Changes in the ground environment under the influence of fires in the territory of the State Natural Reserve «Olekminsky»

This paper discusses the chronology and cause of forest fires on the territory of the State Reserve “Olekminsky”. Forest fires on the territory of the reserve are low-level, caused by dry thunderstorms. The overgrowth of burnt areas occurs at the expense of specific groups of pyrophyte plants. For 2-3 years after the fires, Camenerion angustifolium (L.) Scop., Corydalis sibirica (L.) Pers., Plantago canescens Adams, Crepis tectorum L. and others were found. In waterlogged areas, Tephroseris palustris (L.) Reichenb appear and subsequently do not occur, and mosses: Marshantia polymorpha L., Ceratodon purpureum (Hedw.) Brid. It was found that the restoration of ground cover is mainly due to species characteristic only for intermediate stages: Lichens - Baeomyces carneus, Dibaeis baeomyces and Trapeliopsis granulosa, as well as Arctous erythrocarpa (Small) M. Ivanova, Chamaenerion angustifolium (L.) Scop., Calamagrostis obtusata Trin, Сarex spp., cereals and green mosses. More than 40 species of lichens participate in the formation of the ground cover of the studied larch forests, mainly bushy species of Cladonia, Stereocaulon, Peltigera. Forest fires of a natural nature occurring on the territory of the reserve are the main limiting factor affecting bio-resources and theirrestoration.

White Sweetclover (Melilotus albus) and Narrowleaf Hawksbeard (Crepis tectorum) Seed Germination after Passing through Moose

White sweetclover and narrowleaf hawksbeard are nonindigenous invasive plant species in Alaska that are rapidly spreading, including into areas that are otherwise free of nonindigenous plants. There has been concern that native moose could be dispersing germinable seed from these plants after ingestion. To address this concern, a study was conducted involving tame moose at the University of Alaska Fairbanks Agriculture and Forestry Experiment Station, Matanuska Experiment Farm, Palmer, AK. Objectives were to determine if seeds from these two plant species could survive mastication and digestive passage through moose, whether this passage impacted seed germination, and whether seed passage rates were the same as similar sized Cr-mordanted fiber. In this study, narrowleaf hawksbeard seed rarely survived mastication and digestion with only five seedlings recovered from 42,000 germinable seed fed to the moose. About 16% of germinable white sweetclover seed (3,595 of 22,000) fed to the moose produced seedlings. Most of the sweetclover seedlings came from feces produced 2 and 3 d after feeding. In two moose, sweetclover seedlings were grown from fecal material that was passed 11 d after feeding, raising the possibility that seeds could be transported long distances after ingestion. Cr-mordanted fiber passage did not closely follow seedling producing seed, possibly because time in the rumen might reduce seed germination. Once roadsides in Alaska become infested with white sweetclover, moose can then serve as a transport vector of these weeds into river channels and floodplains, which are distant from roads. This information will impact white sweetclover management programs and alert land managers to the potential for other instances of wildlife-mediated seed dispersal.

Experimental demonstration of floral allocation costs in Crepis tectorum

Information on floral resource costs is fundamental for understanding how selection operates on floral morphology. In this study, I explored the cost of maturing flowers in a self-incompatible population of the ligulate composite Crepis tectorum L. by experimentally manipulating floral investment and then monitoring the response in reproductive effort. Plants on which the heads were removed during the initial stage of ligule expansion had a higher reproductive effort than plants whose heads were removed immediately after flower maturation, and the latter plants had a higher reproductive effort than plants on which all flowers were permitted to set fruit. Judging from biomass estimates and the magnitude of the observed tradeoffs, the amount of resources allocated to maturing flowers was about half as great as the amount of resources devoted to fruit maturation. These and other results suggest that floral tradeoffs may exert negative selection on floral size variables.