Mimicking small scale disturbance regimes to enhance biodiversity in middle-aged Scots Pine forests

Mimicking small scale disturbance regimes to enhance biodiversity in middle-aged Scots Pine forests – a forest restoration experiment

(Poster)

Maria Aljes
maria.aljes@nw-fva.de

Northwest German Forest Research Institute, Grätzelstr. 2, 37079 Göttingen, Germany
,
Peter Meyer
Northwest German Forest Research Institute, Grätzelstr. 2, 37079 Göttingen, Germany
,
Ronja Wörmann
German Federal Environmental Foundation (DBU), DBU Natural Heritage GmbH, An der Bornau 2, 49090 Osnabrück, Germany
,
Heike Culmsee
German Federal Environmental Foundation (DBU), DBU Natural Heritage GmbH, An der Bornau 2, 49090 Osnabrück, Germany

DOI: 10.17011/conference/eccb2018/107281

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In 2005 the Federal Government of Germany has started to transfer valuable areas for nature conservation purposes to the German Federal Environmental Foundation (DBU) and others as National Heritage Sites (NHS). These areas are characterized by being large, relatively undisturbed landscapes with a mixture of forests and open habitats. They are known to host a high share of endangered biotopes and species. The DBU National Heritage aims at sustaining the biological diversity on the sites with the long-term goal, to leave all of the forested area to natural development. Although most of the sites are embedded in relatively natural forest, coastal and water landscapes, a large share of forests still consists of mono-layered scots pine plantations. In order to accelerate forest development towards a more structured and species-rich habitat, it might be advisable to implement forest restoration measures.

The DBU NHS "Rüthnicker Heide" close to Berlin, was chosen to conduct a large scale experiment simulating small-scale disturbance events in approximately 70-year old scots pine stands to investigate short- and long-term effects on structural, functional and species diversity. The experiment encompasses a design of four sample alternatives in four replications, each on a five hectare sample plot. The alternatives are meant to depict an increased structural complexity from 1. small scale to middle scale gaps with timber removal to 2. active deadwood accumulation where timber remains as "fallen deadwood" (downed by harvester) and "standing deadwood" (trees ringbarked by harvester) and 3. active deadwood accumulation with additional planting of deciduous tree saplings. Plots with no active intervention have been left untouched as an example for "passive restoration" (4.). All of the plots were fenced on half of their size to account for deer browsing. Inventories of structural, functional and species diversity were carried out before and after the forest restoration measures.

The study aims to reveal if the increase in structural diversity, i.e. generation of dead wood, gaps and planting of saplings, results in an increased species diversity or a shift in community composition of beetles, fungi and herbaceous plants, as well as an increased density of microhabitats. Preliminary results show no significant effects on plant and fungal diversity, however, a trend towards a higher mean number of plant species can be seen. The most promising short term effects are to be expected for beetles, but results are not available, yet. The restoration measures were able to increase the number of microhabitats (mainly root plates and bark fissures) in alternative 2 and 3 by 730 and 500%, respectively, whereas in passive restoration the increase was about 25%. Natural regeneration showed a significant increase for alternatives 1 to 3 as response towards canopy opening. The outcomes can serve as a blueprint for the treatment of similar forests in protected areas.

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INTRO:
The abstract describes a large-scale restoration experiment in northern Germany, where the effects of different treatments designed to accelerate the creation of forest structural characteristics critical to biodiversity are tested against a no-treatment control (passive restoration).
MERITS:
The abstract is well written, and the background, research question and the experimental setup are all well outlined.
CRITIQUE:
The measurements (i.e., how structure and function were quantified) could have been opened up a bit more. No results are reported, but I suspect this is be because it is work-in-progress?
DISCUSSION:
This is certainly an interesting study on an important topic that appears well planned. I look forward to seeing the results.

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INTRO:
The authors examined the effectiveness of restoration practices, which enhance forest complexity, accumulation of deadwood, and establishment of deciduous trees, by field experiments in German forests. They tested differences in forest structures, taxonomic and functional diversity for insects, fungi and herbaceous plants. They found some positive effect of restoration practices to accelerate biodiversity changes.
MERITS:
This study would provide a good empirical evidence of effectiveness of restoration, and should be helpful for conservation/management practices.
CRITIQUE:
The purpose or aim of study is not very clear in the introductory part, though the authors provide good summary of the current situation of German forests and its management policy. For example, why such experiments were needed, or what the author's expectation for the experiments.
DISCUSSION:
As I pointed out above, it would be great if the authors can clarify the scientific background. It is also informative if the authors can provide numerical information of dataset (e.g. number of species per taxon) and technical details for evaluation of restoration effects (e.g. types of metrics, methods of comparison).

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INTRO:
The study addresses questions regarding the biodiversity benefits of the restoration of structural diversity of monolayered middle-aged pine stands in Germany. The study setting is laudably described, but the study is in initial stage and hence no results are provided.
MERITS:
The study is interesting, because such restoration treatments are mostly conducted in Fennoscandian forests, and studies conducted in middle-Europe are lacking. The study design is well-planned and will provide interesting results in the future.
CRITIQUE:
The results are missing.
DISCUSSION:
The study provides important addition to forest restoration studies in Europe, accounting for the effects of different methods to increase structural variability of forest stands. I especially like the active planting of deciduous component to the monotypic forest, and the addition of exclosure fencing, as browsing causes significant harm in forest restoration and it's importance has not been sufficiently studied.

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INTRO:
This study attempts to precisely describe responses of forest community to four different types of management practices including a passive control. Each practice has four replications and each replication is devided by fenced and open to monitor the impact of deer on vegetation.
MERITS:
The systematic sampling design and a range of monitoring organisms will allow mechanical understanding of the community response to management practices.
CRITIQUE:
Your study doesn't have a treatment "timber removed + planting saplings" or "passive + planting saplings". Weak explanation of why only "timber retention + planting saplings"
DISCUSSION:
With long-term monitoring, your study will provide further understading of management consequences. Monitoring of abiotic conditions are also key elements to assist this study.

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INTRO:
This study is conducted to simulate small scale disturbance in 70-year old scots pine forest to test its effects on biodiversity.
MERITS:
The multispecies approach (including insects, fungi and herbaceous plants) of this study is suitable to evaluate species diversity at the study sites. Linkages between specie diversity and their ecosystem function has conservation merit to set a goal of biodiversity level to sustain function of that ecosystem.
CRITIQUE:
Albeit of clear general interest for biodiversity-ecosystem function topic, this manuscript includes few results.
DISCUSSION:
This manuscript does not include any results and discussion.