High-altitude Tropical Forest Research Articles

Differing Trade-Off Patterns of Tree Vegetative Organs in a Tropical Cloud Forest.

Functional trait ecology demonstrates the significance of the leaf economics spectrum in understanding plants’ trade-off between acquisitive and conservative resource utilization. However, whether trait variations of different vegetative organs are coordinated and whether the plant economics spectrum is characterized by more than one vegetative organ remain controversial. To gain insights into these questions, within a tropical cloud forest in Hainan Island, a total of 13 functional traits of 84 tree species were analyzed here, including leaf, stem and root traits. By using standardized major axis (SMA) regression and principal components analysis, we examined the trait variations and correlations for deciphering plants’ trade-off pattern. We found decreases of leaf phosphorus content, leaf nitrogen content and specific leaf area and increases of leaf mass per unit area (LMA), wood density and leaf thickness along the first principal component, while there were decreases of specific root length and specific root area and increases of root tissue density along the second principal component. Root phosphorus and nitrogen contents were significantly positively associated with the phosphorus and nitrogen contents of both stem and leaf. Wood density was significantly positively associated with LMA and leaf thickness, but negatively associated with leaf thickness and specific leaf area. Our results indicate that, in the tropical cloud forest, there is a “fast–slow” economic spectrum characterized by leaf and stem. Changes of nutrient trait are coordinated, whereas the relationships of morphological traits varied independently between plant above- and below-ground parts, while root nutrient traits are decoupled from root morphological traits. Our findings can provide an insight into the species coexistence and community assembly in high-altitude tropical forests.

Isotopic composition of total gaseous mercury at a high-altitude tropical forest site influenced by air masses from the East Asia continent and the Pacific Ocean

Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particulate-bound mercury (PBM), and the isotopic composition of total gaseous mercury (TGM = GEM + GOM) were measured at the Lulin Atmospheric Background Station (LABS), a mountain background site downwind of the East Asia continent, from February 2015 to January 2016. Mean (±S.D.) concentrations of GEM, GOM, and PBM were 1.54 ± 0.34 ng m−3, 14.0 ± 27.8 pg m−3, and 2.6 ± 3.7 pg m−3, respectively. Concentration-Weighted Trajectory (CWT) analysis indicated that East and coastal China were the main source regions of elevated GEM observed at LABS. Weekly integrated TGM showed significant variations in δ202HgTGM (−0.42 to 0.41‰) and Δ199HgTGM (−0.31 to −0.13‰). Both δ202HgTGM and Δ199HgTGM showed clear seasonal variations, but the seasonal pattern of δ202HgTGM was different from that of Δ199HgTGM. The lowest mean δ202HgTGM was observed in spring (−0.15‰), while the lowest mean Δ199HgTGM was observed in summer (−0.24‰). A significant positive correlation (R2 = 0.38, p < 0.01) existed between δ202HgTGM and normalized difference vegetation index (NDVI), suggesting vegetation activity was an important factor controlling the seasonal variation of δ202HgTGM. In contrast, air mass transport path, which influences the source region of TGM to LABS, was likely the driver for the seasonal variations of Δ199HgTGM. Furthermore, results from the air mass classification showed distinguishable Δ199HgTGM signature for different air mass source regions, with air masses from South China Sea and western Pacific Ocean being characterized by more negative Δ199HgTGM (−0.25 ± 0.04‰). Results of this research demonstrated a clear difference in isotopic compositions of atmospheric Hg between continental and marine air masses.

Pedogenesis in a topo-climosequence in the Agreste region of Pernambuco

The Borborema Plateau is characterized by different stages of relief evolution, which modify the climate and vegetation, and where high-altitude tropical forests can be seen surrounded by caatinga. The aim of this study was to characterize the soils of a topo-climosequence in the Agreste region of the State of Pernambuco, and evaluate the influence of the relief and climate on the pedogenesis. A topo-climosequence was selected, and trenches were opened in the geomorphological features of high-altitude forest (P1), between forest and pediplane (P2) and on a pediplanation surface (P3 and P4). A morphological description and a physical, chemical and micromorphological characterization were carried out. In general, the soils are sandy, with the predominance of a single-grain structure or weak aggregation. Higher values for pH, S, V% and assimilable P were found on the lower parts of the landscape. From the micromorphological analysis, the incipient development of pedogenic structures was detected in the C horizon in P1 and P3, clay translocation in P2 and the degradation of iron micronodules in P4. The P1 and P3 profiles were classified as Neossolos Regoliticos Distroficos espessarenicos (Regolsols), the P2 profile as a Argissolo Amarelo Distrofico tipico (Alisol), and P4 as an Planossolo Haplico Eutrofico arenico (Planosol). Soil variation in the landscape was determined by climate, relief and parent material. Micromorphology was efficient in detecting attributes not seen in the field, such as incipient aggregation in the Neossolos Regoliticos (Regosols) and the degradation of iron micronodules in the Planossolo Haplico (Planosol).

Molecular characterization and morphological description of cryptic haemoproteids in the laughingthrushes (Leiothrichidae) in the western and eastern Himalaya, India

Background: Laughingthrushes (family: Leiothrichidae) consists of diverse and widespread species found in the Indian subcontinent but there is a lack of information on their avian haemosporidians. Methods: We sampled 231 laughingthrushes of 8 species in the western and eastern Himalaya in India. Using parasite morphology and cytochrome b sequences we describe 2 new Haemoproteus species harbored in 3 species of laughingthrushes and report a case of cryptic speciation. Results: First Haemoproteus lineage TROERY01 (GenBank: KY623720) found in Trochalopteron erythrocephalum (27.47%) and Trochalopteron variegatum (2.9%) in mid to high altitude tropical forests in the western and eastern Himalaya, was described as Haemoproteus (Parahaemoproteus) leiothrichus n. sp. (Haemosporida: Haemoproteidae). Second Haemoproteus lineage TROERY02 (GenBank: KY623721) described as Haemoproteus (Parahaemoproteus) homoleiothrichus n. sp. (Haemosporida: Haemoproteidae) was found in T. erythrocephalum (2.19%) and Trochalopteron lineatum (3.84%), albeit in low intensity, only in the western Himalaya. Both H. homoleiothrichus n. sp. and H. leiothrichus n. sp. showed no significant difference in morphological features in blood stages. A genetic divergence of 4.4% along with distinct phylogenetic position indicates that these 2 lineages represent cryptic species. Previously, T. erythrocephalum has been described as an additional host for a morphologically described Haemoproteus timalus in the oriental region. Our described species have several morphological features that are absent in H. timalus. These are, the presence of dumbbell-like shaped mature gametocytes, ‘arm’ like extensions of gametocytes and lateral displacement of nuclei of infected erythrocytes. Illustrations of blood stages of the new species are given, and phylogenetic analysis with morphologically described Haemoproteus species identifies parasites closely related to the 2 described parasites. Conclusions: The lineages described here have been recorded only in the laughingthrushes so far. These are the first parasites to be described with T. erythrocephalum as a type host from the western and eastern Himalaya in India.

Molecular characterization and morphological description of cryptic haemoproteids in the laughingthrushes (Leiothrichidae) in the western and eastern Himalaya, India.

Background: Laughingthrushes (family: Leiothrichidae) consists of diverse and widespread species found in the Indian subcontinent but there is a lack of information on their avian haemosporidians. Methods: We sampled 231 laughingthrushes of 8 species in the western and eastern Himalaya in India. Using parasite morphology and cytochrome b sequences we describe 2 new Haemoproteus species harbored in 3 species of laughingthrushes and report a case of cryptic speciation. Results: First Haemoproteus lineage TROERY01 (GenBank: KY623720) found in Trochalopteron erythrocephalum (27.47%) and Trochalopteron variegatum (2.9%) in mid to high altitude tropical forests in the western and eastern Himalaya, was described as Haemoproteus (Parahaemoproteus) leiothrichus n. sp. (Haemosporida: Haemoproteidae). Second Haemoproteus lineage TROERY02 (GenBank: KY623721) described as Haemoproteus (Parahaemoproteus) homoleiothrichus n. sp. (Haemosporida: Haemoproteidae) was found in T. erythrocephalum (2.19%) and Trochalopteron lineatum (3.84%), albeit in low intensity, only in the western Himalaya. Both H. homoleiothrichus n. sp. and H. leiothrichus n. sp. showed no significant difference in morphological features in blood stages. A genetic divergence of 4.4% along with distinct phylogenetic position indicates that these 2 lineages represent cryptic species. Previously, T. erythrocephalum has been described as an additional host for a morphologically described Haemoproteus timalus in the oriental region. Our described species have several morphological features that are absent in H. timalus. These are, the presence of dumbbell-like shaped mature gametocytes, 'arm' like extensions of gametocytes and lateral displacement of nuclei of infected erythrocytes. Illustrations of blood stages of the new species are given, and phylogenetic analysis with morphologically described Haemoproteus species identifies parasites closely related to the 2 described parasites. Conclusions: The lineages described here have been recorded only in the laughingthrushes so far. These are the first parasites to be described with T. erythrocephalum as a type host from the western and eastern Himalaya in India.

Vanishing bird species in the Atlantic Forest: relative importance of landscape configuration, forest structure and species characteristics

Patch size, isolation, and vegetation structure are expected to strongly affect species persistence in fragmented landscapes, particularly for those with <30% of native habitat remaining. Those influences should be modulated by species characteristics, resulting in complex relationships. In order to investigate how species, habitat structure and landscape factors are related and how they affected species persistence, we studied bird communities in a fragmented Atlantic Forest region. Patch size strongly affected species richness and population abundances. However, some functional groups were more affected than others, particularly endemic and understory insectivores, species that are near the limits of their geographical distribution, those using few forest types, and those with their center of abundance in high altitude tropical forests. The effect of vegetation structure was mainly at the species level, reflecting specific responses to habitat quality. The importance of landscape variables varies according to the species group. For the most affected ones, which usually have low dispersal capacity, patch size and quality were the most relevant factors, whereas patch isolation was associated with the richness of groups with more generalist species. This pattern is due to the limited structural connectivity in the study region, composed of low matrix permeability (e.g. pastures and sugar cane), which isolate the most affected species, making them more dependent on local factors. In such a fragmented landscape, the largest patches should be prioritized for conservation purposes, as they aggregate the most vulnerable species and present the highest alpha diversity. Landscape management, as such, should also reconnect large fragments through corridors or matrix improvements, promoting better conditions for long-term persistence of the most affected species.

Taxonomy and phylogeny in the earliest diverging pleurocarps: square holes and bifurcating pegs

The extant members of the earliest diverging pleurocarpous moss lineages comprise few species but span a wide range of structural and molecular diversity, most of it restricted to temperate and high-altitude tropical forests in the Southern Hemisphere. We present the most comprehensive molecular phylogenetic study of these lineages to date, based on parsimony and Bayesian analyses of four regions from the chloroplast and mitochondrial genomes. In addition to corroborating the findings of parsimony methods in this and previous studies, the results of heterogeneous Bayesian analyses provide strong support for sub-topologies that are also consistently found under parsimony, but are rarely well supported. Careful model specification and investigation of potential sources of error increase confidence in the Bayesian results, which provide the basis for a substantially revised classification reflecting the best currently available hypothesis of evolutionary history. The genera previously classified in the Rhizogoniaceae, together with Orthodontium, Orthodontopsis, Aulacomnium and Calomnion, are recognized in three families, the Orthodontiaceae, Rhizogoniaceae and Aulacomniaceae, and three monofamilial orders, the Orthodontiales ord. nov., Rhizogoniales and Aulacomniales ord. nov. Many of the species previously recognized in Hypnodendron are placed in Sciadocladus, Touwiodendron gen. nov., Dendro-hypnum or Mniodendron. These genera, with the exception of Sciadocladus, are placed in the Hypnodendraceae together with Spiridens, Franciella, Cyrtopus and Bescherellia. Braithwaitea is excluded from the Hypnodendraceae and recognized in the monogeneric Braithwaiteaceae fam. nov., while Sciadocladus is placed with Pterobryella and Cyrtopodendron in the Pterobryellaceae. The Hypnodendraceae, Pterobryellaceae, Braithwaiteaceae and Racopilaceae are recognized in the order Hypnodendrales comb. et stat. nov. We discuss the advantages and limitations of ranked classification systems and propose the abandonment of intercalated Linnaean ranks between order and class levels in Bryopsida. Three node-based informal names, the Pleurocarpids, the Core Pleurocarps and the Homocostate pleurocarps, are defined to represent evolutionarily significant clades within the pleurocarpous group.

High altitude tropical secondary forests: a competitive carbon sink?

High altitude tropical regions have been heavily deforested and offer large areas for carbon offsets by secondary forest regeneration. However, a general assumption exists that productivity, and thus, carbon sequestration of high altitude forests is low, but the scarcity of data from high altitude tropical forests does not allow for a sound confirmation of this assumption. To determine the carbon sequestration potential of natural forest regeneration and reforestation efforts at high altitudes, aboveground biomass was quantified of several successional stages of two monospecific secondary forests in the high Ecuadorian Andes. The studied forests were, at 3200 m, an Alnus acuminata forest with 8-, 20-, 30- and 45-year-old stands and, at 3600 m, a Polylepis incana forest with 6-, 15- and 30-year-old stands and old growth forest without known age. Both trees are pioneer species. Additionally, a soil survey was conducted and leaf N/P ratios and N and P retranslocation rates were determined. Total aboveground biomass (TAGB) estimates of the oldest stages of the two forests were 241 Mg ha −1 for the Alnus and 366 Mg ha −1 for the Polylepis forest. Productivity, expressed as annual aboveground biomass accumulation (ABA) was in both forests highest in the establishment phase (14.2 and 15.0 Mg ha −1 per year at 8 and 6 years, respectively) due to high sapling numbers, and then slowed down significantly (5.9 and 6.9 Mg ha −1 per year, respectively at age 30). TAGB and ABA figures of the investigated forests are comparable to those of lowland tropical forests and do not indicate a significant decrease of these parameters at higher altitudes in the tropics. Analysis of site conditions, ecological requirements and ecophysiological properties of the tree species indicated that in both cases an optimal combination of these factors strongly favoured forest growth. It is not possible to verify whether our forests are representative for other high altitude tropical forests or if they should be treated as exceptional cases. The results do show, however, that high carbon offsets at high altitudes are possible.

Vegetation responses along edge-to-interior gradients in a high altitude tropical forest in peninsular India

A study was conducted in a high altitude tropical forest (shola forest) in peninsular India to examine the changes in floristic composition (mainly woody species regeneration) along an edge to interior gradient in relation to changes in edaphic and microenvironmental factors. Species inventory was taken in 25 m 2 plots, established at 10 m intervals along edge to interior transects. The measured soil variables included pH, organic carbon, total nitrogen, available phosphorus, and soil moisture. Microenvironmental factors including light transmittance, relative humidity, and air and soil temperatures also were monitored. Both edaphic and microenvironmental factors exhibited strong patterns along the edge to interior gradient. Forest edges were characterized by higher light transmittance, higher air and soil temperatures, and lower relative humidity. Soil variables including pH, organic carbon, total nitrogen, available phosphorus, and moisture increased toward the forest interior. Significant increases in organic carbon (53.9%), total nitrogen (47%), and soil moisture (55%) indicated a relatively fertile forest interior compared with the forest edge. A definite floristic compositional pattern also was observed along the edge to interior gradient which was correlated to the edaphic and microenvironmental variables as revealed by canonical correspondence analysis. It appears that edge effects in these high altitude forests penetrate to a distance of 15–30 m. Further, edaphic factors have an important influence on woody species regeneration, perhaps much more than microenvironmental factors. This indicates that any disturbance that significantly exposes theforest floor, thus lowering soil moisture and altering soil nutrient status, can adversely affect the regeneration of many of the shola species.