High altitudinal vegetation dynamics including treeline ecotone in Langtang National Park, Nepal

Identification of high altitudinal vegetation dynamics using remote sensing is important because of the complex topography and environment in the Himalayas. Langtang National Park is the first Himalayan park in Nepal representing the best area to study vegetation change in the central Himalaya region because of the high altitudinal gradient and relatively less disturbed region. This study aimed at mapping vegetation in Langtang National Park and its treeline ecotone using Moderate Resolution Imaging Spectroradiometer (MODIS), Normalized Difference Vegetation Index (NDVI). Two treeline sites with an altitude of 3927 and 3802 meters above sea level (masl) were selected, and species density was measured during the field survey. The linear slope for each pixel and the Mann Kendall test to measure significant trends were used. The results showed that NDVI has significantly increased at the rate of 0.002yr-1 in Langtang National Park and 0.003yr-1 in treeline ecotone during 2000-2017. The average 68.73% equivalents to 1463 km2 of Langtang National Park are covered by vegetation. At the same time, 16.45% equivalents to 350.43 km2 are greening, and 0.25%, i.e., 5.43 km2 are found browning. In treeline ecotone, the vegetation is mostly occupied by grasses, shrublands and small trees where the NDVI was found from 0.1 to 0.5. The relative changes of NDVI in barren lands are negative and vegetative lands above 0.5 NDVI are positive between 2000 and 2017. The dominant treeline vegetation were Abies spectabilis, Rhododendron campanulatum, Betula utilis and Sorbus microphyla, with the vegetation density of 839.28 and 775 individuals per hectare in sites A and B, respectively. The higher average NDVI values, significantly increased NDVI, and higher density of vegetation in both A and B sites indicate that the vegetation in treeline ecotone is obtaining a good environment in the Himalayas of Nepal.

Has tree density increased at alpine treelines on the eastern Tibetan Plateau?

Treeline densification, along with increased growth rates, is considered a primary manifestation of climate warming at alpine treelines. However, treeline densification has typically been inferred from comparisons of present-day tree density with estimates of former densities inferred from current age structure; the densification has not been verified with long-term monitoring data and thus empirical testing is needed. In this study, a series of plots was established along an altitudinal gradient in a treeline ecotone on the eastern Tibetan Plateau; the plots were then surveyed repeatedly for ten years to analyse spatiotemporal variation in tree regeneration. The densities of Abies fargesii var. faxoniana seedlings and saplings increased from low altitude sites to high altitude sites, before dropping to zero beyond the treeline. The density of fir seedlings at the treeline in 2018 was significantly lower than in 2008. There were no significant differences in the density of saplings, small trees, medium trees, or old-growth trees between 2018 and 2008. As compared to regeneration patterns from 65 years ago, treeline densification represents a spatial phenomenon related to altitude, but not a temporal pattern on the eastern Tibetan Plateau. A more comprehensive understanding of the effects of climate warming on treeline regeneration will require further long-term monitoring and research.

Regional opportunities for Siberian tundra conservation in the next 1000 years

The biodiversity of tundra areas in northern high latitudes is threatened by invasion of forests under global warming. However, poorly understood nonlinear responses of the treeline ecotone mean the timing and extent of tundra losses are unclear but policymakers need such information to optimize conservation efforts. Our individual based model LAVESI, developed for the Siberian tundra-taiga ecotone, can help improve our understanding. Consequently, we simulated treeline migration trajectories until the end of the millennium, causing a loss of tundra area when advancing north. Our simulations reveal that the treeline follows climate warming with a severe, century-long time lag, which is overcompensated by infilling of stands in the long run even when temperatures cool again. Our simulations reveal that only under ambitious mitigation strategies (RCP 2.6) will ~30% of original tundra areas remain in the north but separated into two disjunct refugia.

A new species of Podanotum Torres & Johnson, 1996 (Lepidoptera, Lycaenidae) from northern Peru

We describe a new species of the genus Podanotum Torres & Johnson, 1996, Podanotum pajaten Farfán, Cerdeña & Bálint sp. nov. from northern Peru, associated with the Andean treeline ecotone adjacent to cloud forest and wet grassland at 3200 m above sea level. Description of this new species is based on one female adult and is distinguishable from its congeners by the combination of the following morphological characters: dorsal wing pale blue, forewing discoidal line present on ventral side, hindwing tailed, and ostium bursae distally toothed. Podanotum pajaten sp. nov. is separated geographically from the closest spatial species, P. glorissimum Bálint & Wojtusiak, 2002, by approximately 100 km to the south, and represents the second species described for Peru. An identification key to all known species of Podanotum is provided, stating their distributions by country. Publicación registrada en Zoobank/ZooBank article registered:LSIDurn:lsid:zoobank.org:pub:FE6C35CF-2609-410C-9CB5-57737D02DFC3Acto nomenclatural/nomenclatural act:Podanotum pajaten Farfán, Cerdeña & Bálint, 2021LSIDurn:lsid:zoobank.org:act:B8CE9125-0182-4DAB-BD92-D15DC4E16C47

Recent spruce (Picea abies) treeline ecotonal progression since the late1980s in the Swedish Scandes-a repeat photographic narration and analysis

This study reports a case of climate-mediated transformation and physiognomic progression of the Norway spruce (Picea abies) treeline ecotone since the mid-1990s in the Swedish Scandes. The methods include repeat photography and foliation estimates of old-established clonal spruces. An air and soil temperature nadir by the 1980s had caused extensive needle and shoot mortality, evident at the landscape-scale. Subsequent winter and summer temperature rises induced a striking canopy recovery, including densification and vertical growth. Release from low soil temperature stress appears as instrumental for canopy progression and shift from stunted growth to erect tree forms. Seed-based regeneration of new individuals has been virtually nil and the ecotone appears to be spatially stable. Ongoing ecotonal shifts has the character of growth form transformations in accordance with climatic conjunctures.

Diversity and distribution of vascular plants within the treeline ecotone in Mount Iremel (Southern Urals, Russia)

During the last 100 years, rapid advances of trees towards higher elevations and latitudes have been recorded for various regions worldwide, including the Ural Mountains. Climate warming and tree cover increases can lead to significant changes in the high-mountain vegetation. Direct observations on the vegetation of high-mountain regions provide evidence for an increase in the species diversity of plants at high elevations and changes in the composition of the alpine communities. This study investigated the diversity and distribution of vascular plants within the present-day treeline ecotone in Mount Iremel, the Southern Urals. The dataset (Trubina and Nesterkov 2021, available from the GBIF network at https://www.gbif.org/dataset/284f1484-10b7-4ef5-87b7-9de1159e6b42) presents the results of an assessment of species richness and frequency of vascular plants at the different elevation levels (from 1203 to 1348 m a.s.l.) and different biotopes (birch-spruce shrub forest, birch-spruce sparse forest and spruce forest with fragments of meadow plant communities) within the treeline ecotone in Mount Iremel, Southern Urals. Observations were carried out at 700 sampling plots with two estimation methods: small-size plot (0.5 × 0.5 m) sampling (672 plots in total) and large-size plot (10 × 10 m) sampling (28 plots). The dataset includes 700 sampling events (= sampling plots), corresponding to 5585 occurrences (vascular plants, mainly identified to species) observed during July 2003. Only occurrences containing plant taxa (occurrenceStatus = present) have been provided. The dataset includes information about distribution and frequency of the Ural endemic species (Anemone narcissiflora subsp. biarmiensis (Juz.) Jalas, Calamagrostis uralensis Litv., Cerastium krylovii Schischk. & Gorczak., Festuca igoschiniae Tzvel., Hieracium iremelense (Elfstr.) Üksip, Lagotis uralensis Schischk, Pleurospermum uralense Hoffm.) and the Pleistocene relict species (Alopecurus magellanicus Lam., Bistorta vivipara (L.) Delarbre, Cerastium pauciflorum Stev. ex. Ser., Pedicularis oederi Vahl, Saussurea controversa DC., Swertia perennis L.). The dataset also provides information that can be useful for estimating biodiversity and plant communities composition within the treeline ecotone at a specified time period and contributes to the study of biodiversity conservation in the Ural Region.