Does the root to shoot ratio show a hormetic response to stress? An ecological and environmental perspective

Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.     

How to move companies to source responsibly? German implementation of the European Timber Regulation between persuasion and coercion

Mitigating international trade in illegally harvested wood (products) is an international priority. To support this priority, the European Timber Regulation prohibits placing illegally harvested or traded timber on the EU market, requiring companies to undertake due diligence in sourcing wood (products). To take effect, this regulation needs to be implemented in all European member states.Although Germany is one of the first member states to transpose and enact the regulation's provisions, its implementation has recently been portrayed as “weak” and ineffective. This article aims to answer why this perception emerged. It scrutinizes implementation performance of the EUTR in Germany.Based on rich empirical data from stakeholder interviews, documents, and participant observation, this study argues that EUTR performance in Germany is not generally perceived as ineffective. Instead, stakeholder perceptions vary. As stakeholders face major uncertainties connected to market structure and company behaviour, they tend to base their assumptions about the implementation process on two major heuristics. Both focus on the question how to change company behaviour. One stresses the need to pursuade companies to comply, the other stresses the need to coerce them. These heuristics are based on the two larger objectives pursued by different stakeholder groups during policy making of the EUTR: (1) global sustainable forest management and (2) image improvement of the EU wood importing industry.Based on these different policy objectives, the EUTR does not provide clear guidance on which policy instruments should be given priority. As a consequence, national implementation is turned into a policy-making process. The outcome of this struggle will likely affect the future trajectory of EUTR implementation in other EU member states and in countries exporting wood into the EU.     

How are Swedish Forest Owners’ Associations Adapting to the Needs of Current and Future Members and Their Organizations?

This paper examines how Swedish forest owners’ associations are adapting their strategies to fit the changing needs of current and future members, and assesses how this development affects the organizations’ profile and relationship with members. To explore this issue eight semi-structured, face-to-face interviews with chairmen and senior managers from three associations and the Federation of Swedish Family Forest Owners were performed. Results showed that associations have identified an increasing need for management-support activities among members due to their decreasing familiarity with the basics of forestry. Help is increasingly needed both for setting up goals and objectives for their forest ownership, and to practically manage their properties. The associations’ education programmes are also being improved and adapted to suit members’ varying understanding of forestry by the introduction of A-, B- and C-level courses. Education campaigns have proved to be a successful tool for affecting members’ management objectives. Further, the associations see an increasing need for political activity to counter calls for stricter management regulations being made by the media, politicians and environmental organizations and thereby protect members’ ownership rights. Initiatives within the organizations for more efficient governance processes and the professionalization of working procedures within the member organizations may, however, come to reduce individual member involvement in the associations. Members may thus increasingly come to act as customers of service in their interaction with the organizations.     

Correction to: How does light availability affect the aboveground biomass allocation and leaf morphology of saplings in temperate mixed deciduous forests?

New Forests - The original version of this article was inadvertently published without the acknowledgements section.     

Does growth temperature affect the temperature responses of photosynthesis and internal conductance to CO2? A test with Eucalyptus regnans

Internal conductance to CO(2) transfer from intercellular spaces to chloroplasts (g(i)) poses a major limitation to photosynthesis, but only three studies have investigated the temperature dependance of g(i). The aim of this study was to determine whether acclimation to 15 versus 30 degrees C affects the temperature response of photosynthesis and g(i) in seedlings of the evergreen tree species Eucalyptus regnans F. Muell. Six-month-old seedlings were acclimated to 15 or 30 degrees C for 6 weeks before g(i) was estimated by simultaneous measurements of gas exchange and chlorophyll fluorescence (variable J method). There was little evidence for acclimation of photosynthesis to growth temperature. In seedlings acclimated to either 15 or 30 degrees C, the maximum rate of net photosynthesis peaked at around 30 or 35 degrees C. Such lack of temperature acclimation may be related to the constant day and night temperature acclimation regime, which differed from most other studies in which night temperatures were lower than day temperatures. Internal conductance averaged 0.25 mol m(-2) s(-1) at 25 degrees C and increased threefold from 10 to 35 degrees C. There was some evidence that g(i) was greater in seedlings acclimated to 15 than to 30 degrees C, which resulted in seedlings acclimated to 15 degrees C having, if anything, a smaller relative limitation due to g(i) than seedlings acclimated to 30 degrees C. Stomatal limitations were also smaller in seedlings acclimated to 15 degrees C than in seedlings acclimated to 30 degrees C. Based on chloroplast CO(2) concentration, neither maximum rates of carboxylation nor RuBP-limited rate of electron transport peaked between 10 and 35 degrees C. Both were described well by an Arrhenius function and had similar activation energies (57-70 kJ mol(-1)). These findings confirm previous studies showing g(i) to be positively related to measurement temperature.     

Consequences of an Improved Road Network in Rural Iran: Does it Lead to Better Livelihoods and Forest Protection?

Construction of new roads in rural areas is closely linked to market accessibility and economic growth. It also leads to exploitation of natural resources that may accelerate deforestation. These conflicting effects of an improved road network on rural development and depletion of forest resources present a serious challenge to policy makers interested in sustainable development. This paper investigates the effects of road networks on biological and socio-economic behaviour. The analysis was conducted by using a non-linear bio-economic model for a community in southern Zagros, Iran where they manage the adjoining forest according to traditional rules. Data for the model were obtained through village surveys and published resources. The model followed a holistic approach by incorporating a number of livelihood activities, such as, crop cultivation, goat husbandry, charcoal production and hiring out of community labour, along with several logical resource constraints. It was run over a period of 45 years. The results showed that new roads can either fuel forest degradation or contribute to forest protection depending on the choice of policy options. The study concludes that construction of new roads should be accompanied by policies aimed at higher state controls over newly accessible forest areas through regulatory measures, creation of new non-farm employment opportunities and strengthening of traditional institutions through providing extension services for local communities and facilitating NGO involvement so as to minimize the adverse effects on forest resources.     

How much are wood-based cellulosic biofuels worth in the Pacific Northwest? Ex-ante and ex-post analysis of local people's willingness to pay

The National Institute of Food and Agriculture (NIFA) provided a grant to establish a wood-based cellulosic biofuels industry in the US Pacific Northwest. Whether the industry will be sustainable depends largely on social acceptability in general and market acceptability of the biofuels among the public in particular. We conducted contingent valuation surveys of general public in the US states of Oregon and Washington to determine people's willingness to pay (WTP) for wood-based cellulosic biofuels and the factors that influence their WTP decisions. Oregon has an existing cellulosic biorefinery, while Washington's biorefineries are only being planned, allowing us to conduct an ex-ante (Washington) versus ex-post (Oregon) WTP comparison. We sent out mail surveys to 2828 valid mailing addresses between May and July of 2015 and received 757 completed surveys. We used the distribution-free Turnbull estimator to estimate the expected WTP and logistic regression to determine the relative strength of predictors on WTP. About one fifth (18.8%) of the respondents were willing to pay some premium for wood-based cellulosic biofuels. The mean WTP amount was $0.19 ± $0.03/gal. (95% confidence interval: $0.17 to $0.21), which equates to a 6.4% price premium on top of the market price for gasoline. Logistic regression results showed that the offered bid price, knowledge on biofuels, age and religious affiliation of respondents were statistically significant predictors of WTP decisions. No significant differences in ex-ante versus ex-post WTP were observed. We also discussed the policy implications of these results for sustainable management of the wood-based cellulosic biofuels industry.     

Correction to: Breeding and scientific advances in the fight against Dutch elm disease: Will they allow the use of elms in forest restoration?

New Forests - Author had ordered for open access after the article went online in Springer link. The article was changed to open access article.     

Developing farmer and community capacity in Agroforestry: is the Australian Master TreeGrower program transferable to other countries?

The Australian Master TreeGrower (MTG) program was launched in 1996 as an agroforestry extension initiative of The University of Melbourne. The program included a short course for landholders that provided knowledge and practical skills but also had a strong focus on developing the information and peer networks that would provide them, and their community, with on-going support as they implement their agroforestry activities. Since 2010 the MTG has been delivered by The Australian Agroforestry Foundation, a not-for-profit organisation, and integrated with the Peer Group Mentoring (PGM) concept developed by a regional farmer group in Australia. The PGM trains, then pays, past Master TreeGrowers to support other landholders as they design and develop their own agroforestry projects. More than 100 MTG courses have been run across Australia involving over 2000 landholders and more than fifty partner organisations. Independent evaluation shows that participants enthusiastically support the program, increase the area of tree cover on their land, adopt more intensive or purposeful management practices, are more inclined to want to grow trees for a mix of both public and private good outcomes, and, actively encourage others in their community to do the same. This paper reviews the development and delivery of the MTG and PGM in Australia and explores whether the models are transferable to developing countries. To date four MTG courses have been conducted in Africa (Uganda (2) and Niger (2)), seven in Indonesia and one in Timor-Leste. Whilst the structure of the international MTG courses was different to that commonly adopted in Australia the content was similar in that they included: information to support the development and implementation of agroforestry designs that reflect their particular interests and aspirations; a review of market opportunities for agroforestry products and services, training in tree and forest measurement, education in tree growth and silviculture; and, encouragement, guidance and support to encourage landholders to share their experience with others in their community. The response suggests that the MTG, originally developed for Australian farmers, may represent a very different model of agroforestry extension to what is commonly offered to farmers in developing countries, and that it may be worth developing in regions where farmers believe they have relatively secure land tenure and are able to make long-term land management decisions regarding tree establishment and management.     

Participatory development of decision support systems: which features of the process lead to improved uptake and better outcomes?

Decision support systems (DSSs) are important in decision-making environments with conflicting interests. Many DSSs developed have not been used in practice. Experts argue that these tools do not respond to real user needs and that the inclusion of stakeholders in the development process is the solution. However, it is not clear which features of participatory development of DSSs result in improved uptake and better outcomes. A review of papers, reporting on case studies where DSSs and other decision tools (information systems, software and scenario tools) were developed with elements of participation, was carried out. The cases were analysed according to a framework created as part of this research; it includes criteria to evaluate the development process and the outcomes. Relevant aspects to consider in the participatory development processes include establishing clear objectives, timing and location of the process; keeping discussions on track; favouring participation and interaction of individuals and groups; and challenging creative thinking of the tool and future scenarios. The case studies that address these issues show better outcomes; however, there is a large degree of uncertainty concerning them because developers have typically neither asked participants about their perceptions of the processes and resultant tools nor have they monitored the use and legacy of the tools over the long term.     

Does Remoteness from Urban Centres Influence Plant Diversity in Homegardens and Swidden Fields?: A Case Study from the Matsiguenka in the Amazonian Rain Forest of Peru

Swidden cultivation is the traditional agricultural system in most parts of the Amazonian rain forest. In a remote area in the Manu National Park, Peru, this system was analysed in two indigenous Matsiguenka communities. Diversity of cultivated plants on fields and in homegardens are presented in the current study. Cultivated plants were noted on two to four plots per field on 46 fields, making a total of 126 survey plots. Nineteen homegardens were studied as well. Dominating species cultivated on fields is cassava (Manihot esculenta). Fruit trees such as the peach palm (Bactris gasipaes), guava (Psidium guajava) or Inga edulis, but also cotton (Gossypium barbadense) and a medicinal plant (Cyperus sp.) predominate in more than 75 % of the homegardens analysed. Species diversity increases steadily from 18 and 24 species on 1- and 2-year-old fields to 26, 29 and 66 species in young, medium old and old homegardens, respectively. Seventy-one different species in total were found in all homegardens analysed and 25 in swidden fields. Diversity of species cultivated in homegardens is low compared to other studies in the rain forest of the Amazon. This seems to be due to their remoteness from the next urban centre and to the fact that they are native communities with still low external exchange of information. These findings are in contrast to the hypothesis that remoteness from urban centres increases species richness because subsistence production is based on a broad variety of species. In contrast to species richness in homegardens, differences in species richness in swidden fields between the present and other studies could not be found.     

Unraveling the tripartite interactions among the woolly poplar aphid,its host tree,and their environment: a lead to improve the management of a major tree plantation pest?

Key message

For an optimal deployment of poplar resistance to the gall-inducing aphid Phloeomyzus passerinii , a laboratory susceptibility assay has been developed. The nature of aphid–tree interactions during compatible and incompatible situations has been studied in detail. This should help at identifying specific resistance markers and at testing effects of site conditions on tree–pest interactions.

Context

P. passerinii is a major pest of poplar plantations in Europe, and the plantation of resistant poplar genotypes is regarded as the best long-term management strategy for this pest. This requires a sound knowledge of the interactions among the pest, its host and their environment.

Aims

Here, we review the recent advances aiming at developing an optimal deployment of host resistance versus P. passerinii.

Results

Investigations on aphid-host interactions demonstrated that P. passerinii induces pseudogalls within the bark of susceptible hosts. This results in a reduction of starch bark content during aphid outbreaks, which could be involved in tree death. The constitutive level of starch in the bark could be related to the tolerance level of trees. A susceptibility test has been designed for poplar genotypes, discriminating three categories of susceptibility depending on tree’s ability to totally or partially inhibit pseudogall induction. The test still has several limitations however. It neither takes into account the large level of individual genetic diversity of the aphid in France, nor the environmental modulation of tree resistance and tolerance, while water deficit and fertilization could potentially affect these parameters.

Conclusion

The hypotheses drawn regarding the processes leading to tree death or resistance should help at identifying resistance markers, and at testing effects of site conditions on tree–pest interactions.

     

How rare is too rare to harvest?: Management challenges posed by timber species occurring at low densities in the Brazilian Amazon

Tropical forests are characterized by diverse assemblages of plant and animal species compared to temperate forests. Corollary to this general rule is that most tree species, whether valued for timber or not, occur at low densities (<1 adult tree ha⁻¹) or may be locally rare. In the Brazilian Amazon, many of the most highly valued timber species occur at extremely low densities yet are intensively harvested with little regard for impacts on population structures and dynamics. These include big-leaf mahogany (Swietenia macrophylla), ipê (Tabebuia serratifolia and Tabebuia impetiginosa), jatobá (Hymenaea courbaril), and freijó cinza (Cordia goeldiana). Brazilian forest regulations prohibit harvests of species that meet the legal definition of rare – fewer than three trees per 100 ha – but treat all species populations exceeding this density threshold equally. In this paper we simulate logging impacts on a group of timber species occurring at low densities that are widely distributed across eastern and southern Amazonia, based on field data collected at four research sites since 1997, asking: under current Brazilian forest legislation, what are the prospects for second harvests on 30-year cutting cycles given observed population structures, growth, and mortality rates? Ecologically ‘rare’ species constitute majorities in commercial species assemblages in all but one of the seven large-scale inventories we analyzed from sites spanning the Amazon (range 49–100% of total commercial species). Although densities of only six of 37 study species populations met the Brazilian legal definition of a rare species, timber stocks of five of the six timber species declined substantially at all sites between first and second harvests in simulations based on legally allowable harvest intensities. Reducing species-level harvest intensity by increasing minimum felling diameters or increasing seed tree retention levels improved prospects for second harvests of those populations with a relatively high proportion of submerchantable stems, but did not dramatically improve projections for populations with relatively flat diameter distributions. We argue that restrictions on logging very low-density timber tree populations, such as the current Brazilian standard, provide inadequate minimum protection for vulnerable species. Population declines, even if reduced-impact logging (RIL) is eventually adopted uniformly, can be anticipated for a large pool of high-value timber species unless harvest intensities are adapted to timber species population ecology, and silvicultural treatments are adopted to remedy poor natural stocking in logged stands.     

Sprouting characteristics of <Emphasis Type="Italic">Quercus pubescens</Emphasis> Willd. and <Emphasis Type="Italic">Quercus frainetto</Emphasis> Ten. trees after a wildfire: To cut or not to cut the burned trees?

The aims of this study were to analyze the sprouting characteristics of Quercus pubescens and Q. frainetto trees after a wildfire and to recommend the appropriate silvicultural treatments in order to achieve dense sprout origin regeneration. This study was carried out in the area that was burned in a wildfire in northeastern Greece. Three years later, 140 Q. pubescens trees and 140 Q. frainetto trees were selected. Seventy trees for each species were individuals that were cut after the fire and were in the form of stumps, while 70 trees were intact top-killed trees, as a result of fire. In each stump and intact tree that was selected, various parameters were measured or counted: the diameter at the level of ground, the number of the developed sprouts (if any) and the height as well as the basal diameter of the tallest sprout, etc. Both species have similar sprouting behavior after a wildfire. Mother tree dimensions positively influenced the number of sprouts and the growth of the tallest sprout per individual. The mean height of the tallest sprout per stump, after three growing seasons from the forest fire, is high in both species (2.08 m for Q. pupescens and 2.29 m for Q. frainetto). Cut stumps had more sprouts than intact trees in both species. Forest practice, in order to maximize the sprouting of Q. pubescens and Q. frainetto trees after a forest fire, should cut the burned trees before the next growing season.