Chilean Temperate Rainforests Research Articles

From dark to darkness, negative phototropism influences the support-tree location of the massive woody climber Hydrangea serratifolia (Hydrangeaceae) in a Chilean temperate rainforest

ABSTRACT Climbing plants rely on suitable support to provide the light conditions they require in the canopy. Negative phototropism is a directional search behavior proposed to detect a support-tree, which indicates growth or movement away from light, based on light attenuation. In a Chilean temperate rainforest, we addressed whether the massive woody climber Hydrangea serratifolia (H. et A.) F. Phil (Hydrangeaceae) presents a support-tree location pattern influenced by light availability. We analyzed direction and light received in two groups of juvenile shoots: searching shoots (SS), with plagiotropic (creeping) growth vs. ascending shoots (AS), with orthotropic growth. We found that, in accordance with light attenuation, SS and AS used directional orientation to search and then ascend host trees. The light available to H. serratifolia searching shoots was less than that of the general forest understory; the directional orientation in both groups showed a significant deviation from a random distribution, with no circular statistical difference between them. Circular-linear regression indicated a relationship between directional orientations and light availability. Negative phototropism encodes the light environment’s heterogeneous spatial and temporal information, guiding the shoot apex to the most shaded part of the support-tree base, the climbing start point.

Geological History and Forest Mycorrhizal Dominance Effects on Soil Fungal Diversity in Chilean Temperate Rainforests

Geological History and Forest Mycorrhizal Dominance Effects on Soil Fungal Diversity in Chilean Temperate Rainforests

Assessing land surface phenology in Araucaria-Nothofagus forests in Chile with Landsat 8/Sentinel-2 time series

The Araucaria-Nothofagus forests are a unique ecosystem in temperate rainforests of Chile and Argentina. They include red-listed species and have a high cultural importance for the ancestral population and thus require continuous monitoring to support conservation. Monitoring of phenology by satellite observations is a key tool to quantify the impact of climate variability on terrestrial vegetation. Here we aim to provide a first quantification and ecological understanding of the land surface phenology of protected Araucaria-Nothofagus forests in the Conguillío National Park in southern Chile. We exploit time series of enhanced vegetation index from Landsat 8 and Sentinel-2 satellite imagery from 2016 to 2020 to derive start and end-of-season (SOS and EOS) information at 10 × 10 m spatial resolution. Results show that, on average, SOS varies between 11th October and 5th November (quantiles 25% and 75% of all pixels). SOS occurs later at higher elevation, in sparsely vegetated stands, or in stands dominated by Nothofagus antarctica. EOS occurs on average between 24th March and 14th April. EOS shows a high variability between neighboring pixels that cannot be easily associated with forest stands or topography. Comparisons with regional-aggregated temperature and precipitation time series show that SOS is delayed with colder winter and spring temperatures and EOS shows stronger (but contrasting) correlations with summer and fall precipitation. By using a machine learning approach, we find that elevation is the main control on the spatial-temporal variability of SOS and EOS, followed by aspect, slope and total tree cover. These results suggest that meteorological conditions control the inter-annual variability of the phenology of Araucaria-Nothofagus forests but the effect is modified by small-scale topography, climate and stand characteristics.

Genetic divergence and demography of pudu deer (Pudu puda) in five provinces of southern Chile, analyzed through latitudinal and longitudinal ranges

Pudu deer (Pudu puda) is endemic to the temperate rainforests of Chile. Genetic studies at different geographic scales for this species are required to better determine the genetic divergence within and among populations and their demography across the distribution range. These data can provide unique insights into the species or population status for conservation plans and decision-makers. We analyzed the mtDNA control region (CR) and cytochrome b (Cyt b) sequences of pudu deer in five provinces of southern Chile located at different latitudinal locations (Cautín, Valdivia, Osorno, Llanquihue and Chiloé Island) and three geographic areas within the studied provinces, representative of different longitudinal sites (Andes range, Central Valley and Coastal Range), to understand their genetic divergence and demography. The haplotype (H) and nucleotide (Π) diversities of CR and Cyt b ranged from 0.64286 to 0.98333 and from 0.00575 to 0.01022, respectively. CR diversity was significantly different among provinces, with Valdivia showing higher values than Llanquihue and Chiloé Island (H = 0.98333 vs. 0.64286–0.92727, P < 0.05). Cyt b variation also showed significant differences among provinces, particularly, among Cautín and Llanquihue (H = 1.000 vs. 0.222, P < 0.05). Genetic structuring among provinces was relatively high, as indicated by the FST index (FST = 0.41905). Clustering analysis indicated the presence of a distinctive cluster for Chiloé Island individuals. Fu’s FS and Tajima’s D based on CR revealed significant, negative deviations from equilibrium for Chiloé Island (D = -1.65898), Valdivia (Fs = -7.75335) and Llanquihue (Fs = -3.93267), suggesting population expansion in these provinces. Analysis at the longitudinal range showed significant differences among areas based on Π (P < 0.05), with the Andes range and Central Valley showing higher diversity than the Coastal Range. Neither population structuring (FST = 0.01360, P > 0.05) nor distinctive clusters in the longitudinal range were observed. Fu’s Fs and Tajima’s D were negative and significant for the Coastal Range based on CR (Fs = -6.64752, P < 0.001) and Cyt b (D = -1.74110, P < 0.05), suggesting the existence of population expansion. Our results suggest that pudu deer in the analyzed provinces is a genetically structured species, which could be associated with reduced panmixia among populations. The genetic divergence pattern and the population expansion recorded are likely to be associated with past processes of recolonization after Pleistocene glaciation events.

Latitude, paleo-history and forest size matter for Afromontane canopy beetle diversity in a world context

Tree canopies in forests host exceptional levels of biodiversity. However ecologists are still faced with vast regional gaps in need of fundamental information on the nature of tree canopy diversity. The southern Afrotemperate forests at the tip of Africa are ancient, existing today as a biogeographical string of natural remnants from long-past climate events. Their canopy arthropod fauna is scarcely known, but could provide insights into global canopy diversity patterns. As part of the broader Afromontane archipelago and southern hemispheric forests in general, they form part of the last and largest global gaps in canopy science. Here we ask how the canopy beetle diversity of these forests qualitatively and quantitatively compare with other forests around the world. We show that beetle species richness and richness per m2 are closer to temperate than tropical canopies. Estimates for beetle richness most closely matched the latitudinal equivalent Chilean temperate rainforests. However, feeding guild structure of beetles are closer in resemblance to tropical than temperate forest canopies, in line with expectations regarding the region’s paleo-history. The most diverse beetle families, Curculionidae, Staphylinidae and Chrysomelidae, were proportionately similar to both temperate and tropical forest canopies. We discuss the importance of latitude, paleo-history and forest size when considering canopy fauna in a global context.

Diversity and growth-effects of ectomycorrhizal fungi of a Nothofagus pumilio forest in the Andes of Southern Chile

Chilean temperate rainforests have unique climatic, edaphic and biotic conditions, constituting pre-industrial blueprint ecosystems. Mycorrhizal associations play a central role in the biogeochemical processes of these ecosystems´ functioning. Baseline forest ecology studies are necessary in order to better understand diversity patterns, specifically regarding mycorrhizal symbiosis. Therefore, here we described the vegetation characteristics and the mycorrhizal relationships of vascular plants in a Nothofagus pumilio forest. We also described, via morphological methods, the ectomycorrhizal diversity present in this forest. Additionally, we determined whether ectomycorrhizal inoculations confer positive growth effects on N. pumilio seedlings. We founded that from 46 described vascular plant species, 42 (91%) were associated with mycorrhizae and of these 33 (72%) were associated with arbuscular mycorrhizae (AM), two (the dominant trees N. pumilio and N. dombeyi ) were associated with ectomycorrhizae (EM), five were associated with ericoid mycorrhizae, two with orchid mycorrhizae, and four were non-mycorrhizal. Additionally, 26 EM species were detected of which 14 belong to Cortinarius . Finally, there were clear differences in the growth of N. pumilio seedlings inoculated with the ectomycorrhizal fungus Laccaria laccata compared to non-inoculated plants. We suggest that mycorrhizal fungi play a key role in seedling colonization of extreme environments such as the Andean treeline.

Functional land-use change effects on soil fungal communities in Chilean temperate rainforests

Functional land-use change effects on soil fungal communities in Chilean temperate rainforests

Factors affecting arbuscular mycorrhizal fungi of Chilean temperate rainforests

Factors affecting arbuscular mycorrhizal fungi of Chilean temperate rainforests

Correction to: The conservation value of tree decay processes as a key driver structuring tree cavity nest webs in South American temperate rainforests

South American temperate rainforests, a global biodiversity hotspot, have been reduced to nearly 30% of their original extent and most remaining stands are being degraded. Cavity-nesting vertebrate communities are dependent on cavity-bearing trees and hierarchically structured within nest webs. Evaluating the actual degree of cavity dependence (obligate, non-obligate) and the preferred attributes of trees by cavity nesters is critical to design conservation strategies in areas undergoing habitat loss. During three breeding seasons (2010–2013), we studied the cavity-nesting bird community in temperate rainforests of Chile. We found the highest reported proportion of tree cavity nesters (n = 29 species; 57%) compared to non-cavity-using birds for any forest system. Four species were excavators and 25 were secondary cavity nesters (SCNs). Among SCNs, ten species were obligate and 15 were non-obligate cavity nesters. Seventy-five percent of nests of SCNs were located in cavities produced by tree decay processes and the remaining 25% were in cavities excavated mainly by Pygarrhichas albogularis and Campephilus magellanicus. Nest web structure had a low dominance and evenness, with most network interactions occurring between SCNs and large decaying trees. Tree diameter at breast height (DBH) was larger in nest-trees (57.3 cm) than in available trees (26.1 cm). Cavity nesters showed a strong preference for dead trees, both standing and fallen (58% of nests). Our results stress that retaining large decaying and standing dead trees (DBH > 57 cm), and large fallen trees, should be a priority for retention in forest management plans in this globally threatened ecosystem.

Differentiating Structural and Compositional Attributes across Successional Stages in Chilean Temperate Rainforests

The landscape in the lowlands of south-central Chile is dominated by agricultural lands and forestry plantations of exotic species. Natural forests are restricted to successional forests, while old-growth forests are nearly absent. The lack of old-growth forests may deprive society from some ecosystem services. Both successional and old forests differ in their ecological functions and in the ecosystem services they can provide. To promote old-growth characteristics in successional forests, it becomes necessary to know which compositional and structural attributes differentiate forests along succession. We aim at identifying the differential attributes among successional and old-growth forests in the lowlands in the northern portion of the Valdivian Rainforests. We analyzed 19 variables in seven different forests and found statistically significant differences in 13 of them. A subset of these variables illustrated major patterns that differentiate successional stages, of which a few could be more easily controlled through management. The latter include lowering tree densities (from >3000 to <1500 trees per hectare), increasing volume of large trees, especially of shade-tolerant species, and structural heterogeneity (a Gini coefficient >0.7 represents older forests). While successional forest show a rapid recovery, forest managers would need to focus in controlling these attributes to increase their old-growth characteristics.

Effect of aluminium on mineralization of water extractable organic matter and microbial respiration in southern temperate rainforest soils

To date the effect of aluminium (Al) on carbon (C) mineralization has not been extensively studied in Chilean temperate rainforests. Here, we examine to what extent the C mineralization of water extractable organic matter (WEOM) and mineral Ah horizon are affected by differing molar ratios of Al and C (Al:C). It has been postulated that an increase in the concentration of Al in the soil solution does not affect the mineralization of WEOM and Ah horizon until a Al:C threshold is reached, at which point mineralization decreases. We hypothesized that dissolved organic C binds Al that is otherwise toxic to soil microorganism in the soil solution. Subsequently, the organic C remaining is mineralized or lost in water sheds. A microcosm experiment was designed where Al was added to WEOM or Ah horizon (0–8 mg L−1 or kg−1). Potential biodegradation was evaluated by trapping CO2 emitted during 15 days of incubation. Additionally, the amount of living fungal cells in the WEOM and microbial biomass of Ah horizon were quantified. The Al complexation was determined by selective dissolution, and characterized by infrared spectroscopy. In general, the carbon mineralization rates and the amount of fungal cells of WEOM were similar to that of the control (0 Al addition) when the Al:C ratio was <0.16. With increasing Al concentrations, mineralization was reduced up to 80%, accompanied by the formation of organo-mineral complexes, as indicated by infrared analysis. We conclude that Al exerts fine regulation on C availability necessary for microbial growth in both, WEOM and the Ah horizon.

Habitat use and sensitivity to fragmentation in America’s smallest wildcat

Fragmentation and human-wildlife conflicts represent severe threats to wildcats such as the kodkod cat (Leopardus guigna), endemic to the heavily impacted Chilean temperate rainforest. Here we assess to which extent this vulnerable forest specialist is able to use altered habitat (agricultural matrix, forest edge, human presence) by studying its home ranges, habitat use, and patch selection in privately owned rainforest remnants. We radio-tracked five individuals over 33–376days. Mean 95% kernel home ranges were 623ha, with a mean 50% core area of 191ha. Ecological-niche and Mahalanobis distance factor analysis confirmed forest-dependency and revealed that the individuals made intensive use of forest edges, close to water. They did not avoid houses. Generalized linear mixed models showed that the monitored kodkods selected elongated woodland patches. We conclude that the kodkods compensated the non-forest space by maintaining larger home ranges and making efficient use of forest edges probably due to higher prey availability. Future studies should identify ecological traps, and describe connectivity and source-sink dynamics in the agricultural matrix to develop long-term conservation efforts for the smallest cat of the Americas.

Light Environment Has Little Effect on Heteroblastic Development of the Temperate Rain Forest Tree Gevuina avellana Mol. (Proteaceae)

Premise of research. Heteroblastic species are those that show an abrupt change in shape and/or size among individual metamers during ontogeny. Gevuina avellana Mol. (Proteaceae) is a typical tree species in the temperate rain forests of Chile and Argentina. This tree shows drastic heteroblasty, changing from simple leaves at the seedling stage to pinnate leaves during development. It regenerates mostly in shady understories, but juveniles can be found growing under a wide range of light conditions (5%–50% canopy openness). Thus, considering that light has been proposed as a driver of the heteroblastic strategy, G. avellana is an interesting model to study the potential environmental modulation of its ontogenetically programmed heteroblasty. Therefore, the aim of this study was to determine the effect of light availability on G. avellana’s heteroblastic trajectory. We postulated that G. avellana’s ontogenetic changes in leaf complexity (i.e., heteroblasty) increase under high light availability.Methodology. Saplings along most of the light availability gradient were sampled. Plant height was used as a proxy for ontogeny. We measured several leaf traits (leaf area), shape (aspect ratio), pinnation (leaf dissection index), and complexity (fractal dimension index). First, we evaluated the change in each leaf trait with height by means of Pearson’s correlation. Then we tested for differences in leaf traits along the ontogeny between two light environments (higher and lower than 10% canopy openness) by the line-fitting standardized major axis method.Pivotal results. We found positive correlations between each leaf trait and plant height (P < 0.001), while only leaf size and complexity showed higher ontogenetic increases under high light.Conclusions. Light environment has a small but significant effect on the heteroblastic trajectory of G. avellana. In particular, saplings inhabiting microsites with high light availability have larger and more complex leaves. While allometry would explain the ontogenetic trajectory of leaf size, the increased complexity could reflect functional advantages for large leaves in tall plants, especially under high light conditions.

Cohort-specific tuning of foliage physiology to interacting stresses in evergreens.

Leaf economics spectrum is the basic concept linking leaf carbon gain strategies, fast vs slow turnover, to foliage functional traits (Wright et al. 2004). At the heart of the economics spectrum is the reverse correlation among traits responsible for leaf longevity and physiological activity; thus, high leaf longevity in evergreens is associated with traits improving leaf robustness such as high leaf dry mass per unit area and density reflecting enhanced biomass investment in support biomass (Wright et al. 2004). Increased support investments inevitably result in low photosynthetic capacity per dry mass placing evergreens towards the slow return end of the leaf economics spectrum (Wright et al. 2004, Reich 2014). The economics spectrum describes the basic co-variation patterns among leaf functional traits across plant functional types, but it does not implicitly consider several potentially confounding sources of variation such as leaf age (e.g., Niinemets 2014). Evergreens characteristically support multiple leaf age classes with potentially contrasting structural, chemical and physiological characteristics, but due to practical reasons, often only the leaves from the newest fully mature leaf flush are included in analyses involving evergreens. However, older leaves contribute a major proportion of total canopy leaf area in many evergreens (Whitehead et al. 1994, Niinemets et al. 2005), implying that age-specific differences in foliage performance play a major role in whole canopy carbon gain. While the basic age-dependent modifications in foliage functional traits have been studied in evergreens (Kitajima et al. 1997a, Radoglou and Teskey 1997, Ellsworth 2000, Niinemets and Lukjanova 2003, McGarvey et al. 2004, Niinemets et al. 2005), there is limited information on responses of different-aged leaves to environmental stresses with a few exceptions (e.g., Mulkey et al. 1992, Ogaya and Penuelas 2006). Many evergreen species also have a complex phenology of foliage development characterized by multiple foliage flushes during the same growing season. In this issue of Tree Physiology, the study of Morales et al. (2014) conducted in a Chilean temperate rain forest with the evergreen relatively shade-intolerant species Eucryphia cordifolia Cav. demonstrates that seasonality in environmental conditions can strongly affect foliage growth and development as well as physiological potentials of fully mature leaves. They observed major differences in leaf structural, chemical and physiological traits among leaf flushes produced during a given growing season (Figure 1, Morales et al. 2014). Such flush-specific differences in foliage characteristics have been observed in several warm temperate and subtropical conifers (Whitehead et al. 1994, Teskey 1997, Niinemets et al. 2002, McGarvey et al. 2004) and in evergreen angiosperms in climates with seasonal distribution of precipitation (Mulkey et al. 1992, Kitajima et al. 1997b), and collectively emphasize the importance of the timing of leaf flush in foliage functioning. The study of Morales et al. (2014) further found that differences among leaf cohorts in E. cordifolia were amplified in the low-light environment and under water stress (Figure 1). Although stress led to immediate physiological adjustments such as changes in stomatal conductance, the scaling among foliage physiological potentials (maximum carboxylase activity of Rubisco) and leaf nitrogen content was also altered (Figure 1). Such modifications in foliage functioning to stress during foliage growth suggest that the timing of leaf flush is an important driver altering the leaf economics spectrum in Commentary Tree Physiology Advance Access published November 25, 2014

Acclimation of leaf cohorts expanded under light and water stresses: an adaptive mechanism of Eucryphia cordifolia to face changes in climatic conditions?

Eucryphia cordifolia Cav. is a long-lived evergreen tree species, commonly found as a canopy emergent tree in the Chilean temperate rain forest. This species displays successive leaf cohorts throughout the entire growing season. Thus, full leaf expansion occurs under different environmental conditions during growing such as air temperature, vapor pressure deficit and the progress of moderate water stress (WS). These climate variations can be reflected as differences in anatomical and physiological characteristics among leaf cohorts. Thus, we investigated the potential adaptive role of different co-existing leaf cohorts in seedlings grown under shade, drought stress or a combination of the two. Photosynthetic and anatomical traits were measured in the first displayed leaf cohort and in a subsequent leaf cohort generated during the mid-season. Although most anatomical and photosynthetic pigments did not vary between cohorts, photosynthetic acclimation did occur in the leaf cohort and was mainly driven by biochemical processes such as leaf nitrogen content, Rubisco carboxylation capacity and maximal Photosystem II electron transport rather than CO2 diffusion conductance. Cohort acclimation could be relevant in the context of climate change, as this temperate rainforest will likely face some degree of summer WS even under low light conditions. We suggest that the acclimation of the photosynthetic capacity among current leaf cohorts represents a well-tuned mechanism helping E. cordifolia seedlings to face a single stress like shade or drought stress, but is insufficient to cope with simultaneous stresses.

Decadal trends in the pollinator assemblage of Eucryphia cordifolia in Chilean rainforests.

Long-term studies of plant-pollinator interactions are almost nonexistent in the scientific literature. The objective of the present study was to determine changes and trends in the pollinator assemblage of ulmo (Eucryphia cordifolia; Cunoniaceae), a canopy-emergent tree found in Chilean temperate rainforests. We assessed the temporal variability of the pollinator assemblage and identified possible modulators of the observed temporal shifts. We sampled insect visitors to the flowers of 16 individual trees of E. cordifolia during 10 consecutive flowering seasons (2000-2009), recording a total of 137 pollinator species with a mean number of species per year of 44. Only three pollinator species (2.2%) were recorded every year. Two bee species accounted for 50% of all insect visits to flowers. One bee species, Bombus dahlbomii (native), was dominant in one season, whereas Apis mellifera (exotic) dominated during the next season. These interannual shifts in population abundances presented first-order dynamics that were characterized by oscillations with a period of 2 years. Changes in the abundances of the dominant pollinators, as well as differences in temperature and precipitation during insect emergence and flowering, led to a nested temporal structure of pollinator composition. Furthermore, the abundances of less common pollinators were sensitive to the abundance of the dominant bee species and to monthly maximum temperatures and the average precipitation during spring and summer. Based on our results and those from other studies, we predict a decline in the numbers of Bombus dahlbomii and nondominant native pollinators in response to new exotic arrivals.

Bats of the Chilean temperate rainforest: patterns of landscape use in a mosaic of native forests, eucalyptus plantations and grasslands within a South American biodiversity hotspot

Forestry plantations represent about 4 % of the global land cover and demand for wood is steadily increasing worldwide. Impacts of forest plantations on biodiversity are controversial; forest plantations could positively influence biodiversity by producing a buffer zone between native forests and agriculture, while replacement of native forests with plantations could reduce biodiversity. Chile is one of the main producers of wood worldwide, and production is largely based on intensively managed monocultures of exotic tree species. Only a few studies have looked at the effects of forestry plantations on biodiversity in Chile, mainly focusing on pine plantations. The aim of this study was to characterize habitat use and richness of bats between native forests, eucalyptus plantations and grasslands in a biodiversity hotspot in southern Chile to determine how land use affects an important mammalian taxa. We found no difference in use or richness of bats in eucalyptus plantations versus native forests. Regional context within the larger Valdivian watershed (Andes, central valley, coastal range) had a stronger influence on bat activity and richness than land use type (native forest, plantation, grassland), with the Andean region being the most diverse and where most bat activity is concentrated. Our results suggest that the composition and structure of the surrounding landscape mosaic may be fundamental to determine the impacts of forestry and human land use on biodiversity.

Values, animal symbolism, and human-animal relationships associated to two threatened felids in Mapuche and Chilean local narratives

BackgroundThe Chilean temperate rainforest has been subjected to dramatic fragmentation for agriculture and forestry exploitation. Carnivore species are particularly affected by fragmentation and the resulting resource use conflicts with humans. This study aimed at understanding values and human-animal relationships with negatively perceived threatened carnivores through the disclosure of local stories and Mapuche traditional folktales.MethodsOur mixed approach comprised the qualitative analysis of 112 stories on the kodkod cat (Leopardus guigna) and the puma (Puma concolor) collected by students (9-14 years) from 28 schools in the Araucania region within their family contexts, 10 qualitative in-depth interviews with indigenous Mapuche people, 35 traditional Mapuche legends, and the significance of naming found in ethnographic collections.ResultsWe revealed a quasi-extinction of traditional tales in the current knowledge pool about pumas and kodkods, local anecdotes, however, were present in significant numbers. Values associated to both felids were manifold, ranging from negativistic to positive values. While pumas played an important role in people’s spirituality, negative mythological connotations persisted in kodkod stories. Four prominent relationships were derived: (1) Both felids represent threats to livestock, pumas even to life, (2) both felids are symbols for upcoming negative events, (3) pumas are spiritual creatures, and (4) kodkods are threatened by humans. Recommendations are provided for stimulating new ways of perceiving unpopular and threatened carnivores among those who live in vicinity to them.

Evaporative water loss, relative water economy and evaporative partitioning of a heterothermic marsupial, the monito del monte (Dromiciops gliroides)

We examine here evaporative water loss, economy and partitioning at ambient temperatures from 14 to 33°C for the monito del monte (Dromiciops gliroides), a microbiotheriid marsupial found only in temperate rainforests of Chile. The monito's standard evaporative water loss (2.58 mg g(-1) h(-1) at 30°C) was typical for a marsupial of its body mass and phylogenetic position. Evaporative water loss was independent of air temperature below thermoneutrality, but enhanced evaporative water loss and hyperthermia were the primary thermal responses above the thermoneutral zone. Non-invasive partitioning of total evaporative water loss indicated that respiratory loss accounted for 59-77% of the total, with no change in respiratory loss with ambient temperature, but a small change in cutaneous loss below thermoneutrality and an increase in cutaneous loss in and above thermoneutrality. Relative water economy (metabolic water production/evaporative water loss) increased at low ambient temperatures, with a point of relative water economy of 15.4°C. Thermolability had little effect on relative water economy, but conferred substantial energy savings at low ambient temperatures. Torpor reduced total evaporative water loss to as little as 21% of normothermic values, but relative water economy during torpor was poor even at low ambient temperatures because of the relatively greater reduction in metabolic water production than in evaporative water loss. The poor water economy of the monito during torpor suggests that negative water balance may explain why hibernators periodically arouse to normothermia, to obtain water by drinking or via an improved water economy.

Why so many apparently rare beetles in Chilean temperate rainforests?

Se calcularon curvas de abundancia de especies a partir de datos obtenidos por medio de nebulizacion de 52 arboles en bosques de Nothofagus (aproximadamente 46000 ejemplares) y 24 arboles en bosques de Araucaria araucana (aproximadamente 15000 ejemplares) en Chile. Los datos obtenidos no se ajustan a los modelos estandares de abundancia de especies, al igual que los datos obtenidos de bosques tropicales, existen muchas especies representadas por ejemplares unicos. La hipotesis de que los mencionados ejemplares unicos son erraticos y que se encuentran normalmente en otros arboles no fue aceptada, contrario a los bosques tropicales, los bosques de Nothofagus no son diversos y generalmente lo conforman una sola especie. El analisis de tres supuestos a partir de los modelos de equilibrio mas parsimoniosos, demostro que dichos modelos son falsos. Entre ellos, las observaciones de muestreo afectadas por sesgo, desequilibrio de la comunidad y la combinacion de datos procedentes de distintos estratos alimenticios con diferentes curvas de abundancia de especies, parecen ser suficientes para poder explicar la divergencia de los datos para las comunidades de coleopteros con alto numero de especies, a partir del supuesto de cualquier modelo de equilibrio. Hasta que estos tres factores se puedan tomar en cuenta y se pueda detectar divergencia residual, no existe necesidad de proponer mecanismos mas complejos para explicar dichos datos. Los valores estimados de alfa y Simson D estan estrechamente correlacionados al tamano de la muestra, lo cual afecta su valor como estimador de la diversidad biologica.