Biodiversity must be preserved regardless of the climate crisis



by LORENZO CIOTTI

Biodiversity must be preserved regardless of the climate crisis

The simplest way to measure the biodiversity of a collective is to count the number of modalities, that is, of the species present in an ecological community. The relative frequency can be understood as the weight, the importance, the relevance that the modality has within the collective.

It is easy to understand that the relative frequencies as well as the number of modes contribute to defining the degree of diversity. As an example, let's consider two collectives: be they two school classes or two experimental groups on which we want to verify the effectiveness of a training process.

We assume that the two collectives have the same number of modalities. Suppose that the first collective has the same number of units for each modality, while in the second 90% of the units have only one modality while the remaining 10% is distributed among the remaining modalities.

It is natural to attribute a greater degree of diversity to the first collective. Since, although the number of modalities is identical for both cases, in the second example there is a higher homogeneity of the collective, being able to register a strongly prevalent modality compared to all the others which, in our context, are irrelevant.

It is therefore understood that a measure of biodiversity must also take into account the level of irrelevance of the modalities; in the sense that the greater the irrelevant modalities, the lower the biodiversity with the same number of modalities.

Biodiversity must be preserved regardless of the climate crisis

The study: Biodiversity promotes ecosystem functioning despite environmental change, published on the Ecology letters, explained: "Three decades of research have demonstrated that biodiversity can promote the functioning of ecosystems.

Yet, it is unclear whether the positive effects of biodiversity on ecosystem functioning will persist under various types of global environmental change drivers. We conducted a meta-analysis of 46 factorial experiments manipulating both species richness and the environment to test how global change drivers modulated the effect of biodiversity on multiple ecosystem functions across three taxonomic groups.

We found that biodiversity increased ecosystem functioning in both ambient and manipulated environments, but often not to the same degree. In particular, biodiversity effects on ecosystem functioning were larger in stressful environments induced by global change drivers, indicating that high-diversity communities were more resistant to environmental change.

Using a subset of studies, we also found that the positive effects of biodiversity were mainly driven by interspecific complem entarity and that these effects increased over time in both ambient and manipulated environments.

Our findings support biodiversity conservation as a key strategy for sustainable ecosystem management in the face of global environmental change."