To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?-a systematic review protocol

Background: Silviculture and land-use change has reduced the amount of natural forest worldwide and left what remains confined to isolated fragments or stands. To understand processes governing species occurrence in such stands, much attention has been given to stand-level factors such as size, structure, and deadwood amount. However, the surrounding matrix will directly impact species dispersal and persistence, and the link between the surrounding landscape configuration, composition and history, and stand-level species occurrence has received insufficient attention. Thus, to facilitate optimisation of forest management and species conservation, we propose a review addressing 'To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?'.Methods: The proposed systematic review will identify and synthesise relevant articles following the CEE guidelines for evidence synthesis and the ROSES standards. A search for peer-reviewed and grey literature will be conducted using four databases, two online search engines, and 36 specialist websites. Identified articles will be screened for eligibility in a two-step process; first on title and abstract, and second on the full text. Screening will be based on predefined eligibility criteria related to a PECO-model; population being boreal and hemi-boreal forest, exposure being fragmentation, comparator being landscapes with alternative composition, configuration, or history, and outcome being occurrence (i.e., presence and/or abundance) of conservation-relevant species. All articles that pass the full-text screening will go through study validity assessment and data extraction, and be part of a narrative review. If enough studies prove comparable, quantitative meta-analyses will also be performed. The objective of the narrative review and the meta-analyses will be to address the primary question as well as six secondary questions, and to identify important knowledge gaps

The conservation value of forests can be predicted at the scale of 1 hectare

To conserve biodiversity, it is imperative to maintain and restore sufficient amounts of functional habitat networks. Therefore, the location of the remaining forests with natural structures and processes over landscapes and large regions is a key objective. Here we integrated machine learning (Random Forest) and open landscape data to scan all forest landscapes in Sweden with a 1 ha spatial resolution with respect to the relative likelihood of hosting High Conservation Value Forests. Using independent spatial stand- and plot-level validation data, we confirmed that our predictions correctly represent different levels of forest naturalness, from degraded to those with high and associated biodiversity conservation values. Given ambitious national and international conservation objectives and increasingly intensive forestry, our model and the resulting wall-to-wall mapping fill an urgent gap for assessing the achievement of evidence-based conservation targets, spatial planning, and designing forest landscape restoration.Decreased availability of plant substrate can explain the decline in autotrophic respiration at constant temperature during the night, according to a simple respiration model with two carbohydrate pools

The fate of the missing spores

It is well-known that many species with small diaspores can disperse far during extended temporal scales (many years). However, studies on short temporal scales usually only cover short distances (in, e.g., bryophytes up to 15 m). By using a novel experimental design, studying the realized dispersal, we extend this range by almost two orders of magnitude. We recorded establishment of the fast-growing moss Discelium nudum on introduced suitable substrates, placed around a translocated, sporulating mother colony. Around 2,000 pots with acidic clay were placed at different distances between 5 m and 600 m, in four directions, on a raised bog, with increased pot numbers with distance. The experiment was set up in April-May and the realized dispersal (number of colonized pots) was recorded in September. Close to the mother colony (up to 10 m), the mean colonization rates (ratio of colonized pots) exceeded 50%. At distances between 10 and 50 m colonization dropped sharply, but beyond 50 m the mean colonization rates stabilized and hardly changed (1-3%). The estimated density of spores causing establishments at the further distances (2-6 spores/m2) was realistic when compared to the estimated spore output from the central colonies. Our study supports calculations from earlier studies, limited to short distances, that a majority of the spores disperse beyond the nearest vicinity of a source. The even colonization pattern at further distances raises interesting questions about under what conditions spores are transported and deposited. However, it is clear that regular establishment is likely at the km-scale for this and many other species with similar spore output and dispersal mechanism

Protecting forest edges using trap logs - Limited effects of associated push-pull strategies targeting Ips typographus

Bark beetles can cause epidemic outbreaks and kill millions of cubic meters of economical and ecologically important forests around the world. It is well known what attracts and what repels different species of bark beetle, and these chemical cues can be used to protect trees and catch the beetles without using pesticides. Applying this knowledge, we investigated the use of push-pull strategies with trap logs along susceptible edges of a Swedish boreal spruce forest. The repellents (push) used were non-host volatiles (NHV) attached to tree trunks at the forest edge, and the attractants (pull) was a commercial aggregation pheromone attached to trap logs. The aim was to test whether the Ips typographus catch could be significantly increased by combining a push-pull system with traditional trap logs, thereby providing additional protection. The experiment was performed over two years and included the main flight period of I. typographus. The study sites were clear-cuts that had been harvested the preceding winter, and sun-exposed forest edges of mature spruce were targeted for protection. A full factorial setup was used comprising two treatments (repellent and attractant) and a control. Seven replicates of the trap logs were used, three during the first year and four during the second. The number of established I. typographus maternal galleries per square meter of log surface was used as the response variable. The trap logs captured large numbers of I. typographus, at an average density of 353 and 169 maternal galleries per m(2) during year 1 and year 2, respectively, over all treatments. Based on the catch data, with a sufficient number of trap logs, the risk of tree mortality at forest edges may be reduced and we recommend its general use. However, we did not see any significant effect of either the repellent or the attractant on the density of maternal galleries. Hence, we cannot recommend the addition of chemical cues to improve the efficiency of trap logs. Although trap logs are efficient in capturing bark beetles and hence may protect forest edges, it does not imply that they can provide protection on a larger scale. In line with other studies, we hence recommend that forest management to target nature-based solutions that strengthen the resilience of forest stands, by using mixed forest stands and resistant plant species, and nurture habitats for natural predators of I. typographus

North Fennoscandian mountain forests : History, composition, disturbance dynamics and the unpredictable future

North Fennoscandian mountain forests are distributed along the Scandes Mountains between Sweden and Norway, and the low-mountain regions of northern Norway, Sweden and Finland, and the adjacent northwestern Russia. Regionally, these forests are differentiated into spruce, pine or birch dominance due to climatic differences. Variation in tree species dominance within these regions is generally caused by a combination of historical and prevailing disturbance regimes, including both chronic and episodic disturbances, their magnitude and frequency, as well as differences in edaphic conditions and topography. Because of their remoteness, slow growth and restrictions of use, these mountain forests are generally less affected by human utilization than more productive and easily utilizable forests at lower elevations and/or latitudes. As a consequence, these northern forests of Europe are often referred to as "Europe's last wilderness", even if human influence of varying intensity has been ubiquitous through historical time. Because of their naturalness, the North Fennoscandian mountain forests are of paramount importance for biodiversity conservation, monitoring of ecosystem change and for their sociocultural values. As such, they also provide unique reference areas for basic and applied research, and for developing methods of forest conservation, restoration and ecosystem-based management for the entire Fennoscandia. However, the current rapid change in climate is predicted to profoundly affect the ecology and dynamics of these forests in the future. (C) 2016 Elsevier B.V. All rights reserved.Peer reviewe

Long-term dynamics of the iconic old-forest lichen Usnea longissima in a protected landscape

Long-term data on spatial dynamics of epiphytic lichens associated with old-growth forests are fundamental for understanding how environmental factors drive their extinction and colonization in heterogeneous landscapes. This study focuses on Usnea longissima, a flagship species for biodiversity conservation. By using a long-term data set (37 yr.) of U. longissima in old Picea abies forests in Skuleskogen National Park, Sweden, we examined changes in the number of host trees, population size (sum of thallus length), extinction, colonization, dispersal, and distribution in a protected landscape. We surveyed the lichen in 1984-1985 by applying a line transect inventory and a total population inventory and tagged 355 occupied trees with an aluminium plate buried in the ground. We repeated the survey in 2021 using a metal detector and recorded GPS-position of host trees, tree and lichen population characteristics. We also measured the structure and age (tree-ring data) of the forest to understand how disturbance history influenced lichen populations. Usnea longissima occurred on 66 of the tagged trees and we recorded 141 new host trees. The number of host trees decreased with 41.7% and the population size with 41.9%. One third of the decline was caused by deterministic extinction (treefalls) and two thirds by stochastic extinction on standing trees. The probability of stochastic extinction on live trees decreased with population size in logistic regression. The decline in the sites with largest populations (35-87% loss) was more influenced by limited colonization than extinction. Colonization was highest in humid north-facing hillslopes with multi-layered forests driven by gap dynamics. The lichen was strongly dispersal-limited, with a median effective horizontal dispersal of only 3.8 m in 37 yr., explaining its strong dependence of long continuity of forest cover. The populations were clustered and had substantial local turnover, yet with stable distribution at landscape scale. The tree-ring index, growth releases and gap recruitments indicate extensive harvesting similar to 1860-1900, but without major disturbances during the last 70-80 yr. Instead, the decline of U. longissima was probably driven by air pollution, climate change (autumn/winter mortality and heatwaves) and denser forests. Our findings highlight that the long-term survival of this lichen may be at risk even in forests having a strong level of protection

Spared, shared and lost-routes for maintaining the Scandinavian Mountain foothill intact forest landscapes

Intact forest landscapes harbor significant biodiversity values and pools of ecosystem services essential for conservation, land use and rural development. Threatened by fragmentation and loss by transitions to industrial clear-cut forestry, those landscapes are of pivotal interest for protection that secures their intact character. With wall-to-wall land-cover data, we explored opportunities for maintaining intact forest landscapes through comprehensive spatial planning across a 2.5 million hectares boreal to sub-alpine forest region along the eastern slopes of the Scandinavian Mountain range. We analyzed forest and woodland types that are protected, need protection or potentially can be subject to continued forest management. We established that the fraction of already clear-cut forest is very small and that the forest landscape of the Scandinavian Mountain foothills contains a high proportion of protected high conservation value forests, covering almost 2 million ha, and that over 500,000 ha (27%) remains unprotected and may be subject to future protection or continued adapted forest management. We found evident north to south differences with respect to forest landscape configuration, distribution of unprotected forests and land ownership. With a focus on non-industrial private landowners, we conclude that sustainable land-use requires integrative, multi-functional approaches that rely on further protection, forest and forest landscape restoration and a much larger share of continuous cover forestry than presently. Our results provide input into ongoing policy implementation and green infrastructure planning in the context of securing intact forest values and integrative opportunities for rural livelihood and regional development based on multiple value chains

Spared, shared and lost—routes for maintaining the Scandinavian Mountain foothill intact forest landscapes

Intact forest landscapes harbor significant biodiversity values and pools of ecosystem services essential for conservation, land use and rural development. Threatened by fragmentation and loss by transitions to industrial clear-cut forestry, those landscapes are of pivotal interest for protection that secures their intact character. With wall-to-wall land-cover data, we explored opportunities for maintaining intact forest landscapes through comprehensive spatial planning across a 2.5 million hectares boreal to sub-alpine forest region along the eastern slopes of the Scandinavian Mountain range. We analyzed forest and woodland types that are protected, need protection or potentially can be subject to continued forest management. We established that the fraction of already clear-cut forest is very small and that the forest landscape of the Scandinavian Mountain foothills contains a high proportion of protected high conservation value forests, covering almost 2 million ha, and that over 500,000 ha (27%) remains unprotected and may be subject to future protection or continued adapted forest management. We found evident north to south differences with respect to forest landscape configuration, distribution of unprotected forests and land ownership. With a focus on non-industrial private landowners, we conclude that sustainable land-use requires integrative, multi-functional approaches that rely on further protection, forest, and forest landscape restoration and a much larger share of continuous cover forestry than presently. Our results provide input into ongoing policy implementation and green infrastructure planning in the context of securing intact forest values and integrative opportunities for rural livelihood and regional development based on multiple value chains.publishedVersio

Estimating density from presence/absence data in clustered populations

Inventories of plant populations are fundamental in ecological research and monitoring, but such surveys are often prone to field assessment errors. Presence/absence (P/A) sampling may have advantages over plant cover assessments for reducing such errors. However, the linking between P/A data and plant density depends on model assumptions for plant spatial distributions. Previous studies have shown, for example, how that plant density can be estimated under Poisson model assumptions on the plant locations. In this study, new methods are developed and evaluated for linking P/A data with plant density assuming that plants occur in clustered spatial patterns.New theory was derived for estimating plant density under Neyman-Scott-type cluster models such as the Matern and Thomas cluster processes. Suggested estimators, corresponding confidence intervals and a proposed goodness-of-fit test were evaluated in a Monte Carlo simulation study assuming a Matern cluster process. Furthermore, the estimators were applied to plant data from environmental monitoring in Sweden to demonstrate their empirical application.The simulation study showed that our methods work well for large enough sample sizes. The judgment of what is' large enough' is often difficult, but simulations indicate that a sample size is large enough when the sampling distributions of the parameter estimators are symmetric or mildly skewed. Bootstrap may be used to check whether this is true. The empirical results suggest that the derived methodology may be useful for estimating density of plants such as Leucanthemum vulgare and Scorzonera humilis.By developing estimators of plant density from P/A data under realistic model assumptions about plants' spatial distributions, P/A sampling will become a more useful tool for inventories of plant populations. Our new theory is an important step in this direction