Dwarf Forest Research Articles

Estimation of chlorophyll content of Cinnamomum camphora leaves based on hyperspectral and fractional order differentiation

ABSTRACT Hyperspectral remote sensing combined with data preprocessing techniques and machine learning algorithms is a new way to efficiently estimate plant SPAD. In this study, the raw hyperspectral reflectance data of the dwarf forest of Cinnamomum camphora (Linn.) Presl (C. camphora) were subjected to 0-2nd order differential transformations (a step size of 0.25) using SPAD during the harvesting period of C. camphora. The spectral indices with the highest correlation with SPAD in each order were also selected as input variables for the model, and the measured values of SPAD from simultaneous observations were used as the output variable. Support vector machine (SVM), random forest (RF), and backpropagation neural network (BPNN) were used to construct the SPAD inversion model. The results showed that the correlation between the spectral index and the SPAD of the dwarf forest of C. camphora and the accuracy of the constructed prediction model tended to increase and then decrease with increasing differential order. After a comprehensive comparison, the RF-based SPAD prediction model achieved the highest accuracy with a coefficient of determination (R2) of 0.824, root mean square error (RMSE) of 1.619, and mean relative error (MRE) of 3.207% for the validation set, using spectral indices computed by the 1.5-order differential treatment as the input variables. This study provides a theoretical basis for improving the accuracy of plant leaf SPAD inversion based on hyperspectral remote sensing.

2021–2022年广东南岭站日尺度气象数据集

The mountainous forest and biodiversity ecological functional area of the Nanling Mountain forest ecosystem is one of the 25 key ecological functional areas in China, covering a variety of forest vegetation types, including tropical and subtropical moist broadleaf forests, coniferous broad-leaved evergreen mixed forest, and mountain top evergreen broad-leaved dwarf forest. The tropical and subtropical moist broadleaf forests are the most typical vegetation type in the Nanling Mountains. Monitoring the meteorological elements in the community can help understand the response mechanism of the tropical and subtropical moist broadleaf forests in the Nanling Mountains to climate change. Based on the Nanling Forest Ecosystem National Field Scientific Observation Research station ("Nanling Station" for short) in the Nanling Mountains, Guangdong, we carried out positioning research in Nanling National Nature Reserve. In this paper, we disclosed the raw data of 10 min average wind speed, precipitation, air temperature, air pressure, solar radiation (i.e. total radiation, reflected radiation, ultraviolet radiation, net radiation, photosynthetically active radiation) as well as relative humidity continuously collected in the subtropical evergreen broad-leaved forest area of the Nanling Station from 2021-2022 on a daily scale after data processing, quality control and evaluation. The dataset accessible to the public can serve as a valuable resource for further insights into the Nanling Mountain Forest Ecosystem, and provide foundation for efforts related to the restoration and protection of forest ecosystems.

Comparison of Machine Learning Methods for Estimating Leaf Area Index and Aboveground Biomass of Cinnamomum camphora Based on UAV Multispectral Remote Sensing Data

UAV multispectral technology is used to obtain leaf area index (LAI) and aboveground biomass (AGB) information on Cinnamomum camphora (C. camphora) and to diagnose the growth condition of Cinnamomum camphora dwarf forests in a timely and rapid manner, which helps improve the precision management of Cinnamomum camphora dwarf forests. Multispectral remote sensing images provide large-area plant spectral information, which can provide a detailed quantitative assessment of LAI, AGB and other plant physicochemical parameters. They are very effective tools for assessing and analyzing plant health. In this study, the Cinnamomum camphora dwarf forest in the red soil area of south China is taken as the research object. Remote sensing images of Cinnamomum camphora dwarf forest canopy are obtained by the multispectral camera of an unmanned aerial vehicle (UAV). Extreme gradient boosting (XGBoost), gradient boosting decision tree (GBDT), random forest (RF), radial basis function neural network (RBFNN) and support vector regression (SVR) algorithms are used to study the correlation and estimation accuracy between the original band reflectance, spectral indices and LAI and AGB of Cinnamomum camphora. The results of this study showed the following: (1) The accuracy of model estimation based on RF is significantly different for different model inputs, while the other four models have small differences. (2) The accuracy of the XGBoost-based LAI model was the highest; with original band reflectance as the model input, the R2 of the model test set was 0.862, and the RMSE was 0.390. (3) The accuracy of the XGBoost-based AGB model was the highest; with spectral indices as the model input, the R2 of the model test set was 0.929, and the RMSE was 587.746 kg·hm−2. (4) The XGBoost model was the best model for the LAI and AGB estimation of Cinnamomum camphora, which was followed by GBDT, RF, RFNN, and SVR. This research result can provide a theoretical basis for monitoring a Cinnamomum camphora dwarf forest based on UAV multispectral technology and a reference for rapidly estimating Cinnamomum camphora growth parameters.

Intra- and inter-specific responses of plant functional traits to environmental variables: implications for community ecology in the tropical monsoonal dwarf forest on Hainan Island

In the context of tropical monsoonal dwarf forest restoration, it is well known that the interaction between soil properties and plant functional traits influences the dynamics and forest composition of plant communities. The main aim of this study was to determine the relationships and variations between the plant functional traits and environmental variables in tropical coastal secondary forests. However, it is undisputed whether trait variation is coordinated and whether there is a relationship between the community-weighted mean (CWM) traits and soil variables. TNNR conducted a ground survey to collect actual ground data on the biophysical characteristics of individual trees and shrubs, along with soil sample data. All soil samples and plant materials were collected at the end of June, in the 2020 growing season (July and August), in each quadrat with a 400-m2 area. To gain insight into these questions, a total of 4 plant functional traits of 167 species and 5 soil nutrients from 128 soil samples were analyzed from 128 plots in a tropical evergreen monsoon forest on Hainan Island. Using SMA (standardized major axis), wood density (WD), and leaf thickness (LT), as well as specific leaf area (SLA) and relative leaf water content (RLWC), were significantly positively correlated. Using Pearson correlation analysis, leaf thickness (LT) was significantly positively correlated with soil organic matter (OM). Using principal component analysis (PCA), we also found that soil TN and OM were the strongest predictors for functional traits, i.e., WD and LT. Moreover, using path analysis, OM and TN have a major impact on plant CWM traits, e.g., SLA and RLWC. Our results show a significant relationship between functional traits and soil pH and soil nutrients in tropical coastal secondary forests. Our results highlight that plant traits can be used to predict specific soil nutrients and ecosystem functioning in tropical secondary forests, but we are concerned about how variation in the physical structure of plant affect ecosystem function in forest communities. This research can help us to better understand the restoration of habitats and green infrastructure design, suggesting that selecting different species across multiple trait axes can help ensure functionality at the maximum level.

VACCINIUM COARCTATUM (ERICACEAE), AN ULTRAMAFIC-OBLIGATE NEW SPECIES FROM THE DWARF FOREST OF MOUNT REDONDO, DINAGAT ISLAND, PHILIPPINES

A new species of blueberry, Vaccinium coarctatum M.N.Tamayo & Fernando, from the dwarf forest on ultramafic soil of Dinagat Island, Philippines, is described. It closely resembles Vaccinium hamiguitanense P.W.Fritsch but is distinct from that species in having a longer inflorescence, shorter pedicels, longer and persistent bracteoles, white-hirsutulous calyx lobes, and shorter anther spurs. This discovery brings the number of Vaccinium species known from the Philippines to 41. A key to the small-leaved Vaccinium in the Philippines is provided.

Contrasting responses of soil microbial biomass and extracellular enzyme activity along an elevation gradient on the eastern Qinghai-Tibetan Plateau.

Soil microbial community composition and extracellular enzyme activity are two main drivers of biogeochemical cycling. Knowledge about their elevational patterns is of great importance for predicting ecosystem functioning in response to climate change. Nevertheless, there is no consensus on how soil microbial community composition and extracellular enzyme activity vary with elevation, and little is known about their elevational variations on the eastern Qinghai-Tibetan Plateau, a region sensitive to global change. We therefore investigated the soil microbial community composition using phospholipid fatty acids (PLFAs) analysis, and enzyme activities at 2,820 m (coniferous and broadleaved mixed forest), 3,160 m (dark coniferous forest), 3,420 m (alpine dwarf forest), and 4,280 m (alpine shrubland) above sea level. Our results showed that soil microbial community composition and extracellular enzyme activities changed significantly along the elevational gradient. Biomass of total microbes, bacteria, and arbuscular mycorrhizal fungi at the highest elevation were the significantly lowest among the four elevations. In contrast, extracellular enzyme activities involved in carbon (C)-, nitrogen (N)-, and phosphorus (P)- acquiring exhibited the maximum values at the highest elevation. Total nutrients and available nutrients, especially P availability jointly explained the elevational pattern of soil microbial community, while the elevational variation of extracellular enzyme activities was dependent on total nutrients. Microbial metabolism was mainly C- and P-limited with an increasing C limitation but a decreasing P limitation along the elevational gradient, which was related significantly to mean annual temperature and total P. These results indicated a vital role of soil P in driving the elevational patterns of soil microbial community and metabolism. Overall, the study highlighted the contrasting responses of soil microbial biomass and extracellular enzyme activities to elevation, possibly suggesting the differences in adaption strategy between population growth and resource acquisition responding to elevation. The results provide essential information for understanding and predicting the response of belowground community and function to climate change on the eastern Qinghai-Tibetan Plateau.

Ficus tikoua, a new record for Thailand, with associated lectotypifications

Ficus tikoua, a member of the subgenus Sycomosus, is reported for the first time in Thailand. This creeping shrub was discovered in a dwarf forest at high elevation (1,400–1,500 m asl) on the top of Phu Luang Mountain in Phu Luang Wildlife Sanctuary, Loei Province. A key to the Thailand species of Ficus subgenus Sycomorus is given. A description based on Thai collections is provided. We lectotypify the names F. tikoua and F. nigrescens.

A dataset of soil nutrients of typical forest ecosystems in Nanling Mountain in 2020

Soil nutrients are an important component of forest ecosystems, an important carrier for maintaining the survival and development of animals and plants, and a foundation for normal plant growth. They play an important role in soil nutrient cycling and global climate change. Located in the core area of the southern hilly and mountainous area in the national ecological security strategic pattern of "two screens and three belts", Nanling Mountains are an important ecological barrier in Southern China. Due to varying degrees of damage in recent years, ecosystems in Nanling Mountains have proven to be highly sensitive to climate change. It has attracted significant attention from numerous scholars. The estimation of soil nutrient reserves and spatial distribution characteristics have emerged as prominent areas of research focus within this region. However, the absence of data sharing and the limited availability of measured data stand as significant factors contributing to the uncertainty of the research results. In 2020, we carried out standardized field survey and test effort of soil sample collection for ancient woodland in five typical forest ecosystems, namely, valley tropical and subtropical moist broadleaf forests (<800 m), mountain tropical and subtropical moist broadleaf forests (800-1,200 m), evergreen coniferous and broad-leaved mixed forest (1,200-1,500 m), mountaintop grassland (>1,500 m), and mountaintop evergreen broad-leaved dwarf forest (>1,500 m) in Nanling Mountain forest ecosystem. On this basis, we produced a dataset of soil nutrients of typical forest ecosystems in Nanling Mountain in 2020. This dataset includes soil nutrients (organic matter, total nitrogen, total phosphorus, and total potassium) and soil available nutrients (nitrate nitrogen, ammonium nitrogen, available phosphorus, and available potassium) of 0-20 cm topsoil in four quarters, with a view to providing valuable measured data for the study of soil nutrient cycling process in Nanling Mountains.Soil nutrients are an important component of forest ecosystems, an important carrier for maintaining the survival and development of animals and plants, and a foundation for normal plant growth. They play an important role in soil nutrient cycling and global climate change. Located in the core area of the southern hilly and mountainous area in the national ecological security strategic pattern of "two screens and three belts", Nanling Mountains are an important ecological barrier in Southern China. Due to varying degrees of damage in recent years, ecosystems in Nanling Mountains have proven to be highly sensitive to climate change. It has attracted significant attention from numerous scholars. The estimation of soil nutrient reserves and spatial distribution characteristics have emerged as prominent areas of research focus within this region. However, the absence of data sharing and the limited availability of measured data stand as significant factors contributing to the uncertainty of the research results. In 2020, we carried out standardized field survey and test effort of soil sample collection for ancient woodland in five typical forest ecosystems, namely, valley tropical and subtropical moist broadleaf forests (<800 m), mountain tropical and subtropical moist broadleaf forests (800-1,200 m), evergreen coniferous and broad-leaved mixed forest (1,200-1,500 m), mountaintop grassland (>1,500 m), and mountaintop evergreen broad-leaved dwarf forest (>1,500 m) in Nanling Mountain forest ecosystem. On this basis, we produced a dataset of soil nutrients of typical forest ecosystems in Nanling Mountain in 2020. This dataset includes soil nutrients (organic matter, total nitrogen, total phosphorus, and total potassium) and soil available nutrients (nitrate nitrogen, ammonium nitrogen, available phosphorus, and available potassium) of 0-20 cm topsoil in four quarters, with a view to providing valuable measured data for the study of soil nutrient cycling process in Nanling Mountains.

High species richness and turnover of vascular epiphytes is associated with water availability along the elevation gradient of Volcán Maderas, Nicaragua.

Research that has been conducted documenting species richness patterns on tropical mountains has resulted in conflicting observations: monotonic declines with increasing elevation, monotonic increases with increasing elevation, and a mid-elevation "bulge." Currently, it is unclear if these differences are due to environmental differences among study areas, the taxonomic groups or ecological groups (e.g., growth form) sampled, or the scale of study along elevation gradients. Because of the difficulty in sampling and identifying canopy-dwelling plants, the number of inventories quantifying tropical epiphytes is relatively limited and recent. In this study, we provide a detailed qualitative and quantitative assessment of the vascular epiphyte flora and its spatial distribution on Volcán Maderas, Isla de Ometepe, Nicaragua, including weather and environmental measurements along the entire elevation gradient of the volcano. We sampled epiphytes in five distinct forest types associated with increasing elevation as follows: dry forest, humid forest, wet forest, cloud forest, and elfin forest. Five weather stations were placed along the elevation gradient for us to relate observed patterns to environmental conditions. A mid-elevation peak in species richness was detected for all vascular epiphytes at approximately 1000 m in elevation (cloud forest), yet epiphyte abundance increased with increasing elevation. In total we identified 206 taxa of vascular epiphytes belonging to 26 families and 73 genera. The most species-rich family was the Orchidaceae with 55 species for the entire elevation gradient, followed by Bromeliaceae (29 species), Araceae (23), Polypodiaceae (25), Dryopteridaceae (16), and Piperaceae (11), with all other families represented by fewer than 10 species each. We found that richness patterns differ phylogenetically across epiphyte groups, possibly due to different adaptive strategies, and species for the most part appear to be narrowly distributed within specific habitat zones along the elevation gradient. Variables associated with moisture, precipitation, humidity, mist, or cloud cover are key to understanding the observed patterns.

Salt marsh vegetation and secured woody debris facilitate the recolonization of Avicennia germinans

AbstractQuestionsDoes the presence of salt marsh vegetation affect the long‐term regeneration of the pioneer mangrove species Avicennia germinans in a degraded dwarf forest? Does immobilized coarse woody debris (CWD) affect regeneration similarly? Do larger trees suppress or facilitate intraspecific saplings?LocationDwarf mangrove forest in the high intertidal zone on the Bragança peninsula in northern Brazil.MethodsThe spatial patterns of A. germinans, the herbaceous halophyte Sesuvium portulacastrum, and CWD were mapped in three sample plots (each 400 m2) during two consecutive vegetation surveys, conducted in 2011 and 2014. Inhomogeneous Poisson and Thomas point process models were used to assess the distribution of A. germinans life‐history stages (seedlings, saplings, and adult dwarf trees), conditioned on the presence of S. portulacastrum and CWD. In addition, intraspecific interactions between trees and regeneration were assessed based on crown projection mapping. Bivariate point pattern analyses were used to assess the dependence of advance regeneration on dwarf A. germinans trees and S. portulacastrum.ResultsAvicennia germinans saplings and trees were positively associated with S. portulacastrum and CWD, whereas seedlings were located around tree crowns. The density of fruit‐bearing trees was positively associated with sapling density, indicating that regeneration relied on locally dispersed propagules.ConclusionsHerbaceous vegetation and CWD have an important ecological function in degraded mangroves by retaining tidally dispersed propagules. Here, we show that herbaceous vegetation does not suppress the growth of seedlings but facilitates mangrove recolonization. Due to limited tidal dispersal, regeneration relies on local propagule supply. In addition to hydrological restoration, the observed vegetation patterns suggest that, in the absence of propagule‐retaining vegetation, restoration of high‐intertidal mangroves can be facilitated by establishing nuclei of planted trees and installing secured logs.

Typical features of short-profile soils in the Middle Urals

Data on short-profile mountainous soils of the Middle Urals are discussed. In the new Russian soil classification system, these soils belong to the orders of lithozems (Leptosols), petrozems (Lithic Leptosols), organo-accumulative (Skeletic Umbrisols), Al–Fe-humus (Entic Podzols, Albic Podzols), and gley (Gleysols) soils. Information-logical analysis of factual data attests to a close relationship between the thickness of soil profiles and the genetic types of soils. Thus, the degree of development of the profile can be a diagnostic indicator of the type of soil formation. Short-profile soils develop in all high-altitude landscapes. Lithozems are widespread in all vertical zones. Other short-profile soils are more definitely related to certain altitudes. Thus, organo-accumulative soils mainly develop in the subalpine zone at 650–750 m a.s.l. under tall-herb meadows, podburs are found in the mountainous tundra zone at 800–940 m a.s.l. on slightly sloping surfaces. Podzols tend to occur under elfin forest zone (740–850 m) and in the transitional zone between elfin forest and tundra on steep slopes. Gley soils are formed under woodlands on flat or slightly sloping terraces at the ecotone between the zones of mountainous taiga and park woodland.

First description of the nest and juveniles of the Coppery Metaltail (Metallura theresiae), with comments on hummingbird nestling obesity

I provide the first description of the nest and juveniles of the Coppery Metaltail (Metallura theresiae), a hummingbird endemic to Peru. The locality of Unchog, in the elfin forest of the Carpish mountains in Huánuco, is where I found this species nesting. My descriptions are based on 4 nests found on different occasions (April 2013, January 2014, and Jul–Aug 2014). Coppery Metaltail used mainly moss, lichen, lycopodium, and twigs as materials to build their nests. I found 3 nest locations: a tree branch, creek banks, and an abandoned hut. The mean internal diameter of nests was 34.45 mm long by 42.52 mm wide (n = 4). I only measured the depth of 3 of them (mean = 33.83 mm). Metaltail eggs were white and had a mean of 12.93 by 8.3 mm (n = 2). Fledglings (n = 2) were observed in July and one of them reached up to 144% the mass of an adult. I comment on other cases of nestling obesity for different species of hummingbirds. The Coppery Metaltail selects different substrates for nesting and might reproduce throughout the year.

Key factors shaping prokaryotic communities in subtropical forest soils

Microorganisms in subtropical forest soils are responsible for various ecological functions such as decomposing organic matter and driving carbon and nitrogen cycles. It is essential to understand how environmental factors affect microbial community composition and diversity. Prokaryotic communities (including bacteria and archaea) were investigated according to soil layer (0–2 cm and 18–20 cm), forest type (mountain dwarf forest, Guangdong pine forest, and monsoon evergreen broadleaf forest) and season (summer and winter) in Guangdong Nanling National Natural Reserve in China by Miseq sequencing of 16S rRNA genes. This study reveals key factors that shaped prokaryotic community structure and diversity in subtropical forest soils in China. Results show that Acidobacteria and Proteobacteria were the dominant phyla, with a relative abundance of 54.2% and 20.7% respectively. Soil pH, organic matter, total N, hydrolysable N, available P, NO3−, and NH4+ were significantly correlated with prokaryotic community structure and diversity. Soil layer significantly affected prokaryotic community structure and diversity. Forest type significantly influenced prokaryotic community structure but not diversity. Season did not significantly correlate with prokaryotic community structure or diversity.

Rediscovery of the Dusky Starfrontlet Coeligena orina, with a description of the adult plumages and a reassessment of its taxonomic status

After being known only from the type specimen, an immature male, for over 50 years, the Dusky Starfrontlet Coeligena orina was rediscovered in 2004 at the type locality and another site 70 km to the south in the Western Andes of Colombia. Four specimens were collected, permitting the first descriptions of the adult male and female plumages. From these specimens we conclude that C. orina is a distinct species, probably most closely related to C. bonapartei and C. lutetiae, rather than a subspecies of the former (as it has been considered in much recent literature). It differs more in plumage colors and measurements from C. bonapartei, than do the races of the latter among themselves; the differences are comparable in magnitude to those between bonapartei and the sympatric C. helianthea. C. orina appears to be restricted to elfin forest and the páramo-forest ecotone between ca. 3100 and 3500 m in the northern part of the Western Andes. The type locality of Páramo Frontino is currently threatened, and effective protection measures are urgently needed. We recommend that based upon estimates of its current population size and limited available habitat, C. orina be classified as Critically Endangered.

Report on the mammals of Quimsacocha National Recreation Area, Azuay Province, Ecuador

Quimsacocha National Recreation Area is located on the western slope of the Andes in Azuay Province, southern Ecuador. All sampling locations were in the high paramo and high Andean forests (3,572 to 3,865 m). The habitats include paramo, bogs, riparian, patches of elfin forests, and secondary cloud forest. We set Sherman, pitfall, and camera traps (3,600 trap nights), and mist nets to collect 117 specimens. Eight species were collected, including Caenolestes caniventer Anthony 1921; Didelphis pernigra J.A. Allen, 1900; Cryptotis montivagus (Anthony, 1921); Akodon mollis Thomas, 1894; Microryzomys altissimus (Osgood, 1933), Phyllotis haggardi Thomas, 1908; Sigmodon inopinatus Anthony, 1924; and Sylvilagus andinus (Thomas, 1897). Two additional species Coendou rufescens (Gray, 1865) and Odocoileus virginianus (Zimmermann, 1780) were documented photographically. This is the first survey that saved voucher specimens for mammals of Quimsacocha.

Drivers of floristic variation in biogeographic transitions: insights from the ecotone between the largest biogeographic domains of South America

ABSTRACT Ecological transitions usually represent vulnerable ecosystems and high biodiversity. Investigating their drivers is important from both biogeographic and conservationist perspectives. One of these transitions is situated between the two largest biogeographic domains of South America - the Amazon and the Cerrado. We evaluated variation in tree floristic composition throughout this transition and assessed which factors explain this variation. We used 17,240 records of occurrences of 2,530 tree species from the NeotropTree database. We investigated variation in floristic composition using UPGMA cluster analysis with bootstrap resampling and NMDS ordination, and modeled the distribution of species in relation to environmental and spatial predictors by means of transformation-based Redundancy Canonical Analysis (tb-RDA) and variance partitioning. We found four general floristic groups: 1) flooded forests; 2) white sand dwarf-forests; 3) savannic and dwarf forests; and 4) non-flooded forest types. Floristic variation along the transition was influenced by the environment, especially variables related to fire and soil moisture, and by space, especially variables acting on broader scales. Correspondence between the environmental heterogeneity found throughout the transition and our results demonstrates once again the importance of conserving biogeographical transition zones in general, and the most comprehensive of South America in particular.

Xylem form and function under extreme nutrient limitation: an example from California's pygmy forest

Xylem anatomy and function have large implications for plant growth as well as survival during drought, but the impact of nutrient limitation on xylem is not fully understood. This study examines the pygmy forest in California, a plant community that experiences negligible water stress but is severely stunted by low-nutrient and acidic soil, to investigate how nutrient limitation affects xylem function. Thirteen key anatomical and hydraulic traits of stems of four species were compared between pygmy forest plants and nearby conspecifics growing on richer soil. Resistance to cavitation (P50 ), a critical trait for predicting survival during drought, had highly species-specific responses: in one species, pygmy plants had a 26% decrease in cavitation resistance compared to higher-nutrient conspecifics, while in another species, pygmy plants had a 56% increase in cavitation resistance. Other traits responded to nutrient limitation more consistently: pygmy plants had smaller xylem conduits and higher leaf-specific conductivity (KL ) than conspecific controls. Edaphic stress, even in the absence of water stress, altered xylem structure and thus had substantial impacts on water transport. Importantly, nutrient limitation shifted cavitation resistance in a species-specific and unpredictable manner; this finding has implications for the assessment of cavitation resistance in other natural systems.

Mapping forest structural heterogeneity of tropical montane forest remnants from airborne laser scanning and Landsat time series

Abstract Tropical montane forests are important reservoirs of carbon and biodiversity and have a central role in the hydrological cycle. They are, however, very fragmented and degraded, leaving isolated remnants across the landscape. These montane forest remnants have considerable differences in forest structure, depending on factors such as tree species composition and degree of forest degradation. Our objectives were (1) to analyse the reliability of airborne laser scanning (ALS) in modelling forest structural heterogeneity, as described by the Gini coefficient (GC) of tree size inequality; (2) to determine whether models are improved by including tree species-sensitive spectral-temporal metrics from the Landsat time series (LTS); and (3) to evaluate differences between three forest remnants and different forest types using the resulting maps of predicted GC. The study area was situated in Taita Hills, Kenya, where indigenous montane forests have been partly replaced by single-species plantations. The data included field measurements from 85 sample plots and two ALS data sets with different pulse densities (9.6 and 3.1 pulses m−2). GC was modeled using beta regression. We found that GC was predicted more accurately by the ALS data set with a higher point density (a cross-validated relative root mean squared error (rRMSECV) 13.9%) compared to ALS data set with lower point density (rRMSECV 15.1%). Furthermore, important synergies exist between ALS and LTS metrics. When combining ALS and LTS metrics, rRMSECV was improved to 12.5% and 13.0%, respectively. Therefore, if the LTS metrics are included in models, ALS data with lower pulse density are sufficient to yield similar accuracy to more expensive, higher pulse density data acquired from the lower altitude. In Ngangao and Yale, forest canopy has multiple layers of variable tree sizes, whereas elfin forests in Vuria are of more equal tree size, and the GC value ranges of the indigenous forests are 0.42–0.71, 0.20–0.74, and 0.17–0.76, respectively. The single-species plantations of cypress and pine showed lower values of GC than indigenous forests located in the same remnants in Yale, whereas Eucalyptus plantations showed GC values more similar to the indigenous forests. These results show the usefulness of GC maps for identifying and separating forest types as well as for assessing their distinctive ecologies.

ASSEMBLAGE OF NECTARIVOROUS BIRDS AND THEIR FLORAL RESOURCES IN AN ELFIN FOREST OF THE CENTRAL ANDES OF PERU

Nectarivorous birds (hummingbirds, flowerpiercers, and conebills) and their floral resources in an elfin forest of the central Andes of Peru (Unchog, Carpish Mountains) are described. This forest is well-known for its concentration of endemic species, mainly birds. We recorded the nectarivorous birds, vascular plants and the interactions among them between 2011-2014. The birds were recorded by direct observations and mist nets. Plants were evaluated with Gentry plots and occasional collection. A total of 26 nectarivorous bird species have been reported in this forest, however from our observations we detected from this assemblage 17 bird species that feed in plants’ nectar. A total of 27 plant species were visited by the birds. The nectarivorous birds were hummingbirds (Trochilidae, 12 species), flowerpiercers (Thraupidae, 4 species) and a conebill (Thraupidae: 1 specie). The plants were from 16 families and 14 orders. One species of hummingbird, Metallura theresiae, is endemic to Peru. On plants, Greigia macbrideana, Puya pseudoeryngioides, Centropogon isabellinus, Miconia alpina and Brachyotum lutescens are endemic to Peru. We comment on the species reported in previous expeditions and in the current checklists. Since this forest is important for its large number of endemic species, we comment on its current threats and the importance of accounting for ecological interactions to conserve montane forests.

OLD-GROWTH CHARACTERISTICS ON A COAST REDWOOD (SEQUOIA SEMPERVIRENS (D. DON) ENDL.) PYGMY FOREST ECOTONE

Old-growth Sequoia sempervirens (D. Don) Endl. (Cupressaceae) forests are commonly assumed to be populated by massive trees, but those growing on nutrient poor soils can be stunted and display unusual growth-forms. We characterized soils, stand structure, growth form, and crown complexity using a combination of random and targeted stratified sampling across an old-growth redwood/pygmy forest ecotone. ANOVA indicated significant variation in stand structure metrics and soil characteristics [pH, cation exchange capacity (CEC), and nutrient availability] among strata, with tree height, basal area, and the relative dominance of redwood-associated species declining under the influence of pygmy forest soils; while shrub cover and the dominance of pygmy associated species increased. Pearson's coefficients indicated positive correlations between tree height and diameter with CEC, P, K, Ca, and Na. Stepwise linear regression suggested that P, K, and CEC were the strongest predictors of tree height and diameter. Growth form and crown structure of S. sempervirens also varied considerably across the ecotone, with stunted multi-stemmed individuals and clusters of small diameter trees observed where pygmy soil conditions were most extreme, and larger, but still stunted ancient redwoods with complex crown structures, resident epiphytes, and large fire hollows, existing on the edge of the pygmy forest. The ancient redwoods sampled within the old-growth/ pygmy ecotone were remarkably small in stature, yet contained many of the same structural characteristics associated with the largest and oldest S. sempervirens.