The Combined Role of Retention Pattern and Post-Harvest Site Preparation in Regulating Plant Functional Diversity: A Case Study in Boreal Forest Ecosystems

Abstract

Changes in the light availability in forests generated by diversified retention patterns (e.g., clear cut, partial harvest) have been shown to strongly filter the plant species present. Modified soil microsite conditions due to post-harvest site preparation (e.g., mechanical site preparation, prescribed fire) might also be an important determinant of plant diversity. The objective here was to detect how retention pattern and post-harvest site preparation act as filters that explain the understory functional diversity in boreal forests. We also assessed whether these effects were dependent on forest attributes (stand type, time since fire, and time since harvest). We retrieved data from seven different studies within 101 sites in boreal forests in Eastern Canada. Our data included forests harvested with two retention patterns: careful logging and clear cut, plus unharvested control forests. Three post-harvest site preparation techniques were applied: plow or disk trenching after careful logging, and prescribed fire after clear cut. We collected trait data (10 traits) representing plant morphology, regeneration strategy, or resource utilization for common species. Our results demonstrated significant variation in functional diversity after harvest. The combined effect of retention pattern and site preparation was the most important factor explaining understory diversity compared to retention pattern only and forest attributes. According to RLQ analysis, harvested forests with site preparation favored traits reflecting resistance or resilience ability after disturbance (clonal guerilla species, geophytes, and species with higher seed weight). Yet harvested forests without site preparation mainly affected understory plant species via their light requirements. Forest attributes did not play significant roles in affecting the relationship between site preparation and functional diversity or traits. Our results indicated the importance of the compounding effects of light variation and soil disturbance in filtering understory diversity and composition in boreal forests. Whether these results are also valid for other ecosystems still needs to be demonstrated.

Planting density and mechanical site preparation effects on understory composition, functional diversity and planted black spruce growth in boreal forests

“…To our knowledge, our study is the first to evaluate the potential interacting effects of planting density and MSP on functional traits of vascular plants and bryophytes. Our findings for some vascular plant traits were similar to those reported by Wei et al (2019), who found that MSP affected vascular plants traits after soil disturbance and as a function of light availability. Hence, MSP played an important role in understory functional composition and diversity.…”

Interspecific Variability of Water Storage Capacity and Absorbability of Deadwood

“…In addition, deadwood supports multiple functions of the ecosystem including regeneration after disturbances [10], as well as carbon, nutrient, and hydrological cycles [11,12]. Deadwood can have a real impact on the microclimate [13,14].…”

A critical review of successional dynamics in boreal forests of North America

“…Because variability in the severity of a disturbance leads to variable post-disturbance compositional types (e.g., Lecomte et al 2005;Johnstone et al 2010), adapting silvicultural inten-sity to match the desired post-disturbance composition type determines whether forest management goals are met. (iii) By designing silviculture strategies that combine multiple interventions, e.g., prescribed burning after logging, to obtain comparable outcomes as from the interactions among natural disturbance events (e.g., Lafleur et al 2016;Wei et al 2019). (iv) By planting to alter forest composition and tree distribution (e.g., Larouche et al 2011).…”

“…similar effects on productivity and tree growth as crown fires (e.g., Lafleur et al 2016) and combining a retention cut with mechanical site preparation enhances species diversity (Wei et al 2019).…”