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Historical Disturbances Determine Current Taxonomic, Functional and Phylogenetic Diversity of Saproxylic Beetle Communities in Temperate Primary Forests

January 2021
Ecosystems 24(10)

DOI:10.1007/s10021-020-00502-x

Authors:

Daniel Kozák

Czech University of Life Sciences Prague

Marek Svitok

Technical University of Zvolen

Michal Wiezik

Technical University of Zvolen

Martin Mikoláš

Czech University of Life Sciences Prague

Show all 23 authorsHide

The expected future intensification of forest disturbance as a consequence of ongoing anthropogenic climate change highlights the urgent need to more robustly quantify associated biotic responses. Saproxylic beetles are a diverse group of forest invertebrates representing a major component of biodiversity that is associated with the decomposition and cycling of wood nutrients and carbon in forest ecosystems. Disturbance-induced declines or shifts in their diversity indicate the loss of key ecological and/or morphological species traits that could change ecosystem functioning. Functional and phylogenetic diversity of biological communities is commonly used to link species communities to ecosystem functions. However, our knowledge on how disturbance intensity alters functional and phylogenetic diversity of saproxylic beetles is incomplete. Here, we analyzed the main drivers of saproxylic beetle abundance and diversity using a comprehensive dataset from montane primary forests in Europe. We investigated cascading relationships between 250 years of historical disturbance mechanisms, forest structural attributes and the taxonomic, phylogenetic and functional diversity of present-day beetle communities. Our analyses revealed that historical disturbances have significant effects on current beetle communities. Contrary to our expectations, different aspects of beetle communities, that is, abundance, taxonomic, phylogenetic and functional diversity, responded to different disturbance regime components. Past disturbance frequency was the most important component influencing saproxylic beetle communities and habitat via multiple temporal and spatial pathways. The quantity of deadwood and its diameter positively influenced saproxylic beetle abundance and functional diversity, whereas phylogenetic diversity was positively influenced by canopy openness. Analyzing historical disturbances, we observed that current beetle diversity is far from static, such that the importance of various drivers might change during further successional development. Only forest landscapes that are large enough to allow for the full range of temporal and spatial patterns of disturbances and post-disturbance development will enable long-term species coexistence and their associated ecosystem functions.

Study area and plot locations. Data collection was based on a hierarchical stratified random sampling design. Forest stands (circles) were randomly distributed within remnant primary forest and across broad environmental gradients. Individual survey plots were located within stands (circles). Sample sizes (n) in terms of plot numbers within individual stands ranged from four to six. The color gradient indicates the maximum severity disturbance (color gradient) of the ten stands. The reconstructed disturbance history for all studied stands is based on the growth pattern of 15–25 trees per plot. Red line represents mean disturbance severity of given stands smoothed with kernel density function

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Magnitude of disturbance effects on the taxonomic richness of current beetle communities based on linear mixed effects models. Each effect plot shows expected response to a particular variable keeping other variables constant at their mean value. Gray shading delineates 95% confidence limits

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Directed acyclic graph of confirmatory path analysis linking historical disturbances and forest structure with abundance and diversity of current saproxylic beetle communities. Models were fit with data from four subgroups. Arrows represent significant (p < 0.05) positive (solid line) and negative (dashed line) relationships between predictors and responses. Width of the arrows is proportional to standardized regression coefficients. Relative proportion of variance explained by fixed effects (Rm²) is given in parentheses. Note that variables without any significant link are omitted for brevity. Further details can be found in Tables S1 and S2

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Historical Disturbances Determine

Current Taxonomic, Functional

and Phylogenetic Diversity

of Saproxylic Beetle Communities

in Temperate Primary Forests

Daniel Koza

´k,

* Marek Svitok,

2,3

Michal Wiezik,

Martin Mikola

´s

ˇ,

Simon Thorn,

Arne Buechling,

Jen

ˇy

´k Hofmeister,

Radim Matula,

Volodymyr Trotsiuk,

1,5

Radek Bac

ˇe,

Kres

ˇimir Begovic

ˇ,

Vojte

ˇch C

ˇada,

Martin Dus

ˇa

´tko,

Michal Frankovic

ˇ,

Jakub Hora

´k,

Pavel Janda,

Ondrej Kameniar,

Thomas A. Nagel,

1,7

Joseph L. Pettit,

Jessika M. Pettit,

Michal Synek,

Adela Wiezikova

´,

and Miroslav Svoboda

Department of Forest Ecology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamy

´cka 129, 165

21 Prague, Czech Republic;

Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, T.G. Masaryka 24, 960

01 Zvolen, Slovakia;

Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branis

ˇovska

´1760, 370 05

Ceske Budejovice, Czech Republic;

Field Station Fabrikschelichach, Biocenter, University of Wu¨ rzburg, Glashu¨ ttenstraße 5, 96181

Rauhenebrach, Germany;

Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zu¨ rcherstrasse 111, 8903 Bir-

mensdorf, Switzerland;

Department of Forest Protection and Entomology, Faculty of Forestry and Wood Sciences, Czech University

of Life Sciences Prague, Kamy

´cka 129, 165 21 Prague, Czech Republic;

Department of Forestry and Renewable Forest Resources,

Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia

ABSTRACT

The expected future intensiﬁcation of forest dis-

turbance as a consequence of ongoing anthro-

pogenic climate change highlights the urgent need

to more robustly quantify associated biotic re-

sponses. Saproxylic beetles are a diverse group of

forest invertebrates representing a major compo-

nent of biodiversity that is associated with the

decomposition and cycling of wood nutrients and

carbon in forest ecosystems. Disturbance-induced

declines or shifts in their diversity indicate the loss

of key ecological and/or morphological species

traits that could change ecosystem functioning.

Functional and phylogenetic diversity of biological

communities is commonly used to link species

communities to ecosystem functions. However, our

knowledge on how disturbance intensity alters

functional and phylogenetic diversity of saproxylic

beetles is incomplete. Here, we analyzed the main

drivers of saproxylic beetle abundance and diver-

sity using a comprehensive dataset from montane

primary forests in Europe. We investigated cas-

cading relationships between 250 years of historical

Received 12 November 2019; accepted 22 March 2020;

published online 20 April 2020

Electronic supplementary material: The online version of this article

(https://doi.org/10.1007/s10021-020-00502-x) contains supplementary

material, which is available to authorized users.

Authors Contributions: DK, MM, MW, ST, MSvi, MSvo, JHor con-

ceived the ideas and designed study. DK, MW, MM, PJ, RB, VC

ˇ, VT, OK,

AW, MSy, MD and MF contributed to and organized data collection.

MSvi, ST, DK analyzed the data. DK, ST, AB, MM, TAN, JLP, JMP, JHof,

RM led the writing of the manuscript. All authors contributed critically to

the study and gave ﬁnal approval for publication.

*Corresponding author; e-mail: kozakdaniel12@gmail.com

Ecosystems (2021) 24: 37–55

https://doi.org/10.1007/s10021-020-00502-x

2020 Springer Science+Business Media, LLC, part of Springer Nature

Content courtesy of Springer Nature, terms of use apply. Rights reserved.

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Wood-inhabiting fungi and saproxylic beetles are threatened by habitat degradation. Our understanding of the importance of macroclimate and local factors determining their taxonomic diversity has increased, but determinants of functional and phylogenetic diversity are poorly understood. We investigated assemblages of wood-inhabiting fungi and saproxylic beetles along a 1000 m elevational gradient of a temperate low mountain range. We (i) tested the relative importance of macroclimate (i.e. elevation) and local variables (microclimate, i.e. canopy closure, amount and diversity of dead wood) in determining observed and rarefied diversities and (ii) explored whether determinants of observed functional and phylogenetic diversities match those of taxonomic diversity. For both taxa, the determinants of observed phylogenetic and functional diversities largely matched those of taxonomic diversity. The diversity of wood-inhabiting fungi was predominantly determined by local variables, whereas that of saproxylic beetles was determined by both local variables and elevation. Taxonomic and phylogenetic diversities of saproxylic beetles decreased with increasing elevation, but standardized functional richness and entropy of both groups increased with increasing elevation. Diversities of wood-inhabiting fungi increased with canopy closure, while diversities of saproxylic beetles decreased with increasing canopy closure. Microclimate and dead-wood amount and diversity affected the observed and rarefied diversity of both saproxylic taxa, which justifies conservation actions that focus on attributes of dead wood and canopy cover. The contrasting responses of fungi and beetles highlight the need for amounts of diverse dead wood in the various microclimates to preserve functional and phylogenetic diversities of saproxylic organisms.

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As the terrestrial human footprint continues to expand, the amount of native forest that is free from significant damaging human activities is in precipitous decline. There is emerging evidence that the remaining intact forest supports an exceptional confluence of globally significant environmental values relative to degraded forests, including imperilled biodiversity, carbon sequestration and storage, water provision, indigenous culture and the maintenance of human health. Here we argue that maintaining and, where possible, restoring the integrity of dwindling intact forests is an urgent priority for current global efforts to halt the ongoing biodiversity crisis, slow rapid climate change and achieve sustainability goals. Retaining the integrity of intact forest ecosystems should be a central component of proactive global and national environmental strategies, alongside current efforts aimed at halting deforestation and promoting reforestation.

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Nicholas J. Gotelli

Primary forest distribution and representation in a Central European landscape: Results of a large-scale field-based census

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Profile of tree-related microhabitats in European primary beech-dominated forests

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Jul 2018
FOREST ECOL MANAG

Tree-related microhabitats (TreMs) are important features for the conservation of biodiversity in forest ecosystems. Although other structural indicators of forest biodiversity have been extensively studied in recent decades, TreMs have often been overlooked, either due to the absence of a consensual definition or a lack of knowledge. Despite the increased number of TreM studies in the last decade, the role of drivers of TreM profile in primary forests and across different geographical regions is still unknown. To evaluate the main drivers of TreM density and diversity, we conducted the first large-scale study of TreMs across European primary forests. We established 146 plots in eight primary forests dominated by European beech (Fagus sylvatica L.) in the Carpathian and Dinaric mountain ranges. Generalized linear mixed effect models were used to test the effect of local plot characteristics and spatial variability on the density and diversity (alpha, beta, and gamma) of TreMs. Total TreM density and diversity were significantly positively related with tree species richness and the proportion of snags. Root mean square tree diameters were significantly related to alpha and gamma diversity of TreMs. Both regions reached similarly high values of total TreM densities and total TreM densities and diversity were not significantly different between the two regions; however, we observed between the two regions significant differences in the densities of two TreM groups, conks of fungi and epiphytes. The density and diversity of TreMs were very high in beech-dominated mountain primary forests, but their occurrence and diversity was highly variable within the landscapes over relatively short spatial gradients (plot and stand levels). Understanding these profile provides a benchmark for further comparisons, such as with young forest reserves, or for improving forest management practices that promote biodiversity.

Importance of Primary Forests for the Conservation of Saproxylic Insects

Chapter

May 2018

Primary forests represent the ultimate intact habitat for saproxylic insects. However, their extent has been considerably reduced over the past centuries, and those remaining are very heterogeneously distributed. Primary forests are still locally abundant in tropical and boreal zones but are rare in temperate zones. Consequently, many saproxylic insects that were adapted to typical characteristics of primary forests, such as large amounts of dead wood or overmature and senescent trees, might have become extinct regionally due to habitat loss. The remaining primary forests therefore function as refuges for those saproxylic species that cannot survive in managed forests because of their high ecological requirements. Here we identify six characteristics of primary forests important for saproxylic insects that differentiate these forests greatly from managed forests, namely, absence of habitat fragmentation, continuity, natural disturbance regimes, dead-wood amount and quality, tree species composition and habitat trees. These six characteristics highlight the importance of primary forests for the conservation of saproxylic insects in all three main climatic domains (tropical, boreal and temperate). As primary forests are rare in northern temperate zones and are being dramatically lost in boreal and tropical zones, we propose that they should be strictly conserved independently of their climatic zone. Furthermore, we recommend that studies in primary forests intensify to provide reference data for integrating primary forest characteristics into managed forests to improve the conservation of saproxylic species.

The Importance of Dead-Wood Amount for Saproxylic Insects and How It Interacts with Dead-Wood Diversity and Other Habitat Factors

Chapter

May 2018

Natural amounts of dead wood in a forest vary considerably, depending on living tree biomass, decomposition rates, and rates of dead-wood development. In natural forests, dead wood is created by the senescence of trees and natural disturbances. However, dead-wood amounts in many forest ecosystems worldwide nowadays are largely influenced by human activities, such as timber and fuel wood production and post-disturbance salvage logging. The biodiversity of saproxylic insects is usually positively correlated with the amount of dead wood, and dead-wood amount affects species composition and functional characteristics of saproxylic assemblages. Dead-wood amount is in turn correlated with dead-wood diversity, and several studies highlight the importance of dead-wood diversity for saproxylic biodiversity, which suggests that habitat heterogeneity is a major driver behind the positive relationship between dead-wood amount and biodiversity. The strength of this relationship is mediated by temperature. Effects of both temporal forest continuity and spatial connectivity are often linked to differences in dead-wood amount. Frequent interactions and correlations between dead-wood amount and other habitat factors indicate that future studies should aim more precisely at unraveling the importance of individual factors for saproxylic biodiversity, which will help to improve conservation strategies to counteract negative effects of anthropogenically altered dead-wood amount and diversity. Such conservation strategies, particularly in Europe and North America, include passive and active measures to retain dead wood in managed forests and to restore amounts and diversity of dead wood similar to levels in natural forests. More research is needed in the subtropics and tropics where conservation strategies rarely consider dead wood, although the few existing studies suggest that dead wood is an important factor for biodiversity in these regions.

Historical Disturbances Determine Current Taxonomic, Functional and Phylogenetic Diversity of Saproxylic Beetle Communities in Temperate Primary Forests

Abstract and Figures

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