Turnover of beetle assemblages after a large scale wildfire in a boreal forest landscape

Date:
2018/06/13

Time:
12:15

Room:
A2 Wivi

Turnover of beetle assemblages after a large scale wildfire in a boreal forest landscape

(Oral and Poster)

Emelie Fredriksson
emelie.fredriksson@slu.se

Wildlife, Fish and Environmental studies -Swedish University of Agricultural Sciences, Sweden
,
Therese Lövroth
Wildlife, Fish and Environmental studies - Swedish University of Agricultural Sciences, Sweden
,
Roger Mugerwa Pettersson
Wildlife, Fish and Environmental studies - Swedish University of Agricultural Sciences, Sweden

DOI: 10.17011/conference/eccb2018/107927

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Fire is considered the most important natural disturbance in the boreal forest [1]. Fire suppression has made large-scale forest fires rare in the managed boreal landscape and caused a significant habitat loss for species dependent on stand replacing disturbance. Before the middle of the 17th century, lightning ignitions could explain the fire interval. During the 19th century the number of ignitions increased but the total burnt area decreased due to increased human activity combined with effective fire suppression. Fire suppression impacts all parts of this landscape, even large protected areas with limited human influence. Beetles are a very rich and diverse species group in the boreal forest and has been widely used in ecological research. The impact of long term fire suppression are hard to establish but Johansson, 2011 [2] suggests that the effects of large scale forest fires on beetle assemblages can be influenced by the management history of the landscape. To better understand the species turnover of beetles after a large natural fire in a landscape less impacted by modern forestry, we monitored beetles during three years after a >300 ha wildfire in Muddus national park. Muddus is the largest national park below the mountain range in Sweden, located in the northern boreal zone. We used 10 flight intercept traps on a transect through the burnt area. The area is dominated by old growth pine (Pinus sylvestris) forest and reoccurring fires has been recorded since the 15th century [3]. The beetles were divided into functional groups depending on substrate and nutrient preferences, red-list category as well as their dependency on fire. Species composition, abundance and species richness changed significantly between the tree years. There was a continuous turnover of species with unique species each year. The second year after fire was the most abundant and species rich. This pattern was most prominent for the saproxylic beetles, especially cambiovores, and predators. We found several red-listed and fire dependant species including the Cerambycidae; Acmaeops septentrionis. This study show that reintroduction of fire benefit pyrophilious species even after a century of landscape level fire suppression. Prescribed burning might have the potential to be more beneficial for biodiversity conservation management if allocated to areas with low human impact and unbroken fire history.

1. Zackrisson, O., Influence of Forest Fires on the North Swedish Boreal Forest. Nordic Society Oikos, 1977. 29(No. 1): p. 22-32.
2. Johansson, T., et al., Short-term responses of beetle assemblages to wildfire in a region with more than 100 years of fire suppression. Insect Conservation and Diversity, 2011. 4(2): p. 142-151.
3. Engelmark, O., Forest fires in the Muddus National Park (northern Sweden) during the past 600 years. Canadian Journal of Botany, 1984. 62(5): p. 893-898.

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INTRO:
Beetle assemblages were affected by fire disturbance in Muddus national park, including a change in species composition during the first three years after the wildfire and benefits for saproxylic species.
MERITS:
This study aims to study the direct effect of a large wildfire on beetle assemblages after a century of landscape level fire suppression.
CRITIQUE:
The introduction is really focused on the management history of the landscape in terms of fire suppression. But I am not sure to understand how the fire history was considered in this study. Could you compare your results to those of other sites with a different management history?

I am also confused about the study design. Did you collect the data from a single transect only? Do you have replicates (i.e., multiple transects in the burned area) to more accurately assess beetle assemblages and reinforce your results?

Could you compare your results to unburned control transects?
DISCUSSION:
This project has implications for biodiversity conservation by increasing the understanding of species responses to wildfire. But see my comments in the critique section.

- - -
INTRO:
This study documents the change in the beetle community through three years after a boreal fire. Community structure significantly varied among years, most importantly many species of conservation value were detected in the burned area.
MERITS:
The results suggest the reintroduction of pyrophilic beetle species in the area after the fire, and some of them are of conservation concern. These are important results in terms of conservation biology and have significant implications for the fire management in the region.
CRITIQUE:
It would be better if the authors gave the number of species detected, and which portion of the beetles were of conservation priority (red-listed and pyrophilic ones).
DISCUSSION:
Time-scale of the study can be extended to more year through the post-fire successional process.

- - -
INTRO:
This study examined beetle turnover and richness following a wildfire event in an area of Sweden, where fire events are rare. The study found that certain beetle species were positively affected by the reintroduction of fire.
MERITS:
The study examines the impacts of fire events and fire exclusion on beetle species composition and richness. Given fire events are likely to increase under climate change scenarios, and the increasingly frequent use of prescribed burning activities to mitigate the severity of wildfires, understanding fire effects on species is important.
CRITIQUE:
As with many fire studies, replication is very hard to achieve particularly after a single wildfire. While it's important to study single fires, multiple fire events would strengthen the predictive power of your results. It might be worth considering/mentioning that these results come from a single fire event, and that more replication would be needed to further support your results.

More clarification is needed over how many sites you sampled, at the moment it sounds like you established one transect in the burnt forest, and deployed 10 traps? If this is the case, I would suggest that this is not enough replication.
DISCUSSION:
The discussion regarding the reintroduction of fire into an area where fire events have been effectively excluded for many years is interesting.

Turnover of beetle assemblages after a large scale wildfire in a boreal forest landscape

Date:2018/06/13

Time:12:15

Room:A2 Wivi

Turnover of beetle assemblages after a large scale wildfire in a boreal forest landscape

(Oral and Poster)

SEE PEER REVIEW

SEE PEER REVIEW

Date:
2018/06/13

Time:
12:15

Room:
A2 Wivi