From picking wild asparaguses to studying vegetation responses to fire regimes
The post provided by Sabina Burrascano
This post refers to the article “Transiently richer but profoundly changed: fire regime triggers physiognomic changes in sub-Mediterranean vegetation” by Lorenzo Caucci, Francesca Napoleone and colleagues, published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.70047)
The first time I visited the Natural Reserve of Monte Catillo, I was an MSc student, always eager for field activities. I was with a renowned entomologist and friend. Lacking a car and a driving licence, he decided to sample insects just in Monte Catillo, whose closeness to the town of Tivoli makes it easily reachable by train. He was taking advantage of the insect behaviour called “hilltopping”, during which species with low population densities gather on hilltops to find a mate.
As a young botanist, I was soon bored by the swinging of the insect net and started roaming around the hilltops. I was looking at plants at first, but very soon I focused on the young sprouts of Asparagus acutifolius. This Mediterranean spinescent low shrub grows in relatively open areas and thrives in burnt places. Its young sprouts have a unique flavour that is worth the hand scratches needed to pick them among the thorns. It was a wonderful day, gloriously ended with a flavoury asparagus omelette.
Little did I know, while enjoying my omelette, that I would roam those hilltops very often in the future.
About 15 years later, as a university teacher, I was struggling with the increasing costs and administrative burden of renting buses, which were posing a risk to a consistent share of students’ excursions. I started searching for train routes intersecting valuable natural areas and soon recalled my omelette and the Natural Reserve of Monte Catillo. I swiftly planned a field survey to organize an excursion by train.
This time, my visit in the Reserve went well beyond hilltops: I crossed the famous cork oak (Quercus suber) forest with a unique Styrax officinalis understorey; I enjoyed the blooms of Judas trees (Cercis siliquastrum); but also noticed the wide areas dominated by Mauritanian grass (Ampelodesmos mauritanicus) and sageleaf rock rose (Cistus salviifolius), whose dominance was clearly favoured by recent fires.
On that very first day back in the Reserve, I met by chance the main Reserve manager, Maria Vinci, who works for the administration of the Metropolitan City of Rome. Maria started co-leading students’ excursions with me and expressed the need for further studies on the vegetation of the Reserve.
We decided to start with an updated vegetation map and vascular plant checklist. For his MSc thesis first, and for a scholarship later, Lorenzo Caucci carried out these tasks with passion. In July 2021, we delivered both the map and the checklist.
A few weeks later, a massive fire hit the Reserve and burned about 300 of the 1,320 hectares of its extension. The Reserve has been experiencing fires frequently, but never underwent such a wide and, in some areas, severe wildfire.
We decided to perform a purposedly designed study to understand the effects of fire in this area involving another researcher, Francesca Napoleone, an MSc student, Pietro Giovanni Stoppani, and a young professional, Giulio Ferrante. We sampled areas across a gradient of fire frequency and assessed fire severity using satellite images.
We found that frequently burnt areas are richer in species, while severity substantially alters the evenness of plant communities by increasing the abundance of dominant species. Overall, severe and frequent fires negatively impacted deciduous tree species, while favouring Mediterranean herbs and low shrubs.
This means that a human alteration of fire regimes, increasing fire frequency and severity, may cause a turnover of species that, in sub-Mediterranean areas, reduces the extent of thermophilous deciduous woodlands while favouring strictly Mediterranean species and communities. Interestingly, based on pollen records (Di Rita et al., 2022), we can imagine that this process has been taking place since about 6,000 years ago, when humans started to claim agricultural land, with a substantial increase in Mediterranean evergreen species.
Among many others, getting me to know the Natural Reserve of Monte Catillo is one of the reasons to be grateful to my insect-loving friend. I owe him a wonderful omelette, an interesting study, and a pleasant collaboration with the Reserve managers and with highly skilled young professionals. The latter kept exploring the biodiversity of this unique natural area, and created a short documentary* that I suggest for a virtual hike in the Reserve.
*For English language subtitles: on YouTube, click the gear icon (⚙️) at the bottom right of the video player; go to “Subtitles/CC” and click “Auto-translate”; select “English” from the list.
Brief personal summary of the author: Sabina Burrascano is an Associate Professor at Sapienza University of Rome. Her research activities focus on the multi-taxon biodiversity response to human pressures in forests and grasslands. She is involved in several conservation and research projects on these topics, ranging from local to continental scales.
