Different pathways from litter to CO2 help to predict greenhouse gas burden

Ecologist Hans Cornelissen, together with coauthors from several countries, published a review in the Tansley Review Series of New Phytologist.

10/03/2017 | 1:24 PM

They revealed how the interactions between the two main fates of dead plant material (litter), i.e.  natural decay and fire, are critical for the release of  CO2  back to the atmosphere.

CO2 is one of the greenhouse gases that  contribute to the global climate. The authors stated that the characteristics of the dominant plant species in different ecosystems play an important role in the interactions between  decay and fire of the litter layer on the soil surface. Cornelissen explains: “For example, pine and spruce trees both drop dead needles that are tough and still full of lignin and resins, which make them slow to decay compared to birch or poplar leaves. This then results in accumulation of needle litter, which serves as fuel for fire under dry conditions. But whether this fuel will actually burn depends on the size and shape of the litter pieces on the surface.” “Pine needles are larger and connected in pairs or triplets, so that they stack very loosely on the soil surface,” Cornelissen continues. “This means that enough oxygen can blow through the litter for a fire to get started and keep going. Spruce needles are small and fall off one by one, so that they form dense layers on the surface. Because of lack of oxygen these layers will not burn easily.”  

The authors argue in the review in New Phytologist, one of the leading journals in plant science, that measuring these and more litter characteristics of different species can help to understand both decay and fire behaviour of different ecosystems with different species compositions. It can also help to predict how and how much of the carbon in dead plant material will be released back as CO2 to the atmosphere in future ecosystems, with different climates and different plant species. 

Fig. 2