Valdivian Rainforest Research Articles

Factors Driving Unexpected Drought-Induced Nothofagus dombeyi Mortality in a Valdivian Temperate Rainforest, Argentina

Understanding the drivers of drought-induced tree mortality remains a significant scientific challenge. Here, we investigated an unexpected mortality event of Nothofagus dombeyi (Mirb.) Oerst. following the 2014–15 drought in a Valdivian rainforest, Argentina. Our focus was on long-term growth trend differences between vital and dead trees, and how the mixing of species in tree neighbourhoods drives tree growth during drought. The inter-annual variation of basal area increments of vital and 2014–15-dead N. dombeyi trees showed a similar pattern through the 1930–2015 period, while the climate–growth relationships indicated that precipitation during the growing season promoted growth in both vitality classes, regardless of whether they were in the wettest location. For the period 1990–2015, both vitality classes showed similar estimated growth regardless of competition level, whereas species mingling in the neighbourhood significantly affected the dead tree growth. Network analysis revealed that drought performance covaried positively with a neighbourhood dominated by species functionally different from the focal species only in vital trees. These findings suggest a nuanced response of N. dombeyi to drought, shaped by multifaceted interactions at both the individual tree and neighbourhood levels. This research underscores that species-specific relationships under different mixtures imply different tree responses within a stand, and add complexity to understanding drought response at the individual level.

Development of a temperate rainforest zonation on the Pacific slopes of the North Patagonian Andes since ∼18 ka

Few studies along the western slopes of the Andes in Northwestern Patagonia (NWP: 40°-44°S) allow examining vegetation development through environmental gradients in latitude and elevation along a time continuum since the Last Glacial Termination (T1, ∼18-11 ka). This complete biostratigraphic context is necessary for assessing the sequence, timing, rates, and direction of compositional/structural changes of the former vegetation, and for deciphering their environmental drivers. Here we report palynological results from two NWP sites spaced ∼22 km apart on the western Andean slopes, Caleta Puelche roadside section located near sea level and Lago Reflejos at mid elevations (∼800 m a.s.l.) and assess their continuous records since local ice-free conditions against other NWP sites. We find that cold-tolerant early successional trees dominated the initial stages of vegetation development in the Seno Reloncaví lowlands (∼18-17 ka), followed by thermophilous shade-tolerant North Patagonian rainforest (NPRF) trees, which achieved their maxima between ∼17 and 15 ka at low-elevations. A spread of cold- and shade-tolerant hygrophilous NPRF conifers ensued (∼14.8-13 ka) reaching similar magnitude at low- and mid-elevations, interrupted by increases in trees favored by canopy fragmentation linked to fire and explosive volcanism (∼13-11 ka). Thermophilous, shade-intolerant, summer-drought tolerant Valdivian rainforest (VRF) trees increased and achieved maxima between ∼10 and 8 ka, most notably in the lowlands, coeval with peak abundance of the NPRF conifers Fitzroya/Pilgerodendron and Podocarpus nubigena in mid-elevation Lago Reflejos, contemporaneous with their virtual disappearance near sea level. Widespread increases in cold-tolerant hygrophilous NPRF trees occurred after ∼8 ka, followed by mixing of NPRF and VRF elements in the lowlands after ∼6.3 ka with centennial-scale alternations. Inter-site and regional coherences of our findings suggest that variations in Southern Westerly Wind influence, along with disturbance regimes of natural and human origin, have driven the composition, structure, dynamics, and zonation of temperate rainforests in NWP since T1. We observe that Lago Reflejos features the highest abundance of Fitzroya cupressoides at regional scale since ∼12 ka, attesting to the importance of mid-elevation Andean environments for the persistence of these highly valued trees in the context of postglacial climate evolution, shifts in fire regimes, volcanic, and human disturbance in NWP.

Abundance and distribution of plant derived leaf waxes (long chain n-alkanes & fatty acids) from lake surface sediments along the west coast of southern South America: Implications for environmental and climate reconstructions

Southern South America is the only large landmass that extends through the core of the Southern Westerly Winds (SWW), controlling hydrological and ecosystem variability in the region. In fact, the vegetation along the west coast changes from Temperate and Valdivian Rain Forest to the North Patagonian Evergreen Forest (ca. 42°S) due to the latitudinal influence of the SWW. Climate is an important driver of organic matter accumulation in lakes, hence changes in vegetation would be recorded in lacustrine sedimentary archives. This study evaluated leaf waxes contained in lake surface sediments as indicators of climate change along the west coast of southern South America, providing a biogeochemical dataset for ongoing and future (paleo)climate and environmental research. The fatty acid and n-alkane sediment leaf wax datasets are compared with latitudinal, orographic, and climatic (Mean Annual air Temperature [MAT] & Precipitation [MAP]) trends extracted from a monthly gridded reanalysis product of the Climate Forecast System Reanalysis. Fatty acids are more abundant than n-alkanes, with high abundances characterizing the transition between seasonal and year-round precipitation along the coast (ca. 42°S). The abundance of both leaf wax groups increases with MAP, suggesting precipitation as the main control on sedimentary leaf wax delivery to the lake sediments in the study area. The Carbon Preference Index (CPI) of the two groups show opposite trends, but both highlight the climate transition at ca. 42°S, and have a linear relationship with MAP. The opposite significant trends between n-alkane CPI and fatty acid CPI with MAP are interpreted as higher n-alkane production at much higher precipitation because leaf wax fatty acids are the precursors of n-alkanes. Hence, past periods during which these leaf waxes show opposite trends in CPI might be interpreted as a precipitation change, especially if additional information such as pollen, diatoms, chironomids and stable isotopes is available.

Effects of habitat degradation on bird functional diversity: A field test in the Valdivian rainforest

Deforestation and forest degradation are among the main biodiversity loss drivers worldwide. The expansion of productive activities, such as forest plantations, often results in the loss and degradation of native forests, affecting native species in many ways. While many studies have assessed the effects of habitat degradation on taxonomic diversity, the effects on functional diversity have been little explored. Functional diversity provides a robust framework for understanding how anthropogenic disturbance changes biodiversity. We assessed how bird functional diversity changes along a habitat degradation gradient in the Valdivian rainforests (southern Chile). We used four functional diversity indices and compared four habitat types (old-growth, secondary, and logged native forests and exotic plantations) to assess how functional diversity changes depending on habitat structure and bird life history, and behavioral traits. We found that most functional diversity differences occur between old growth and secondary native forests, being the latter the less functionally diverse habitat. Further, secondary forests lack natural tree cavities, and birds nesting there are more prone to be affected by brood parasitism. Changes in habitat structure seem to be determinant for bird functional diversity along a habitat degradation gradient. Therefore, habitat degradation can lead to functional homogenization beyond changes in species richness or abundance, with less evident ecological consequences.

Effects of landscape configuration on the occurrence and abundance of an arboreal marsupial from the Valdivian rainforest

BackgroundHabitat fragmentation and degradation processes affect biodiversity by reducing habitat quantity and quality, with differential effects on the resident species. However, their consequences are not always noticeable as some ecological processes affected involve idiosyncratic responses among different animal groups. The Valdivian temperate rainforests of southern Chile are experiencing a rapid fragmentation and degradation process despite being a biodiversity hotspot. Deforestation is one of the main threats to these forests. There inhabits the arboreal marsupial Dromiciops gliroides, an iconic species from the Valdivian rainforest, it is the only extant representative of the ancient Microbiotheria order, and it is currently threatened by habitat loss. Here we tested the effects of habitat configuration on D. gliroides occurrence and abundance along 12 landscapes of southern Chile with different disturbance levels.MethodsWe estimated D. gliroides occurrence and abundance using camera traps and related those metrics with landscape configuration indices obtained from FRAGSTATS (i.e., forest %, connectivity, patch number, contiguity, and distance to the nearest patch) using Bayesian linear mixed models.ResultsWe found that D. gliroides occurrence was not influenced by landscape configuration, while its abundance was positively influenced by forest contiguity.ConclusionsAlthough this arboreal marsupial is present in disturbed forests, its restricted movement capabilities and high dependency on the forest three-dimensional structure may affect its long-term persistence. We urge to rethink native forest conservation and management policies to improve habitat connectivity with possible positive consequences for native fauna.

The last glacial termination in northwestern Patagonia viewed from the Lago Fonk (∼40°S) record

The anatomy of the Last Glacial Termination (T1) in the southern mid-latitudes, and its relationship with changes in the Southern Westerly Winds (SWW), offers empirical constraints for understanding the mechanisms involved in the transition from the Last Glacial Maximum into the current interglacial. Northwestern Patagonia (40°-44°S) is a sensitive region for monitoring past changes in the SWW, the Patagonian Ice Sheet, terrestrial ecosystems, and fire regimes through T1. Here we present results from Lago Fonk (∼40°S) to examine the structure of T1 based on the palynological, macroscopic charcoal, elemental, and isotopic composition of organic lake sediments.We observe an instantaneous establishment of Nothofagus-dominated forests at the onset of T1, followed by a diversification and densification trend that culminated with the establishment of thermophilous, Myrtaceae-dominated North Patagonian rainforests between ∼15.6–14.7 cal ka BP. The expansion of the conifer Podocarpus nubigena marks a shift to cool-temperate and hyperhumid conditions, coeval with high lake levels and enhanced algal productivity between ∼14.7–11.9 cal ka BP. Stand-replacing fires, driven by enhanced seasonality or high-frequency rainfall variability, started at ∼12.4 cal ka BP and catalyzed the rapid spread of Weinmannia trichosperma. Subsequent warming and a decline in precipitation at ∼11.4 cal ka BP led to intense fire activity, lake-level lowering, and establishment of the Valdivian rainforest trees Eucryphia/Caldcluvia. Our results suggest a coherent linkage between changes documented in the amphi south Pacific region and Antarctic ice cores during T1. This implies a zonal and hemispheric response to changes in the position/intensity of the SWW that emphasizes their central role as a key driver of the hemispheric and global climate evolution through T1.

Vegetation dynamics under residual large trees following a volcanic eruption in a Valdivian temperate rainforest

Vegetation dynamics under residual large trees following a volcanic eruption in a Valdivian temperate rainforest

Climate exposure shows high risk and few climate refugia for Chilean native vegetation

The many Gondwanic vegetation types found across the extensive latitudes and elevation gradients of South America's southern cone contribute to Chile's global biodiversity hotspot ranking. Species loss in global biodiversity hotspots is an ongoing climate change concern and land managers need spatially explicit climate risk maps to adapt conservation strategies to climate change in these areas. We modeled future climate risk for Chile's terrestrial vegetation using a high-resolution vegetation map and tested the relationship to climate risk for each type's latitudinal and elevation range. We found that 43.6% of all vegetation has high climate risk in Global Circulation Models (GCMs) under a high emissions scenario (RCP8.5). All forest types in the country, including Southern Beech (Nothofagus sp.), Alerce (Fitzroya cupressoides), Araucaria (Araucaria araucana), and Sclerophyllous, as well as the Valdivian rainforest, Altiplanic Steppes, and Salares, face high levels of climate risk. Tests for trends in risk across elevation and latitude showed that exposure for all types increased with elevation based on the MIROC5 GCM, and decreased with latitude based on the Had2GEM-ES GCM. Our results suggest that vegetation types with smaller latitudinal ranges typically have higher levels of climate risk, but a type's elevation range is not significantly correlated with risk of exposure. We identified climatically stable areas which could act as vegetation refugia in Patagonia, the central Andes mountains between latitudes 27.5°S and 32.5°S, and some coastal areas. Conservation strategies in Chile should include the protection of climatically stable areas to safeguard current Gondwanic biodiversity and active habitat restoration in climatically exposed areas to facilitate vegetation shifts.

An exotic magnet plant alters pollinator abundance and behavior: a field test with a native mistletoe

Exotic species can threaten biodiversity by disrupting ecological interactions among native species. Highly-attractive exotic species can exert a ‘magnet effect’ by attracting native pollinators, which may have either competitive or facilitative effects on co-flowering native plants. However, those effects may be context-dependent. We used a mistletoe-hummingbird pollination system in the Valdivian rainforest (southern Chile) to test whether the exotic tree Eucalyptus globulus (a highly attractive species to pollinators) acts as a magnet species, affecting the co-flowering native mistletoe. We compared hummingbird abundance, visitation rates, and activity patterns between native forest and abandoned E. globulus plantations. We found that hummingbirds were more abundant and visited more flowers at the plantation irrespective of E. globulus flowering. We observed a significant change of pollinator activity at the native habitat during E. globulus flowering, as hummingbirds visited mistletoe flowers more frequently early in the morning at the plantations and in the afternoon at the native forests. Our results showed that E. globulus acts as an exotic magnet species and can alter pollinator abundance and behavior. Our findings demonstrate the importance of considering local- and landscape-scale processes to understand the effects of magnet species on native plants and suggest that magnet species may influence even highly-attractive plants.

The role of climate and disturbance regimes upon temperate rainforests during the Holocene: A stratigraphic perspective from Lago Fonk (∼40°S), northwestern Patagonia

Climate and disturbance regimes play key roles in shaping the structure, composition and functioning of terrestrial ecosystems. Despite this importance, very few stratigraphic studies in the temperate rainforests from northwestern Patagonia have explored this relationship in detail along a time continuum through the entire Holocene. Here we present a high-resolution fossil pollen and charcoal record from Lago Fonk (median resolution: 20 years), a small closed-basin lake in the lowlands of the Chilean Lake District (41°S), where wildfires and explosive volcanism have intermittently taken place during the Holocene, along with pronounced human-induced disturbance in post-colonial time. Our results show persistence of temperate rainforest throughout the Holocene, with changes in the composition and structure of Valdivian rainforests (VRF) at millennial timescales. We detect centennial-scale alternations in dominance between the VRF tree Eucryphia/Caldcluvia and generalist trees found in VRF and North Patagonian rainforests after ∼6.5 cal ka BP. Intervals dominated by VRF coincide with enhanced fire occurrence signaling negative hydroclimate anomalies with a mean duration of ∼150 years, which alternate with positive hydroclimate anomalies lasting ∼312 years on average.Our results suggest that the magnitude and rapidity of vegetation changes detected at 10.2–9.9, 4.0–3.0, ∼1.0, and ∼0.7 cal ka BP were amplified by disturbance regimes, and led to the establishment and maintenance of Eucryphia/Caldcluvia-dominated forests in the Longitudinal Valley of the Chilean Lake District. On several occasions the higher incidence of fire disturbance during warm/dry climate intervals coincided with episodes of heightened explosive volcanic activity from multiple eruptive centers within the Southern Andean Volcanic Zone.

Timing and structure of vegetation, fire, and climate changes on the Pacific slope of northwestern Patagonia since the last glacial termination

By virtue of its location in the southern mid-latitudes, northwestern Patagonia (40°-44°S) offers the opportunity to unravel the mechanisms involved in the initiation and propagation of paleoclimate signals of hemispheric and global significance. Of particular importance is deciphering the evolution of the Southern Westerly Winds (SWW) considering their influence at continental, zonal, hemispheric, and global scale. Here I present a multi-decadal record from Lago Proschle, a small closed-basin lake located on the Pacific slope of northwestern Patagonia, to examine the timing and structure of vegetation, fire, and climate change along a continuum since the onset of the Last Glacial Termination (T1). The record shows rapid glacier recession during T1, reaching the western Andean foothills in ∼400 years or less. Nothofagus-dominated forests established between ∼17.4–17 ka, followed by closed-canopy North Patagonian Rain Forests (NPRF) with shade-tolerant thermophilous trees between ∼16.3–15.4 ka. These changes suggest an abrupt warming trend and an increase in precipitation at ∼16.3 ka, associated with a northward shift of the SWW. Subsequent increases in cold-tolerant hygrophilous trees between ∼15.4–12.8 ka imply a shift to cold, more humid conditions during the Antarctic Cold Reversal, suggesting stronger SWW influence. This was followed by stand-replacing fires brought by a sudden decline in summer precipitation at ∼12.8 ka, associated with a millennial-scale southward shift of the SWW which was contemporaneous with the onset of the Younger Dryas. Dominance of thermophilous, summer-drought tolerant Valdivian rainforest trees and high fire activity ensued between ∼10.3–7.8 ka, suggesting peak warmth and overall decline in annual precipitation associated with weakening of the SWW during the early Holocene. A multi-millennial cooling and wetting trend started at ∼7.8 ka, brought by stronger SWW influence, followed by recurrent, centennial-scale variations in temperature and precipitation starting at ∼6.4 ka. Deforestation, fire, and spread of non-native herbs by Chilean/European settlers began during the late 18th century. Abrupt vegetation changes in the Lago Proschle record were driven by rapid climate changes over the last 17,400 years amplified, in some instances, by fire disturbance.

Variability and variation in Rhyncholestes raphanurus Osgood (Paucituberculata, Caenolestidae)

BackgroundCaenolestids are a group of poorly known South American marsupials with a restricted distribution in Páramo and Subpáramo environments of the Andes from Colombia and western Venezuela to Bolivia (represented by the genera Caenolestes and Lestoros), and Valdivian rainforest in southern Chile (including a separate population in Chiloé Island) and Argentina, where a single species lives: the Long-nosed shrew opossum (Rhyncholestes raphanurus). The objectives of this work were to analyze the intraspecific variability of R. raphanurus, which includes an anatomical description of the skull and dentition, describe its geographic variation, test for sexual dimorphism, and assess potential differences between continental and Island populations.MethodsLinear Mossimann-transformed variables were used to assess sexual differences within a large population (La Picada), compare sexes within other continental populations, and in a separate analysis, compare continental from Island samples. A full model Principal Components Analysis was performed to assess differences between males and females of the continental and Island populations. A thorough description of the skull and teeth of the species and comparisons with other living Caenolestidae is presented.ResultsRhyncholestes raphanurus presents little geographic variation, even between Island and continental populations. Similarly, we found no significant difference between sexes of this species in cranial and dental measurements. We provide a detailed description of cranial morphology and its variation, and also, the first description of the occipital bones, which haven’t been previously described for any Paucituberculata.ConclusionsComparative studies of continental and Chiloé Island specimens support the treatment of R. raphanurus as a single valid species, especially since morphologic and morphometric differences fall within the extremes of continental populations. The morphology of R. raphanurus clearly separates this genus from other extant Caenolestidae, and in a much greater degree than the differences found between Lestoros and Caenolestes.

New record of the endemic jewel beetle Pygicera scripta krahmeri (Coleoptera, Buprestidae, Nacionini) from a coastal forest of Hualpén, Biobío Region, Chile.

Pygicera Kerremans, 1903 is an endemic genus of jewel beetle of Chile distributed in the central Chile hotspot, which is distributed from the Atacama Desert in the north to the Valdivian Forest in the south (Myers et al., 2000). Currently, Pygicera is composed of one species and two subspecies: Pygicera scripta scripta Laporte Gory, 1837 and the Valdivian rainforest subspecies Pygicera scripta krahmeri Moore 1981 (Figs 2-6). The first subspecies is distributed from Limarí in the Coquimbo Region to Curicó in the Maule Region, both in the coast as well as Andean foothills. This is considered the common subspecies (Moore, 1981; Moore Vidal, 2015). The southern subspecies is distributed from Victoria in the Araucanía Region to La Unión in Los Ríos Region (Moore, 1981; Moore Vidal, 2015) and is the rarest and less abundant subspecies. The larvae of both subspecies have been recorded in the "maitén" (Maytenus boaria) Molina, from which they have been reared (Moore, 1981, 1987; Moore Vidal, 2015).

Assessing mammal community composition in the Huinay Biological Reserve (Chile) through questionnaire surveys: biases associated with respondents

The study of people’s knowledge through interviews and questionnaires can provide a good picture of the composition of mammal communities. However, there is considerable potential for error and bias in these surveys, including some associated with the familiarity of respondents with wildlife. Our main goals were: 1) to assess mammal community composition of the Huinay Biological Reserve, a remote Valdivian rainforest area in southern Chile, and 2) to evaluate the relationship between the degree of respondents’ contact with native mammals and their knowledge about the mammal community. A questionnaire was designed to gather data about the mammal species recorded by people who lived in, or had visited, the area between 2010 and 2013. A total of 13 mammal species were mentioned by 43 participants in the survey. Overall, all the mammal species that inhabit the study area according to general mammal distribution maps were identified in our survey. Both the total number of species mentioned (observed or not) and the number of species seen by the respondents were positively associated with the time they stayed in the area. Our findings suggest that questionnaire surveys may provide useful information about the composition of mammal communities in remote areas of southern Chile, but selecting knowledgeable respondents is challenging.

Southernmost records of Dromiciops gliroides: extending its distribution beyond the Valdivian rainforest

The geographic range of a species is often limited by sampling approaches, underestimating the actual distribution. This is likely the case of Dromiciops gliroides (Microbiotheria), an endemic marsupial from southern South America. We used camera-traps to record D. gliroides for the first time in Chaiten and Futaleufu (southern Chile), expanding its known distribution 100 km to the south. Climate and forest composition in this area differs from the typical Valdivian rainforest. Activity assessments show a narrow activity patterns compared to northern populations.

Revision of Tropopterus Solier: A disjunct South American component of the Australo-Pacific Moriomorphini (Coleoptera, Carabidae)

TropopterusSolier, 1849, precinctive to southern South America, is taxonomically revised. Six new species are described:T. peckorumsp. nov.,T. robustussp. nov.,T. canaliculussp. nov.,T. trisinuatussp. nov.,T. minimucrosp. nov., andT. fieldianussp. nov.Merizodus catapileanusJeannel, 1962, is synonymized withT. montagneiSolier, 1849. Lectotypes are designated forT. montagnei,T. giraudyiSolier,T. duponcheliiSolier, andT. nitidusSolier (=T. duponchelii).Tropopterus peruvianusStraneo is noted as anomen dubium, with its identity and taxonomic placement to be substantiated via neotype designation. Phylogenetic relationships amongTropopterusspp. are hypothesized based on 37 morphological characters, the distributions of which are analyzed under the parsimony criterion, with the cladogram root established betweenTropopterusand its adelphotaxon from New South Wales, Australia. Speciation in the group has occurred predominantly at a limited geographical scale relative to the overall generic distribution, with three pairs of sister species sympatric. However phylogenetic divergence between taxa in the more northern, sclerophyllous forest characterized byNothofagus obliqua(Brisseau de Mirbel) and those occupying the Valdivian and North Patagonian Rain Forest dominated byN. dombeyi(Brisseau de Mirbel) is observed in two instances of phylogenetic history. Using specific collecting locality records, it is shown thatTropopterusbeetles have been collected syntopically and synchronically with species ofGlypholomaJeannel (Coleoptera, Staphylinidae),AnaballetusNewton, Švec & Fikáček (Coleoptera, Leiodidae),AndotypusSpangler (Coleoptera, Hydrophilidae), andNovonothrusBalogh (Acari, Oribatida). These concordant ecological occurrences document a cohesiveNothofagusforest leaf-litter community. These genera plus other Valdivian Rain Forest invertebrate taxa all exhibit an Austral disjunct biogeographical pattern that corroborates trans-Antarctic vicariance between theNothofagusforests of southern South America and Australia. Male genitalic antisymmetry is shown to be a synapomorphy ofTropopterus, though the female reproductive tract retains the plesiomorphic orientation observed in all other moriomorphine taxa.

New excavations at the late Pleistocene site of Chinchihuapi I, Chile

AbstractThis paper presents new excavation data on the Chinchihuapi I (CH-I) locality within the Monte Verde site complex, located along Chinchihuapi Creek in the cool, temperate Valdivian rain forest of south-central Chile. The 2017 and 2018 archaeological excavations carried out in this open-air locality reveal further that CH-I is an intermittently occupied site dating from the Early Holocene (~10,000 cal yr BP) to the late Pleistocene (at least ~14,500 cal yr BP) and probably earlier. A new series of radiocarbon dates refines the chronology of human use of the site during this period. In this paper, we describe the archaeological and stratigraphic contexts of the recent excavations and analyze the recovered artifact assemblages. A fragmented Monte Verde II point type on an exotic quartz newly recovered from excavations at CH-I indicates that this biface design existed in at least two areas of the wider site complex ~14,500 cal yr BP. In addition, associated with the early Holocene component at CH-I are later Paijan-like points recovered with lithic tools and debris and other materials. We discuss the geographic distribution of diagnostic artifacts from the site and their probable relationship to other early sites in South America.

A Vertical Forest Within the Forest: Millenary Trees from the Valdivian Rainforest as Biodiversity Hubs

A Vertical Forest Within the Forest: Millenary Trees from the Valdivian Rainforest as Biodiversity Hubs

Evaluating acoustic indices in the Valdivian rainforest, a biodiversity hotspot in South America

Passive acoustic monitoring is becoming an extensively used tool to evaluate the status and variation of populations of sound producing animals. The analyses of extensive acoustic recordings for identification and detection of acoustic signals of different species is highly time-consuming, either by traditional audiovisual procedures or by developing effective automated recognizers. These drawbacks in data analysis have promoted research efforts aimed to develop acoustic diversity indices, which are relatively easily obtained by means of different algorithms considering spectral and/or temporal properties of the sounds contained in the recordings. Nevertheless, studies performed in different environments and geographical areas reveal inconsistencies in the association between acoustic diversity indices and biodiversity, suggesting the need of new studies to evaluate commonly used acoustic diversity indices as proxies of the richness of sound producing animal species. The Valdivian rainforest from Chile, South America, is recognized as a biodiversity hotspot because of the high proportion of endemic species and their threatened status associated to anthropogenic activity. As it is imperative to evaluate cost-effective strategies for biodiversity monitoring, in this study we evaluated seven acoustic indices to assess their reliability as proxies of the variation in bird and anuran species richness, two important components of the biodiversity of this threatened environment. Our results indicate that most of the acoustic indices tested fail to describe satisfactorily the variation in species richness. Nevertheless, two indices, namely the Temporal Entropy and the Acoustic Evenness Index, may potentially serve as an indicator of bird richness, but future studies should fine-tune these indices to obtain a robust validation of its use within this environment. We expect that this work will contribute to the understanding of the significance and potential use of acoustic indices within this biodiversity hotspot as well as in other regions of interest for conservation.

A vertical forest within the forest: millenary trees from the Valdivian rainforest as biodiversity hubs.

A vertical forest within the forest: millenary trees from the Valdivian rainforest as biodiversity hubs.