Temperate Rainforest Research Articles

Long-Term Patterns in Forest Soil CO2 Flux in a Pacific Northwest Temperate Rainforest

Soil CO2 efflux (Fs) plays an important role in forest carbon cycling yet estimates of Fs can remain unconstrained in many systems due to the difficulty in measuring Fs over long time scales in natural systems. It is important to quantify seasonal patterns in Fs through long-term datasets because individual years may show patterns that are not reflective of long-term averages. Additionally, determining predictability of net patterns in soil carbon flux based on environmental factors, such as moisture and temperature, is critical for appropriately modeling forest carbon flux. Ecosystems in moderate climates may have strong CO2 efflux even during winter, and so continuous quantification of annual variability is especially important. Here, we used a 2008–2023 dataset in a lowland temperate forest ecosystem to address two main questions: (1) What are the seasonal patterns in Fs in a highly productive temperate rainforest? (2) How is average Fs across our study area predicted by average coincident temperature, soil moisture and precipitation totals? Data showed clear seasonality where Fs values are higher in summer. We also find Fs across our measurement network was predicted by variation in abiotic factors, but the interaction between precipitation/moisture and temperature resulted in greater complexity. Specifically, in spring a relatively strong relationship between air temperature and Fs was present, while in summer the relationship between temperature and Fs was flat. Winter and autumn seasons showed weak positive relationships. Meanwhile, a negative relationship between precipitation and Fs was present in only some seasons because most precipitation falls outside the normal growing season in our study system. Our data help constrain estimates of soil CO2 fluxes in a temperate rainforest ecosystem at ~14–20 kg C ha−1 day−1 in summer and autumn, and 6.5–10.5 kg C ha−1 day−1 in winter and spring seasons. Together, estimates suggest this highly productive temperate rainforest has annual soil-to-atmosphere fluxes of CO2 that amount to greater than 4.5 Mg C ha−1 year−1. Sensitivity of such fluxes to regional climate change will depend on the balance of Fs determined by autotrophic phenological responses versus heterotrophic temperature and moisture sensitivity. Relatively strong seasonal variation coupled with comparatively weak responses to abiotic variables suggest Fs may be driven largely by seasonal trends in autotrophic respiration. Accordingly, plant and tree responses to climate may have a stronger effect on Fs in the context of climate change than temperature or moisture changes alone.

Assessing the invasion potential of five common exotic vine species in temperate Australian rainforests

To compare the capacity of native and exotic vine species established under a rainforest canopy, a comparison of growth rates and resource allocation was made amongst five exotic vine species that are serious and common invaders and two common native vine species under two light conditions reflective of edge and interior canopy conditions. All species experienced heavy reductions in growth parameters in the low-light treatment, but three exotic species showed stronger growth under the low light. All exotic species had higher plasticity in leaf morphology showing a significant increase in SLA under low light. Native vines may have a lower capacity to change leaf morphology in shade, as a result of local adaptation to edge habitats. Higher SLA under both low and high light conditions suggests that exotic vines species are able to exploit a range of forest conditions better than the native species. Three species, Anredera cordifolia, Araujia sericifera and Cardiospermum grandiflorum, appear particularly capable of invading rainforest interiors. Individuals produced few leaves, focusing resources on roots and stems suggesting a response to reach the canopy quickly. With their long-distance seed dispersal, plasticity in leaf SLA and high RGR, these species appear most likely to invade undisturbed rainforest.

The microclimate occupied by the hyperoceanic liverwort Leptoscyphus cuneifolius (Hook.) Mitt. within a temperate rain forest in Wales

ABSTRACT Introduction Because climate change risks serious negative impacts on drought-sensitive species in Britain, in the short as well as the long term, the microclimate occupied by the hyperoceanic liverwort Leptoscyphus cuneifolius within a temperate rain forest in Wales was investigated. Methods At Coed y Rhygen, Gwynedd, Wales, 10 trees occupied by the liverwort were randomly selected, and its abundance was measured on the southerly and northerly aspect of each trunk. Data loggers were installed to measure temperature, relative humidity and illuminance on both aspects, from 1 January 2020 to 31 December 2022. Temperature and relative humidity values were used to calculate vapour pressure deficit (VPD). Bootstrap paired t-tests were used to test for significant differences in the mean number of locations of Leptoscythus cuneifolius on the southerly versus northerly aspects of trunks, and in the monthly mean values of temperature, VPD and illuminance on the southerly versus northerly aspects. Results and conclusions Leptoscyphus cuneifolius is significantly more abundant on the northerly aspect of trunks, and the microclimate that it occupies is dynamic, both spatially and temporally. In early spring, a sharp peak occurs in solar radiation and VPD, especially on the southerly aspect, caused by the altitude of the sun rising from its winter low and the subsequent emergence of the deciduous forest leaf canopy. Further study is required to understand the effects of the macroclimate on the microclimate occupied by hyperoceanic bryophytes in temperate rain forest, and to what extent this habitat may provide a refuge from climate change.

Identifying Old-Growth Forests in Complex Landscapes: A New LiDAR-Based Estimation Framework and Conservation Implications

Old-growth forests provide many ecosystem services and benefits. However, they are becoming increasingly rare and thus are an urgent priority for conservation. Accurately mapping old-growth forests is a critical step in this process. Here, we used LiDAR, an improved individual tree crown delineation algorithm for broadleaved forests, Gaussian mixture modelling, and a rule-based classification key to map the extent and location of old-growth forests across a topographically and ecologically complex landscape of 337,548 ha in southeastern Australia. We found that variation in old growth extent was largely driven by the old growth definition, which is a human construct, rather than by uncertainty in the technical aspect of the work. Current regulations define a stand as old growth if it was recruited prior to 1900 (i.e., >120 years old) and is undisturbed (i.e., <10% regrowth canopy cover and no visible disturbance traces). Only 2.7% (95% confidence intervals ranging from 1.4 to 4.9%) of the forests in the study landscape met these criteria. However, this definition is overly restrictive as it leaves many multi-aged stands with ecologically mature elements (e.g., one or more legacy trees amid regrowth) unprotected. Removing the regrowth filter, an indicator of past disturbances, increased the proportion of old-growth forests from 2.7% to 15% of the landscape. Our analyses also revealed that 60% of giant trees (>250 cm in diameter at breast height) were located within 50 m of cool temperate rainforests and cool temperate mixed forests (i.e., streamlines). We discuss the implication of our findings for the conservation and management of high-conservation-value forests in the region.

First record of the plant bug genus Punctifulvius Schmitz from the Oriental Region, with descriptions of three new species (Hemiptera, Heteroptera, Miridae, Cylapinae).

Three new species of the fungal-inhabiting plant bug genus Punctifulvius Schmitz, 1978 (Cylapinae: Fulviini) are described, namely P. aleksanderi n. sp. from Selangor, Malaysia, P. parvus n. sp. from East Kalimantan, Indonesia, and P. sakaerat n. sp. from Nakhon Ratchasima, Thailand. The present discovery represents the first record of the genus from the Oriental Region. Punctifulvius members are now confirmed to be widespread from the cold temperate climatic zones in the eastern Palearctic regions, across the tropics of the Oriental Region, to the temperate rainforest of Australia. Punctifulvius kerzhneri Schmitz, 1978 is recorded from Taiwan for the first time. The systematic position of Teratofulvioides Carvalho & Lorenzato, 1978 is discussed, and its single species Teratofulvioides punctatus Carvalho & Lorenzato, 1978 is redescribed. Color adult habitus images of Punctifulvius aleksanderi, P. kerzhneri, P. parvus, P. sakaerat, and Teratofulvius punctatus, images of male (P. parvus and P. sakaerat) and female (P. aleksanderi) genitalic structures, as well as scanning electron micrographs of selected structures of P. aleksanderi, P. kerzhneri, P. parvus, P. sakaerat, and T. punctatus are provided. Key to the species of Punctifulvius is given.

Changes in forest structure over 23 years under disturbances in a warm temperate rain forest on Yakushima Island, Japan

AbstractClarifying the influence of disturbances by biotic and abiotic agents on long‐term changes in forest structure and demographic rates is an important task of forest ecology. Here, we investigated changes in forest structure and demographic rates and the effects of biotic and abiotic factors (sika deer, ambrosia beetle, neighborhood trees, and indices of strong wind and wetness) in a 4‐ha long‐term ecological study plot in a lowland warm temperate rain forest on Yakushima Island, Japan, from 1996 to 2019 for three regeneration groups related to gap dynamics (gap demander: GD, light shade tolerant: LS, and strong shade tolerant: SS). GD had relatively lower recruitment and survival than LS and/or SS. Changes in demographic rates were not significantly correlated with those in the index of strong wind in any regeneration group. The effects of sika deer on demographic rates did not differ among groups. Stems of Fagaceae species belonging to LS attacked by ambrosia beetles recorded in 2013 did not significantly differ in RGR and survival rates. Our results indicate that despite the relatively long monitoring period of 23 years, we did not detect significant effects of strong winds on demographic rates among regeneration groups, and shade‐tolerant species (LS and SS) showed better demographic performance than light‐demanding species (GD) and an increase in total basal area over time. We need longer monitoring of forest dynamics to understand forest responses to disturbances considering several factors, including the time lag of demographic responses to disturbances and the long‐term effects of disturbances.

Summer calling activity patterns of a bird assemblage in a Valdivian temperate rainforest biodiversity hotspot

ABSTRACT Birds generally produce vocalisations in specific daily temporal windows. Describing diel-calling activity patterns along with taxonomic group and guild membership increase the knowledge about potential factors shaping the behaviour of these animals. This information is also highly relevant for the enhancement of monitoring plans for conservation. We performed a passive acoustic monitoring to describe the diel calling activity patterns of a bird assemblage within the Valdivian temperate rainforest, associating the patterns to taxonomic group and diet guild, and also aiming to contribute to the enhancement of ecological monitoring within this biodiversity hotspot. Our results indicate that high richness levels are detected around sunrise and sunset. Also, within the bird assemblage studied, most birds show diurnal vocal activity, among which several were also active during crepuscular periods, and only two species had nocturnal vocal activity. Among diurnal birds with enough number of detections to perform a detailed description of diel calling patterns, our results did not show clear trends considering diet guild or taxonomic group. We expect that this information encourages future research to increase the understanding on the factors influencing vocal activity patterns, as well as population and community trends from this biodiversity hotspot.

Comparing diversity of the terrestrial mammal communities inhabiting native forests and exotic plantations in southern Chile

The mammal community of the Coastal Range of southern Chile has been little studied even though they inhabit an environment under severe threats due to anthropic disturbance. During the spring-summer seasons of 2020–2021 and 2021–2022, we characterized the communities of wild terrestrial mammals in a native forest (NF) and an exotic plantation of Eucalyptus (PL) of the Coastal Range of Osorno province by phototrapping. We used 1,060 camera-trap days in the NF and 960 camera-trap days in the PL to explore the effect of habitat type on wild mammal diversity in two localities (L-1 and L-2). We quantified the species richness, abundance, community similarity and daily distribution of mammal communities. Species richness was higher in the NF (7–8 spp) than in the PL (3–4 spp). Two community similarity index (CSI) was significantly higher between native forests (CSI = 0.728 ± 0.088) than between Eucalyptus plantations (CSI = 0.211 ± 0.097) (95% CI). Mean abundance was also higher in the NF than in the PL (L-1: 0.011 vs. 0.004 occurrence/camera-trap day (OCT); L-2: 0.008 vs. 0.004 OCT). In L-1, the most abundant mammals in the NF were Leopardus guigna (45.3% of relative occurrence (RO)) and Pudu puda (18.9% RO), and in the PL, they were Lycalopex culpaeus (50% RO) and L. guigna (37.5% RO). In L-2, the highest abundances in the NF were for P. puda (34.5% RO) and Puma concolor (27.6% RO), while in the PL, P. puda was predominant (66.7% RO). In NF of both localities, 22.2% of melanic L. guigna individuals were observed. The highest frequency of occurrences in both locations was between 12:00 and 23:59 hours, with 60% and 76.9% of detections, respectively. The species richness found in native forest is in accordance with studies carried out in other temperate rainforests of southern Chile. In addition, native forests support a richer and more similar community of terrestrial mammals than exotic forest plantations, which indicates that native forests are the main habitat for most mammals detected and that exotic plantations function as a complementary habitat for some species.

Effects of selective logging on genetic diversity and population structure of a keystone mistletoe

AbstractThe effects of habitat degradation remain not fully understood. A recent study reported low effects of habitat degradation on plant genetic diversity but indicates that reduction in habitat quality could impact it as well as gene flow indirectly via ecological interactions. Selective logging is a way of habitat degradation, but studies examining its effects on plant genetic diversity on non‐logged forest plant species are relatively scarce. Using 3470 single‐nucleotide polymorphisms, we assess the effects of different selective logging intensities on the genetic diversity of 66 individuals of a keystone mistletoe (Tristerix corymbosus). We also examined the possible relationship with its seed disperser (Dromiciops gliroides) abundance in three sites of the temperate rainforests of southern Chile, with different levels of selective logging intensity. Our results show that selective logging increases allelic richness and inbreeding in this mistletoe; inbreeding increased with selective logging intensity, and heterozygosity decreased with D. gliroides abundance. While wood extraction seems to positively affect T. corymbosus genetic diversity, its long‐term consequences—such as increased inbreeding—are yet to be assessed in future studies.

The oribatid mite superfamily Eutegaeoidea (Acari, Oribatida), with descriptions of new taxa from Australia and New Caledonia and a re-assessment of genera and families.

Twenty-four new species of Eutegaeoidea from Australia and New Caledonia are described, and two new genera are proposed. These are Eutegaeus woiwurrung sp. nov., E. nothofagi sp. nov., E. bidhawal sp. nov., E. ptilosus sp. nov., Humerotegaeus carinatus gen. et sp. nov., H. concentricus gen. et sp. nov., Atalotegaeus crobylus sp. nov., Neoeutegaeus torsteini sp. nov., N. melipsilon sp. nov. N. malcolmi sp. nov., N. corniculatus sp. nov. (Eutegaeidae), Compactozetes goongerah sp. nov., C. crenellatus sp. nov. (Compactozetidae) and Pterozetes lawrencei sp. nov. (Pterozetidae) from temperate rainforests in Victoria and Tasmania; Compactozetes bundjalung sp. nov., C. calderi sp. nov., C. duonodulus sp. nov., Sadocepheus remus sp. nov. (Compactozetidae) and Porrhotegaeus githabul sp. nov. (Porrhotegaeidae fam. nov.) from temperate and sub-tropical rainforests of the Great Dividing Range in central and northern New South Wales and southern Queensland, Porrhotegaeus catherinae sp. nov. from scalybark closed forest on Lord Howe Island, Eutegaeus odontatus sp. nov. and Compactozetes pirumorpha sp. nov. from moist upland forest on Norfolk Island and Neseutegaeus wardi sp. nov. and Atalotegaeus deficiens sp. nov. from tropical rainforest and moss forest in New Caledonia. Based on the predominantly Southern Hemisphere distribution of Eutegaeoidea, indicating strong Gondwanan affinities, and the morphology of adults and immatures, this taxon is treated as distinct from the Cepheoidea which has a distribution almost entirely within the Northern Hemisphere. Eutegaeoid species previously described from Australia (Eutegaeus soror P. Balogh, 1985, Atalotegaeus mensarosi J. & P. Balogh, 1983, Neseutegaeus monteithi J. & P. Balogh, 1983, Neoeutegaeus phyllophorus J. & P. Balogh, 1983 and Porrhotegaeus ornatus J. Balogh & Mahunka, 1966) are redescribed based on type material and new distribution records provided. Species have distribution patterns predominantly indicative of short-range endemics associated with remnant Gondwanan rainforest. Neseutegaeus monteithi is recombined with Atalotegaeus Luxton, 1988a. The definitions of genera and families of Eutegaeoidea are revised, and their relationships are reconsidered. Birotegaeus Luxton, 1988a and Pareutegaeus Woolley, 1965 are designated junior synonyms of Eutegaeus Berlese, 1916. Immatures are described for the genera Atalotegaeus, Eutegaeus, Neoeutegaeus Aoki, 1964 and Porrhotegaeus J. Balogh & Mahunka, 1966. Neoeutegaeidae fam. nov. is established for Neoeutegaeus Aoki, 1964 and Humerotegaeus gen. nov., Porrhotegaeidae fam. nov. for Porrhotegaeus and Bornebuschiidae fam. nov. for Bornebuschia Hammer, 1966 and Dicrotegaeus Luxton, 1988 which had previously been placed in Cerocepheidae or Compactozetidae. Eutegaeus aysenensis Ermilov, 2021 and E. queulatensis Ermilov, 2021 from Chile, are recombined with Atalotegaeus. A key is provided to the genera of the eight families of Eutegaeoidea, as recognised herein: Eutegaeidae, Neoeutegaeidae fam. nov., Cerocepheidae, Compactozetidae, Bornebuschiidae fam. nov., Pterozetidae and Porrhotegaeidae fam. nov.

Exploring structural and molecular diversity of Ericaceae hair root mycobionts: a comparison between Northern Bohemia and Argentine Patagonia.

Core Ericaceae produce delicate hair roots with inflated rhizodermal cells that host plethora of fungal symbionts. These poorly known mycobionts include various endophytes, parasites, saprobes, and the ericoid mycorrhizal (ErM) fungi (ErMF) that form the ErM symbiosis crucial for the fitness of their hosts. Using microscopy and high-throughput sequencing, we investigated their structural and molecular diversity in 14 different host × site combinations in Northern Bohemia (Central Europe) and Argentine Patagonia (South America). While we found typical ericoid mycorrhiza in all combinations, we did not detect ectomycorrhiza and arbuscular mycorrhiza. Superficial mantles of various thickness formed by non-clamped hyphae were observed in all combinations except Calluna vulgaris from N. Bohemia. Some samples contained frequent intercellular hyphae while others possessed previously unreported intracellular haustoria-like structures linked with intracellular hyphal coils. The 711 detected fungal OTU were dominated by Ascomycota (563) and Basidiomycota (119), followed by four other phyla. Ascomycetes comprised Helotiales (255), Pleosporales (53), Chaetothyriales (42), and other 19 orders, while basidiomycetes Sebacinales (42), Agaricales (28), Auriculariales (7), and other 14 orders. While many dominant OTU from both hemispheres lacked close relatives in reference databases, many were very similar to identical to unnamed sequences from around the world. On the other hand, several significant ericaceous mycobionts were absent in our dataset, incl. Cairneyella, Gamarada, Kurtia, Lachnum, and Leohumicola. Most of the detected OTU could not be reliably linked to a particular trophic mode, and only two could be reliably assigned to the archetypal ErMF Hyaloscypha hepaticicola. Probable ErMF comprised Hyaloscypha variabilis and Oidiodendron maius, both detected only in N. Bohemia. Possible ErMF comprised sebacinoid fungi and several unnamed members of Hyaloscypha s. str. While H. hepaticicola was dominant only in C. vulgaris, this model ErM host lacked O. maius and sebacinoid mycobionts. Hyaloscypha hepaticicola was absent in two and very rare in six combinations from Patagonia. Nine OTU represented dark septate endophytes from the Phialocephala fortinii s. lat.-Acephala applanata species complex, including the most abundant OTU (the only detected in all combinations). Statistical analyses revealed marked differences between N. Bohemia and Patagonia, but also within Patagonia, due to the unique community detected in a Valdivian temperate rainforest. Our results show that theericaceous hair roots may host diverse mycobionts with mostly unknown functions and indicate that many novel ErMF lineages await discovery. Transhemispheric differences (thousands of km) in their communities may be evenly matched by local differences (scales of km, m, and less).

Modeling heterothermic fitness landscapes in a marsupial hibernator using changes in body composition.

Hibernation is an adaptive strategy that allows animals to enter a hypometabolic state, conserving energy and enhancing their fitness by surviving harsh environmental conditions. However, addressing the adaptive value of hibernation, at the individual level and in natural populations, has been challenging. Here, we applied a non-invasive technique, body composition analysis by quantitative magnetic resonance (qMR), to calculate energy savings by hibernation in a population of hibernating marsupials (Dromiciops gliroides). Using outdoor enclosures installed in a temperate rainforest, and measuring qMR periodically, we determined the amount of fat and lean mass consumed during a whole hibernation cycle. With this information, we estimated the daily energy expenditure of hibernation (DEEH) at the individual level and related to previous fat accumulation. Using model selection approaches and phenotypic selection analysis, we calculated linear (directional, β), quadratic (stabilizing or disruptive, γ) and correlational (ρ) coefficients for DEEH and fat accumulation. We found significant, negative directional selection for DEEH (βDEEH = - 0.58 ± 0.09), a positive value for fat accumulation (βFAT = 0.34 ± 0.07), and positive correlational selection between both traits (ρDEEH × FAT = 0.24 ± 0.07). Then, individuals maximizing previous fat accumulation and minimizing DEEH were promoted by selection, which is visualized by a bi-variate selection surface estimated by generalized additive models. At the comparative level, results fall within the isometric allometry known for hibernation metabolic rate in mammals. Thus, by a combination of a non-invasive technique for body composition analysis and semi-natural enclosures, we were characterized the heterothermic fitness landscape in a semi-natural population of hibernators.

Sporocarp nutrition of ectomycorrhizal fungi indicates an important role for endemic species in a high productivity temperate rainforest.

Endemic species of ectomycorrhizal fungi (EMF) are found throughout many biomes, but it is unclear whether their localized distribution is dictated by habitat filtering or geographical barriers to dispersal. We examined community composition (via long-read metabarcoding) and differences in sporocarp nutrition between endemic and cosmopolitan EMF species across perhumid temperate rainforests of British Columbia, characterized by soils with high nitrogen (N) supply alongside low phosphorus (P) and cation availability. Endemic EMF species, representing almost half of the community, had significantly greater sporocarp N (24% higher), potassium (+16%), and magnesium (+17%) concentrations than cosmopolitan species. Sporocarp P concentrations were comparatively low and did not differ by fungal range. However, sporocarp N% and P% were well correlated, supporting evidence for linkages in N and P acquisition. Endemics were more likely to occur on Tsuga heterophylla (a disjunct host genus) than Picea sitchensis (a circumpolar genus). The Inocybaceae and Thelephoraceae families had high proportions of endemic taxa, while species in Cortinariaceae were largely cosmopolitan, indicating some niche conservatism among genera. We conclude that superior adaptive traits in relation to perhumid soils were skewed toward the endemic community, underscoring the potentially important contribution of these localized fungi to rainforest nutrition and productivity.

Spatial aggregation patterns in four mistletoe species: ecological and environmental determinants.

Plant spatial distribution is an important topic in ecology as it determines species coexistence and biodiversity dynamics. Usually, plants show clustered distributions in nature. Mistletoes are a good example of aggregated distributions, as they form dense aggregations due to several factors (availability of competent hosts, seed dispersal vectors, microclimate conditions). We analysed four native mistletoe species with divergent life histories and host ranges: Desmaria mutabilis and Tristerix corymbosus from the temperate rainforests of southern Chile; and Tristerix aphyllus and Tristerix verticillatus from the northern semi-desert zone. While T. corymbosus and T. verticillatus have a wide host range, T. aphyllus and D. mutabilis are specialists that can parasitize only a few plant species. We hypothesized that specialized species would be more aggregated due to ecological and environmental restrictions. We used heterogeneous Poisson models to quantify spatial aggregation. Three of the four mistletoe species were spatially clustered at both environments, with aggregation being stronger in the temperate rainforest of southern Chile and particularly in the host-specialist species. Our results suggest that environmental constraints are more important than ecological constraints (host range) in shaping mistletoe spatial structure. Mistletoe aggregated spatial distribution depends primarily on the environment that they inhabit, which conditions host spatial availability, and arrangement.

Abundance of microbial community genes encoding terminal proteins of the aerobic and denitrification respiratory chains as indicators of ecohydrologic gradients in a coastal temperate rainforest

The persistence of soil organic carbon (SOC) is closely linked to the capacity of the soil microbial community to catalyze oxidative degradation of organic matter. This study uses a landscape-scale metagenomics approach to examine the relative abundances of genes encoding different terminal electron acceptors used for aerobic respiration and denitrification between soil microbial communities across an ecohydrologic gradient. The perhumid zone of the North Pacific coastal temperate rainforest serves as a template to test the associations between these differing respiratory pathways, soil conditions, and tree species biomass. We used the occurrence of reads in soil metagenomes as a proxy for the relative abundance of genes across the ecohydrologic gradient and identified distinct microbial fingerprints differentiating the driest (upland forest) and wettest (palustrine scrub-shrub and palustrine emergent wetland) ecosystem types. There was little gene-based differentiation between the ecosystem types at the wettest end of the ecohydrologic gradient - scrub-shrub wetland and emergent wetlands – while forested wetlands, which occur as gradient sites between upland forests and emergent wetlands on the landscape, were characterized by substantial metagenomic variability and, consequently, overlapped in their soil metagenome with the other ecosystem classes. Hydrology, as measured by groundwater depth was a predictor of O2 and N-oxide reductase abundances. High affinity O2 reductase genes were associated with wetter topographic positions, which has not been shown at the ecosystem scale, or in soils in-situ previously. N-oxide reductase genes were more associated with plant communities found at wetland sites but were not related to soil inorganic nitrogen, suggesting that nitrate supply may be limiting to denitrifiers ubiquitously across this gradient. Two plant species, Tsuga heterophylla (TSHE) and Pinus contorta spp. contorta (PICO), were more strongly correlated with O2-reductase and N-oxide reductase genes than site hydrology, respectively. This research represents a step toward fingerprinting the ecosystem microbiome using genes coding for specific terminal electron acceptors that control the fate of SOC and their ecohydrologic controls.

Forest bathing diminishes anxiety in undergraduate students: a pilot study in the Valdivian temperate rainforest

ABSTRACT Urban life has generally resulted in lifestyles characterised by high stress and anxiety, all which has increased the pervasiveness of mental disorders. University students, a group highly vulnerable to these problems, are likely to develop mental pathologies associated with anxiety and substance abuse. Forest bathing is one nature-oriented intervention aimed at improving physical as well as psychological well-being by reducing anxious symptomatology and stress. Here we evaluated the healing impact of forest bathing on the stress and anxiety of undergraduate students at one local university. We also included others key aspects of psychological mental health that have received scarce attention in forest bathing research like mindfulness, wellbeing and self-regulated learning. Twenty-one students belonging to the Universidad Austral de Chile were randomly assigned to the city or forest groups and took part in an intervention consisting in a low-impact 30 minute walk and a 15-minute contemplation afterwards. Five instruments to evaluate overall mental health (and blood pressure) were applied before and after the intervention. Our results showed that a rather short session of forest bathing is enough to reduce anxiety in undergraduate university students. The other measures of psychological or physiological health showed no statistical differences before and after the intervention (between city and forest) or time effects (within the forest or city treatment). A potential reason for this might be related to the short duration of the intervention itself. Our results are encouraging regarding mental health therapy, as this type of intervention could easily be implemented on campus.

Homogeneous colleters in Myrteae (Myrtaceae).

Colleters are secretory structures characteristic of the apices of more than 60 botanical families. In the Myrtaceae, three types of colleters were previously described: petaloid, conical, and euriform. In Argentina, most species of the Myrtaceae family grow in subtropical regions and a few in the temperate-cold zones of Patagonia. We evaluated the vegetative buds of five species of the subfamily Myrtoideae, tribe Myrtea: Amomyrtus luma, Luma apiculata, and Myrceugenia exsucca, native to the temperate rainforests of Patagonia and Myrcianthes pungens and Eugenia moraviana from the riparian forest of northwestern Corrientes, in order to analyze the presence and morphological types and main secretion products of colleters. Optical and scanning electron microscopy was used to identify the presence of colleters in vegetative organs. Histochemical tests were performed to identify the main secretion products in these structures. The colleters are on the inner side of the leaf primordia and cataphylls and on the edge of the petiole, where they replace the stipules. They are classified as homogeneous because they consist of epidermis and internal parenchyma, both formed by cells with similar characteristics. They lack vascularization and originate from the protodermis. The colleters are of the conical type in L. apiculata, M. pungens, and E. moraviana and of the euriform type in A. luma and M. exsucca, the latter being identified by its dorsiventrally flattened shape. Histochemical tests showed the presence of lipids, mucilage, phenolic compounds, and proteins. This is the first time that colleters have been described in the analyzed species; the taxonomical and phylogenetic importance of this structures is discussed in relation to the Myrtaceae family.

Projected increases in extreme drought frequency and duration by 2040 affect specialist habitats and species in Scotland

Abstract Climate‐driven increases in drought occurrence are an overlooked risk in temperate climates, which may be less resilient to water scarcity than arid habitats. Scotland provides an example of a temperate oceanic climate in which drought risk is understudied, but could have substantial ecological impacts, particularly in combination with additional stressors. We modelled changes to risk of extreme drought occurrence in Scotland, and considered potential impacts of these changes on two key habitats, ombrotrophic (precipitation fed) wetlands and temperate rainforest. Using temperature and precipitation data from the UK Climate Projections 2018 and the drought index Standardized Precipitation‐Evapotranspiration Index, we calculated and mapped likely changes in extreme drought for the near future (2021–2040) in comparison to a baseline (1981–2001). We found likelihood of extreme drought events increased from an average of one event every 20 years in the baseline period, to one event every 3 years by 2040. Typical events were projected to be up to 2–3 months longer, with an average of 11 extra drought months per decade. Increases were projected throughout the country, but the effect was most severe in the east, and during autumn. Ombrotrophic wetlands have some level of adaptive resilience to drought, but are considered at high risk as several key sites are in drought hotspot areas. In contrast, Scotland's temperate rainforest is located in lower risk areas, but is typically less drought resilient. Potential impacts on these habitats include reductions in ecosystem services including carbon capture, reduced breeding success for multiple taxa and increased competition among plant communities, which threatens drought‐sensitive species. These projections suggest that climate‐driven drought risk is a significant and imminent threat, even in wet climates. In Scotland, the results can direct mitigation and management actions to areas likely to be at greatest risk, as well as informing conservation interventions that can cope with drought. Additionally, other areas with a temperate oceanic climate may be at risk of extreme drought and could experience similar consequences. Therefore, these results have implications both for facilitating improved resilience to extreme drought in Scotland and for potentially overlooked impacts of drought in oceanic climates elsewhere.

Small, Coastal Temperate Rainforest Watersheds Dominate Dissolved Organic Carbon Transport to the Northeast Pacific Ocean

AbstractThe northeast Pacific Coastal Temperate Rainforest (NPCTR) extending from southeast Alaska to northern California is characterized by high precipitation and large stores of recently fixed biological carbon. We show that 3.5 Tg‐C yr−1 as dissolved organic carbon (DOC) is exported from the NPCTR drainage basin to the coastal ocean. More than 56% of this riverine DOC flux originates from thousands of small (mean = 118 km2), coastal watersheds comprising 22% of the NPCTR drainage basin. The average DOC yield from NPCTR coastal watersheds (6.20 g‐C m−2 yr−1) exceeds that from Earth's tropical regions by roughly a factor of three. The highest yields occur in small, coastal watersheds in the central NPCTR due to the balance of moderate temperature, high precipitation, and high soil organic carbon stocks. These findings indicate DOC export from NPCTR watersheds may play an important role in regional‐scale heterotrophy within near‐shore marine ecosystems in the northeast Pacific.

The trait‐mediated trade‐off between growth and survival depends on tree sizes and environmental conditions

Abstract Interspecific relationships between growth and survival are critical determinants of tree species diversity maintenance in forests. The trade‐offs between growth and survival in co‐occurring tree species are believed to arise along a continuum of life‐history strategies. For example, co‐occurring species range from those that grow slowly and survive well in resource‐poor environments to those that grow quickly but have low survival rates in resource‐rich environments. However, uncertainties remain regarding how growth–survival trade‐offs are related to species traits, tree sizes or environmental conditions. We examined how the relationships between species traits and growth–survival relationships shift in response to changes in stem sizes and across census periods with different climate conditions (frequency of strong winds, drought intensity) across 45 co‐occurring tree species based on 23 years of growth and survival records in a warm temperate rainforest on Yakushima Island, Japan. We developed hierarchical Bayesian models of relative growth and survival rates, including leaf traits, wood density and 95‐percentile maximum stem diameter as explanatory variables. We tested the relationships between estimated trait‐mediated growth–survival relationships and the indices of climate events during five census periods. Each trait's effects on growth–survival relationships differed across the five census periods in response to climate conditions. Interspecific growth–survival relationships affected by a single trait axis for leaves or wood tended to be negative. In contrast, those affected by the maximum stem diameter tended to be positive. Such trends increased with more frequent strong winds or more intense droughts. The single‐trait effects on growth–survival relationships were stronger for smaller sizes than for larger sizes. For all traits combined, we found a significant growth–survival trade‐off only for small‐sized stems in three of five census periods. Synthesis. Our results indicate that the effect of species traits on the growth–survival relationships depended on tree sizes, the census periods or both in response to the frequency or intensity of climate events. We argue the importance of incorporating spatial and temporal variations in environmental conditions into long‐term data from tree census to predict forest dynamics.