Introduction 6
Materials and method 8
1.2 General characteristics of the Yamal Peninsula and its vegetation cover 8
1.2. Community of small rodents on the Yamal Peninsula 12
1.3 Study area 15
1.4 Method of snap trapping and abundance of small rodents 16
1.5 Climate data 19
1.6 Shrubs expansion 20
Results 22
Discussion 29
Conclusion 34
References 36
On the Yamal Peninsula, different tundra subzones alternate. Here several species of small rodents play a key role in the plant-herbivore-predator system. Nowadays, terrestrial Arctic ecosystems have undergone important changes (Ims et al., 2013; Ims and Fuglei, 2005). Climate change, namely warming, which during last 40 years occurs nearly four times faster at high latitudes than in the globe (Rantanen et al., 2022; Chylek et al., 2022), and is a major driver of biodiversity changes as well as other anthropogenic impacts such as industrial development and land use which play a significant role in interactions with climate (IPCC, 2023). Vegetation composition shifts, and in particular, shrub expansion across the Arctic tundra is the most important and widely described responses of high-latitude ecosystems to rapid climate warming.
Willow thickets (Salix spp) are prominent structural features in the southern Arctic tundra, where they serve important ecological functions by providing food, shelter, and/or breeding sites for wildlife. At the same time there is an increase in the area of willow thickets due to climate warming (Chapin et al., 2005; Tape et al., 2006). In general, communities of certain species prefer certain types of habitats. But with an increase in the area of willow thickets in the Arctic, southern species related to this microhabitat can penetrate into the tundra. So, the main habitat may not be able to accommodate all individuals as densities increase and some animals move to neighboring habitats, which in turn are native for local species. Therefore, one of the main predicted consequences of climate change, which has a serious impact on the structure and functioning of tundra food webs, is shifts in the ranges of species due to changes in their usual habitat as a result of shrubs spreading to the north, which leads directly to changes in biodiversity.
Long-term observations and possible explanations of such shifts caused by climate change are rare in the Arctic, while are critical for the entire food webs of terrestrial tundra ecosystems.
The purpose of the study - is to document, evaluate and predict changes in the small rodent’s community under spreading of willow thickets.
Tasks:
• reveal the preference of different habitats by different species;
• assess the geographical patterns of long-term fluctuation density and identify trends in the abundance of small rodents;
• check the spill-over effect in the years of increase in the abundance of particular species;
• formulate a forecast of changes in the rodent community under the spreading of shrubs.
Hypotheses based on the assigned tasks:
• from literature analysis - the narrow-headed vole prefers thickets, the Middendorff's vole prefers wet tundra, and the collated lemming prefers dry tundra;
• all three study species would show spill-over effect with the growing density (i.e. “going out from their preferred habitat”).
The aim of this work was to document, evaluate and predict changes in the small rodent’s community under spreading of willow thickets. As the results it was recorded that the rodent community in the shrub tundra of Southern Yamal was dominated by two species: the Middendorff's vole and the narrow-headed vole, which were the most numerous species in the trapping areas. The narrow-headed vole was trapped mainly in areas located at the edge of willow thickets, when, as for the Middendorff's vole, the mostly wet tundra with a thick layer of sphagnum moss was the most preferred habitat. The predominance of collared lemmings has been documented in dry tundra. Hence, it supports the 1st hypothesis of this study.
Narrow-headed voles have shown a statistically significant tendency of moving out of their preferred habitat (thickets) not only to neighboring meadows, but even into the alternative types of biotopes (wet and dry areas of tundra). Contrary, two native arctic species (colored lemming and Middendorff vole) doesn’t show such significant trend despite of their high abundance in some years. That conclusion is partly contrary to 2nd hypothesis of the study.
The obtained long-term climatic data also support positive trend and increase of mean summer temperatures on the study area and in the region (from 9,3 up to 11,6 degrees). At the same time many studies confirm the positive relation between climate change (namely warming) and the expansion of shrubs. Many studies confirm the increase and spread of both deciduous shrub species such as birch (Betula spp.), willow (Salix spp.), and alder (Alnus spp.), as well as prostrate evergreen shrubs in response to warming on Yamal and in other parts of Arctic. And since narrow-headed and Middendorff's voles feed on grasses and forbs, their increasing distribution is most likely caused by the growth of shrubs, forbs and grasses due to longer and warmer summers.
To reach our task about formulating a forecast of changes in the rodent community under the condition of spreading shrubs, our findings allow us to predict explosion further to the north of more southern species (narrow-headed vole) into the tundra, where it possibly can negatively affect native arctic species in their preferred habitats. It will ultimately affect the entire food webs of terrestrial arctic ecosystems, namely abundance and breeding performance of symbolic arctic species, such as snowy owls and arctic foxes.
