Climate Benefits of Increasing Plant Diversity in Perennial Bioenergy Crops

Abstract

Bioenergy from perennial grasses mitigates climate change via displacing fossil fuels and storing atmospheric CO 2 belowground as soil carbon. Here, we conduct a critical review to examine whether increasing plant diversity in bioenergy grassland systems can further increase their climate change mitigation potential. We find that compared with highly productive monocultures, diverse mixtures tend to produce as great or greater yields. In particular, there is strong evidence that legume addition improves yield, in some cases equivalent to mineral nitrogen fertilization at 33-150 kg per ha. Plant diversity can also promote soil carbon storage in the long term, reduce soil N 2 O emissions by 30%-40%, and suppress weed invasion, hence reducing herbicide use. These potential benefits of plant diversity translate to 50%-65% greater life-cycle greenhouse gas savings for biofuels from more diverse grassland biomass grown on degraded soils. In addition, there is growing evidence that plant diversity can accelerate land restoration.

Enzymatic Pretreatment with Laccases from Lentinus sajor-caju Induces Structural Modification in Lignin and Enhances the Digestibility of Tropical Forage Grass (Panicum maximum) Grown under Future Climate Conditions

“…In addition, P. maximum has high efficiency in producing biomass through photosynthesis (30 ton/ha). It can grow in lands no longer utilized for agricultural uses, which minimize the food vs. fuel conflict and lead to costeffective feedstock production [17,18].…”

Soil and root carbon storage is key to climate benefits of bioenergy crops

“…The experiment begun in 1994 and has ~160 plots (9 m by 9 m), assigned to a combination of 1, 2, 4, 8, and 16 species randomly selected from a pool of 18 native grassland species consisting mostly of C4 grasses, C3 grasses, legumes and forbs. Because it is mainly C4 grasses, such as switchgrass and big blue stem, that have been proposed as bioenergy feedstocks (Yang et al, 2019a), only plots planted with at least one C4 grass species (~100 plots) are analyzed. All monoculture plots are thus C4 perennial grasses.…”

“…Given the dispersed and variable nature of soil, it is challenging to accurately measure and monitor changes in soil properties at large scales (Paustian et al, 2016). More funding can be directed to basic and applied research aimed at improving the accuracy, reliability, and cost-effectiveness of measuring soil C. In addition, there are many other environmental and ecological benefits associated with increasing plant diversity in perennial bioenergy crops, including weed suppression, lower soil N2O emissions, ecosystem stability, and resilience against climate variability (Tilman et al, 2006b;Isbell et al, 2017;Yang et al, 2019a). Few studies have quantified these other aspects under the life cycle assessment framework to determine the totality of biodiversity benefits.…”

Evidence for the impact of different environmental factors on the establishment of Sainfoin ( Onobrychis viciifolia ) in pastures: a systematic map protocol.

“…With natural nitrogen-fixing qualities, legumes are a key component of sustainable grassland systems (Malisch et al 2017) and have been recognised for enhancing soil fertility alongside improved aboveground and belowground production of subsequent crops (Conant, Paustian & Elliott, 2001). Evidence suggests that sowing legumes into forage crops increases yield and by expanding plant diversity, benefits soil microbial activity and long-term soil carbon sequestration (Yang et al 2019). Additionally, by establishing a varied seed mix and enhancing the diversity of swards, floral resources for pollinators can be increased in grasslands (Woodcock et al 2014).…”