Functional traits of a plant species fingerprint ecosystem productivity along broad elevational gradients in the Himalayas

1. It is a challenge to scale-up from simplified proxies to ecosystem functioning since the inherent complexity of natural ecosystems hinders such an approach. One way to address this complexity is to track ecosystem processes through the lens of plant functional traits. Elevational gradients with diverse biotic and abiotic conditions offer ideal settings for inferring functional trait responses to environmental gradients globally. However, most studies have focused on differences in mean trait values among species, and little is known on how intraspecific traits vary along wide elevational gradients and how this variability reflects ecosystem productivity. 2. We measured functional traits of the sub-shrub Koenigia mollis (Basionym: Polygonum molle; a widespread species) in 11 populations along a wide elevational gradient (1515–4216 m) considering from subtropical forest to alpine treeline in the central Himalayas. After measuring different traits (plant height, specific leaf area, leaf area, length of flowering branches, leaf carbon isotope (δ13C), leaf carbon and leaf nitrogen concentrations), we investigated drivers on changes of these traits and also characterized their relationships with elevation, climate and ecosystem productivity. 3. All trait values decreased with increasing elevation, except for δ13C that increased upwards. Likewise, most traits showed strong positive relationships with potential evapotranspiration, while δ13C exhibited a negative relationship. In this context, elevation-dependent water–energy dynamics is the primary driver of trait variations. Furthermore, six key traits (plant height, length of flowering branch, specific leaf area, leaf carbon, leaf nitrogen and leaf δ13C) explained 90.45% of the variance in ecosystem productivity. 4. Our study evidences how elevation-dependent climate variations affect ecosystem processes and functions. Intraspecific variability in leaf functional traits is strongly driven by changes in water–energy dynamics, and reflects changes in ecosystem productivity over elevation. K. mollis, with one of the widest elevational gradients known to date, could be a model species to infer functional trait responses to environmental gradients globally. As inferred from K. mollis, the water–energy dynamics can be a hydrothermal variable to understand the formation of vegetation boundaries, such as alpine treeline. This study sheds new insight on how plants modify their basic ecological strategies to cope with changing environments.This work was supported by the National Natural Science Foundation of China (42030508, 41988101) and the Second Tibetan Plateau Scientific Expedition and Research Program (STEP; 2019QZKK0301). MBR was supported by long-term research development project number RVO 67985939 (www.ibot.cas.cz). J.P. was supported by the Spanish Government (grants PID2019-110521GB-I00 and TED2021-132627B-I00), the Catalan Government (grant SGR 2017-1005) and the Fundación Ramón Areces (grant CIVP20A6621)

Habitat Ecology of Ophiocordyceps sinensis in Western Nepal

As a valuable entomophagus fungus species, caterpillar fungus (Ophiocordyceps sinensis) is endemic to the alpine meadows of the Tibetan Plateau and adjoining Himalayas. However, little is known about its ecological niche and habitat. We investigated its associated plant species and habitat across different sites in Dolpa, west Nepal, and explored how associated plant species and soil characteristics affect its density and growth during the months of June and July in 2 consecutive years. Detrended correspondence analysis was used to capture the distribution pattern of plant species. Principal component analysis was applied to visualize the gradients of the soil data, and generalized linear models were employed to test the effects of nutrients and vegetation on the availability and size of caterpillar fungus. A total of 33 plant species were frequently associated with caterpillar fungus across the investigated sites. The abundance of the fungus was significantly affected by vegetation composition, whereas the individual fungal traits were independent of soil nutrients or vegetation composition. Therefore, it is essential to protect associated plant species to better conserve caterpillar fungus at high elevations

Epiphytic Orchid Diversity along an Altitudinal Gradient in Central Nepal

Epiphytic orchids are common in subtropical forests, but little is known about the factors that determine their diversity. We surveyed two sites (north-facing Phulchowki and south-facing Shivapuri hills), in the sub-tropical forest in the Kathmandu valley, central Nepal. Along five transects per site, spanning an altitudinal gradient of 1525–2606 m a.s.l., we recorded all epiphytic orchids and the host species on which they were growing. The data were analyzed using a generalized linear model (GLM) and redundancy analysis (RDA). Species richness significantly decreased with increasing altitude and was higher in larger hosts and in places with high temperature. Species composition was affected by altitude, distance from the forest edge, host type, and precipitation. This study indicates that the most important factors affecting epiphytic orchid diversity was altitude, even if other factors were associated with patterns in composition. The low-altitude habitats with high species diversity are the best places for epiphytic orchids in this region. The altitudinal species richness and patterns in composition revealed by this study provide a baseline for further studies on epiphytic orchids

Heterogeneous Landscapes on Steep Slopes at Low Altitudes as Hotspots of Bird Diversity in a Hilly Region of Nepal in the Central Himalayas

<div><p>Understanding factors determining the distribution of species is a key requirement for protecting diversity in a specific area. The aim of this study was to explore the factors affecting diversity and distribution of species of birds on different forested hills in central Nepal. The area is rich in species of birds. Because the area is characterized by steep gradients, we were also interested in the importance of altitude in determining the diversity and species composition of the bird communities. We assessed bird diversity and species composition based on point observations along a gradient of increasing altitude in two valleys (Kathmandu and Palung) in central Nepal. Data on environmental variables were also collected in order to identify the main determinants of bird diversity and species composition of the bird communities. We recorded 6522 individual birds belonging to 146 species, 77 genera and 23 families. Resident birds made up 80% (117 species) of the total dataset. The study supported the original expectation that altitude is a major determinant of species richness and composition of bird communities in the area. More diverse bird communities were found also in areas with steeper slopes. This together with the positive effect of greater heterogeneity suggests that forests on steep slopes intermixed with patches of open habitats on shallow soil at large spatial scales are more important for diverse bird communities than more disturbed habitats on shallow slopes. In addition, we demonstrated that while different habitat characteristics such as presence of forests edges and shrubs play an important role in driving species composition, but they do not affect species richness. This indicates that while habitat conditions are important determinants of the distribution of specific species, the number of niches is determined by large scale characteristics, such as landscape level habitat heterogeneity and altitude. Thus, to protect bird diversity in the mid-hills of central Nepal, we should maintain diverse local habitats (viz. forest, shrubs, open land, etc.) but also make sure the natural habitats on steeper slopes with large scale heterogeneity are maintained.</p></div

Diversity, distribution and host-species associations of epiphytic orchids in Nepal

Associations between epiphytes and their hosts are among the main factors affecting the biodiversity and distribution of epiphytes. While several previous studies explored the association between epiphyte diversity and host characteristics, very little is known about the generality of such associations at larger spatial scales. We aim to explore the associations between diversity and distribution of epiphytic orchids and host characteristics in different localities in Nepal. Epiphytic orchids and their hosts were recorded along the transects in total of 23,539 host individuals. To describe the diversity of orchids in the different localities, a rarefaction function was used. Univariate and multivariate analyses were carried out to explore the associations with locality, host characteristics, and their interactions with locality. In total, we recorded 141 species of orchids growing on 192 host species. The five localities significantly differed in orchid diversity and abundance. The number of orchid individuals per host species significantly increased with increasing number of host individuals. Species richness, abundances, occupancy of orchid species on host species and composition of orchids varied across the localities. Species richness and abundance was significantly higher on hosts in the higher strata and differed between families of host species. Abundance was higher on evergreen hosts. Composition of orchid communities are also associated with host characteristics, such as habit (shrub/tree/climber), bark texture, nature (deciduous/evergreen) and the plant families of host species. This study revealed a high diversity of epiphytic orchids in the localities studied and strong associations between the orchids and their hosts. Future studies looking at the relationships between epiphyte communities and host characteristics need to identify relationships at a wider scale in order to determine whether they are really general rather than site-specific

Maps showing the location of the study area and land use in the Palung and Kathmandu valleys, Nepal, along with pie-charts recording bird diversity in terms of feeding habits.

<p>Maps showing the location of the study area and land use in the Palung and Kathmandu valleys, Nepal, along with pie-charts recording bird diversity in terms of feeding habits.</p

Relationship between species richness and altitude at different localities in central Nepal.

<p>Relationship between species richness and altitude at different localities in central Nepal.</p

Xanthones Content in Swertia multicaulis D. Don from Nepal

The medicinal plant Swertia multicaulis D. Don was collected in Rasuwa District (Nepal) and the xanthone content of its ethyl acetate extracts was studied. The total amount of xanthones in S. multicaulis determined by HPLC reaches almost 13 g of xanthones per 1 kg of dry matter. The identification of xanthones in S. multicaulis was achieved by a combination of HPLC, LC&ndash;MS and LC&ndash;NMR. The final assignment of the individual chemical structures was provided by NMR, supported by preparative HPLC. In eight chromatographic peaks, four major xanthones were identified&mdash;1,3-dihydroxy-5,8-dimethoxyxanthone, 1-hydroxy-3,5,8-trimethoxyxanthone, bellidifolin (1,5,8-tri-hydroxy-3-methoxyxanthone), and decussatin (1-hydroxy-3,7,8-trimethoxyxanthone)

Relationship between bird species richness and altitude in central Nepal.

<p>Relationship between bird species richness and altitude in central Nepal.</p

The relationship between the proportion of insectivorous bird species and altitude.

<p>The relationship between the proportion of insectivorous bird species and altitude.</p