Mounding treatments set back bryophyte recovery on linear disturbances in treed peatlands

Abstract

Treed peatlands are dominated by bryophytes, particularly Sphagnum spp., which create the characteristic hummock-hollow microtopography. This, in turn, shapes the distribution of bryophyte communities. Disturbances can lead to a loss of this microtopographic variation, impacting the bryophyte community. Seismic lines are deforested linear disturbances (approximately 3-8 m wide) created during oil and gas exploration and very extensive in Alberta, Canada. Loss of microtopographic variation leads to slow tree recovery on seismic lines in treed peatlands. To facilitate tree establishment, mounding is being applied to restore the microtopography on seismic lines. We compared bryophyte communities on unmounded and mounded seismic lines (18 years after seismic line creation, 3 years after mounding), and in adjacent treed fens as the reference, to evaluate how recovery varies with microtopographic position (i.e., top of hummock, slope or side of the hummock, and level ground). We found that recovery on the unmounded seismic lines was underway 18 years after seismic lines were created, while mounding redisturbed the sites and thus set back recovery, at least in the short term (3 years post-mounding). In unmounded seismic lines, Sphagnum cover was similar to that of reference treatments at all microtopographic positions. In contrast, mounded seismic lines had lower Sphagnum cover and higher cover of true mosses (sans feather mosses) than reference and unmounded treatments. Overall, these results show mounding sets back the recovery of bryophyte communities-the very organisms responsible for the microtopographic variation we are trying to establish. Further monitoring is needed to understand how this changes over time.

Silviculture treatments hasten seedling growth on seismic disturbances in boreal treed fens

“…Emerging research in BERA and elsewhere demonstrates the complexity and interrelated nature of these elements with particular focus on water, carbon and methane cycling (e.g. Davidson et al 2020; Kleinke et al 2022; Schmidt et al 2022) and on bryophyte and other understory communities (Echiverri et al 2020; Echiverri et al 2022). We encourage restoration managers to remain sensitive to a range of ecosystem values, and to stay open to continual improvement and multiple treatment types that may increase the likelihood of favorable restoration outcomes (Rader et al 2022).…”

Inverted Soil Mounding as a Restoration Approach of Seismic Lines in Boreal Peatlands: Implications on Plant and Arthropod Abundance and Diversity

“…We expect the ingress of open-habitat species colonizing the newly disturbed sites will lead to increased richness and diversity across all taxa on both untreated and mounded seismic lines. In addition, arthropod assemblages are influenced by plant communities [22,23]; thus, we also expect arthropod assemblages to differ among treated, untreated, and reference conditions, as plant communities are altered by mounding [16,17]. Previous studies have shown mounding reduces bryophyte and total understory cover [16,17] at the top of the created mounds; thus, we expect mounded seismic lines to have lower bryophyte and understory cover compared to reference fens.…”

“…It is a silvicultural technique used by the forest industry to establish suitable conditions for tree growth by creating a drier elevated microhabitat and reducing competing vegetation [11,14]. While studies have found that mounded seismic lines have higher tree regeneration [12], other studies have also shown inverted mounding alters peat properties [15], reduces understory cover [16,17], and significantly increases heterogeneity in microtopography compared to adjacent reference fens [18]. However, additional research is needed to further explore the impact of mounding treatments on overall ecosystem properties and biodiversity, especially as the loss in vegetative cover can affect habitat quality (i.e., biophysical conditions) for peatland fauna.…”

“…In contrast to assessments of single taxa, assessments of multiple taxa are more valuable as they provide a broader understanding of biodiversity responses to treatment applications, which in turn can better inform restoration outcomes. While vegetation responses to peatland restoration efforts are commonly assessed [12,17,19], arthropod responses are rarely evaluated; however, see [20,21]. Arthropods are useful bioindicators as they are abundant, highly diverse, and responsive to disturbances [22,23].…”

Regeneration measures in time and space: Site preparation, planting and digital tools

“…The major soil disturbance caused by site preparation can also alter the forest vegetation composition of the future (Haeussler et al, 2017). With the large disturbance early successional species are promoted which initially can increase species richness (Roberts and Zhu, 2002;Pykälä, 2004) but the recovery of other species groups, such as lichens (Eriksson and Raunistola, 1990) or bryophytes (Echiverri et al, 2022), may be hampered. Additionally, in combination with shorter rotation lengths such species may not recover by the time of the next felling, resulting in loss of biodiversity (Petersson et al, 2019;Lariviere, 2023).…”