Offsite effects of mining on the frequency and abundance of five understorey plant species in western Québec (Canada)

Although the mining industry provides minerals and metals for the global market and represents important economic opportunities, it also constitutes a major anthropogenic disturbance in the ecosystems where it takes place. However, little is known about its offsite impacts on plant communities. We assessed the frequency and the abundance of five common boreal understorey plant species (Coptis trifolia, Cornus canadensis, Linnaea borealis, Lysimachia borealis and Maianthemum canadense) at different distances around six mines of Abitibi-Témiscamingue and Nord-du-Québec (Québec). Our results showed that Coptis trifolia and Maianthemum canadense were negatively affected by the presence of mines, suggesting that they might be sensitive to the loss of forest cover, particle deposition and soil contamination induced by mining. Conversely, Cornus canadensis was favoured by mining activity, which indicates its resilience to the stress caused by mines and its ability to exploit the niche space left by more sensitive species. No effects on Linnaea borealis and Lysimachia borealis were observed. Our study confirms the presence of offsite impacts of mines on plant communities and further studies considering enigmatic impacts should be made to develop our understanding of the broader environmental footprint of mining activity.

Understorey plant community assemblage of Australian Eucalyptus woodlands under elevated CO2 is modulated by water and phosphorus availability

Aims Given the key functional role of understorey plant communities and the substantial extent of forest cover at the global scale, investigating understorey community responses to elevated CO2 (eCO2) concentrations, and the role of soil resources in these responses, is important for understanding the ecosystem-level consequences of rising CO2 concentrations for forest ecosystems. Here, we evaluated how experimentally manipulated the availabilities of the two most limiting resources in an extremely phosphorus-limited eucalypt woodland in eastern Australia woodland (i.e. water and phosphorus) can modulate the response of the understorey community to eCO2 in terms of germination, phenology, cover, community composition, and leaf traits. Methods We collected soil containing native soil seed bank to grow experimental understorey plant communities under glasshouse conditions. Important findings Phosphorus addition increased total plant cover, particularly during the first four weeks of growth and under high-water conditions, a response driven by the graminoid component of the plant community. However, the treatment differences diminished as the experiment progressed, with all treatments converging at ~80% plant cover after ~11 weeks. In contrast, plant cover was not affected by eCO2. Multivariate analyses reflected temporal changes in the composition of plant communities, from pots where bare soil was dominant to high-cover pots dominated by a diverse community. However, both phosphorus addition and the interaction between water availability and CO2 affected the temporal trajectory of the plant community during the experiment. Elevated CO2 also increased community-level specific leaf area, suggesting that functional adaptation of plant communities to eCO2 may precede the onset of compositional responses. Given that the response of our seedbank-derived understorey community to eCO2 developed over time and was mediated by interactions with phosphorus and water availability. Our results suggest that a limited role of eCO2 in shaping plant communities in water-limited systems, particularly where low soil nutrient availability constrains productivity responses.

Facilitation and biodiversity jointly drive mutualistic networks

ABSTRACTFacilitation by legume nurse plants increase understorey diversity and support diverse ecological communities. In turn, biodiversity shapes ecological networks and supports ecosystem functioning. However, whether and how facilitation and increased biodiversity jointly influence community structure and ecosystem functioning remains unclear.We performed a field experiment disentangling the relative contribution of nurse plants and increasing understorey plant diversity in driving pollination interactions to quantify the direct and indirect contribution of facilitation and diversity to ecosystem functioning. This includes analysing pollinator communities in the following treatment combinations: (i) absence and presence of nurse plants, and (ii) understorey richness with none, one and three plant species.Facilitation by legume nurse plants and understorey diversity synergistically increase pollinator diversity. Our findings reflect diverse assemblages in which complementarity and cooperation among different plants result in no costs for individual species but benefits for the functioning of the community and the ecosystem. Drivers of network change are associated with increasing frequency of visits and non-additive changes in pollinator community composition and pollination niches.Synthesis Plant–plant facilitative systems, where a nurse shrub increases understorey plant diversity, positively influences mutualistic networks via both direct nurse effects and indirect plant diversity effects. Supporting such nurse systems is crucial not only for plant diversity but also for ecosystem functioning and services.

Diversity, biomass, and carbon stock of understorey plants in the rubber agroforestry and rubber monoculture systems in Central Tapanuli District, North Sumatra, Indonesia

Muhdi, Hanafiah DS, Butar-Butar RD. 2020. Diversity, biomass, and carbon stock of understorey plants in the rubber agroforestry and rubber monoculture systems in Central Tapanuli District, North Sumatra, Indonesia. Biodiversitas 21: 3508-3518. Understorey vegetation plays an important role in carbon stock in forest. The objectives of the research were to identify the species of understorey, to find out the amount of carbon stored in the understorey, and to compare the understorey carbon stocks in rubber agroforestry and rubber monoculture. The research was done in Sijungkang Village, Andam Dewi Sub-district, District of Central Tapanuli and Forest Products Chemistry Laboratory, Faculty of Forestry, IPB University on August-October 2016. The method used was the plant vegetation analysis of a stand and understorey. Destructive sampling method was used to harvest of understorey plant in 1 m × 1 m sample plot. The carbon of understorey was analyzed by independent sample t-test. The results showed that there were 23 species in rubber agroforestry and 15 species in rubber monoculture. The understorey species dominant of rubber agroforestry was Stachytarpheta jamaicensis and rubber monoculture was Asystasia gangetica with important value index 30.64% and 33.01%, respectively. The average understorey plant biomass in rubber monoculture was 0.94 tons/ha and in rubber agroforestry were 0.84 tons/ha, respectively. The carbon stocks of understorey in rubber agroforestry were 0.21 tons/ha and in rubber monoculture were 0.25 tons/ha, respectively. The result of t-test showed that there is not significant difference between carbon stock of understorey in rubber agroforestry and rubber monoculture.