Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years

An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l.

Decadal Modeling (2004-2021) Ecosystem Recovery Impacted by Mount Semeru Eruption Volcanic Activities using Vegetation Succession as a Proxy in the Lava Flow Stream

Volcano eruptions undoubtly cause environmental impacts and damages. After the eruption, there will be vast barren land that was previously fertile ground covered by vegetation and tree line. Lava from an eruption will flow to the land via a river stream, destroying everything in its path, including vegetation. While the ecosystem actually has an ability to recover. The natural process of ecosystem recovery is related to the succession of vegetation. Then this study aims to assess and model how the ecosystem can recover and how the vegetation can respond to the damage caused by Semeru, one of the most powerful volcanic eruptions on Java island. The study areas were 2 regions that had been impacted by the Semeru lava flow for the period of 2004–2021. Based on the results, the ecosystem recovery of Semeru post-eruption was achieved within 5 years. During this time, the vegetation succession rate, as measured by vegetation cover, increased nearly ten folds. The post-eruption ecosystem recovery was indicated by the ecosystem transformation from a damaged ecosystem indicated by a lava-dominated surface to one with the presence of vegetation and hardened lava. The recovered ecosystem in Semeru's posteruption was composed of solid lava covers (39%), liquid lava (34%), and vegetation covers (27%).Then, the presence of vegetation and its succession rate can be used as a proxy of ecosystem recovery after a vast volcanic eruption.

Beyond the Tree-Line: The C3-C4 “Grass-Line” Can Track Global Change in the World’s Grassy Mountain Systems

von Humboldt’s tree-line concept has dominated mountain ecology for almost two hundred years, and is considered a key indicator for monitoring change in biome boundaries and biodiversity shifts under climate change. Even though the concept of life zones and elevation gradients are a globally observed phenomenon, they have not been thoroughly explored for many contexts. One such example is the tree-line ecotone, a widely used conceptual tool to track climate change in many regions, which has limited application in the widespread tree-sparse, grassy systems that comprise a third of the world’s mountain systems. Among grasses (Poaceae), temperature is linked to variation in photosynthetic performance and community dominance for C3 and C4 metabolic groups, due to its role in limiting photorespiration in the C3 photosynthesis process. Here, we investigate this community shift in grassland-dominated mountains to demonstrate the role of climate in driving this transition and discuss the potential applications of this tool to mountain ecosystem conservation worldwide. For identifying grass-dominated mountains worldwide, we measured the grass-cover using satellite data. We then compiled Poaceae distribution data for ten grass-dominated mountains spanning from 42°S to 41°N and determined the temperature intervals and elevation ranges at which each genus was found, testing for effects of temperature, precipitation, and latitudinal gradients on the dominance of C3-C4 grasses. Temperature was the main driver of C3 dominance, with the richness of C3 genera tending to surpass the taxonomic dominance of C4 plants along mountain temperature gradients where the annual mean temperature was colder than ca. 14.6°C. Similar patterns were observed in eight out of ten mountains, suggesting that this may constitute an isotherm-driven ecotone. Consequently, this C3-C4 transition offers a promising tool for monitoring climate change impacts in grassy mountains. C3-C4 grass community shifts in response to environmental change will likely have major implications for fire frequency and severity, rangeland productivity and livelihoods, food security, and water budgets in mountain systems. Given the severity of the implications of global change on these social-ecological systems, we propose that a “grass-line” monitoring protocol be developed for global application.

1. The Arctic world

‘The Arctic world’ begins with the definition of the Arctic, which is understood as the land, sea, and ice lying north of the Arctic Circle set at a latitude of approximately 66.5° N. The Arctic tree line is a robust indicator of Arctic-ness as everything to the north is a landscape characterized by shrubs, dwarf trees, and lichen. Arctic warming occurs at least twice as rapidly as the global average, which is a phenomenon known as Arctic amplification. Since 1980, the warming trajectory in the Arctic has been much steeper than that of the rest of the planet.

Seasonal Characteristics of Temperature Gradient in a Glaciated Catchment in Eastern Himalaya

With climatic information from four stations in Rathong Chu valley for the period from 2017 to 2018, this study presents monthly and seasonal characteristics of the temperature lapse rate (TLR) in the eastern Himalayas. The station heights utilised in the study ranged from 1,742 to 4,450 m. The TLRs were assessed utilising a linear regression model. The mean yearly TLR for eastern Himalaya is less sheer (-0.52°C/100 m) beneath the tree line than (-0.47°C/100 m) over the tree line. The series of TLR exhibits two peaks in a year which confirms the distinctive controlling elements in the individual seasons. The highest TLR was found to be -0.60 °C/100 m during the pre-monsoon season below the tree line and -0.64 °C/100 m above the tree line. The post-monsoon has the second highest lapse rate change beneath the tree line (-0.58 °C/100 m) and in the monsoon (-0.57 °C/100 m) above the tree line. The minimum lapse rates were observed in the winter season below the treeline (-0.42 °C/100 m) and (-0.18 °C/100 m) above the tree line. The outcomes of this study add to the insight of elevation-dependent warming affected by worldwide climate change. Results also suggest that the climate and glacier modelling using the satellite temperature records or by applying the environmental lapse rate on temperature records from low altitudes may not be presenting the actual temperature trends.

FACTORS DETERMINING THE PHENOMENA IN THE UPER TREE LINE ECOTONE IN THE POLAR URALS MOUNTAINS

The article presents the results of the analysis of long-term studies dedicated to the reaction of woody plants to various extreme factors in the Rai-Iz mountain massif and Chernaya mountain, which are located on the southeastern slope of the Polar Urals in the Sob River basin (Russia). The analysis was performed using a unique archive of landscape photos, which were made by the authors from the beginning of the 1960s until the present. The classifi cation and description of the phenomena that are caused by the infl uence of environmental factors on woody vegetation, as well as their presentation using landscape photos, allow us to expand the possibilities of using ground-based images for the purposes of environmental photo monitoring of woody vegetation at the tree line. They can be used as an independent data source to identify factors that determine a morphological structure and spatial altitude of woody vegetation.

On the occurrence of the Himalayan Wolf Canis lupus, L. 1758 (Mammalia: Carnivora: Canidae) in the Gaurishankar Conservation Area, Nepal; its existence confirmed through sign and visual evidence in Rolwaling Valley

The Himalayan Wolf Canis lupus L., a top predator of the Third Pole, is proposed to be of a distinct wolf lineage (C. himalayensis) relative to the Holarctic Grey Wolf as described by mtDNA analyses. A biodiversity survey organized by the Gaurishankar Conservation Area Project (GCAP) has captured images of wolves in three different regions, and the study team has observed wolf scats in five additional regions above the tree line in Rolwaling Valley. Further, interviews with local herders provided evidence of wolf depredation of livestock in the area. The Rolwaling Valley in the Gaurishankar Conservation Area was the study area which was divided into 12, 4 x 4 km (16 km2) grid cells, each supplied with one camera trap operated continuously from June to November 2019 (only 6 out of 12 cameras functioned for the duration of our study). Wolf detections were recorded by camera traps from Yalung Pass (4,956 m), Tsho-Rolpa glacial Lake (4,536 m) and the Dudhkunda ridgeline (5,091 m). The photo capture rate index (PCRI) for wolves was 0.71. Our study reports the first photographic evidence of the Himalayan Wolf in the Rolwaling Valley.