Maire Holz et al. provide an intriguing insight into root biology, this time in terms of this organ’s impact upon carbon sequestration within the soil. Studying barley (Hordeum vulgare), they showed that root hairs increased the rhizosphere (‘the narrow zone of soil surrounding plant roots that is characterised by root exudation and an abundance of micro-organisms which can be beneficial or harmful to plants, or have no effect on root growth and function’) three-fold, to 1.5 mm. And, total exudation of carbon-rich materials – onto filter paper – was three times greater for wild type plants (which naturally had hairs) than for root-hairless mutants.
Consequently, and if these results are found in nature, they not only suggest that root hairs enhance rhizosphere interactions and nutrient cycling in the soil, but also that root hairs may therefore be beneficial to plants under nutrient-limiting conditions. But, one of the biggest potential impacts of these root outgrowths may be that greater carbon allocation below ground – via the organic exudates – may facilitate carbon sequestration. Which would have benefits to a world where increases in atmospheric CO2 concentrations are of global concern. Global warming, finally getting to the root of the solution..? But, just as root hairs have a hitherto unappreciated role in carbon sequestration, another easily overlooked resource in that regard is the dirt in one’s backyard. Well, not ‘dirt’ exactly, as this is rather a dismissive term to apply to the life-sustaining component of the biosphere we consider next – but soil.
In the intriguingly-titled ‘Current and historical land use influence soil-based ecosystem services in an urban landscape’, Carly Ziter and Monica Turner examine the value of soils in an urban setting from an ecosystem services point of view. In particular they emphasise the role that such soils can play in terms of their ability to store carbon – and may even be better than soil in some natural habitats at this. In this way, such ‘green’ spaces not only improve well-being of humans, but of the whole planet in playing an important part in storing carbon, and keeping some of that out of the atmosphere.
Such findings are some comfort when one considers how important are ecosystems such as mangal (what we used to call mangrove swamps in less enlightened times). Mangroves in mangal store large amounts of carbon, and are therefore important sinks in combatting carbon-created climate change. Yet, mangroves are being cut down for various reasons – such as the creation of ‘shrimp’ farms – and their important ecosystem service in carbon-sequestration is thereby diminished. If one is to influence human behaviour and show such deforesters the error of their ways it is important to provide evidence of the ill effects of those activities.
In an attempt to provide such ‘ammunition’, Stuart Hamilton and Daniel Friess have assessed global carbon stocks within mangroves, and potential emissions due to their deforestation, during the period 2000 to 2012. But, in the meantime, and until we stop unnecessary destruction of the mangal carbon sink, don’t rush to replace your backyard with a concreted drive for your car(s) – especially given the carbon emissions involved in cement production!