Maintaining forest diversity ensures their productivity and has the potential to improve carbon and nitrogen storage in the soil. This, in turn, helps maintain soil fertility and combat global climate change. That’s the key finding of a new study that analyzed data from hundreds of sites in Canada’s National Forest Inventory to examine the relationship between tree diversity and soil carbon and nitrogen changes in native forests.
Numerous experiments with biodiversity manipulation show that greater tree diversity can lead to greater storage of carbon and nitrogen in forest soils. But according to the authors, a new study published online April 26 in the journal Nature is the first to show a similar result in natural forests.
The researchers used a statistical method called structural equation modeling to estimate the relationship between tree diversity and carbon and nitrogen storage in the soil. They found that increased tree diversity increased soil carbon storage by 30-32% and nitrogen storage by 42-50% over ten years.
“Our work demonstrates for the first time the enduring benefits of tree diversity in storing soil carbon and nitrogen in natural forests,” said lead study author Xinli Chen, a postdoctoral fellow at the UM Institute for Global Change Biology and a postdoctoral fellow at the university. of Alberta.
“Our results highlight that promoting tree diversity not only increases productivity but also mitigates global climate change and reduces soil degradation. And the diversity dividend is huge. This reinforces the importance of preserving biodiversity in forests and will guide incremental efforts to use forests to separate carbon and nitrogen. ”
The researchers calculated changes in carbon and nitrogen accumulation in soil over time by comparing data from two National Forest Inventory censuses, one from 2000-2006 and the other from 2008-2017. They measured tree diversity as functional diversity based on species richness, species uniformity, and functional characteristics of the tree.
Species richness is the number of tree species in a sample plot, while species evenness is a measure of the relative abundance of tree species. Functional diversity is the variety of functional characteristics (such as leaf nitrogen content and mature tree height) of tree species in a community. The research team found that increasing species uniformity from minimum to maximum increased carbon storage in the soil’s organic layer by 30% and nitrogen storage by 42%. Maximizing tree functional diversity increased carbon storage in the soil mineral layer by 32% and nitrogen storage by 50%.
“We found that greater tree diversity is associated with greater soil carbon and nitrogen storage, which supports the findings from biodiversity manipulation experiments,” said Peter Reich, director of the Institute for Global Change Biology and forest ecologist, who is part of the school. environment and sustainable development of UM.
“Greater species diversity translates into a mix of different tree species with different ways of obtaining and storing biomass – both in living trunks, roots, branches and leaves, and in soil and recently dead and decaying plant debris in the soil.”
Canada’s national forest inventory database is based on a land network that covers most of the country’s landmass. The new study analyzed organic soil samples from 361 sites and mineral soil samples from 245 sites. Different types of fir, maple, birch, spruce, pine, poplar, cedar, hemlock and other tree species grow in these areas.
Forest soils play an important role in absorbing carbon produced from carbon dioxide, which warms the planet during photosynthesis. These soils store at least three times more carbon than living plants. Nitrogen is an important nutrient that stimulates carbon assimilation and plant growth in forest ecosystems. Plant diversity is rapidly decreasing all over the world, which leads to deterioration of ecosystem functions, including soil functions.
Source: Port Altele
