Herbivore Impacts on Carbon Cycling in Boreal Forests

Airborne laser scanning reveals increased growth and complexity of boreal forest canopies across a network of ungulate exclosures in Norway

“…Our study also shows that excluding ungulates increased both the vertical canopy diversity and the AGB (hence also aboveground carbon stocks) of the early regrowth forests. This study provides support for using ALS to analyse diverse ungulate exclosure experiments across biomes (see Vuorinen et al, 2020) in a standardized and cost-effective way, and puts us closer of being able to quantify the role of large herbivores in the global climate system (Leroux et al, 2020;Schmitz et al, 2018).…”

“…Although work is ongoing, there is still no clear idea about the net effect of large herbivores on climate forcing. For this reason, Leroux et al (2020) urged the scientific community to come together and create a 'network of long-term exclosure experiments', and also point to remote sensing as a tool for gaining a comprehensive understanding of the impact that large herbivores have on carbon source-sink dynamics. We believe these two elements can be united in a joint solution.…”

“…Information on these forest parameters is essential for developing a complete understanding of how herbivores affect climate forcing because of how the canopy height and structure influences energy flows, for example in terms of heat exchange or the absorption of radiation (Thompson et al, 2004). Yet, these parameters are rarely, if ever, reported from ungulate exclosure studies, demonstrating the challenges of developing biome wide experimental networks (as called for by Leroux et al, 2020). Developing protocols for collecting such data is therefore vital.…”

The role of large wild animals in climate change mitigation and adaptation

“…Terrestrial soil organic matter provides climate mitigation and adaptation services via erosion control, water and nutrient retention 52 and carbon storage (globally $2770 Pg carbon in the top 3 m 53 ). The impact of large animals on soil carbon stocks varies, partly due to differences between biomes and scales, herbivore assemblages and densities and soil community adaptation (Figure 1 and Tables 1 and S1) 6,[54][55][56][57] . For example, herbivores can help preserve soil carbon by maintaining permafrost in the Arctic 58 , maintaining below-ground carbon in fire-prone ecosystems 59,60 , stabilising soil carbon through soil mixing 61 and through the activities of their associated soil macrofauna (e.g.…”

Frugivore zoogeochemistry in tropical forest ecosystems

“…Recent progress in the field of zoogeochemistry (sensu Schmitz et al., 2018) has emerged which clearly demonstrates an important role for animals in elemental cycling at local and landscape extents. For example, moose exclosure experiments in North America (Ellis & Leroux, 2017; Pastor et al., 1993) demonstrate that areas with moose browsing and trampling can have much less carbon (C) and nitrogen (N) in the form of plant litter and in soils than areas where moose have been excluded and these impacts may influence the spatial heterogeneity in forest patches and matter at landscape extents (Leroux et al., 2020; Pastor et al., 1997). The majority of zoogeochemical studies focus on antagonistic carnivore or herbivore interactions leaving important gaps in our understanding of other key interactions underlying animal‐ecosystem processes.…”