Characteristics of boreal and hemiboreal herb-rich forests as polypore habitats

(Poster)

Karoliina Hämäläinen
lindakaroliina.hamalainen@gmail.com

University of Eastern Finland, Finland
,
Kaisa Junninen
Metsähallitus - Parks & Wildlife Finland, Finland
,
Teemu Tahvanainen
University of Eastern Finland, Finland

DOI: 10.17011/conference/eccb2018/107524

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Habitat deterioration caused by intensive silvicultural actions has resulted in the decline of saprotrophic species, including polypore fungi (Basidiomycota). Polypore assemblages in herb-rich forests remain little studied, regardless of the fact that these forests are considered as biodiversity hotspots in the boreal zone.

The aim of this study is to evaluate the significance of herb-rich forests as polypore habitats and assess the relationships between stand- and substrate-scale variables and polypore species richness, abundance and diversity. In addition, an alternative way to measure the diversity of coarse dead wood (CWD) is presented. Polypore fruit body and CWD inventories were conducted in 75 herb-rich forest stands from hemiboreal to middle boreal vegetation zones. Overall, the data covers 5097 dead wood units and 3046 observations of 101 species, including 19 herb-rich forest associated and 15 red-listed species. The largest size class of CWD units (diameter >40 cm) hosted up to 4.5 times more polypores than the smallest size class (10-14 cm). Results of GLMs and correlation analyses showed that the total polypore species richness, and the number of observations of red-listed and herb-rich forest associated species have differing responses to habitat and substrate quality. For instance, the diversity of CWD, northern coordinate and abundance of large-diameter (>30 cm) dead wood all significantly explained variation in total species richness, whereas the red-listed species responded only to the number of large dead wood units. In NMDS-ordination, the polypore assemblages were strikingly different between host-tree species, with the clearest division between coniferous and deciduous trees.

The results highlight the importance of dead wood diversity and large-diameter dead wood, especially aspen and birch, for polypore assemblages in boreal herb-rich forests. Comparing the results to previous studies, herb-rich forests are likely to host lower polypore species richness and smaller populations of red-listed species than old-growth spruce forests. However, because of a high proportion of deciduous trees in the dead wood profile, herb-rich forests can be presumed to sustain polypore assemblages divergent from those found in conifer-dominated boreal heath forests.

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INTRO:
The study addresses a potentially important, but relatively poorly studied habitat for polypore fungi, which are a flagship taxon group in boreal forests. As such, the results are likely to interest both forest ecologists and conservation managers.
MERITS:
The study material is solid: 75 forests studied, >3000 species observations, and >100 species. Statistical methods appear to be appropriate as much as can be judged from the (generally indicative) abstract.
CRITIQUE:
I missed important details; the abstract is too indicative (as opposed to informative). Examples: (1) What is the scale for the stand-scale analyses, and was it fixed across plots? (2) What was the survey method, and was it fruit-body based only? (3) What was the age range and management history of the stands? (4) What kind of alternative way to measure the diversity of CWD will be presented? (5) What kind of "differing responses" were observed for total species richness and the subgroups? (6) What other species of deciduous trees besides aspen and birch were studied? (7) What method was used to distinguish "herb-rich forest associated species"; what were the assemblages for comparison? Was the study carried out in Finland, and where were the comparison datasets from? (8) I was puzzled with the conclusion that "herb-rich forests are likely to host a specific polypore mycota that are not found in managed forests". Does this mean that herb-rich forests are not just a forest type, but a management stage? What kind of management is meant here?
DISCUSSION:
I have no doubt that the study provided important data for local forest conservation. However, it would be important to elaborate the wider-ranging implications: who and where could learn what from your study? I may miss something but your presented management conclusions (last paragraph) seem rather trivial for my country (Estonia), and I wonder what might be the unused potential of your nice dataset in terms of practical conclusions. For example, do your study stands allow some analyses of management impacts on the fungal biota?

Characteristics of boreal and hemiboreal herb-rich forests as polypore habitats