PS 13-120 - Landscape composition and configuration and its role on boreal bryophyte diversity

Background/Question/Methods

Fragmentation and habitat loss change the landscape composition and configuration (LCC), affecting species persistence and ecological processes. In boreal forests, the effects of LCC on species diversity are not well known, especially in sessile organisms, such as the bryophytes. Bryophytes (mosses and liverworts) are ideal plants to evaluate LCC effects due to their high species richness, biomass, and sensitivity to environmental changes. The objectives of this study are 1) to evaluate if LCC influences bryophyte diversity at stand scale and 2) to know if mosses or liverworts are more sensitive to the LCC changes. We calculated bryophyte diversity (richness, common, and dominant species) in 90 old forest patches distributed across western Quebec. Subsequently, we evaluated the LCC around each forest patch (10 km radius). Forest composition was evaluated via the percent area of classes of young (< 40 years), mature (41-80 years), and old ( > 81 years) forests in the landscape. Configuration was evaluated via the patch density of each age class calculated dividing the number of patches within the landscape area (n/ha). Then, we used generalized additive models to determine a relationship between bryophyte diversity and LCC.

Results/Conclusions

Our results suggest that bryophyte groups respond differently to LCC. Moss richness decreased proportionally to the increase of percent old and young forest area in the landscape. For liverworts, common species decreased when the percent young forest in the landscape reached around 50 %. Also, the number of common liverworts species fluctuates depending on the young forest density. Our results show that LCC effects can differ between bryophyte guilds. For mosses, our study supports the idea that habitat amount is more critical than fragmentation to explain diversity patterns at a stand scale. Also, the results for mosses contrast the premise that the species richness will increase with more pristine areas in the landscape. However, for liverworts, our study suggests that the increase at more than 50% of young forests in the landscape can reduce their number of species at stand scale. In the case of liverworts, habitat amount is also essential, but the relationship is not linear as mosses. Our findings provide the basis for identifying landscape drivers that conserve regional biodiversity in old boreal forests and provide new evidence of the LCC role to explain species diversity patterns in a related group of plants.