Each ecosystem has its own identity and understanding it in depth is necessary to be able to perceive symptoms of collapse.
When we talk about species, we know that population size, age structure and genetic diversity are direct indicators of their risk of extinction and key factors to take into account for their conservation. But, when we talk about ecosystems, do we know what those indicator variables of health and risk of collapse are?
First of all we must understand what an ecosystem is and what collapse is.
Unlike species, which are considered extinct when their last individuals disappear from their entire range; Ecosystems can be considered collapsed when they disappear from their entire extensión, but also when they experience environmental degradation (changes in their abiotic components) or when biota that perform key roles in ecosystem functioning are greatly reduced in abundance and lose the ability to recruit (Bland et al. 2017). That is, an ecosystem does not have to have disappeared spatially to have collapsed, the collapse can occur long before it disappears if it loses other components of its identity such as biotic and abiotic components..
In order to perceive functional symptoms of collapse, that is, those that are not related to changes in spatial distribution, we must understand very well the identity of the ecosystem, know what its key components are, what differentiates it from others, what is the natural variability of each of its components and how they interact with each other.
For example, in bottom-up ecosystems such as high Andean rivers and lakes, phytoplankton and periphyton are key biotic components. The abundance of these two groups determines the presence and abundance of herbivores and, consequently, of consumers from higher levels of the trophic chain. On the other hand, the abundance of phytoplankton and periphyton is determined by abiotic factors such as incidence of light, water transparency and nutrient availability; and it is precisely these key factors that can be indicators of the state of the ecosystem.
Changes beyond its natural variation in any of these indicators can be a symptom of collapse.
Semi-frozen high Andean stream in the Pampa Galeras-Bárbara d'Achille National Reserve, Peru. Here the biofilm is the base of the trophic chain on which invertebrates and tadpoles feed.
Ecosystems are characterized by networks of interactions that we must understand in depth in order to assess their risk of collapse. Thus, promoting research to better understand the ecology of our ecosystems is necessary to generate more complete and higher quality RLE assessments.
In the Assessments section of our website you can find examples of RLE assessments for various ecosystems around the world.
Written by: Michelle Castellanos
Style and format: Michelle Castellanos and Lila Garcia
Translated by: Antonieta Parilli
Provita Sep 21, 2020