Search

In high-mountain habitats, summer frosts have negative consequences for plant fitness, therefore high-mountain plants have developed mechanisms of avoidance and tolerance to cope with freezing temperatures. Various hypotheses have been proposed to explain the prevalence of one freezing-resistance mechanism over another, focusing on thermal conditions without a consensus. We hypothesize that the prevalence of a freezing-resistance mechanism depends on the life-history strategy of the species, and is probably the consequence of a trade-off between growth/reproduction and the cost of the mechanism. Specifically, short-lived annual species should be freezing avoidant, whereas perennial long-lived species should be freezing tolerant. We used thermal analysis to determine the mechanism of freezing resistance of leaves and flowers for 10 annual and 14 perennial herb species from an alpine ecosystem in the Central Chilean Andes. We found that 70% of the annual species, their flowers and leaves were freezing avoidant, indicating that avoidance was their predominant freezing-resistance mechanism. In the case of perennial species, both mechanisms were almost equally represented in flowers and leaves. Overall, our results showed that a species freezing-resistance mechanism depends on its life-history strategy, and that leaves and flowers of single species exhibit the same freezing resistance mechanism, suggesting a common whole plant strategy. Further, freezing resistance strategies were not found to be mutually exclusive. In some cases, a specific combination of phenological, structural, and functional strategies may determine how freezing resistant vegetative and reproductive organs are to freezing during the growing season.

In high-mountain habitats, summer frost events can have negative consequences for plant fitness. Despite this, most studies have evaluated the consequences of frosts for vegetative structures of perennial plants, and neither for leaves nor for flowers of annual plants. We hypothesize that the degree of freezing resistance of flowers and leaves of a species depends on its life-history strategy (LHS), and is probably the consequence of a trade-off between growth/reproduction and the cost of the freezing resistance. Specifically, flowers and leaves of short-lived annual species should be less freezing resistant than those of perennial plant species. We compared the freezing resistance of flowers and leaves of 10 annual and 12 perennial plant species from the Andes of central Chile using the electrolyte leakage method. Temperature damage for 50% tissue (LT50) of annual species was − 9.6 °C in flowers and − 11.9 °C in leaves. In perennial species, LT50 was similar in flowers (− 12.3 °C) and leaves (− 12.5 °C). Despite that, these differences were not significant (except the flowers of annual species), we found remarkable differences between LHS when freezing resistance was analyzed species by species. Like this, 58% and 83% of perennial species resist temperatures ≤ − 10 °C in their flowers and leaves, respectively, compared with only 30% and 40% of annual species. Additionally, in most of the species, the freezing resistance of leaves was greater than that of flowers, with this proportion being greater in annual (58%) than in perennial species (43%). Thus, we concluded that the degree of freezing resistance depends on the LHS, such that annual species, which are less freezing resistant than perennial species, have an infrequent occurrence and a distribution restricted to low elevation in high-mountain habitats.

1. Plant functional traits impact the fitness and environmental niche of plants. Major plant functional types have been characterized by their trait spectrum, and the environmental and phylogenetic imprints on traits have advanced several ecological fields. Yet, very few trait data on epiphytes, which represent almost 10% of vascular plants, are available. 2. We collated 76,561 trait observations for 2,882 species of vascular epiphytes and compared these to non-epiphytic herbs and trees to test hypotheses related to how the epiphytic habit affects traits, and if epiphytes occupy a distinct region in the global trait space. We also compared variation in traits among major groups of epiphytes, and investigated the coordination of traits in epiphytes, ground-rooted herbs and trees. 3. Epiphytes differ from ground-rooted plants mainly in traits related to water relations. Unexpectedly, we did not find lower leaf nutrient concentrations, except for nitrogen. Mean photosynthetic rates are much lower than in ground-rooted plants and lower than expected from the nitrogen concentrations. Trait syndromes clearly distinguish epiphytes from trees and from most non-epiphytic herbs. 4. Among the three largest epiphytic taxa, orchids differ from bromeliads and ferns mainly by having smaller and more numerous stomata, while ferns differ from bromeliads by having thinner leaves, higher nutrient concentrations, and lower water content and water use efficiency. 5. Trait networks differ among epiphytes, herbs and trees. While all have central nodes represented by SLA and mass-based photosynthesis, in epiphytes, traits related to plant water relations have stronger connections, and nutrients other than potassium have weaker connections to the remainder of the trait network. Whereas stem-specific density reflects mechanical support related to plant size in herbs and trees, in epiphytes it mostly reflects water storage and scales with leaf water content. 6. Synthesis. Our findings advance our understanding of epiphyte ecology, but we note that currently mainly leaf traits are available. Important gaps are root, shoot and whole plant, demographic and gas exchange traits. We suggest how future research might use available data and fill data gaps. ISSN:0022-0477

The Andes of central Chile is a geographical gradient with a marked variation in its climatic conditions. Along its slopes, are distributed the evergreen Nothofagus dombeyi and deciduous Nothofagus pumilio species that show differences in their leaf habits, range extensions, and in their limits of latitudinal distribution. Plant ecology proposes that unfavorable climatic conditions are limiting factors that determine the tree species distributions and that the functional hydraulic traits responses allow understanding the mechanisms underlying the current distribution of them. We hypothesize that both species will have lower mean values of KL and KS in populations near to distribution limits compared with middle populations due that unfavorable climatic conditions are predominant in the latitudinal range limits. We quantify in situ the leaf (KL) and xylem (KS) specific hydraulic conductivities in populations of N. dombeyi and N. pumilio near their northern and southern limits of distribution as well as in a middle population along Chilean Andes. Results showed that both species had lower mean values in populations near northern and southern limits compared to populations distributed in middle sites. Also, we found that the hydraulic performance population of N. pumilio distributed in the middle site had higher than N. dombeyi. We concluded that lower hydraulic conductivity associated with distribution limits for both study species implies a lower probability of being affected by embolism, independently of their leaf habits, showing a functional hydraulic convergence to low water availability or cold.

Premise of research. Tolerance to herbivory is the capacity of plants to reduce the negative effects of damage on fitness. Increased growth rate and photosynthesis are two important mechanisms behi...

RESUMEN Los remanentes de los bosques esclerófilos mediterráneos costeros en Chile tienen una baja representatividad en el Sistema Nacional de Áreas Silvestres Protegidas, a pesar de su alto endemismo y riqueza de especies. En la Región del Biobío, la Estación de Biología Terrestre de Hualpén (EBT) conserva un remanente de este tipo de bosque, para el cual no existen revisiones que describan su flora, lo que dificulta la formulación y el desarrollo de estrategias para su protección y conservación. Este trabajo tiene como objetivos: a) describir la composición taxonómica de las plantas vasculares de la ETB y b) entregar información sobre su origen geográfico, hábito y estado de conservación. El listado florístico obtenido incluye tanto las especies determinadas a través del muestreo sistemático en el área de estudio durante un año, así como las especies de la EBT ingresadas en la colección del Herbario de la Universidad de Concepción. Se determinaron 294 especies de plantas vasculares de las cuales 71 son endémicas, 124 son nativas y 99 son introducidas. Desde el punto de vista florístico, la familia Asteraceae fue la má diversa con 36 especies, seguidas de Poaceae con 32 especies y Fabaceae con 18 especies. Las hierbas fueron el hábito de crecimiento más frecuente (77,2%), seguida de las categorías arbusto (13,9%), árbol (7,5%) y subarbustos (1,4%). Diecinueve especies endémicas y nativas han sido clasificadas en alguna categoría de conservación en Chile continental, destacando Gomortega keule y Pitavia punctata, ambas clasificadas como especies En peligro, y el helecho Asplenium trilobum catalogado bajo la categoría Preocupación menor en Chile y Vulnerable en la Región del Biobío. A pesar de la reducida superficie protegida en la EBT (70 ha), el lugar cuenta con una alta riqueza de especies nativas si se la compara con datos obtenidos en otros estudios de flora en sitios de Chile central.

Background: Functional traits related to water transport in plants, their variations and correlations can be related to the latitudinal range limits of tree species.Aims: We evaluated whether the variation and covariation of traits related to safety and efficiency in water transport in Nothofagus dombeyi could help to explain its climatic and geographic limits along the Chilean Andes.Methods: We quantified and correlated the intraspecific variations of leaf mass per area, wood density (WD) and leaf and xylem hydraulic conductivities in three populations of N. dombeyi near its northern and southern range limits and in its mid-latitudinal distribution.Results: N. dombeyi showed a considerable intraspecific variation in traits related to safety and efficiency of water transport. These traits showed functional restrictions both in the northern and southern distribution limits, where climatic conditions could be considered stressful. We found a negative covariation between safety and efficiency traits ...

Premise of research. Crassulacean acid metabolism (CAM), a photosynthetic pathway that evolved in response to aridity, is beneficial for plant species in arid and semiarid environments, with positive effects on plant fitness. However, since it implies a higher metabolic cost compared with that for C3 plants, its expression under moist conditions, where it might be less necessary, could have fewer positive or even negative effects on plant fitness. Variations of the effects of CAM expression under different moisture regimes have never been addressed. Our objectives were to determine whether there are such variations and, if so, their possible ecological and evolutionary implications.Methodology. We measured CAM expression (as nocturnal acidification, ∆H+) and moisture-related morphological leaf traits, estimating their impact on reproductive effort in two populations of Puya chilensis living under contrasting moisture regimes in a natural climatic gradient in central Chile. To evaluate the effects of the m...

The climbing habit is a key innovation in plants: climbing taxa have higher species richness than non-climbing sister groups. We evaluated the hypothesis that climbing plant species show greater among-population genetic differentiation than non-climber species. We compared the among-population genetic distance in woody climbers (8 species, 30 populations) and trees (7 species, 29 populations) coexisting in 9 communities in a temperate rainforest. We also compared within-population genetic diversity in co-occurring woody climbers and trees in two communities. Mean genetic distance between populations of climbers was twice that of trees. Isolation by distance (increase in genetic distance with geographic distance) was greater for climbers. Climbers and trees showed similar within-population genetic diversity. Our longevity estimate suggested that climbers had shorter generation times, while other biological features often associated with diversification (dispersal and pollination syndromes, mating system, size and metabolic rate) did not show significant differences between groups. We hypothesize that the greater population differentiation in climbers could result from greater evolutionary responses to local selection acting on initially higher within-population genetic diversity, which could be driven by neutral processes associated with shorter generation times. Increased population genetic differentiation could be incorporated as another line of evidence when testing for key innovations. This article is protected by copyright. All rights reserved

La variabilidad en atributos anatómicos de las plantas podría estar relacionada con las condiciones del medio donde ellas se desarrollan (bajas temperaturas, estrés hídrico, corta estación de crecimiento), y esta variabilidad reflejaría la capacidad de una especie de establecerse en hábitats que difieren en la disponibilidad de estas condiciones. Maihuenia poeppigii (Otto ex Pfeiff.) K. Schum. no sólo es una de las especies de la familia Cactaceae con distribución más austral de América, sino que además presenta poblaciones creciendo en un amplio rango altitudinal (aprox. desde 15 hasta 2.600 m s.n.m.), en donde el clima varía notablemente. Este estudio evalúa la variabilidad en atributos anatómicos del tallo, relacionados con la conducción del xilema (densidad, diámetro y conductividad hidráulica relativa de los vasos) y almacenamiento de agua (grado de suculencia del tallo y hojas), de tres poblaciones de M. poeppigii que se encuentran establecidas en un gradiente de altitud en la zona centro sur de Chile. Adicionalmente, se determinó la altura máxima de los cojines de forma de estimar el grado de exposición de estos al ambiente, considerando la variación en la altura de las plantas a mayores altitudes. El promedio de la densidad, diámetro y conductividad hidráulica relativa de los vasos varió significativamente entre las poblaciones de distinta altitud. Con el incremento en la altitud aumentó la densidad de vasos y disminuyó el diámetro y el aporte relativo de los mismos a la conductividad hidráulica. Asimismo, con el aumento en la altitud disminuyó la altura de los cojines y aumentó la suculencia de los tallos. La suculencia de las hojas no difirió entre las tres poblaciones. La variación encontrada en dichos atributos anatómicos refleja una estrategia diferencial en la utilización y almacenamiento del agua entre las poblaciones establecidas en el gradiente de altitud. Este patrón de respuestas funcionales puede explicar la capacidad de esta especie de cactácea de ocupar sitios inhóspitos que difieren en altitud.

The regeneration niche differentiation helps to explain plant coexistence and thus biodiversity. The study of the regeneration niche has been traditionally based on sexual recruitment, while overlooking clonal growth. Root suckering offers a successful alternative for local dispersal under suboptimal conditions for sexual reproduction. For light-limited forests, we hypothesized that: 1) root suckering would increase the regeneration niche towards high-light conditions in shade-tolerant trees and towards dark conditions in light-demanding species; 2) contrasting responses of survival and growth to light availability would explain niche differentiation of both suckers and saplings; and 3) distinct responsiveness to light among species and recruit-types would reflect differences in functional traits. We tested these hypotheses with two evergreen tree species that coexist in the temperate rainforest of southern South America: Embothrium coccineum (light-demanding) and Eucryphia cordifolia (shade-tolerant). We measured the light availability in two study plots above each recruit and along transects established in the understory. Niche selection, niche differentiation and changes in survival probability with light were inferred from the analysis of the light frequency distributions. We evaluated the effect of light on the relative volumetric change in stems over a 1-year period. Functional traits of leaves, stems, and crowns were measured in suckers and saplings growing under similar light conditions; these traits were then compared among size classes, recruit-types and species. Root suckering was the prevalent reproduction mode of both studied species, extending the light niche towards open microenvironments only during the earliest ontogenetic stages. The poor structural strength of the leaves and wood of small Eucryphia saplings explains its underuse of open microsites. Neither photosynthetic assimilation nor carbon subsidy can sustain Embothrium suckers at the shadiest microsites. Suckering proved to increase the persistence of Embothrium until advanced stages of forest succession, facilitating its coexistence with the late-successional Eucryphia. Our study emphasizes that clonal growth is essential to understand the dynamics of temperate rainforests.

Aim Habitat reduction in fragmented landscapes provides an opportunity to study the biogeographic patterns that drive changes in diversity in poorly studied metacommunities. In this study, colonization–extinction dynamics were indirectly evaluated through the analysis of the species–area relationship and the nestedness of vascular epiphytes and climbing plants in 30 swamp forest fragments. Location Coast of the Araucanía Region in Chile. Taxon Vascular epiphytes (16 species, mainly Pteridophytes) and climbing plants (15 species). Methods We used the database in Pincheira‐Ulbrich et al. (New Zealand Journal of Botany, 54, 2016, 458), where 904 trees were sampled and a total abundance of 41,097 fern fronds and 3,098 climbing stems were reported. For the species–area relationship, a simple linear regression model (SLR) and two models that consider the spatial autocorrelation of species richness among fragments, generalized least squares (GLS) and simultaneous autoregressive model (SAR), were compared. For the species nestedness, the nestedness measure based on overlap and decreasing fills (NODF) and weighted nestedness metric based on overlap and decreasing fill (WNODF) indexes were used on presence–absence and abundance matrices, respectively. These matrices were sorted by area size and distance from the largest fragment and then contrasted with the probability distribution of a randomized null model based on 10,000 simulations. Results The results showed that the area size had a significantly positive effect on epiphyte species richness, while spatial autocorrelation played a fundamental role in explaining the richness of climbing plants. Both metacommunities had a general nestedness structure in terms of species incidence, which was determined first by area size and secondly by isolation. Main conclusions Our results indicate that local colonization processes determined by species’ dispersal capacities could be the predominant mechanism for the spatial configuration of climbing plant species composition. On the other hand, selective extinction determined by patch size could characterize the spatial structure of epiphyte species’ composition.

Several interspecific studies have related functional traits to alien plant invasiveness. Few studies have explicitly addressed how intraspecific variation in functional traits influences alien plant distribution across environments. In an old-growth temperate rainforest, we evaluated alien plant distribution across the light gradient, its relationship with native plant diversity and abundance, and variation in functional traits related to light capture that could explain the ecological breadth of alien plant species across the light gradient. In addition, we estimated possible ecological and phylogenetic constraints to intraspecific variation in these functional traits. In sixty 8-m2 plots we recorded light availability together with richness and abundance of alien and native plant species. We measured in 14 alien plant species three functional traits (specific leaf area, chlorophyll content and root/shoot ratio) and calculated their coefficient of variation. We estimated ecological constraints by measuring correlations among traits that could limit functional responses to light. We assessed phylogenetic constraints by calculating the phylogenetic signal of those functional traits. Richness and abundance of alien plant species were positively associated with light availability, while abundance was negatively related to native plant species abundance. Dominance of alien species increased with light availability, but some of them were dominant even in the shade. Phenotypic variation of functional traits was positively associated with ecological breadth and dominance of alien plant species. We found little evidence of ecological or phylogenetic constraints on functional trait variation. Light availability and functional trait variation correlated with the distribution and dominance of alien plants in this temperate rainforest. Alien plant species showed considerable phenotypic variation in low light, which may facilitate colonization of the forest understory. This process would not be hindered by ecological or phylogenetic constraints. Intraspecific variation in functional traits can render insightful information on current and future alien plant distribution across environmental gradients.

In a Valdivian forest stand, we identified vascular plant species occurring as accidental epiphytes, and we determined the contribution of accidental epiphytism on their local abundance. Four species were found as accidental epiphytes, being the fern Blechnum mochaenum the species showing the higher abundance proportion as accidental epiphyte (40 %). Unexpectedly, individuals of this species occurring as accidental epiphytes did not differ in functional traits related to nutrient availability (LMA-leaf mass ratio- and leaf C/N ratio) from those that usually occur on the forest ground. As a shade tolerant and slow growing species, B. mochaenum apparently is not affected by the environmental restrictions of the epiphytic habitat.

The vertical distribution of Hymenophyllaceae species has been related to microenvironmental variations around host trees. We addressed the questions: Do the vertical microenvironmental conditions within forest stands of differing successional statuses vary significantly? Does the diversity of Hymenophyllaceae species differ between forest successional statuses? Are the vertical distribution and diversity of Hymenophyllaceae species related more to humidity or light availability? Are there any interspecific differences in the desiccation tolerance of these species which can be related to their vertical distribution? We characterized the microhabitat conditions (vapor pressure deficit [VPD], air relative humidity [RH], and light availability [PAR]) and the vertical distribution of Hymenophyllaceae species in host trees, in both a secondary forest and an old-growth temperate rainforest in Chile. Chlorophyll fluorescence was used to monitor the integrity of the photosynthetic apparatus during desiccation experiments. The stand basal area, tree height, and leaf area index were all significantly greater in the old-growth forest stands, but VPD, RH, and PAR showed no significant differences between the two forests. Both successional statuses showed the same amount of filmy fern species in terms of both abundance and diversity. In both successional statuses VPD and RH decreased while PAR increased with the height of the hosts. Regardless of the forest's age, abundance and diversity of filmy ferns were greater in microsites of greater humidity and less light availability. Desiccation tolerance differed significantly among Hymenophyllaceae species. The distribution pattern could be better explained by the specific microenvironmental requirements and desiccation tolerance rather than the forest's successional status.

The contemporary relegation of conifers mainly to cold or infertile sites has been ascribed to low competitive ability, as a result of the hydraulic inefficiency of tracheids and their seedlings' initial dependence on small foliage areas. Here it is hypothesized that, in temperate rainforests, the larger leaves of angiosperms also reduce self-shading and thus enable display of larger effective foliage areas than the numerous small leaves of conifers.This hypothesis was tested using 3-D modelling of plant architecture and structural equation modelling to compare self-shading and light interception potential of seedlings of six conifers and 12 angiosperm trees from temperate rainforests. The ratio of displayed leaf area to plant mass (LAR(d)) was used to indicate plant light interception potential: LAR(d) is the product of specific leaf area, leaf mass fraction, self-shading and leaf angle.Angiosperm seedlings self-shaded less than conifers, mainly because of differences in leaf number (more than leaf size), and on average their LAR(d) was about twice that of conifers. Although specific leaf area was the most pervasive influence on LAR(d), differences in self-shading also significantly influenced LAR(d) of large seedlings.The ability to deploy foliage in relatively few, large leaves is advantageous in minimizing self-shading and enhancing seedling light interception potential per unit of plant biomass. This study adds significantly to evidence that vegetative traits may be at least as important as reproductive innovations in explaining the success of angiosperms in productive environments where vegetation is structured by light competition.

En el bosque templado de Chile, el helecho Blechnum chilense se encuentra principalmente en lugares abiertos y soleados, mientras que el helecho Blechnum mochaenum esta restringido a lugares sombrios. En este estudio se evalua si ambas especies de Blechnum, de lugares abiertos y sombreados, se comportan de manera similar respecto de sus rasgos anatomicos y fisiologicos, y si existe diferencia en la correlacion entre estos rasgos. Se midio la tasa fotosintetica maxima (Amax), conductancia estomatica (gs), evapotranspiracion (E) y SLA (area foliar especifica) in situ en 20 individuos de cada especie de helecho. Adicionalmente, se estimo la densidad estomatica (SD), el indice estomatico (SI) y el tamano de los estomas en hojas de cada individuo muestreado. Blechnum mochaenum, la especies sombra-tolerante, presento menor SD, SI, Amax y E, y mayor tamano de estomas y SLA que B. chilense. Una frecuencia estomatica mayor podria resultar en una mayor tasa de intercambio de gases en los sitios abiertos para B. chilense. La fisiologia de las hojas de estas especies de helechos parece depender, en parte, de las caracteristicas estomaticas.

Light requirements and functional strategies of plants to cope with light heterogeneity in the field have a strong influence on community structure and dynamics. Shade intolerant plants often show a shade avoidance strategy involving a phytochrome-mediated stem elongation in response to changes in red : far red ratio, while shade-tolerant plants typically harvest light very efficiently. We measured plant size, stem diameter, internode and leaf lengths in randomly chosen saplings of 11 woody species differing in their shade tolerance in both a secondary forest and an old-growth temperate evergreen rainforest in southern Chile. We also recorded the irradiance spectrum and the diffuse and direct light availabilities at each sampling point. Significant differences were found for the mean light environment of the saplings of each species, which also differed in basal stem diameter, internode length and leaf length, but not in plant height. Both plant slenderness (plant height/stem diameter) and mean internode length increased with increasing light availability, but no relationship was found between any of these two traits and red : far red ratio. The change in plant slenderness with light availability was of lesser magnitude with increasing shade tolerance of the species, while internode change with light availability increased with increasing shade tolerance of the species. Shade tolerators afford higher costs (thicker stems and plants), which render more biomechanically robust plants, and respond more to the light environment in a trait strongly influencing light interception (internode length) than shade intolerant species. By contrast, less shade-tolerant plants afforded higher risks with a plastic response to escape from the understorey by making thinner plants that were biomechanically weaker and poorer light interceptors. Thus, species differing in their shade tolerances do differ in their plastic responses to light. Our results contribute to explain plant coexistence in heterogeneous light environments by improving our mechanistic understanding of species responses to light.

El pdf del artículo es la versión post-print., In the South American temperate evergreen rainforest (Valdivian forest), invasive plants are mainly restricted to open sites, being rare in the shaded understory. This is consistent with the notion of closed-canopy forests as communities relatively resistant to plant invasions. However, alien plants able to develop shade tolerance could be a threat to this unique forest. Phenotypic plasticity and local adaptation are two mechanisms enhancing invasiveness. Phenotypic plasticity can promote local adaptation by facilitating the establishment and persistence of invasive species in novel environments. We investigated the role of these processes in the recent colonization of Valdivian forest understory by the perennial alien herb Prunella vulgaris from nearby populations in open sites. Using reciprocal transplants, we found local adaptation between populations. Field data showed that the shade environment selected for taller plants and greater specific leaf areas. We found population differentiation and within-population genetic variation in both mean values and reaction norms to light variation of several ecophysiological traits in common gardens from seeds collected in sun and shade populations. The colonization of the forest resulted in a reduction of plastic responses to light variation, which is consistent with the occurrence of genetic assimilation and suggests that P. vulgaris individuals adapted to the shade have reduced probabilities to return to open sites. All results taken together confirm the potential for rapid evolution of shade tolerance in P. vulgaris and suggest that this alien species may pose a threat to the native understory flora of Valdivian forest. © 2010 Springer Science+Business Media B.V., OG wants to acknowledge financial support provided by the Spanish Ministry for Education and Science grants RASINV GL2004-04884-C02 02/BOS (as part of the coordinate project RINVE). A CSIC CONICYT collaborative grant to FV and EG contributed to the development of this study.

Question: Are vines light-demanding species? Location: Temperate evergreen rain forest of southern Chile (40139 0 S, 72111 0 W). Methods: In 45 plots of 25 m 2 distributed in treefall canopy gaps, secondary forest stands and oldgrowth forest (15 plots per light environment), all climbing and non-supported vines were counted and identified to species level, and canopy openness was quantified using hemispherical photographs. Vine abundance and diversity (species richness and Simpson’s index) were compared in the three light environments and similarity between vine communities was estimated using Jaccard’s similarity coefficient. We also determined the relationship between light niche breadth and local dominance at the species level. Results: In total there were 2510 vine individuals of 14 species. Canopy openness was significantly different in the three light environments. Species richness, diversity, community composition and density of vines were similar in treefall gaps, secondary and old-growth forest. Of the seven more common vine species, which accounted for 91% of all vines, three had even distribution, two were more abundant in the shaded understorey, and two had higher density in well-lit sites. Local dominance of vine species and niche breadth were not significantly associated. Conclusions: Our study in a temperate rain forest questions the widespread notion of vines as pioneer-like species, which may be a consequence of the abundance of some lianas in disturbed sites of tropical forests. Functional arguments are needed to justify a general hypothesis on light requirements of vines, which constitute a vast group of species.

In Chilean evergreen temperate forest, fern species of the genus Blechnum occur in diverse microhabitats in a light gradient. We hypothesized that differences in the habitat preferences of three co-occurring Blechnum species would be associated with differences in the magnitude of responses of light capture [chlorophyll (Chl) content] and use (photosynthetic capacity and performance) to light availability. We measured the abundance, chlorophyll content, photosynthetic capacity (A), and photosynthetic performance (chlorophyll fluorescence of photosystems I and II) of juvenile individuals of each species growing in different light levels in the field. While Blechnum magellanicum covers a broad light environments range, B. mochaenum is restricted to shade, and B. penna-marina occupies full sun sites. Despite significant interspecific differences in average total chlorophyll content, this trait did not differ among species along the light gradient. There was significant interspecific variation in both the mean value and the plasticity of Chl a:Chl b ratio and A to light availability. While B. penna-marina showed a flatter reaction norm (lower response) of Chl a:Chl b ratio to light availability than its two congeners, B. mochaenum showed a lower response of A to light availability. B. penna-marina and B. magellanicum individuals from open sites had higher light saturation points of the electron transport rate (ETR) of both photosystems (ETRLSP I and II) and photochemical quenching (qL and NA) than the shade restricted B. mochaenum. Additionally, non-photochemical quenching values for both photosystems (NPQ and ND) were higher in ferns species occurring in shaded sites. The adjustment of the photosynthetic capacity and performance to light availability appears to be an important mechanism of acclimation in these three Blechnum species that differ in their habitat preferences across a light gradient.

Question: Are differences in microhabitat preferences of co-occurring epiphytic Hymenophyllaceae species (filmy ferns) correlated with differences in ecophysiological responses to light availability and humidity in the host tree? Location: The Andean foothills in south-central Chile. Methods: We evaluated the distribution pattern of nine filmy fern species in microhabitats that differ in light availability and humidity in four host tree species. A DCA was developed to assess Hymenophyllaceae species microhabitat preference in terms of canopy openness (CO) and relative humidity. We assessed whether differences in chlorophyll content, maximum photochemical efficiency (Fv/Fm), photosynthetic capacity (Amax), evapotranspiration (E) and instantaneous water use efficiency (WUE) are consistent with any pattern. Results: CO and relative humidity differed significantly with height in the host trees. While CO increased with height in a host tree, relative humidity decreased. DCA analysis showed that filmy fern species distribution within and among trees was mainly explained by the relative humidity of the microhabitat. Chlorophyll content, chlorophyll a/b ratio, Amax and E differed significantly among filmy fern species. Amax and E were correlated with axis 1 scores from the DCA analysis. Conclusions: The vertical distribution and abundance of filmy fern species in Chilean temperate rain forest seems to be closely related to the different microhabitats offered by host trees. This pattern may reflect interspecific differences in ecophysiological traits related both to light availability and humidity. Our results suggest that humidity is the main environmental factor driving functional responses and habitat preferences of these filmy fern species.

Unlike other species of the genus Blechnum, the fern Blechnum chilense occurs in a wide range of habitats in Chilean temperate rainforest, from shaded forest understories to abandoned clearings and large gaps. We asked if contrasting light environments can exert differential selection on ecophysiological traits of B. chilense. We measured phenotypic selection on functional traits related to carbon gain: photosynthetic capacity (Amax), dark respiration rate (Rd), water use efficiency (WUE), leaf size and leaf thickness in populations growing in gaps and understorey environments. We assessed survival until reproductive stage and fecundity (spo- rangia production) as fitness components. In order to determine the potential evo- lutionary response of traits under selection, we estimated the genetic variation of these traits from clonally propagated individuals in common garden experiments. In gaps, survival of B. chilense was positively correlated with WUE and negatively correlated with leaf size. In contrast, survival in shaded understories was positively correlated with leaf size. We found positive directional fecundity selection on WUE in gaps population. In understories, ferns of lower Rd and greater leaf size showed greater fecundity. Thus, whereas control of water loss was optimized in gaps, light capture and net carbon balance were optimized in shaded understories. We found a significant genetic component of variation in WUE, Rd and leaf size. This study shows the potential for evolutionary responses to heterogeneous light environments in functional traits of B. chilense, a unique fern species able to occupy a broad successional niche in Chilean temperate rainforest.

Los musgos son plantas no vasculares poiquilohidricas, usualmente con algun grado de tolerancia a la desecacion. Los musgos dendroides tienen tejidos conductores que los hacen analogos a las plantas vasculares. Sin embargo, los estudios funcionales en estos musgos son escasos. Dendroligotrichum dendroides es un musgo dendroide que crece en Chile en el sotobosque del bosque templado, donde puede exponerse a sequia estival. En este trabajo se estudia la tolerancia a la desecacion y la capacidad de rehidratacion en D. dendroides de dos poblaciones con diferente precipitacion. Muestreamos plantas de la parte norte de su distribucion (Contulmo, Region de la Araucania; baja precipitacion), y de la parte sur en Katalapi (Region de Los Lagos; alta precipitacion). Se midio el contenido relativo de agua y la eficiencia maxima del PSII (Fv/Fm) en plantas expuestas a desecacion y rehidratacion. Las plantas de ambas poblaciones mostraron tolerancia a la desecacion y fueron capaces de recuperar el Fv/Fm luego de la rehidratacion. Sin embargo, la poblacion del norte perdio agua mas lento y recupero su Fv/Fm a valores mayores comparado con la poblacion del sur. La poblacion norte puede estar expuesta a periodos de sequia en verano. La poblacion del sur recibe lluvia durante todo el ano. Estas diferencias podrian atribuirse a adaptacion local a los distintos regimenes de precipitacion de cada sitio. Mas estudios se requieren para entender los mecanismos fisiologicos y bioquimicos que subyacen la tolerancia a la desecacion en D. dendroides.

BACKGROUND AND AIMS A long-running debate centres on whether shade tolerance of tree seedlings is mainly a function of traits maximizing net carbon gain in low light, or of traits minimizing carbon loss. To test these alternatives, leaf display, light-interception efficiency, and simulated net daily carbon gain of juvenile temperate evergreens of differing shade tolerance were measured, and how these variables are influenced by ontogeny was queried. METHODS The biomass distribution of juveniles (17-740 mm tall) of seven temperate rainforest evergreens growing in low (approx. 4 %) light in the understorey of a second-growth stand was quantified. Daytime and night-time gas exchange rates of leaves were also determined, and crown architecture was recorded digitally. YPLANT was used to model light interception and carbon gain. RESULTS An index of species shade tolerance correlated closely with photosynthetic capacities and respiration rates per unit mass of leaves, but only weakly with respiration per unit area. Accumulation of many leaf cohorts by shade-tolerant species meant that their ratios of foliage area to biomass (LAR) decreased more gradually with ontogeny than those of light-demanders, but also increased self-shading; this depressed the foliage silhouette-to-area ratio (STAR), which was used as an index of light-interception efficiency. As a result, displayed leaf area ratio (LAR(d) = LAR × STAR) of large seedlings was not related to species shade tolerance. Self-shading also caused simulated net daily carbon assimilation rates of shade-tolerant species to decrease with ontogeny, leading to a negative correlation of shade tolerance with net daily carbon gain of large (500 mm tall) seedlings in the understorey. CONCLUSIONS The results suggest that efficiency of energy capture is not an important correlate of shade tolerance in temperate rainforest evergreens. Ontogenetic increases in self-shading largely nullify the potential carbon gain advantages expected to result from low respiration rates and long leaf lifespans in shade-tolerant evergreens. The main advantage of their long-lived leaves is probably in reducing the costs of crown maintenance.

†Background and Aims While the climbing habit allows vines to reach well-lit canopy areas with a minimum investment in support biomass, many of them have to survive under the dim understorey light during certain stages of their life cycle. But, if the growth/survival trade-off widely reported for trees hold for climbing plants, they cannot maximize both light-interception efficiency and shade avoidance (i.e. escaping from the understorey). The seven most important woody climbers occurring in a Chilean temperate evergreen rainforest were studied with the hypothesis that light-capture efficiency of climbers would be positively associated with their abundance in the understorey. †Methods Species abundance in the understorey was quantified from their relative frequency and density in field plots, the light environment was quantified by hemispherical photography, the photosynthetic response to light was measured with portable gas-exchange analyser, and the whole shoot light-interception efficiency and carbon gain was estimated with the 3-D computer model Y-plant. †Key Results Species differed in specific leaf area, leaf mass fraction, above ground leaf area ratio, light-interception efficiency and potential carbon gain. Abundance of species in the understorey was related to whole shoot features but not to leaf level features such as specific leaf area. Potential carbon gain was inversely related to light-interception efficiency. Mutual shading among leaves within a shoot was very low (,20 %). †Conclusions The abundance of climbing plants in this southern rainforest understorey was directly related to their capacity to intercept light efficiently but not to their potential carbon gain. The most abundant climbers in this ecosystem match well with a shade-tolerance syndrome in contrast to the pioneer-like nature of climbers observed in tropical studies. The climbers studied seem to sacrifice high-light searching for coping with the dim understorey light.

La especie introducida Fallopia sachalinensis (F.Schmidt) Ronse Decr. es registrada por primera vez en el territorio chileno, naturalizada fuera de zona urbanas. Se entrega la descripción taxonómica, características ecológicas de la especie y de la población registrada, así como también la fotografía de ésta. Los especímenes fueron recolectados en ambos costados de la carretera que une la ciudad de Osorno con el aeropuerto Cañal Bajo de la misma ciudad (40°35'55''S; 73°03'50''W).

La especie introducida Fallopia japonica (Houtt.) Ronse Decr. es registrada por primera vez en Chile fuera de zonas urbanas. Se entrega descripcion y fotografia de esta especie, potencial invasora de areas silvestres protegidas. Los especimenes fueron colectados en la localidad de Coirentoso, borde del Parque Nacional Alerce Andino (41°27'11"S: 72°39'32"W).

Some epiphytic Hymenophyllaceae are restricted to lower parts of the host (< 60 cm; 10-100 μmol photons m(-2) s(-1)) in a secondary forest of Southern Chile; other species occupy the whole host height (≥ 10 m; max PPFD > 1000 μmol photons m(-2) s(-1)). Our aim was to study the photosynthetic light responses of two Hymenophyllaceae species in relation to their contrasting distribution. We determined light tolerance of Hymenoglossum cruentum and Hymenophyllum dentatum by measuring gas exchange, PSI and PSII light energy partitioning, NPQ components, and pigment contents. H. dentatum showed lower maximum photosynthesis rates (A max) than H. cruentum, but the former species kept its net rates (An) near Amax across a wide light range. In contrast, in the latter one, An declined at PPFDs > 60 μmol photons m(-2) s(-1). H. cruentum, the shadiest plant, showed higher chlorophyll contents than H. dentatum. Differences in energy partitioning at PSI and PSII were consistent with gas exchange results. H. dentatum exhibited a higher light compensation point of the partitioning of absorbed energy between photochemical Y(PSII) and non-photochemical Y(NPQ) processes. Hence, both species allocated energy mainly toward photochemistry instead of heat dissipation at their light saturation points. Above saturation, H. cruentum had higher heat dissipation than H. dentatum. PSI yield (YPSI) remained higher in H. dentatum than H. cruentum in a wider light range. In both species, the main cause of heat dissipation at PSI was a donor side limitation. An early dynamic photo-inhibition of PSII may have caused an over reduction of the Qa+ pool decreasing the efficiency of electron donation to PSI. In H. dentatum, a slight increase in heat dissipation due to acceptor side limitation of PSI was observed above 300 μmol photons m(-2)s(-1). Differences in photosynthetic responses to light suggest that light tolerance and species plasticity could explain their contrasting vertical distribution.

In Chilean evergreen temperate forest, fern species of the genus Blechnum occur in diverse microhabitats ranging from large gaps to heavily shaded understoreys. We hypothesised that differences in the ecological breadth of three co-occurring Blechnum species would be associated with differences in magnitude of ecophysiological responses to light availability. We quantified the field distribution of each species in relation to diffuse light availability (% canopy openness), and measured in situ variation in photosynthetic capacity (A), dark respiration (R (d)) and specific leaf area (SLA) across the light gradient. The response of SLA of each species was also evaluated in a common garden in two light conditions (understorey and forest edge). The three Blechnum species differed significantly in the range of light environments occupied (breadth: B. chilense > B. hastatum > B. mochaenum). Despite significant interspecific differences in average A and R (d), the response of these traits to light availability did not differ among species. However, there was significant interspecific variation in both the mean value and the plasticity of SLA to light availability, the species with least ecological breadth (B. mochaenum) showing a flatter reaction norm (lower response) than its two congeners. This pattern was also found in the common garden experiment. The adjustment of leaf morphology (SLA) to light availability appears to be an important mechanism of acclimation in these Blechnum species. The narrow range of light environments occupied by B. mochaenum may be at least partly attributable to its inability to display phenotypic plasticity in SLA to changes in light availability.

La reabsorcion de nutrientes desde tejidos senescentes es un aspecto importante en la economia de nutrientes de las plantas perennes, y una influencia relevante sobre la dinamica de nutrientes en los ecosistemas. Han sido poco exitosos los intentos de interpretar el significado adaptativo de la variacion en la reabsorcion de nutrientes, llevando algunos cientificos a enfatizar la necesidad de investigar las bases bioquimicas y fisiologicas de la reabsorcion. Una hipotesis sugiere que la reabsorcion esta controlada por el efecto sumidero dentro de la planta. De acuerdo a esta hipotesis, se esperaria que la proficiencia de reabsorcion tenga una correlacion positiva con la tasa de crecimiento. Dicho patron se esperaria no solo para comparaciones entre especies o poblaciones, sino tambien cuando se comparan individuos conespecificos creciendo a distintas tasas, o en estudios de la misma planta durante diferentes fases del ciclo anual de crecimiento. Medimos la variacion estacional de la concentracion de N y P en la hojarasca en cuatro especies arboreas del bosque valdiviano, poniendo a prueba la hipotesis del efecto sumidero. En las cuatro especies la concentracion de N y P muestra una marcada variacion estacional. Todas las especies mostraron una baja proficiencia de reabsorcion (alta [N] en hojarasca) en invierno, lo que esta de acuerdo con la hipotesis sumidero. Sin embargo, la mayoria de las especie presentaron una baja concentracion de N y P (alta reabsorcion) en otono. Dado que el declive otonal del crecimiento vegetativo deberia determinar un debil efecto sumidero, este resultado parece contrario a la hipotesis inicial

Climbing plants are a key component of rainforests, but mechanistic approaches to their distribution and abundance are scarce. In a southern temperate rainforest, we addressed whether the dominance of climbing plants across light environments is associated with the expression of ecophysiological traits. In mature forest and canopy gaps, we measured leaf size, specific leaf area, photosynthetic rate, and dark respiration in six of the most abundant woody vines. Mean values of traits and their phenotypic change (%) between mature forest and canopy gaps were predictor variables. Leaf size and specific leaf area were not significantly associated with climbing plant dominance. Variation in gas-exchange traits between mature forest and canopy gaps explained, at least partly, the dominance of climbers in this forest. A greater increase in photosynthetic rate and a lower increase in dark respiration rate when canopy openings occur were related to the success of climbing plant species. Dominant climbers showed a strategy of maximizing exploitation of resource availability but minimizing metabolic costs. Results may reflect phenotypic plasticity or genetic differentiation in ecophysiological traits between light environments. It is suggested that the dominant climbers in this temperate rainforest would be able to cope with forest clearings due to human activities.