Relict Forest Research Articles

Long‐term interactions between Mediterranean climate, vegetation and fire regime at Lago di Massaciuccoli (Tuscany, Italy)

Summary A Holocene sedimentary sequence from a coastal lake in the Mediterranean area (Lago di Massaciuccoli, Tuscany, Italy, 0 m a.s.l.) was sampled for pollen and microscopic charcoal analyses. Contiguous 1‐cm samples represent an estimated time interval of c. 13 years, thus providing a high‐resolution sequence from 6100 to 5400 cal. years bp. Just before 6000 cal. years bp, sub‐Mediterranean and Mediterranean forests were present together with fir (Abies alba), a submontane species that is today absent at low altitudes in the Mediterranean. A sharp vegetational change occurred after 6000 cal. years bp involving a drastic decline of Abies alba around the site. Time‐series analyses suggest that increased fire activity at this time caused a strong decline in Abies alba, a highly fire‐sensitive species. During 100 years of higher fire incidence, diverse (predominantly evergreen) forest communities were converted to low‐diversity fire‐prone shrub communities. Cross‐correlations reveal that fire during the mid‐Holocene hindered the expansion of holm oak (Quercus ilex), the most common tree species today in Mediterranean environments. While the factors that triggered the Holocene expansion of this species in the Mediterranean area are unclear, our results do not support the hypothesis that fire was key for holm oak expansion. Diatom analyses of the same sediment core provide an independent palaeoenvironmental proxy for palaeoclimatic reconstruction. A change in the eutrophy and salinity of the lake occurred just before 6000 cal. years bp, suggesting that a climatic shift towards aridity may have triggered the observed change in hydrology and possibly also in fire regime. Over the millennia fire has decisively contributed to the establishment of the present fire‐adapted vegetation type (macchia). Native fire‐sensitive species were displaced or repressed, and arboreal vegetation became less diverse. Combined ecological and palaeoecological data may help to assess possible future scenarios of biosphere responses to global change. Our results imply that the forecasted global warming and fire increase may trigger irrecoverable biodiversity losses and shifts in vegetational composition within a few decades or centuries at most. In particular, fire and drought‐sensitive vegetation types, such as the relict forests of Abies alba in the Apennines, seem particularly threatened by large‐scale displacement.

An inventory of forest relicts in the pastures of Southern Tibet (Xizang A.R., China)

An inventory of isolated tree stands surrounded by desert pastures in Southern Tibet (A.R. Xizang, China) revealed more than 50 sites with vigorous trees of Juniperus convallium Rehder & E.H. Wilson and Juniperus tibetica Kom and additional more than 10 records where juniper trees had been destroyed between 1959-1976. The tree stands are not restricted to any specific habitat, and occur within an area stretching 650 km westwards from the current forest border of Southern Tibet. The trees are religious landmarks of the Tibetan Buddhists. The highest trees were found at an elevation of 4,860 m. Vegetation records, rainfall correlations and temperature data collected by local climate stations and successful reforestation trials since 1999 indicate that forest relicts fragmented through human interference could regenerate if current cattle grazing and deforestation practices are halted. The drought line of Juniperus forests in Southern Tibet is approximately 200-250 mm/a. A first pollen diagram from Lhasa shows forest decline associated with the presence of humans since at least 4,600 yr BP. The currently degraded commons developed in the last 600 yr. To date, no findings of remains of ancient forests in the Central Tibetan Highlands of the Changtang have been reported.

On the seasonal effect of landscape structure on a bird species: the thorn-tailed rayadito in a relict forest in northern Chile

Forest bird species exhibit noticeable seasonal behavioral changes that might lead to contrasting effects of landscape pattern upon species abundance and performance. We assessed if the effect of patch and habitat attributes on the landscape use of thorn-tailed rayaditos (Aphrastura spinicauda), a forest bird in a relict patchy forest in northern Chile, varied temporally in association with changes in the behavior of individuals linked to breeding vs. non-breeding conditions. We also assessed the relationship between nest success and patch and habitat attributes, as nest success might be associated to the density rayaditos during the breeding season. We found that density of rayaditos was affected by patch size and functional connectivity but not by habitat structure and that the magnitude of the effect of patch size was greater during the non-breeding season, thus supporting the existence of a temporally variable effect of landscape pattern. Similarly, the nest success of rayaditos was positively affected by functional connectivity and negatively by structural connectivity. We hypothesize that these results emerged from the interaction among territorial behavior, resource limitation and predation risk. Despite the variable intensity of the effect of patch size upon density, however, this landscape attribute, in addition to connectivity, is essential for the persistence of rayaditos at this relict patchy forest landscapes.

Vegetation of Kilimanjaro: hidden endemics and missing bamboo

AbstractKilimanjaro has a large variety of forest types over an altitudinal range of 3000 m containing over 1200 vascular plant species. Montane Ocotea forests occur on the wet southern slope. Cassipourea and Juniperus forests grow on the dry northern slope. Subalpine Erica forests at 4100 m represent the highest elevation cloud forests in Africa. In contrast to this enormous biodiversity, the degree of endemism is low. However, forest relicts in the deepest valleys of the cultivated lower areas suggest that a rich forest flora inhabited Mt Kilimanjaro in the past, with restricted‐range species otherwise only known from the Eastern Arc mountains. The low degree of endemism on Kilimanjaro may result from destruction of lower altitude forest rather than the relatively young age of the mountain. Another feature of the forests of Kilimanjaro is the absence of a bamboo zone, which occurs on all other tall mountains in East Africa with a similarly high rainfall. Sinarundinaria alpina stands are favoured by elephants and buffaloes. On Kilimanjaro these megaherbivores occur on the northern slopes, where it is too dry for a large bamboo zone to develop. They are excluded from the wet southern slope forests by topography and humans, who have cultivated the foothills for at least 2000 years. This interplay of biotic and abiotic factors could explain not only the lack of a bamboo zone on Kilimanjaro but also offers possible explanations for the patterns of diversity and endemism. Kilimanjaro's forests can therefore serve as a striking example of the large and long‐lasting influence of both animals and humans on the African landscape.

The small mammal community of Mukogodo Forest, Kenya

AbstractSpecies richness and diversity of rodents and insectivores were investigated at relict forest patches of Mukogodo, Laikipia, Kenya using Sherman's live traps and pitfall traps. Two hundred and nineteen individuals were captured in 3021 trap‐nights. There were eleven species in two taxonomic groups, Rodentia and Insectivora. Two other rodent species were sighted but not captured. Thirteen bats belonging to four species (Epomophorous wahlbergi, Pipistrellus kuhlii, Scotophilus dingani and Nycteris thebaica) were opportunistically trapped using mist nets. Two of the four species accumulation curves for forest patches did not reach an asymptote. Species richness and diversity were highest at Kurikuri compared with other patches because of habitat variability. The results support the prediction that forest disturbance and degradation lead to an increase in generalist species as compared with specialists and highlight the importance of relict afromontane forests in the conservation of small mammals in Kenya.

Ilex Canariensis Poir. (Aquifoliaceae) Post-dispersal Seed Predation in the Canary Islands

Alien species have many negative effects on insular ecosystems worldwide. We investigated Ilex canariensis post-dispersal seed predation by introduced rats (Rattus spp.) in relict forests of the Canary Islands at different spatial scales: among microhabitats within the same forest, among forest types within the same island, and among different islands of the archipelago. Seed predation intensity was very high (>70%) in all cases considered, irrespective of the spatial scale. We did not find significant differences between forest interior, edges or gaps, as well as between different forest types in four islands of the archipelago. Comparatively low predation intensity was found in El Hierro island, where more than 50% of the seeds survived at the end of the experiment, while highest seed predation was observed in Tenerife island. It is concluded that post-dispersal seed predation by rats, due to its extent and intensity, could have an important effect on Ilex canariensis recruitment, especially in successional areas where this light tolerant tree can naturally establish.

Insemination, pregnancy and abortion rates in a population of <i>Glossina palpalis palpalis</i> (robineau-desvoidy) at a relict forest in the Southern Guinea Savanna, Nigeria

The female populations of Glossina palpalis palpalis were surveyed at the relict forest of River Kajim, Manchok, Nigeria with the objective of determining rates of fertility, types of reproductive losses and the constraints responsible for the reproductive losses. Nullipars constitutes 21.7% of the 272 females dissected. 80.2% of the 213 pars were at different stages of pregnancy; 32.5% had eggs and 20.3%, 17.5% 9.9% had 1st, 2nd and 3rd-instar larvae in their uteri, while 42 pars had empty uteri. Mean monthly pregnancy rates were 70.2 ± 0.03% (57.1%-100%), highest in the peak wet season (34.5%) (July-September) and low in both warm wet (10.6%) (October) and hot dry (11.8%) (February-March) seasons. Virgin females were generally scarce. Abortion, insemination failure and ovular blockage were the common reproductive abnormalities in the population, totaling 9.9%. The results indicate that nutritional and physical stress were the likely constraints to optimum productivity.Keywords: insemination, pregnancy, reproductive abnormality, G. p. palpalis, Southern Guinea SavannaTropical Veterinarian Vol. 23(1) 2005: 25-31

Los bosque relictos del noroeste de Perú y del suroreste de Ecuador

Los bosques relictos o fragmentos de bosque en las vertientes andinas Noroccidentales del Perú y Suroccidentales de Ecuador, son frágiles ecosistemas, que en el pasado fue un todo continuo. La importancia y singularidad de los bosques como «refugios» y hábitats con poca dinámica radica en su compleja diversidad florística y endemismos, consecuencia de su complicada topografía y ecología de sus hábitats. En este artículo introductorio se analizan 12 trabajos de investigación expuestos en el Taller sobre Bosques Relictos de la Vertiente Occidental Andina del Norte del Perú y Sur del Ecuador en mayo del 2004 en el X CONABOT, Trujillo-Perú. Aquí, los conocimientos sobre el tema son consolidados y actualizados, es así que los fragmentos de bosque suman más de 20 en el norte del Perú, enfatizando a dos de gran importancia: Bosque La Oscurana (Cajamarca) y Kañaris (Lambayeque). Así mismo, se determinan las relaciones entre los bosques relictos, analiza su dinámica, caracterización y como puede lograrse su conservación inmediata. Se plantean los aspectos cruciales para alcanzar la conservación de estos bosques remanentes: investigar y mostrar urgentemente su gran biodiversidad, subrayar el valor económico potencial de la fitodiversidad que poseen para la región y revalora su papel como áreas de captación de agua para los ríos que son fuente prioritaria para la agricultura y vida urbana en la costa.

La Oscurana (Cajamarca), un bosque relicto más para conservar en las vertientes occidentales andinas del norte del Perú

Se presenta un análisis de la composición florística, formas de vida, importancia y estrategias para la conservación de un bosque relicto de la Vertiente Occidental Andina del norte del Perú, descrito por primera vez y denominado La Oscurana (caserío El Nogal, distrito Bolívar, provincia San Miguel de Pallaques, Cajamarca; 6°90’S y 79°08’O, 2000-2800 m). El análisis preliminar incluye 85 familias, 169 géneros y 258 especies de plantas vasculares, de las cuales 15 familias corresponden a Pteridophyta y 70 a Magnoliophyta. En los ámbitos genérico y específico las Asteraceae son las mejor representadas de las Magnoliopsida y las Orchidaceae de las Liliopsida. Las formas de vida predominantes en cuanto a familia se reúnen en seis categorías: hierbas con 29 familias (34%), arbustos con 14 (16%), árboles con 9 (11%), trepadoras/lianas con 9 (11%), hierbas/arbustos con 7 (8%) y hierbas/epífitas con 5 familias (6%). Se encontró que además de albergar una diversidad excepcional y brindar utilidad económica local, muchas de las especies no están registradas en las vertientes occidentales andinas del norte y del sur. Por la importancia que posee y por ser uno de los últimos bosques relictos existentes, la conservación legal de éste frágil ecosistema es urgente. Se propone que debe ser declarada zona de protección o intangible y que su conservación debe ser integral, involucrando a científicos, Estado, gobiernos regionales, gobiernos locales y población.

Refugia, dispersal and divergence in a forest archipelago: a study of Streptocarpus in eastern South Africa

We describe a scenario of plant speciation across a relict forest archipelago in South Africa involving Pleistocene habitat expansion-contraction cycles, dispersal and adaptation to lower temperatures. This is the first population level study using molecular data in South African forests and has significant implications for conservation efforts in this area. Populations of the mesophytic forest floor herbs Streptocarpus primulifolius sensu lato and Streptocarpus rexii were sampled throughout their range in the naturally fragmented forests of eastern South Africa in order to investigate population genetic and phylogenetic patterns within the species complex, using nuclear microsatellites, nuclear ribosomal ITS (internal transcribed spacer) sequences and chloroplast genome sequences. S. primulifolius harbours high levels of genetic diversity at both the nuclear (mean HE = 0.50) and the chloroplast level (each population fixed for a unique haplotype). This is consistent with populations of these coastal species being Pleistocene relicts. In contrast, populations of S. rexii in cooler habitats at higher altitudes and lower latitudes harbour little or no nuclear genetic diversity (mean HE = 0.09) and most share a common chloroplast haplotype. The split of S. rexii from populations intermediate between the two species (S. cf. primulifolius) occurred between 0 and 0.44 million years ago according to the calibrated ITS phylogeny of the taxa. The low genetic diversity and homogeneity of S. rexii is congruent with this species having reached its current range during the Holocene. We found no evidence of monophyly of any of the taxa in this study, which we consider a consequence of recent evolution in a fragmented habitat.

Phytosociology ofFagus hayatae forests in Taiwan

We aimed to clarify the floristic composition and phytosociological characteristics of beech (Fagus hayatae) forests in Taiwan. An attempt was also made to compare the flora of theF. hayatae forest and adjacent evergreen forests and/or Japanese beech (F. crenata) forests using information from previous phytosociological studies.F. hayatae forests are confined to a small part of north-eastern Taiwan. Thus, sampling sites were designed to cover all the knownF. hayatae forests. A total of 23 releves were sampled and 163 species were recorded. The number of common species betweenF. hayatae forests and other forest ecosystems such as lower evergreen forests and Japanese forests were compared. Adjacent evergreen, broad-leaved forests in Taiwan consist of 29 common species withF. hayatae forests, while 57 component species ofF. hayatae forest were found common with the Japanese forests. A vegetation table was developed and one association (Yushanio-Fagetum hayatae Suzuki T. 1954, ex Hukusimaet al. 2004), with two subassociations and four variants were identified. In addition, a higher phytosociological unit was defined, in which the alliance Fagion hayatae Suzuki T. ex Hukusimaet al., the order Fagetalia hayatae nov.; and the class Fagetea crenatae Miyawaki, Ohba et Murase, 1964 were identified and/or proposed.F. hayatae forests in Taiwan distribute mainly on the summit and ridge part of the north-eastern mountains and were considered relict forest.

Fire regime in a conservation reserve in Chihuahua, Mexico

Fire regime characteristics were reconstructed from fire-scarred trees in the Tutuaca reserve, a newly designated protected area in the Sierra Madre Occidental of western Chihuahua. The reserve was created to protect thick-billed parrot nesting habitat (large snags) and a relict forest of Chihuahua spruce (Picea chihuahuana Martínez). We collected fire-scarred samples from conifers (Pinus ayacahuite Ehrenb., Pinus durangensis Martínez, and Pseudotsuga menziesii (Mirb.) Franco) in three 25-ha sites arrayed at different watershed positions, from a low site adjacent to the spruce trees up to the watershed divide. Fire analysis periods began in 1702, 1704, or 1761 and continued through the final fire in 1955 (two sites) or 1995. All sites had frequent fire regimes (mean fire interval (MFI) 3.9–5.2 years; MFI for years in which 25% or more of the samples were scarred: 6.9–8.4 years). Almost all fires occurred before cambial growth began or early during the season of cambial growth. Fire years were significantly dry, and the years immediately preceding fire were significantly wet. After 1955, no further fires occurred at two of the three study sites, a pattern similar to that observed elsewhere in northern Mexico. The third site had fires in 1987 and 1995. The extended fire-free period in portions of the Tutuaca landscape may result in fuel accumulation and eventually in severe wildfire. For effective conservation of fire-susceptible habitat features, managers should seek to incorporate surface fire as a management tool.

TREES BY THE SEA: ADVANTAGES AND DISADVANTAGES OF OCEANIC CLIMATES

Proximity to the ocean can have both positive and negative effects for tree survival. Across the world relict forests that were once trans-continental in their distribution depend for their continued survival on coastal refugia. The tree species that dominate the cloud-zone forests of Macaronesia, the coastal redwoods of California, the Atlantic forests of Brazil, and the Podocarp forests of New Zealand's South Island are all examples of palaeoendemic species that once had a much wider distribution and appear to owe their survival to the particular environmental conditions provided by coastal sites and oceanic islands. By contrast, in the islands of the North Atlantic, oceanic conditions appear to limit tree regeneration and make forests vulnerable to human disturbance. Paradoxically, winter warmth appears to be harmful to trees in northern cool and moist oceanic conditions. There may be many reasons why the warm winters of maritime environments can be detrimental for woody species. Insect attack, pathogenicity and metabolic dysfunction with loss of frost hardiness and over-wintering carbohydrate reserves are all possibilities. Where long, mild winters are combined with wet soil conditions, metabolic dysfunction brought about by prolonged periods of oxygen deprivation can deplete root meristems of carbohydrate reserves that are essential for avoiding postanoxic injury when the soil profile once again becomes aerated in spring. In areas where the temperature remains below zero for the greater part of the winter, this is not a danger. However, in oceanic habitats there is always the risk, even in the far north, of temperatures rising above zero. Model predictions and field observations confirm the potential dangers of warm winters by suggesting that any significant degree of winter warming will cause a retreat of Pinus sylvestris and other woody species from oceanic regions at northern latitudes.

Trees by the Sea: Advantages and Disadvantages of Oceanic Climates

Proximity to the ocean can have both positive and negative effects for tree survival. Across the world relict forests that were once trans-continental in their distribution depend for their continued survival on coastal refugia. The tree species that dominate the cloud-zone forests of Macaronesia, the coastal redwoods of California, the Atlantic forests of Brazil, and the Podocarp forests of New Zealand's South Island are all examples of palaeoendemic species that once had a much wider distribution and appear to owe their survival to the particular environmental conditions provided by coastal sites and oceanic islands. By contrast, in the islands of the North Atlantic, oceanic conditions appear to limit tree regeneration and make forests vulnerable to human disturbance. Paradoxically, winter warmth appears to be harmful to trees in northern cool and moist oceanic conditions. There may be many reasons why the warm winters of maritime environments can be detrimental for woody species. Insect attack, pathogenicity and metabolic dysfunction with loss of frost hardiness and over-wintering carbohydrate reserves are all possibilities. Where long, mild winters are combined with wet soil conditions, metabolic dysfunction brought about by prolonged periods of oxygen deprivation can deplete root meristems of carbohydrate reserves that are essential for avoiding post anoxic injury when the soil profile once again becomes aerated in spring. In areas where the temperature remains below zero for the greater part of the winter, this is not a danger. However, in oceanic habitats there is always the risk, even in the far north, of temperatures rising above zero. Model predictions and field observations confirm the potential dangers of warm winters by suggesting that any significant degree of winter warming will cause a retreat of Pinns sylvestris and other woody species from oceanic regions at northern latitudes.

Spatial patterns of past wood exploitation, natural wood supply and growth conditions: indications of natural tree species distribution by anthracological studies of charcoal-burning remains

In close-to-nature silviculture one strives to derive the advantages of the natural adaptations of tree species to different growth conditions. Evidence of the natural distribution of tree species is obtained through vegetation science (recent ground vegetation, primeval forest relicts), studies of old written sources, and pollen and macrofossil analyses. Here we have analysed macrofossil samples of charcoal kiln sites and the recent ecological conditions in the vicinity of these sites, as well as secondary written sources on forest and land-use history. From charcoal analysis of kiln sites we were looking for spatial patterns of past tree species exploitation, with special regard to regional and local differences in the forest growth conditions and the natural wood supply. Therefore, we selected remote forest areas characterised by a high density of kiln sites and significant differences in the ecological conditions. The sample sites ranged over a landscape profile of 40 km, covering many ecological site types. The anthracological results of 181 post-medieval kiln sites were evaluated, considering two spatial scales: the total 40-km profile and a fine-scale profile of 4 km. Considering the charcoal material analysed as a whole, all of the tree taxa to be expected based on the natural conditions were found. The frequencies of the exploited taxa also reflected a natural situation. Wood of the climax vegetation, Fagus, Abies and Picea, was mainly used and all other taxa were quantitatively unimportant. The results for the individual sites showed considerable differences in taxa composition, from which regular spatial patterns of the past tree species distribution were deduced. These regional and local patterns are explained by natural differences in the ecological conditions in the vicinity of the sample sites. At the same time, new indications of the natural tree species composition of our forests are inferred. A pronounced dependency of charcoal production on the local natural wood supply is discernible. No indications of tree species selection or forest degradation could be found.

Effects of forest fragmentation on the beetle assemblage at the relict forest of Fray Jorge, Chile.

Habitat fragmentation is recognized as one of the main factors associated with species extinction and is particularly acute in South American forest habitats. In this study, we examined the effects of forest fragmentation on the beetle assemblage at the relict temperate forest of Fray Jorge (Chile). We evaluated the following hypotheses: (1) there is a strong edge effect, so that the number of beetle species and individuals increases away from the edge, towards the inner part of each fragment, (2) this pattern should be apparent in the larger fragments but not in the smaller ones, where edge effects are expected to be stronger, and (3) there should be a significant interaction between number of species/individuals found inside and outside fragments (i.e., in the matrix) and season, because of an increase in aridity and water stress during austral summer months. We found that the relationship between the number of individuals and number of species vs distance from the matrix towards the forest interior was affected by fragment size and season. In general, both number of species and individuals tended to increase from the matrix towards the forest edge and then either decrease, increase or maintain a constant level, depending on fragment size and season. The result of an ANOVA analysis, which used season, size, and position (inside vs outside fragments) as factors and number of individuals as the response variable, showed a significant effect of fragment size, position, and season and a significant interaction between fragment size and season, season and position, and size and position. ANOVA analysis using number of species as the response variable showed that area, season, and position all had significant effects. The results also showed a significant interaction between size and season and between season and position. Our results emphasize the existence of strong fragment-size and seasonal effects modulating both the response of beetles to fragmentation and their abundance and distribution in temperate areas. Thus, seasonal dynamic effects can be of paramount importance to demonstrate and understand the effect of habitat fragmentation upon arthropod assemblages in temperate areas.

Seedling bank dynamics of Fagus grandifolia var. mexicana before and after a mast year in a Mexican cloud forest

Abstract. Fagus grandifolia var. mexicana seedling dynamics were studied in a relict forest inside the crater of a volcano where it is the only canopy tree species. The objectives of the study were (1) to determine changes in seedling density before and after a mast year, as well as to monitor seedling recruitment, mortality and growth rate in relation to the micro‐environment, and (2) to discuss the impact of masting on seedling dynamics of the population. Before masting, seedling density was 8.8 seedlings m–2, afterwards seedling density peaked at 51.5 seedlings m–2, then decreased by 50% in 3 months and by 85% after 8 months, down to levels of before the mast year (9.9 seedlings m–2) after 16 months. Seedlings in the forest floor before the mast‐seeding event showed a low relative growth rate – 0.14 mm mm–1 mo–1 against 1.27 mm mm–1 mo–1 for seedlings that emerged immediately after masting. Seed germination was high (83%) and rapid (L50= 7 days) following masting. Seedling growth was positively correlated with soil water content but not with temperatures and relative humidity. Data suggested that seed production in mast years is important in maintaining the seedling bank, and thus the viability of relict Fagus populations.

Conservation of temperate forest birds in Chile: implications from the study of an isolated forest relict

We characterize the bird assemblage of an isolated relict temperaterainforest (Santa Ines) in terms of its structure, composition anddynamics. The relict character and long-term isolation of this forest remnant,immersed in a matrix of semiarid scrub, provide a natural experiment to assessthe consequences of long-term isolation and forest area reduction for temperatebird species. Bird surveys were conducted in a forest fragment and thesurrounding scrub matrix between April 1999 (austral autumn) and October 2000(austral spring) on a seasonal basis. Within the forest fragment wedistinguished two microhabitat types: creeks and areas far from creeks (i.e.slopes). A total of 36 species were recorded in the study site, of which 21were inside the relict forest. Highest bird abundance and richness wererecorded during winter and spring, and these were always higher in creek plotsrather than slope plots. Comparisons between this assemblage and thosedistributed in the continuous temperate forest (located more than 900km southwards) indicate that this bird assemblage shares moresimilarities, with regard to bird species composition, to southern temperateforest localities and to other relict forests, than to nearer scrub habitats.However, there are eight species, endemic to temperate forests in southern SouthAmerica, missing from our system. In this regard, our analyses indicate thatthese eight endemic species should be of great conservation concern and willlikely be the ones that will go extinct first if the fragmentation of thetemperate forest continues.

Phylogeny and Biogeography of the Flowering Plant Genus Styrax (Styracaceae) Based on Chloroplast DNA Restriction Sites and DNA Sequences of the Internal Transcribed Spacer Region

Phylogenetic relationships within the flowering plant genus Styrax were investigated with DNA sequence data from the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA) and with chloroplast DNA restriction site data from the genes trnK, rpoC1, and rpoC2. The data sets from each genome were analyzed separately and in combination with parsimony methods. The results strongly support the monophyly of each of the four series of the genus but provide little phylogenetic resolution among them. Reticulate evolution may at least partly explain discordance between the molecular phylogenetic estimates and a prior morphological estimate within series Cyrta. The historical biogeography of the genus was inferred with unweighted parsimony character optimization of trees recovered from a combined ITS and morphological data set, after a series of combinability tests for data set congruence was conducted. The results are consistent with the fossil record in supporting a Eurasian origin of Styrax. The nested phylogenetic position of the South American members of the genus within those from southern North America and Eurasia suggests that the boreotropics hypothesis best explains the amphi-Pacific tropical disjunct distribution occurring within section Valvatae. The pattern of relationship recovered among the species of section Styrax ((western North America + western Eurasia) (eastern North America + eastern Eurasia)) is rare among north-temperate Tertiary forest relicts. The monophyly of the group of species from western North America and western Eurasia provides qualified support for the Madrean–Tethyan hypothesis, which posits a Tertiary floristic connection among the semiarid regions in which these taxa occur. A single vicariance event between eastern Asia and eastern North America accounts for the pattern of relationship among intercontinental disjuncts in series Cyrta.

Effect of browsing by ungulates on sapling growth of Scots pine in a Mediterranean environment: consequences for forest regeneration

The impact of mammalian herbivory on Scots pine ( Pinus sylvestris L.) sapling performance was quantified in three native forests located in two Mediterranean mountains, the Sierra Nevada and Sierra de Baza (SE Spain). More than 98% of the damage to terminal shoots was caused by goats and Spanish ibex in Sierra Nevada and sheep in Sierra de Baza. Some 72% of the tagged saplings ( n = 619) were browsed during at least 1 year of monitoring (1995–1997). There were between-forest differences in herbivory pressure. Moreover, the herbivory pressure was significantly higher during a dry year (1995) than during wet ones (1996 and 1997). Overall, when browsing a sapling, ungulates consumed almost 30% of its apical shoots, and 85% of saplings were browsed more than once after establishment. As a consequence, ungulates severely affected the Scots pine sapling growth rate, and therefore browsed saplings grew slower than saplings unbrowsed by ungulates. Thus, according to exponential growth equations, the time necessary to attain a height threshold to escape from mammalian herbivores (150 cm height in our study forests) and start reproduction was retarded by the herbivory up to 12 years. Ungulates are a major factor hindering the natural regeneration and conservation of the last relict forests of Scots pines in SE Spain.