Pyrodiversity- What is it, and is it Really Helpful?
Pyrodiversity is said to "beget biodiversity", but to what extent is that true?
Wildfires exist in a peculiar gray area in society's collective consciousness. People often fear wildfires because they are frequently associated with danger due to their destructive nature. On the flip side, people are also aware of wildfires' benefits for humanity, creating a duality of fires being helpful but harmful. Frequent wildfires help humans by preventing large, intense wildfires from forming and supporting biodiversity through pyrodiversity. Pyrodiveristy is the variation in wildfire over space and time. The idea behind a pyrodiversity-biodiversity hypothesis is that having a range of fires will create different stages of succession. Patch Mosaic burning employs the concept of succession to maximize biodiversity, succession being the process of change in an ecosystem that mixes the species in a habitat over time. However, what type of biodiversity does pyrodiversity create, where is it practical, and why is that important?
There are three different ways of looking at species diversity; alpha diversity, which is the diversity of species at one site in an area, beta diversity, which is the difference of species between sites, and gamma diversity, which is the diversity of species pooled across sites within an area. Scientists base the theory that pyrodiversity produces biodiversity on the results from beta diversity, which scientists assumed would result in more species overall, aka a higher gamma diversity. However, recent studies question whether that assumption is accurate for every situation.
Experimental Evidence
In a study by Farnsworth et al. 2014, this assumption is called into question for reptiles in the Mallee ecosystem of south-eastern Australia. This study differentiated plots by the age of their vegetation and the number of fire age classes. It then took surveys of reptiles to formulate models to test the pyrodiversity against the three diversity measures previously discussed.
Figure provided by Farnsworth et al. 2014. The line represents the fitted relationship between the given diversity of reptiles and the properties of fire mosaics. The dark shaded interval shows the 95% confidence interval. Graphs a, b and c represent the total reptile assemblage and d, e, and f represent only the litter dwelling species.
This graph shows that pyrodiversity has little evidenced effect on the gamma diversity of reptile species. The graph shows this by demonstrating an unchanging gamma diversity while the extent of time since the last burn changes, indicating these variables do not correlate. Farnsworth et al. explain this lack of correlation through the other parts of the graph, where alpha and beta diversities oppose each other, nulling the gamma diversity. This study has some drawbacks, mainly its lack of diverse spatial scales; however, we can still draw meaningful conclusions from this study to help preserve biodiversity. Namely, it is likely unhelpful to burn fire mosaics in Mallee ecosystems. Instead, fire management should work on maintaining mid-successional and long unburnt vegetation to most efficiently retain high biodiversity.
Why does this matter?
Biodiversity is important because it protects the health of the ecosystems that provide for humanity through Ecosystem services. Ecosystem services are what ecosystems provide to people to allow us to exist. The most apparent services are oxygen and water, but others include fish, wood, pollination, nutrient cycles, and cultural inspiration. Biodiversity keeps these services going by ensuring the stability of the ecosystem and the organisms that provide those services. In researching how to maintain biodiversity effectively, we are also learning how to best protect ecosystems for those who will inhabit this earth in the future. This study proves that to do this, we must appreciate the research and knowledge we have, but we must also examine the applicability of our ecological knowledge to each situation.
Citations
I liked how this related to what we learned in lecture about wildfires and succession. I am still curious about how we can determine which ecosystems will best benefit from pyrodiversity. I also wonder if reptile diversity was able to provide the best measure of the effects of pyrodiversity. Perhaps the study would have come to a different conclusion had it looked at a plant species instead. This brings me to another question of how target species are identified as subjects of pyrodiversity studies. Is the target species in itself a variable that can impact the outcome of the experiment?
ReplyDeletegood point!
DeleteI didn't even know pyrodiversity was a field, let alone its ineffectiveness. I still believe that controlled fires can be helpful in boosting local ecosystem fitness. However, more research needs to go into this field to understand its full consequences, and what is the ideal location and level of frequency/ severity to max out its effectiveness.
ReplyDeleteComment from Crystal:
ReplyDeleteThis was a very interesting read. I’m from California, and the topic of fires is brought up fairly often- it’s a really big issue. I do think that controlled fires are important and necessary for vegetation control and managing the intensity. More research is definitely needed to have a better understanding of pyrodiversity, especially as climate change increases the global temperature and fires become more frequent.