Rapid Changes in Ground Vegetation of Mature Boreal Forests—An Analysis of Swedish National Forest Inventory Data

Abstract

The boreal forest floor vegetation is critical for ecosystem functioning and an important part of forest biodiversity. Given the ongoing global change, knowledge on broad-scale changes in the composition and abundance of different plant species and species groups is hence important for both forest conservation and management. Here, we analyse permanent plot data from the National Forest Inventory (NFI) on changes in the vegetation over a 10-year period in four regions of Sweden. To limit the direct and relatively well-known effects of forest management and associated succession, we only included mature forest stands not influenced by forestry during the 10 years between inventories, and focused on vegetation change mainly related to other factors. Results show strong decrease among many species and species groups. This includes dominant species such as Vaccinimum myrtillus and Deschampsia flexuosa as well as several forest herbs. The only species increasing are some mosses in the southern regions. Our data do not allow for a causal interpretation of the observed patterns. However, the changes probably result from latent succession in combination with climate change and nitrogen deposition, and with time lags complicating the interpretation of their relative importance. Regardless of the cause, the observed changes are on a magnitude that suggest impacts on ecosystem functioning and hence highlight the need for more experimental work.

Airborne eDNA captures three decades of ecosystem biodiversity

“…3D). Field-based studies have more recently emphasized the threats to these and other core genera posed by soil scarification ( 50 ), insufficient dead wood quantity or quality ( 25 ), habitat fragmentation ( 51, 52 ), or the altered light and moisture regimes from high planting densities and fire suppression ( 46, 48 ). Together, this suggests the largest change in airborne eDNA diversity resulted from commercial forest management across the landscape.…”

“…3D). These genera, and the species within them, occur in different habitats but are all directly affected by forest management (46)(47)(48).…”

Understory functional groups and fire history but not experimental warming drive tree seedling performance in unmanaged boreal forests

“…However, warmer temperatures at the level expected in boreal forests (1.5-4 • C) and an increase in precipitation (Gauthier et al, 2015;IPCC, 2021) can also affect the cover and abundance of understory functional groups (Hedwall et al, 2015(Hedwall et al, , 2019 and thus indirectly influence seedling responses. Overall, climate change is expected to decrease the cover of shrubs (Hedwall et al, 2015;Jonsson et al, 2021), while climate change effects on moss cover are less clear; potentially leading to an increase (Jonsson et al, 2021), but also a reduction (Alatalo et al, 2020). A decrease in shrub cover in future forests may in particular favor P. abies and P. sylvestris regeneration, because these species profited from shrub removal in terms of growth and P. sylvestris additionally benefitted from shrub removal in terms of survival.…”

The decreasing availability of reindeer forage in boreal forests during snow cover periods: A Sámi pastoral landscape perspective in Sweden

“…At the level of bottom-layer vegetation, they mainly compete against mosses and vascular plants, and have a competitive advantage on dry soils as they source nutrients from moisture and elements in the air (Horstkotte and Moen 2019 ). At local scales of forest structure, dense canopies create light-limiting conditions, and therefore, open-canopy forests better support lichen recovery and dominance (Jonsson Čabrajič et al 2010 ; Jonsson et al 2021 ). Therefore, so-called pine-heaths (coniferous forests on dry soil dominated by Scots pine) tend to be most conducive to ground lichen dominance (see Horstkotte and Moen 2019 ).…”