Montane Forest Research Articles

Insights into The Diversity of Nepenthes L. (Nepenthaceae) Across Peninsular Malaysia, Including The First Sighting of an Undescribed Taxon with Flared Peristomes and Quadruple-Row Ventral Wings

The discoveries of six taxa between 2019 and 2022 have brought the total number of Nepenthesspecies occurring in Peninsular Malaysia to 18. This article serves as a comprehensive overview, incorporating the latest information and taxonomic insightsconcerningallspecies native to the peninsula. The information is derived from published taxonomic records and cumulative field observations conducted since 2013.Notably, it further reports heretoforeundocumented discoveries, making it a significant contribution to the current knowledgeof tropical pitcher plants. Theseinclude a sighting of a population of Nepenthes with unusual traits in the upper montane forest of Banjaran Titiwangsa, which may represent the 19thtaxonin Peninsular Malaysia. The plantsexhibit conspicuously expandedperistomes and an unusual wing morphology, which altogether provide compelling evidence supporting the recognition of these individuals as a distinct and previously unknown species. Therefore, a provisional taxonomic name—Nepenthessp. Titiwangsa (pesonawangsa_223) A. Amin—is assigned.The species is inferred to belongto the N. macfarlaneigroup based on its toothed peristome and the presence of fine hairs below the lid. The partial description, speciesnote, photographs,and a dichotomous keyof the proposednew speciesare provided.In addition, a velvety N. sanguineapopulation has been observed in northern Banjaran Titiwangsa and treated as a new natural variation (var. velutina) in this article.

Seasonal and diel variations in the acoustic communication of tree hyraxes in Taita Hills, Kenya

Tree hyraxes (Dendrohyrax spp.) are highly vocal, elusive nocturnal mammals that live in forests across much of Sub-Saharan Africa. Here, we studied how tree hyrax acoustic communication activity varies during the year in a moist montane forest in Taita Hills, Kenya. Our study increases the knowledge about the seasonal and diel variation in tree hyrax calling activity and on the impact of exogenous factors on the calling behavior of the species. A group of tree hyraxes called 700–2000 times during the night, and calling rate was highest during dry season months. Calling activity was bimodal, with peaks between 19.00 and 20.00 h in the evening and between 04.00 and 05.00 h in the morning; however, counter-calling bouts occurred throughout the night. Singing peaked in May, possibly coinciding with the species’ mating season. Calling activity decreased during full moon phases, probably because the animals felt vulnerable to predation. Tree hyrax calling was suppressed by rain, as rainfall is a powerful acoustic competitor. Annual changes in night temperature, the background chorus of vocalizing orthopterans, or the competing calls of nocturnal primates did not reduce tree hyrax calling rates. The latter suggests that sympatric nocturnal mammals have adapted to each other’s calls as an intrinsic feature of the soundscape of their forest habitat.

Seeing the Disturbed Forest for the Trees: Remote Sensing Is Underutilized to Quantify Critical Zone Response to Unprecedented Disturbance

AbstractUnderstanding the severity and extent of near surface critical zone (CZ) disturbances and their ecosystem response is a pressing concern in the face of increasing human and natural disturbances. Predicting disturbance severity and recovery in a changing climate requires comprehensive understanding of ecosystem feedbacks among vegetation and the surrounding environment, including climate, hydrology, geomorphology, and biogeochemistry. Field surveys and satellite remote sensing have limited ability to effectively capture the spatial and temporal variability of disturbance and CZ properties. Technological advances in remote sensing using new sensors and new platforms have improved observations of changes in vegetation canopy structure and productivity; however, integrating measures of forest disturbance from various sensing platforms is complex. By connecting the potential for remote sensing technologies to observe different CZ disturbance vectors, we show that lower severity disturbance and slower vegetation recovery are more difficult to quantify. Case studies in montane forests from the western United States highlight new opportunities, including evaluating post‐disturbance forest recovery at multiple scales, shedding light on understory vegetation regrowth, detecting specific physiological responses, and refining ecohydrological modeling. Learning from regional CZ disturbance case studies, we propose future directions to synthesize fragmented findings with (a) new data analysis using new or existing sensors, (b) data fusion across multiple sensors and platforms, (c) increasing the value of ground‐based observations, (d) disturbance modeling, and (e) synthesis to improve understanding of disturbance.

Comparative Assessment of the Effects of two Vegetation Zone Forests on Plant Litter Quantity and Quality in Taraba State, Nigeria

The study was carried out to assess plant litter quantity and quality between montane and high forest zones of Taraba State, Nigeria. Two forest reserves were randomly selected out of the forest zones in Taraba State for this study; the forests were River Amboi and Ngel Yaki forest reserves for high forests and montane forest zones respectively. Two 10 kilometers line transects were established in each of the forest reserves along which 20 m x 20 m plots were laid at 2 kilometers intervals. Plants litter samples were systematically collected from each plot for onward transfer to the laboratory for analysis using standard laboratory procedures. Plant litter was analysed for litter quantity and quality parameters. Student’s t-test and Pearsons correlation coefficient were used to compare and determine the relationship between the plant litter parameters assesed respectively between the two forest zones. There was significant difference in plant litter quantity (P<0.05) between Montane forest (0.6630) and High forest (0.5040). The distribution of litter quality, Mg (0.000) and Na (0.000) showed that montane forest significantly higher than the high forest (p ˂ 0.05). Organic carbon (0.357), Total nitrogen (0.598), available Phosphorus (0.662), K (0.428), Ca (0.531), and S (0.564) show no significant differences (p ˃ 0.05) between the montane and high forest zones. The result showed that in montane forest correlation between Na and Ca were significant (0.684) at (p ˂ 0.05). However, litter quantity and available phosphorus was significantly and negatively correlated (- 0.655) at (p ˂ 0.05). At high forest K and organic carbon was significantly and negatively correlated (- 0.644) at (p ˂ 0.05) litter quantity and TN also showed significantly and negatively correlation (- 0.751) at (p ˂ 0.05). Inclusion montane forest had higher litter quantity and quality than high forest.

Mapping deforestation and recovery of tropical montane forests of East Africa

Deforestation poses a major threat to the tropical montane forest ecosystems of East Africa. Montane forests provide key and unique ecological and socio-economic benefits to the local communities and host diverse flora and fauna. There is evidence of ongoing deforestation and forest clearance in these montane forests although estimates diverge among different sources suggesting rates of 0.4%–3% yr−1. Quantifying deforestation rates and forest disturbance is critical to design conservation and sustainable management policies for forest management. This study quantified the rate of deforestation and forest recovery over the last three decades for the Mau Forest Complex and Mount Elgon forests in Kenya and Uganda using Landsat time-series satellite imagery. With the analysis, classification accuracies of 86.2% and 90.5% (kappa 0.81 and 0.88) were achieved for the Mau Forest Complex and the Mt Elgon forests, respectively. 21.9% (88,493 ha) of the 404,660 ha of Mau forest was lost at an annual rate of −0.82% yr−1 over the period between 1986 and 2017. More positively, 18.6% (75,438 ha) of the forest cover that was disturbed during the same period and is currently undergoing recovery. In Mt Elgon forest, 12.5% (27,201 ha) of 217,268 ha of the forest cover was lost to deforestation at an annual rate of −1.03% yr−1 for the period between 1984–2017 and 27.2% (59,047 ha) of the forest cover disturbed is undergoing recovery. The analysis further demonstrated agriculture (both smallholder and commercial) was the main driver of forest cover loss in Mau forest, accounting for 81.5% (70,612 ha) of the deforestation, of which 13.2% was due to large scale and 68.3% was related to the smallholders. For the Mt Elgon forest, agriculture was also the main driver accounting for 63.2% (24,077 ha) of deforestation followed by the expansion of human settlements that contributed to 14.7% (5,597 ha) of forest loss. This study provides accurate and novel estimates of the rate of deforestation for the Mau forest complex and Mt Elgon forest ecosystems. These rates are higher than previously estimated and recent deforestation has been identified, which provides a quantitative basis for forest restoration programs and to design conservation policies.

Soil Phosphorus Availability Controls Deterministic and Stochastic Processes of Soil Microbial Community along an Elevational Gradient in Subtropical Forests

Revealing the assembly mechanisms of the soil microbial community, which is crucial to comprehend microbial biodiversity, is a central focus in ecology. The distribution patterns of microbial elevational diversity have been extensively studied, but their assembly processes and drivers remain unclear. Therefore, it is essential to unravel the relationship between the deterministic and stochastic processes of the microbial community assembly and elevational gradients. Here, our study built upon previous physicochemical analyses of soil samples collected along an elevational gradient (900–1500 m) in Daiyun mountain, a subtropical forest located in southeastern China. Using the phylogenetic-bin-based null model analysis (icamp) and multiple regression on matrices approach, we explored the major drivers that influence the assembly processes of soil bacterial and fungal community across elevations. The results showed that: (1) bacterial rare taxa exhibited a broad habitat niche breadth along the elevational gradient; (2) homogeneous selection and homogenizing dispersal proved to be the most important assembly processes for the bacterial and fungal community; (3) soil phosphorus availability mediated the relative importance of deterministic and stochastic processes in the soil microbial community. Notably, the relative abundance of dominant microbial taxa controlled by homogeneous selection and homogenizing dispersal increased with increasing soil phosphorus availability. Collectively, the assembly processes of microbial elevational communities of the subtropical mountains in China can be explained to some extent by variations in the soil phosphorus availability. This conclusion provides valuable insights into the prediction of soil microbial diversity and phosphorus nutrient cycling in subtropical montane forests.

Discovery and conservation of Monanthotaxis bali (Annonaceae) a new Critically Endangered (possibly extinct) montane forest treelet from Bali Ngemba, North West Region, Cameroon

SummaryMonanthotaxis bali is the only known, solely montane (occurring solely above 2000 m alt.) species of the genus. It joins M. orophila (Rwanda) and M. discolor (Tanzania), two other species that can also occur above 2000 m alt. Monanthotaxis bali is an addition to the small number (28) of the tree species of the surviving montane forests of the Cameroon Highlands of which only eight other species are endemic. Due to its supra-axillary inflorescences, and petals arranged in one whorl but with the outer petals overlapping the inner petals distally, and rounded flower buds, the new species is placed in Monanthotaxis clade B of Hoekstra. The new species is unusual in having the largest outer petals in clade B, in being a treelet in a predominantly lianescent genus, and in lacking the glaucous underside of the leaf-blades that usually characterises the genus. Monanthotaxis bali takes the number of continental African species of the genus to 80, and makes Cameroon, with 30 species, the most species-diverse country for the genus. Monanthotaxis bali is known only from the Bali Ngemba Forest Reserve, a forest remnant under great pressure of degradation and clearance in the Bamenda Highlands of Cameroon. The case for protecting Bali Ngemba for its unique plant biodiversity is made. Monanthotaxis bali may already be extinct due to logging and agricultural activities. Here it is described, illustrated, mapped and assessed as Critically Endangered (Possibly Extinct) using the IUCN 2012 criteria.

Southbound - the southernmost record of Tylototriton (Amphibia, Caudata, Salamandridae) from the Central Highlands of Vietnam represents a new species.

A new species of the genus Tylototriton is described from Ngoc Linh Mountain, Kon Tum Province, in the Central Highlands of Vietnam based on integrative taxonomy, namely by combining molecular and morphological evidence. Tylototritonngoclinhensissp. nov. differs from all other congeners based on morphological data, allopatric distribution, and molecular divergence. In terms of genetic divergence, Tylototritonngoclinhensissp. nov. distinctly differs from the sister species T.panhai (6.77%) and from T.ngarsuensis (12.36%) based on the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene. Tylototritonngoclinhensissp. nov. is a moderate sized and robust salamander species with large cephalic edges, parotoids, and vertebral ridge orange in coloration. The new taxon differs from its congeners by a combination of the following morphological characteristics: size medium (SVL 60.8-66.5 mm, TL 57.6-61.8 mm in males, and SVL 72.5-75.6 mm, TL 62.9-67.9 mm in females); head longer than wide; parotoids very prominent and enlarged, projecting backwards; tail length shorter than snout-vent length; vertebral ridge large, high and glandular in appearance; 14 large and distinct dorsolateral glandular warts; gular fold present; tips of fore and hind limbs overlapping when adpressed along the body; tips of fingers reaching between eye and nostril when foreleg is laid forward; dorsal surface and lateral sides of the head, upper and lower lips, dorsolateral glandular warts, vertebral ridge, the peripheral area of the cloaca and the ventral edge of the tail orange in coloration; the presence of a distinct black line extending from the posterior end of the eye towards the shoulder. Tylototritonngoclinhensissp. nov. is restricted to evergreen montane forests near water bodies on Ngoc Linh Mountain. We suggest that the new species should be classified as Endangered (EN) in the IUCN Red List. This new important discovery represents the eighth Tylototriton taxon described from Vietnam, and at the same time constitutes the southernmost distributional record for the whole genus in Asia.

VARIATION IN THE COMPOSITION AND STRUCTURE OF NATURAL LOWLAND FORESTS AT BODOGOL, GUNUNG GEDE PANGRANGO NATIONAL PARK, WEST JAVA, INDONESIA

An analysis of the composition and structure of lowland natural forests was carried out in Bodogol, Gunung Gede Pangrango National Park (GGPNP). The two study plots (P1CS and P2CS) were located on Cisuren and one plot (P3CP) on Cipadaranten hill. We recorded 107 species and 48 families with an average basal area of 19.73 m2/ha, and an average density of 348 trees/ha. The species richness was poorer than those of the typical lowland rainforests of Kalimantan and Sumatra but comparable to those of the montane forests of Java. The IUCN-Red Listed species were Castanopsis argentea and Castanopsis tungurrut (critical) and Saurauia bracteosa (vulnerable). Based on the two dominant species, the forests can be designated as the Maesopsis eminii-Syzygium acuminatissimum association and Syzygium acuminatissimum-Lithocarpus korthalsii association. Maesopsis eminii was dominant in P1CS (IV= 56.46%) and P3CP (IV=55.94%), while Syzygium acuminatissimum in P2CS (IV= 43.67%). Maesopsis eminii was a strongly aggressive and invasive species, that endangered the purity of the natural forest GGPNP, therefore, it must be eradicated. Vertically, P2CS and P3CP consisted of four strata, while P1CS had three strata. This one-hectare study can be considered as a minimal area to reflect the floristic representation of lowland forest and submontane forest.

A dataset of carbon fluxes of the deciduous broad-leaved forest at Maoershan Station from 2016 to 2018

Forest ecosystem dominates the terrestrial ecosystem carbon (C) cycle, thus the accurate estimation of C flux in the forest ecosystem is essential to understanding the impact of global change on global C cycle. Based on the micrometeorology theory, the eddy covariance technique is one of the standard methods for C flux monitoring in terrestrial ecosystems, which has been widely used in the long-term monitoring of C flux in forests, grasslands, croplands and other ecosystems. Heilongjiang Maoershan Forest Ecosystem National Observation and Research Station has a continental monsoon climate, dominated by natural secondary forests (temperate deciduous broad-leaved forestd) which are typical in the montane forests of Northeast China. In this dataset, we compiled the measured C flux data and routine meteorological data of a deciduous broad-leaved forest at Maoershan Station from 2016 to 2018, including gross primary productivity, ecosystem respiration, net ecosystem exchange, incoming solar radiation, incoming photosynthetically active radiation, air temperature, soil temperature, soil moisture and precipitation. The dataset is divided into four time scales: half-hourly, daily, monthly and yearly. The establishment and sharing of this dataset will provide necessary, accurate and reliable data to support the evaluation of the role of natural secondary forests in the regional C cycle and the optimization of C cycle models.

BREEDING ECOLOGY, NESTING HABITAT AND THREATS TO A BLACK-AND-CHESTNUT EAGLE SPIZAETUS ISIDORI POPULATION IN THE MONTANE FORESTS OF CENTRAL PERU

The Black-and-chestnut Eagle Spizaetus isidori is an endangered and little-known top predator of South American montane forests. To better understand the breeding ecology and threats of this eagle, we studied several pairs between 2017 and 2022 in the central Andes of Peru. We recorded 62 adults, one immature, and 36 juveniles in 36 territories. These territories were in mountainous areas (altitudinal range 690–3,810 m a.s.l.), widely covered by montane forests (43.8–99.7% cover), and secondarily by open land (0.3–56.2% cover), far from urban settlements (1.3–27.1 km). Nesting sites (N = 15) were at medium altitudes (1,330–2,330 m a.s.l.) in steep hillsides or ravines (15–55°), having no preferential cardinal orientation, and relatively close to permanent water courses (20–800 m), open areas (30–930 m) and sites with human activity (120–2,200 m). Nests (N = 15) were placed at the top of tall (28–40 m) and thick-stemmed (DBH range 0.53–1.52 m) emergent trees of nine genera, with Ficus and Juglans being the most used. Incubation and brood-rearing occurred during the dry season (Mar–Nov). The wooded slopes where the eagles nested are being replaced by crops and livestock pastures, causing an estimated loss of 218.2 km2 of forest cover in our study area (5,056 km2) during the last 20 years. We detected human persecution in 55.5% of the territories, resulting in 26 juveniles, four adults, two immatures, and nine unaged eagles killed. Preventing the local extinctions of these eagles will require long-term population monitoring, improving knowledge of its ecology, mitigation of human-eagle conflict, development of education programs, and strengthening of land use inspection.

Systematic Revision of Thomasomys cinereus (Rodentia: Cricetidae: Sigmodontinae) from Northern Peru and Southern Ecuador, With Descriptions of Three New Species

Thomasomys cinereus is the type species of Thomasomys, type genus of the sigmodontine tribe Thomasomyini. As currently recognized, Thomasomys includes 48 species, all of which are endemic to humid montane or premontane forests in the tropical Andes. Although it has been suggested that T. cinereus is a species complex, this hypothesis has yet to be critically evaluated. Herein we provide a revision of the species based on a qualitative assessment of external, craniodental, and soft morphological traits; morphometric analyses; a phylogenetic analysis based on cytochrome b gene sequences; species delimitation methods; and first-hand examination of type material. Our analyses of genetic data recovered four distinct clades within T. cinereus, one corresponding to T. cinereus sensu stricto (restricted to the montane forests delimited by the Río Marañón, Río Huancabamba, and Río Tablachaca in Cajamarca department, Peru) and three new species: Thomasomys lojapiuranus, sp. nov., from the montane forests of Piura department, Peru, and Loja province, Ecuador; T. shallqukucha, sp. nov., restricted to the Kañaris montane forests in the Peruvian department of Lambayeque; and T. pagaibambensis, sp. nov., restricted to the montane forests of Pagaibamba in Cajamarca department, Peru. These species can be distinguished by several discrete morphological traits of the skull, dentition, mandible, stomach, palatal rugae, and glans penis. Genetic distances among these taxa range from 5.06%–7.65% at the cytochrome b locus, and delimitation analyses based on cytochrome b sequence data support their recognition as distinct species. Our results suggest the existence of previously unsuspected dispersal barriers in the Andes of northern Peru, and they confirm that the Río Marañón is a formidable barrier that limits the distribution of species of Thomasomys as well as other sigmodontine rodents.

Begonia saxifragoides sp. nov. and two new records of Begonia (Begoniaceae) from northern Vietnam

Surveys in montane forests in northern Vietnam have revealed one new species and two new records of Begonia. The new species, B. saxifragoides resembles B. minhaniae but is distinguished by the orbicular to reniform (vs. broadly ovate) leaves with rounded (vs. acute to acuminate) apex, the petioles densely covered with pilose or villous (vs. subappressed tomentose), ovary trigonous-globose (vs. trigonous-ellipsoid) and wings pilose or glandular hairs (vs. glabrous or sparsely tomentose). The newly recorded species from Vietnam were B. laotica Y.H.Tan & H.B.Ding previously known from Laos, and B. adscendens C.B.Clarke from India, Myanmar and Laos.

Comparison of multi-source remote sensing data for estimating and mapping above-ground biomass in the West Usambara tropical montane forests

Above-ground biomass (AGB) estimation is important to better understand the carbon cycle and improve the efficiency of forest policy and management activities. AGB estimation models, using a combination of field data and remote sensing data, can largely replace traditional survey methods for measuring AGB. There are, however, critical steps for mapping AGB based on satellite data with an acceptable degree of accuracy, such as choice of remote sensing data, the proper statistical modelling method, and remote sensing predictor variables, at known field locations. This study sought to identify the optimal optical and synthetic aperture radar (SAR) remote sensing imagery from five sensors (PlanetScope, Sentinel-2, Landsat 8 OLI, ALOS-2/PALSAR-2, and Sentinel-1) to model 159 field-based AGB values from two montane forests under semiparametric (Generalized Additive Model; GAM) and non-parametric (eXtreme Gradient Boosting; XGB) approaches using information from four groups of predictor variables (spectral bands/polarizations, vegetation indices, textures, and a combination of all). The study's results showed that PlanetScope (rRMSE = 69.19%; R2 = 0.161) was the most precise optical sensor while ALOS-2/PALSAR-2 (rRMSE = 70.76; R2 = 0.165) was the most precise amongst the SAR sensors. XGB models generally resulted in those with lower prediction errors as compared to GAMs for the five sensors. Models having textures of vegetation indices and polarization bands achieved greater accuracy than models that incorporated spectral bands/polarizations and vegetation indices only. The study recommends that PlanetScope and ALOS-2/PALSAR-2 remote sensing data using the XGB-based technique is an appropriate approach for accurate local and regional estimation of tropical forest AGB particularly for complex montane forest ecosystems.

Frugivoria: A trait database for birds and mammals exhibiting frugivory across contiguous Neotropical moist forests

AbstractMotivationBiodiversity in many areas is rapidly declining because of global change. As such, there is an urgent need for new tools and strategies to help identify, monitor and conserve biodiversity hotspots. This is especially true for frugivores, species consuming fruit, because of their important role in seed dispersal and maintenance of forest structure and health. One way to identify these areas is by quantifying functional diversity, which measures the unique roles of species within a community and is valuable for conservation because of its relationship with ecosystem functioning. Unfortunately, the functional trait information required for these studies can be sparse for certain taxa and specific traits and difficult to harmonize across disparate data sources, especially in biodiversity hotspots. To help fill this need, we compiled Frugivoria, a trait database containing ecological, life‐history, morphological and geographical traits for mammals and birds exhibiting frugivory. Frugivoria encompasses species in contiguous moist montane forests and adjacent moist lowland forests of Central and South America—the latter specifically focusing on the Andean states. Compared with existing trait databases, Frugivoria harmonizes existing trait databases, adds new traits, extends traits originally only available for mammals to birds also and fills gaps in trait categories from other databases. Furthermore, we create a cross‐taxa subset of shared traits to aid in analysis of mammals and birds. In total, Frugivoria adds 8662 new trait values for mammals and 14,999 for birds and includes a total of 45,216 trait entries with only 11.37% being imputed. Frugivoria also contains an open workflow that harmonizes trait and taxonomic data from disparate sources and enables users to analyse traits in space. As such, this open‐access database, which aligns with FAIR data principles, fills a major knowledge gap, enabling more comprehensive trait‐based studies of species in this ecologically important region.Main Types of Variable ContainedEcological, life‐history, morphological and geographical traits.Spatial Location and GrainNeotropical countries (Mexico, Guatemala, Costa Rica, Panama, El Salvador, Belize, Nicaragua, Ecuador, Colombia, Peru, Bolivia, Argentina, Venezuela and Chile) with contiguous montane regions.Time Period and GrainIUCN spatial data: obtained February 2023, spanning range maps collated from 1998 to 2022. IUCN species data: obtained June 2019–September 2022. Newly included traits: span 1924 to 2023.Major Taxa and Level of MeasurementClasses Mammalia and Aves; 40,074 species‐level traits; 5142 imputed traits for 1733 species (mammals: 582; birds: 1147) and 16 sub‐species (mammals).Software Format.csv; R.

Sap flow responses in pioneer and late-successional tree species in secondary tropical montane forests of Eastern Himalaya, India.

The interactive role of life-history traits and environmental forcing on plant-water relations is crucial for understanding species response to climate change but remains poorly understood in secondary tropical montane forests (TMFs). Comparing contrasting life-history traits (pioneer vs late-successional species) in a biodiverse Eastern Himalayan secondary TMF, we investigated sap flow responses in co-occurring pioneer species, Symplocos racemosa (n=5) and Eurya acuminata (n=5), and late-successional species, Castanopsis hystrix (n=3), using modified Granier's Thermal Dissipation probes. The fast-growing pioneers S. racemosa and E. acuminata) had 2.1- and 1.6-times higher sap flux density than the late-successional C. hystrix, respectively, and exhibited characteristics of long-lived pioneer species. Significant radial and azimuthal variability in sap flow (V) between species was observed and attributed to life history traits and the canopy's access to sunlight. Nocturnal V (1800-0500hr) was 13.8 % of daily V and is attributed to stem recharge for evening V (1800-2300hr) and to endogenous stomatal controls for pre-dawn V (0000-0500hr). Both the shallow-rooted pioneer species exhibited midday depression in V attributed to photosensitivity and diel moisture stress response. In contrast, deep-rooted C. hystrix transpired unaffected across the dry season likely accessing groundwater. Thus, the secondary broadleaved TMFs, with the dominance of shallow-rooted pioneers, are more prone to the negative impacts of drier and warmer winters than primary forests, which are dominated by deep-rooted species. The study provides an empirical understanding of life-history traits and microclimate modulating plant-water use in widely distributed secondary TMFs in Eastern Himalaya and highlights their vulnerability against warmer winters and reduced snowfall due to climate change.

Heisteria austroecuadorica (Erythropalaceae): A new species from southeastern Ecuador

Heisteria austroecuadorica, a new species of Erythropalaceae from the conserved evergreen montane forest at the San Francisco reserve, in southeastern Ecuador, is here described and illustrated. It is characterized by the flowers with 10 stamens, and relatively large fruits, with the apex conspicuously depressed, and the calyx not covering the base of the fruits. Heisteria austroecuadorica is assessed provisionally as Endangered.

The North American Monsoon buffers forests against the ongoing megadrought in the Southwestern United States.

The US Southwest has been entrenched in a two-decade-long megadrought (MD), the most severe since 800 CE, which threatens the long-term vitality and persistence of regional montane forests. Here, we report that in the face of record low winter precipitation and increasing atmospheric aridity, seasonal activity of the North American Monsoon (NAM) climate system brings sufficient precipitation during the height of the summer to alleviate extreme tree water stress. We studied seasonally resolved, tree-ring stable carbon isotope ratios across a 57-year time series (1960-2017) in 17 Ponderosa pine forests distributed across the NAM geographic domain. Our study focused on the isotope dynamics of latewood (LW), which is produced in association with NAM rains. During the MD, populations growing within the core region of the NAM operated at lower intrinsic and higher evaporative water-use efficiencies (WUEi and WUEE , respectively), compared to populations growing in the periphery of the NAM domain, indicating less physiological water stress in those populations with access to NAM moisture. The disparities in water-use efficiencies in periphery populations are due to a higher atmospheric vapor pressure deficit (VPD) and reduced access to summer soil moisture. The buffering advantage of the NAM, however, is weakening. We observed that since the MD, the relationship between WUEi and WUEE in forests within the core NAM domain is shifting toward a drought response similar to forests on the periphery of the NAM. After correcting for past increases in the atmospheric CO2 concentration, we were able to isolate the LW time-series responses to climate alone. This showed that the shift in the relation between WUEi and WUEE was driven by the extreme increases in MD-associated VPD, with little advantageous influence on stomatal conductance from increases in atmospheric CO2 concentration.

Different trends and divergent responses to climate factors in the radial growth of Abies georgei along elevations in the central Hengduan Mountains

Climate change has been unprecedented in the last half-century. Tree growth dynamics and responses to climate warming at different elevations vary by study area due to regional diversity in site-specific climatic conditions in the central Hengduan Mountains. A. georgei is the dominant species in high-elevation montane forests in the central Hengduan Mountains. To study the response of A. georgei radial growth to climate and identify tree growth trends at different elevations, tree-ring width chronologies at four elevations across the subalpine A. georgei forest belt were built and growth-climate relationships were analyzed. The primary findings of this study were as follows: (1) radial growth rates of A. georgei decreased with elevation; (2) warming alleviated the limitation of low temperatures and abundant precipitation on tree radial growth at the highest sampling site; and (3) unlike at other elevations, the trend of trees basal area increment (BAI) at the lowest sampling site showed a significant decline over the past 20 years. This suggests the presence of an elevational inflection point, likely between 3800 m and 4000 m, where tree growth trends diverge. These results confirmed that A. georgei at higher elevation in the central Hengduan Mountains currently benefits from higher temperatures. However, the effects of drought on A. georgei at lower elevations would cause radial growth to decrease with climate warming. Therefore, it is critical to establish effective management strategies based on how A. georgei responds to climate change at various elevations.

A New Species of Werauhia (Bromeliaceae: Tillandsioideae) from Montane Cloud Forests of Costa Rica

Werauhia oenophylla Cascante & J. F. Morales (Bromeliaceae), a new species of Tillandsioid epiphytic bromeliad, is described from the montane forests of Costa Rica. The new species is related to W. umbrosa (L. B. Sm.) J. R. Grant by its compound inflorescence with several flowers in short (< 10 cm) lateral branches and coriaceous floral bracts that are longer than the pedicel. Werauhia oenophylla is distinguished by the combination of reddish-wine coloration on the abaxial surface of leaves and peduncle bracts and reddish-rose floral bracts. This species is only known from the country’s cloud forests in the Central Volcanic Mountain Range.