Liverworts from Attu Island, Near Islands, Aleutian Islands, Alaska (USA) with comparison to the Commander Islands (Russia)

Abstract

The liverwort flora of Attu Island, the westernmost Aleutian Island in the United States, was studied to assess species diversity in the hyperoceanic sector of the northern boreal subzone. The field study was undertaken in sites selected to represent a spectrum of environmental variation, primarily within the eastern part of the island. Data were analyzed using our own collections on Attu Island, supplemented with information from published reports to compare bryophyte distribution patterns at three levels, the Northern Hemisphere, North America, the Commander Islands of Russia, and Alaska. A total of 112 liverworts were identified and a substantial number, 34 species (30%), were new reports from Attu Island and one was new to Alaska. Geographic elements dominating the flora included arctomontane (26%), arctoboreomontane (23%), montane (20%), and boreal (14%) species, while arctic species were almost absent (1%). The liverworts of the Attu Island-Commander Islands region were widespread species with over 70% circumpolar, or nearly circumpolar; nevertheless large gaps were present in some of their distributions with a floristic depression in liverwort distribution between Attu and the Commander Islands.

New Updates on the Distribution of Scapania umbrosa (Schrad.) Dumort. (Scapaniaceae, Marchantiophyta) in Pacific Asia

“…However, given the limited material available from the Commander Islands, it may be that we failed to identify some traits that could be considered environmentally induced and which could correlate with genetic differences. In addition, the lack of information on the distribution of Scapania umbrosa in the Aleutian Islands is not at all proof of the real absence of the species there, given the fragmentary data on the flora of Aleutian liverworts in general [46,47]. Thus, both of the following are equally probable: the distribution of the Alaskan and Commander haplotypes in the Aleutian Arch; and the distribution of only one (identified by us) haplotype, which may be connected by transitions with the haplotype known from Alaska, or may not be connected with it by the transitions.…”

“…It is interesting that the species is not yet known in the Aleutians [46,47], although such findings of the species seem logical and expected; given the modern distribution of the species, it is logical to assume that it could migrate to Bering Island from Alaska through the Aleutian chain. Additionally, birds could be considered possible agents for reaching the island.…”

Gyrothyraceae (Marchantiophyta) — a new family for the Russian liverwort flora

“…The dominate climate type in all those regions is Warm-summer Mediterranean (Beck et al, 2018), thus the same as mentioned above for the British Columbia occurrence of the species. The climate of Aleutians is classified by the ecoclimatic-phytogeographical system of Tuhkanen (1984, original not seen, cited after Talbot et al, 2018) as northern boreal, hyperoceanic, and perhumid. Unlike to the latter, the Köppen-Geiger climate classification cited above refers climate in the western Aleutians (westward of Unalaska) to Subpolar Oceanic Climate type.…”

Increased biocrust cover and activity in the highlands of Iceland after five growing seasons of experimental warming

“…Only a handful have been conducted involving ecosystems that are at least partially covered with biocrust (Chapin et al, 1991;Rousk et al, 2018;Sullivan et al, 2008;Wahren et al, 2005). In our study, we investigated the potential effects of warming on biogeochemical and ecological properties of a sub-Arctic alpine biocrust characterized by the liverwort Anthelia jurkatzkana (Salazar et al, 2022) -a type of biocrust common in Icelandic highlands with heavy snow cover (Aradottir and Halldorsson, 2018;Arnalds et al, 2015;Ortiz-Rivero et al, 2023) and in other high latitude regions (Bakalin et al, 2022;Belland, 1983;Konstantinova and Savchenko, 2008;Smith, 1917;Talbot et al, 2018).…”