Some illustrative examples are shown for sap flow measurements carried out on individuals of Erica arborea L., which has needle-like leaves, and Myrica faya Ait., a broadleaf species. We show that, although DeltaT(max) values obtained by the proposed method may be similar in some instances to the DeltaT(max) predicted at night, in general the values differ. The procedure presented has the potential of being applied not only to Granier's method, but to other heat-based sap flow systems that require a zero flow calibration, such as the Cermák et al. (1973) heat balance method and the T-max heat pulse system of Green et al. (2003).

The role of traditional Erica arborea L. management practices in maintaining northeastern Sicily's cultural landscape

The tree heath ( Erica arborea L.), a small evergreen tree found in the Mediterranean region and parts of Eastern and Central Africa, produces lignotubers that are highly valued for making smoking pipes. The Peloritani Mountains of northeastern Sicily are historically one of the most important areas in Italy for the production of these high quality lignotubers, known as briar root wood. In the past, tree heath shrublands were also an important source of charcoal. Erica arborea utilisation has declined dramatically during the past century, mostly due to the decreasing demand for smoking pipes, as well as the increasing frequency of wildfires and large-scale afforestation activities in this region. Until recent decades, Erica arborea management (grub felling), which represented an important economic activity for some local communities, also contributed to wildfire prevention by maintaining low heath tree cover which helped to inhibit fire spread. The majority of Erica arborea maquis is currently found on State-owned lands where traditional harvesting practices (i.e., uprooting trees) is discouraged, leading to higher density stands more susceptible to fire. At present, the tree heath industry is in sharp decline, with irregular management of the resource and poor commercial value of heath root wood due in part to frequent fires. Recently social trends and the establishment of new protected areas in tree heath shrublands discourage the utilization of Erica arborea and the conservation of the material culture and landscape associated with its management. It is proposed that tree heath cultivation be continued only in those areas best suited in order to preserve its cultural and environmental roles, and that forest management practices be improved to increase the economic viability of tree heath grub felling activities.

Acidophytic shrublands in the north-west of the Italian peninsula: Ecology, chorology and syntaxonomy

The shrublands growing on siliceous and/or calcium-poor substrata of the hilly and mountainous areas of north-western and central Italy were studied. This secondary vegetation is dominated by several acidophilous shrubs like Ulex europaeus, Cytisus scoparius, Erica arborea, E. scoparia and Calluna vulgaris. The synecology, synchorology and syntaxonomy of this vegetation was studied using multivariate methods, and discussed in comparison with similar types described in other zones of the Italian peninsula. Two new subassociations are proposed here: Erico arboreae-Arbutetum unedonis genistetosum germanicae and Calluno-Sarothamnetum ericetosum scopariae. Calluno-Sarothamnetum is typified; the Sarothamnion alliance is discussed and referred to Cytisetea scopario-striati. The presence of Calluno-Ulicetea and Cytisetea scopario-striati classes is discussed, and a syntaxonomical scheme is proposed.

Antioxidant activity of Erica arborea

The antioxidant properties of the methanol extract of leaves and flowers of Erica arborea and the ethyl acetate, butanol and water soluble fractions were investigated. The ethyl acetate extract was found to be the richest for phenolic and flavonoid content which showed the highest antioxidant activity.

Deciduous and semi-deciduous oak forests (Quercus robur, Q. petraea and Q. pyrenaica) floristic composition in the Northwest Iberian Peninsula

Oak forests in the Northwest Iberian Peninsula represent climax communities with a high floristic diversity of vascular plants. This study presents data from 189 botanical samples randomly collected in stands of deciduous and semi-deciduous oak as Quercus robur (98), Q. petraea (50) and Q. pyrenaica (41). Within these stands, 187 species or subspecies were identified, in addition to 20 genera and 68 families, all of them present in forests of Quercus robur. A total of 126 species occur in more than five releves. The largest number of species corresponds to Poaceae (22), Fabaceae (19) and Rosaceae (14). The biological spectrum is dominated by hemicryptophytes, with mainly Atlantic and Sub-Atlantic floristic elements. The distribution of the stands has been studied by using Two-Way Indicator Species Analysis, obtaining like pseudo-species, with shrubby and arborea form, the following ones: Fagus sylvatica, Castanea sativa, Sorbus aucuparia, Corylus avellana, Crataegus monogyna, Pyrus cordata, Erica arborea, Frangula alnus and Cytisus scoparius.

The use of n-alkanes to estimate diet composition of ruminants grazing on species diverse plant communities — Effect of feeding selectivity on diet composition estimates

Abstract The present study aimed to evaluate the effect of feeding selectivity (FS) within a dietary group comprising plant species with similar alkane profile, on the estimates of diet composition of goats, sheep and cows grazing on vegetation composed of gorse-heathland with areas of improved pastures. Plant species collected in the field study were grouped in four dietary groups according to cluster analysis: D1 ( Lolium perenne , Pseudarrhenatherum longifolium and Agrostis capillaris ), D2 ( Calluna vulgaris , Erica cinerea , Erica umbellata , Erica australis ), while Erica arborea (D3) and Ulex gallii (D4) remained as individual components due to their distinct n -alkane profiles. The application of different levels of feeding selectivity (0, 5, 15, 30, 60, 90 and 100%) to the graminaceous species included in D1 group affected significantly ( P L. perenne and C. vulgaris were removed from D1 and D2 dietary groups and treated as individual components, there was a decrease in the FS effect on the diet composition estimates. The results obtained show that dietary groups formed by multivariate statistical analysis should be used carefully as they could be sensitive to feeding selectivity, with consequently large effects on the estimates of diet composition. This effect will depend on the similarity in the alkane profile of the plant species that composed the dietary group.

Évaluation de la valeur énergétique des espèces végétales prélevées par le Cerf de Barbarie (Cervus elaphus barbarus, Bennet 1833) dans la zone d’El Ayoune (parc national d’El Kala, Algérie)

Evaluation of the energy value of plant species consumed by the Barbary Deer (Cervus elaphus barbarus, Bennet 1833) in the area of El Ayoune (El Kala National Park, Algeria). — Plant species taken for food by the Barbary Deer were determined by direct observation during one year. On the basis of their chemical composition and phenological stage, the energy value of the grazed plant species has been expressed in stag-units as suggested by Brelurut et al. (1990). Results show that the more energygiving elements are plants from the herbaceous layer and the acorns of Cork Oak (Quercus suber). From the shrubby layer, the Strawberry-tree (Arbustus unedo) comes fi rst with an energy value comparable to that of green grass fodder, followed by Tree Heath (Erica arborea), Lentisc (Pistacia lentiscus) and Filaria (Phillyrea augustifolia) with energy values comparable to those of grass hays. The energy values of the other shrubby plant species are comparable with those of cereal straws ; they do not ensure but the needs for maintenance.

Application of n-alkanes as diet composition markers in grazing/browsing goats and sheep: effect of using different faecal recovery corrections and plant species grouping approaches

The present study aimed to test the effect of applying different sets of n-alkane faecal recoveries and different plant species grouping approaches on the estimates of the diet selected by goats and sheep when grazing/browsing complex vegetation communities composed of mosaics of heather-gorse vegetation interspersed with patches of perennial ryegrass. The use of different sets of n-alkane faecal recoveries significantly affected the estimated proportions of most vegetation components in both animal species. The diet estimates were also significantly affected by the calculation approach: A1 (using all individual plant species); A2 (grouping plant species with similar n-alkane profile, with equal weighting within the group); and A3 (grouping plant species with similar n-alkane profile, with different weighting according to the botanical composition of the plot). There was a significant interaction between calculation approach (A) and faecal recovery sets (FR) on the resulting estimates of the Ericaceae species in the diet of goats and of all diet components in sheep. When using A1 approach, the estimated proportion of Agrostis capillaris in the diets was high and seemed to be overestimated, compared with its low availability (1.1% of total cover) in the field. However, the application of calculation approaches A2 and A3 gave lower dietary proportions of component D2 (Agrostis capillaris and Ulex gallii) and higher proportions of components D1 (Lolium perenne and Pseudarrhenatherum longifolium), D3 (Erica umbellata, Erica cinerea, Erica australis, Calluna vulgaris) and Erica arborea. These results indicate that the application of the n-alkane technique for estimation of the diet composition in field with complex vegetation conditions is sensitive to the use of faecal recovery corrections and to the grouping of possible dietary components.