Current Forestry Reports最新文献

Purpose of Review

Because tree seeds have been considered a low-risk pathway for the spread of plant pathogenic fungi, their international movement is not subject to strict phytosanitary regulation. However, recent studies have provided scientific evidence that the biosecurity risk of seed trade may not be as negligible as assumed. This review summarises current knowledge about seed trade activity across the world and seed-borne plant pathogenic fungi and highlights knowledge gaps that need to be filled to mitigate the risk of spreading tree pathogens via seeds.

Recent Findings

Several outbreaks of severe tree diseases in natural forests and plantations worldwide have been linked to fungal pathogens spread by seed trade. Indeed, recent studies based on modern sequencing technologies have shown that tree seeds harbour highly diverse fungal communities, including well-known pathogens and fungal taxa belonging to unknown species. While it has become clear that even apparently healthy seeds can carry potentially pathogenic fungi, the likelihood of seed-borne pathogens being introduced and becoming established, spreading and causing impact in the new environment is still unclear which challenges the assessment of the phytosanitary risk posed by seed trade.

Summary

Our analyses show that large amounts of tree seeds have been traded among countries and continents. Based on published literature, the risk of spreading pathogenic fungi via tree seed movement is high. However, the role of the taxonomically and functionally diverse fungal communities associated with seeds is still poorly understood. In particular, more research is needed to assess the likelihood of seed-borne fungi being transmitted to the seedlings and spreading and causing impact in the new environment.

Purpose of Review

The aim of this review is to provide an overview of the functional role of large wood in the functioning of fluvial ecosystems, ranging from the scale of microhabitats to entire catchments. To this purpose, this review is structured according to the major ecosystem processes occurring at different spatial scales, ranging from the microhabitat scale, e.g. the internal processes of organic matter breakdown by microbes, to the catchment scale, e.g. the catchment-scale-processes of water flow, sediment transport, and nutrient fluxes.

Recent Findings

Recent research increasingly shows that dead wood drives a complex of multi-scaled processes. The role of large wood as a channel structuring entity and a driver of hydromorphological functioning is well known, but the importance of large wood at higher spatial scales has not been fully acknowledged. This encompasses the importance of large wood in enhancing multiple channel — floodplain interactions by creating a dynamic exchange of matter (water, sediments, nutrients) and energy. It also strengthens the water retention and storage capacity of rivers, attenuating floods and droughts and plays an important role in sediment, nutrient and organic matter interception, and processing. All these attributes contribute to ecosystem complexity and functioning, as well as providing valuable ecosystem services. Furthermore, large wood also acts as an important dispersal vector which, together with the multiple scale processes, promotes biodiversity.

Summary

Recognising the multiple scale spatial and temporal processes acting in, around, and induced by large wood can strongly support future fluvial management, especially regarding the re-introduction and way of installing of large wood in rivers. As large wood management is context-dependent, research should focus on catchment specific processes.

Abstract

Purpose of Review

The successful application of thermal infrared (TIR) remote sensing in the agricultural domain, largely driven by the arrival of new platforms and sensors that substantially increased thermal data resolution and availability, has sparked interest in thermography as a tool for monitoring forest health. In this review, we take a step back to reflect on what physiological responses are reflected in leaf and canopy temperature and summarise research activities on TIR remote sensing of stress responses in forest environments, highlighting current methodological challenges, open questions, and promising opportunities.

Recent Findings

This systematic literature review showed that whilst the focus still remains on satellite imagery, Uncrewed Aerial Vehicles (UAVs) are playing an increasingly important role in testing the capabilities and sensitivity to stress onset at the individual tree level. To date, drought stress has been the focal point of research, largely due to its direct link to stomatal functioning at leaf level. Though, research into thermal responses to other stressors, e.g. pathogens, is also gaining momentum.

Summary

Disentangling stress-induced canopy temperature variations from environmental factors and structural influences remains the main challenge for broader application of TIR remote sensing. Further development and testing of approaches for thermal data analysis, including their applicability for different tree species and sensitivity under different climatic conditions, are required to establish how TIR remote sensing can best complement existing forest health monitoring approaches.

Purpose of Review

The main goal of this study was to review the latest developments in the use of wood-based building materials and systems over the last 5 years. The methodology was carried out by using the systematic review procedure. This study considered only peer-reviewed articles written in English published over the last 5 years (2018 to 2022) on materials used in structural systems and building envelopes.

Recent Findings

The energy demand for cooling and heating represents from 40 to 60% of a building’s energy consumption depending on the energy mix. Every increase in energy efficiency increases the pressure on the energy embedded in the materials. In this context, bio-based and especially wood-based materials are gaining popularity. Their use is significant in structural and envelope systems, making them a powerful tool for working on both efficiency and embedded energy. Furthermore, the building construction industry is among the most significant in the economy of industrialized countries.

Summary

Forests are a carbon asset for our societies. Since buildings have been identified as a global warming mitigation tool, an increase in the use of wood and bio-based products should be considered. To support a better scientific understanding of building carbon sequestration under climate changes, a thorough understanding of structural and envelope systems is needed. Various materials are used in these complex systems, and a variety of assembly options are available. In structural systems, research has tended to be incremental over the last 5 years, with a focus on prefabrication and hybrid structures. As new designs and materials are introduced in the future, building physics principles will become increasingly important to ensure the quality of building envelopes. This review presents the latest research related to wood structural and envelope systems to support their use in the construction industry.

Purpose of Review

Continuous cover forestry (CCF) is a sustainable management approach for forestry in which forest stands are manipulated to create irregular stand structures with varied species composition. This approach differs greatly from the traditional approaches of plantation-based forestry, in which uniform monocultures are maintained, and thus, traditional methods of assessment, such as productivity (yield class) calculations, are less applicable. This creates a need to identify new methods to succeed the old and be of use in operational forestry and research. By applying remote sensing techniques to CCF, it may be possible to identify novel solutions to the challenges introduced through the adoption of CCF.

Recent Findings

There has been a limited amount of work published on the applications of remote sensing to CCF in the last decade. Research can primarily be characterised as explorations of different methods to quantify the target state of CCF and monitor indices of stand structural complexity during transformation to CCF, using terrestrial and aerial data collection techniques.

Summary

We identify a range of challenges associated with CCF and outline the outstanding gaps within the current body of research in need of further investigation, including a need for the development of new inventory methods using remote sensing techniques. We identify methods, such as individual tree models, that could be applied to CCF from other complex, heterogenous forest systems and propose the wider adoption of remote sensing including information for interested parties to get started.

Purpose of Review

Forests support most global terrestrial biodiversity and contribute to the livelihood of billions of people, but these and other benefits are in jeopardy due to global change. This leads to questions, such as how to address the challenges of global change in forest management, given the lack of knowledge and deep uncertainty about future developments. In addition, many of the impediments to implement adaptation strategies are unknown.

Recent Findings

Here, we present an overview of results from a global survey of 754 forestry professionals (370 researchers and educators, 227 practicing foresters, 37 policymakers, 64 administrators, and 56 with other or unspecified roles) from 61 countries across 6 continents who were interested in global change issues. These professionals were asked about their opinion regarding three different adaptation strategies: resist, adapt, and transform. Most respondents agreed that the majority of global change factors will negatively influence the ability of forests to provide desired ecosystem services. Similarly, they agreed about major challenges when implementing adaptation strategies and specifically whether our current knowledge base is sufficient. These concerns were not limited to ecological aspects, but respondents also highlighted the need for a better appreciation of social/political and economic barriers, especially regarding transformation strategies. In addition, the response patterns, including differences due to economic status, highlight the importance of developing and evaluating adaptation strategies in a local social–ecological context.

Summary

Our study demonstrates a widespread perception on the part of forestry professionals around the world, especially among researchers and practitioners, that many global change factors will affect sustainable forest management negatively, resulting in the need for active silvicultural adaption. The results also suggest potential barriers to different adaptation strategies, particularly a relative lack of information and social acceptance for transform strategies. Further, this study highlights the importance of social and political factors and the need to understand the general public’s values regarding adaptation strategies as well as how the influence of public opinion is perceived by forest managers.

Purpose of Review

The demand for forest tree seedlings is increasing globally, and Sphagnum peat moss is widely used as a component of growing media for container plant production. However, peat extraction is environmentally unsustainable. The forest nursery sector needs to switch to more sustainable alternatives to peat. This review aims to identify potential substitutes for peat by reviewing the worldwide literature on alternative materials for growing media in forest nurseries.

Recent Findings

Most studies on alternative growing media focused on single plant species growing under local conditions, thereby limiting generalizations about the effectiveness of alternative materials for plant production. To our knowledge, no systematic reviews of scientific literature on the effectiveness of new, alternative-to-peat materials for enhancing plant growth and the associated growing media characteristics for the forest nursery sector are currently available.

Summary

Most of the analyzed case studies focused on angiosperms (73.1%), with the majority of studies coming from tropical seasonal forests/savannas (36.5%), followed by woodlands/shrublands (31.6%), and temperate forests (15.0%) biomes. Compost was the most studied material (19.5%), followed by bark, other organic materials, and manure (9.8, 9.7, and 8.0%, respectively). Green and municipal wastes were the principal sources of compost (> 60%), while agriculture and green wastes were the first sources of other materials (> 90%). Tested materials were dependent on the geographic region. Thus, manure was the most tested material in Africa and South America, tree bark in North America, and compost in Europe, Asia, and Oceania. Alternative materials effectively provided optimal physicochemical characteristics of growing media and enhanced seedling nursery growth when compared with peat-based growing media in more than 60% of the case studies. This review helps to identify research gaps and, most importantly, provides the basis for the future application of alternative growing media materials in forest nursery management worldwide.

Purpose of Review

Harsher abiotic conditions are projected for many woodland areas, especially in already arid and semi-arid climates such as the Southwestern USA. Stomatal regulation of their aperture is one of the ways plants cope with drought. Interestingly, the dominant species in the Southwest USA, like in many other ecosystems, have different stomatal behaviors to regulate water loss ranging from isohydric (e.g., piñon pine) to anisohydric (e.g., juniper) conditions suggesting a possible niche separation or different but comparable strategies of coping with stress. The relatively isohydric piñon pine is usually presumed to be more sensitive to drought or less desiccation tolerant compared to the anisohydric juniper although both species close their stomata under drought to avoid hydraulic failure, and the mortality of one species (mostly piñon) over the other in the recent droughts can be attributed to insect outbreaks rather than drought sensitivity alone. Furthermore, no clear evidence exists demonstrating that iso- or anisohydric strategy increases water use efficiency over the other consistently. How these different stomatal regulatory tactics enable woody species to withstand harsh abiotic conditions remains a subject of inquiry to be covered in this review.

Recent Findings

This contribution reviews and explores the use of simplified stomatal optimization theories to assess how photosynthesis and transpiration respond to warming (H), drought (D), and combined warming and drought (H+D) for isohydric and anisohydric woody plants experiencing the same abiotic stressors. It sheds light on how simplified stomatal optimization theories can separate between photosynthetic and hydraulic acclimation due to abiotic stressors and how the interactive effects of H+D versus H or D alone can be incorporated into future climate models.

Summary

The work here demonstrates how field data can be bridged to simplified optimality principles so as to explore the effect of future changes in temperature and in soil water content on the acclimation of tree species with distinct water use strategies. The results show that the deviations between measurements and predictions from the simplified optimality principle can explain different species’ acclimation behaviors.

Purpose of Review

Forestry in northern temperate and boreal regions relies heavily on conifers. Rapid climate change and associated increases in adverse growing conditions predispose conifers to pathogens and pests. The much longer generation time and presumably, therefore, lower adaptive capacity of conifers relative to their native or non-native biotic stressors may have devastating consequences. We provide an updated overview of conifer defences underlying pathogen and pest resistance and discuss how defence traits can be used in tree breeding and forest management to improve resistance.

Recent Findings

Breeding of more resilient and stress-resistant trees will benefit from new genomic tools, such as genotyping arrays with increased genomic coverage, which will aid in genomic and relationship-based selection strategies. However, to successfully increase the resilience of conifer forests, improved genetic materials from breeding programs must be combined with more flexible and site-specific adaptive forest management.

Summary

Successful breeding programs to improve conifer resistance to pathogens and pests provide hope as well as valuable lessons: with a coordinated and sustained effort, increased resistance can be achieved. However, mechanisms underlying resistance against one stressor, even if involving many genes, may not provide any protection against other sympatric stressors. To maintain the adaptive capacity of conifer forests, it is important to keep high genetic diversity in the tree breeding programs. Choosing forest management options that include diversification of tree-species and forest structure and are coupled with the use of genetically improved plants and assisted migration is a proactive measure to increase forest resistance and resilience to foreseen and unanticipated biotic stressors in a changing climate.