Efficacy of fungicides on Hymenoscyphus fraxineus and their potential for control of ash dieback in forest nurseries

Twenty‐six commercial formulations of fungicides at six concentrations were evaluated in vitro for their efficacy on mycelial growth of Hymenoscyphus fraxineus (anamorph Chalara fraxinea). The results are presented as EC₅₀, EC₉₀ and minimal inhibitory concentration values; the comparisons with the recommended application concentrations showed that 10 of the 26 fungicides were highly effective in their ability to inhibit the mycelial growth of the pathogen. The eight most effective fungicides identified based on multiple comparisons analysis were azoxystrobin, bitertanol, captan (in two‐component preparation with trifloxystrobin), difenoconazole, kresoxim‐methyl, spiroxamine (in multicomponent preparation with tebuconazole and triadimenol), tebuconazole and trifloxystrobin. Azoxystrobin, difenoconazole, kresoxim‐methyl, mancozeb, myclobutanil, pyrimethanil, tebuconazole and trifloxystrobin were selected to verify their effectiveness in in planta tests. During two field tests in nurseries, it was found out that tebuconazole (triazole), trifloxystrobin and kresoxim‐methyl (strobilurins) and mancozeb (dithiocarbamate) were significantly effective against H. fraxineus. The best results were gained with tebuconazole, when mean percentage of diseased saplings was 16.3%, whereas in the control, it was 63.6%. The combination and alternation of fungicides from the triazole, strobilurine and dithiocarbamate chemical groups should be an effective tool for protecting ash saplings in forest nurseries. Moreover, exact timing of the treatment reflecting rainfall and development of first symptoms in the foliage will be also important.     

GNBP1 as a potential RNAi target to enhance the virulence of Beauveria bassiana for aphid control

Journal of Pest Science - Gram-negative binding proteins (GNBPs) are important in the innate immune system of insects in recognition of fungi pathogen, such as Beauveria bassiana. However, this...     

On a forest as a commodity and on commodification in the discipline of forestry

This essay revolves around two dates separated by a decade: a retrospective look based on Samuelson (1976), and a prospective one that relies on Mitra-Wan (1985–1986). It concerns a tension between two communities: to understand the basis of this dissonance, and to open lines of communication that seek to dispel it. More specifically, it relies on two frameworks (Walrasian general equilibrium theory, as in Arrow-Debreu-McKenzie-Uzawa-Gale-Nikaido-Kuhn and others, and the Ramseyian theory of optimal growth, as in Samuelson-Solow-Cass-Koopmans-Uzawa-Srinivasan and others), formalized and continually refined in the last half of the 20th century to deal with interaction and with time, both essential considerations in any kind of economics of forestry. It also gives prominence to the Muir- Pinchot controversy at the very beginning of the 20th century, and thereby underscores its relevance to current ongoing tensions and anxieties regarding issues of sustainability and global-warming. From a purely analytical point of view, it alludes in passing to the potential relevance to forestry economics of mean field theories in physics, and of subgame-perfect equilibria in the theory of non-cooperative games.     

Analysis of the potential of small-scale enterprises of artisans and sawyers as instruments for sustainable forest management in Puerto Rico

Small-scale forest enterprises have been recognized as a potential instrument for sustainable development. In particular, the production of handicrafts is a major form of cultural expression and a significant source of income in several developing countries. In this study, we characterize the local handicraft sector in Puerto Rico to identify essential elements for fostering small-scale forest enterprises. Artisans and sawyers were home-based microenterprises that harvested, processed, and traded a wide variety of local forest products, including 125 types of wood and several non-wood forest products. Nonetheless, severe competition from cheaper imported crafts, low demand, and high product variability hamper the development of the local handicraft sector. Despite globalization, sawyers and artisans in Puerto Rico, as part of the U.S., have access to the largest markets of tropical woods and home accessories in the world. But, to participate in these markets, they must increase competitiveness. Lack of institutional effectiveness is a major constraint for the success of the artisan development program in Puerto Rico. Therefore, cooperation and linkages between all support organizations, including government agencies, non-governmental organizations, and associations of artisans, need to be enhanced to provide effective technical assistance, marketing, and financial services to artisans.     

An in vitro method for screening Colletotrichum gloeosporioides as a biological control agent for western hemlock dwarf mistletoe

An in vitro system using detached western hemlock branches infected with dwarf mistletoe was developed to screen the virulence of five isolates of Colletotrichum gloeosporioides, a hyperparasite of dwarf mistletoe shoots and berries. Detached branches infected with dwarf mistletoe were placed in nutrient‐saturated rock‐wool blocks and mistletoe shoots were inoculated with a conidial suspension of C. gloeosporioides. One month after inoculation, lesions on mistletoe stems and berries were well developed. Infection levels for individual isolates varied from 40% to 60% of shoots and 60% to 80% of berries. Significant differences were found between the isolates and control (p = 0.02 and 0.001, respectively) while no differences were noted between the isolates for both the shoots and berries. Parallel inoculation of mistletoe shoots detached from hemlock branches on moist filter paper and in rock‐wool blocks failed because these shoots deteriorated rapidly, fragmenting into segments within a week. This in vitro test may provide an alternative method for rapid screening of potentially virulent C. gloeosporioides isolates.     

Evaluation of potential gross income from non-timber products in a model riparian forest for the Chesapeake Bay watershed

The creation of riparian forest buffer zones for water quality management in agricultural landscapes takes land out of production, incurring an economic loss for the landowner. However, planting and harvesting techniques, such as those employed in indigenous systems of tropical agroforestry, can enhance riparian forest buffer strips with economically viable species. This kind of riparian forest buffer can be harvested and generate income from otherwise unproductive tracts of land. This practice would make the implementation of riparian forest buffers more acceptable to farmers, by generating income while helping to improve water quality. The present project provides an economic model for the harvest of non-timber products (fruits, nuts and ornamentals) from riparian forest buffer zones in the Chesapeake Bay region. Potential gross income from harvest is calculated to demonstrate the feasibility of this strategy. Given certain assumptions, the gross income can amount to $60,934.30/ha/year. This revised version was published online in June 2006 with corrections to the Cover Date.     

The potential of 44 native and non-native tree species for woodland creation on a range of contrasting sites in lowland Britain

A series of species trials were set up to investigate the establishmentand early growth (up to 14 years old) of 44 native and non-nativetree species on a variety of different site types in lowlandBritain. On good quality lowland afforestation sites, Platanusx hispanica (London plane) established and grew more successfullythan the native trees tested, and may be an example of a speciesthat could theoretically be established in anticipation of futureclimate change. Experiments on a variety of community woodlandsites indicated that a range of exotic species, such as X Cupressocyparisleylandii (Leyland cypress), may have the potential for establishinga woodland cover on poorly restored land where few other treeswould grow. However, on less challenging, better restored sites,a wide range of native species also grew successfully. Furtherlong-term and larger scale trials on a wider variety of sitesare required to confirm the potential of the species testedfor British conditions. The results from these experiments alsoshowed that relative growth rates of different species can varythrough time, highlighting the danger in making premature judgementsabout species suitability based solely on very early tree growth.     

内蒙古林区木材生产方式和布局调整分析

随着天保工程在内蒙古林区的全面实施，过去几十年偏重追求木材产量的生产模式和布局已不适应实施天保工程的需要，现结合内蒙古林区现有的基础条件及现状，在社会生态效益和经济效益统一原则指导下，从森林调查设计、森林采伐、木材运输、贮木场等方面提出了具体的调整方法，旨在降低木材生产成本，提高经济效益，真正实现林区资源的永续利用目标。     

Traditional mule logging method in Hyrcanian Forest: a study of the impact on forest stand and soil

We inventoried plant regeneration and soil compaction along mule trails to evaluate damage to forest stands and regeneration follow-ing mule hauling before and after operations in Kheyrud Forest in the...     

郴州市松材线虫病防治方法评析

对郴州市松材线虫病发生情况进行分析,对采取的几种防治方法进行评析,试图为今后防治松材线虫病提供思路。     

Effect of burnt wood removal on the natural regeneration of Pinus halepensis after fire in a pine forest in Tus valley (SE Spain)

To determine the effect of burnt tree removal on post-fire natural regeneration of Pinus halepensis, two 2 500 m² areas were selected six months after the fire in a totally destroyed mature (>70 years) pine forest. In one area, all the trees were cut down and removed 10 months after the fire and, in the other, all the trees were left standing (control). In each area, 20 permanent plots of 20 m² each were randomly placed, and all seedlings emerging within them labeled by individual numbered plastic tags. Emergence, mortality, density and growth (height) of 6649 P. halepensis seedlings were monitored during the first four post-fire years. Seedling emergence was concentrated in the first post-fire autumn–winter period. No positive effect on seedling emergence was detected as a consequence of burnt trunk dragging and subsequent turning over of soil. Wood removal produced an immediate average seedling mortality of 33%, and notably increased seedling mortality during the subsequent summer, probably due to increased exposure of seedlings to sunlight and the possible debilitation of many individuals by mechanical contact during burnt wood removal. A negative correlation of pine seedling mortality with height was detected, which increased significantly on wood removal in the third post-fire year. That is, short seedlings (<10 cm) in treated plots were the most likely to die during this period. In spite of the detrimental effect of wood removal on sapling survival, seedling density four years after fire in the cleared area was large (3.3 seedlings/m²). Wood removal treatment reduced seedling growth: seedling height was significantly higher in the control stand, and differences in seedling height growth rate became particularly noticeable in the fourth post-fire year. The results denote that traditional wood removal practices do not threaten natural post-fire P. halepensis re-establishment if initial seedling density is large enough. However, further studies focused on wood removal effects on the final tree development level and other ecological aspects are necessary to choose adequate post-fire forest management.     

Climate,plant organs and species control dissolved nitrogen and phosphorus in fresh litter in a subalpine forest on the eastern Tibetan Plateau

Key message

Fresh litter contains a higher concentration of dissolved phosphorus (DP) than dissolved nitrogen (DN), which implies a more efficient DN transformation or reabsorption in the subalpine forest on the eastern Tibetan Plateau. Both DN and DP concentrations increased with the increase of mean monthly temperature, although the concentrations were also regulated by plant organs and species.

Context

The dissolved nitrogen (DN) and dissolved phosphorus (DP) released from fresh litter are important pathways by which total nitrogen and phosphorus are transferred from the vegetation to soil in forest ecosystems. However, few studies have paid attention to the DN and DP in fresh litter, which affects our understanding of the nitrogen and phosphorus cycles.

Aims

The objectives of this study were to elucidate the dynamic characteristics of the concentrations and storage of DN and DP, and to analyze how DN and DP are affected by different plant species and organs, and climate factors.

Methods

Fresh litter was collected in three plots in a spruce-fir forest and classified by different plant species and organs. Concentration and storage of DN and DP in fresh litter were determined and related to the climatic variables that were monthly recorded.

Results

The concentration of DP was higher than that of DN in fresh litter, and the concentrations of both elements were determined by plant organs and species. Moreover, The DN and DP concentration was positively related to mean monthly temperature, while DN and DP storage was negatively correlated with mean monthly temperature and monthly precipitation. The storage of DN and DP was determined by litter biomass, which the order in litter from different plant organs was leaves>twigs>miscellaneous>flowers and fruits. The storage of DN and DP in leaves showed two peaks in April and October, but that in twigs and the miscellaneous showed only one peak in October.

Conclusion

Our results indicated that dissolved nitrogen (DN) is transferred and reabsorbed more than dissolved phosphorus (DP) before plant leaf senescence and other organs fall. Furthermore, DN and DP were associated with climate, plant organs and species in a subalpine forest on the eastern Tibetan Plateau.

     

Fourier transform-infrared spectroscopy as a new method for evaluating host resistance in the Dutch elm disease complex

Resistance of elms (Ulmus spp.) to the pathogenic fungus Ophiostoma novo-ulmi Brasier depends on chemical and anatomical factors that confine the spread of the pathogen in the vascular system of the host. This study focused on detecting chemical differences in 4-year-old Ulmus minor Mill. seedlings before and after inoculation with a virulent O. novo-ulmi isolate. According to symptom development over 60 days, the trees were divided into resistant (0-33% wilting) and susceptible (67-100% wilting) groups. Histochemical tests and Fourier transform-infrared (FT-IR) spectroscopy analysis were performed on transverse sections of 2-year-old twigs, 2 days before and 40 days after inoculation. Although histochemical tests did not clearly discriminate susceptible from resistant elms, chemical differences between resistant, susceptible and control trees were detected by FT-IR. The average spectrum for resistant tree samples had higher absorbance peaks than the spectra from the susceptible and control samples, indicating increased formation of lignin and suberin. The roles of lignin and suberin in the resistance of the elms against O. novo-ulmi and the usefulness and sensitivity of the FT-IR technique for analyzing metabolic changes caused by pathogens in plants are discussed.     

Hillside forest land as a safety net for local people in a mountain village in West Java: an examination of differences in the significance of national and private lands

 In Kemang, a mountain village in West Java, Indonesia, the local people call the hillsides pasir, a term which includes both privately owned hillside land or nationally owned forest land. It is apparent that the national forest lands function as a social safety net, serving as land where the middle-class and the poor can conduct “informal” cultivation, through temporary agreements with the state forestry corporation, or even “illegal” cultivation without permission. In this study, the households cultivating on national forest lands were identified as: (1) having most household members living together; (2) having a relatively young head person; (3) cultivating a small area of rice field; (4) having participated in the former perhutanan sosial system; (5) being dependent on the income from hillside land; (6) taking advantage of the rare opportunities for off-farm income; and (7) having a low total income. Meanwhile, the talun-huma system is dominant on privately owned hillside land, where a part of the talun, or tree garden, is cleared for use as a swidden on a 30-year rotation. In such cases, the land functions as a safety net only for the limited number of people who are permitted access to the land. The function of the privately owned hillside land, through the mutual-aid system, should not be overestimated; it is probably less important than national forest land in terms of income redistribution. It is recommended that the government of Indonesia consider the possibility of formally ensuring the long-term rights of local people to utilize the national forest lands in Java. Received: April 6, 2001 / Accepted: October 24, 2002 Acknowledgments This paper is in part a result of the research activities of the Core University Program in Applied Bioscience between the University of Tokyo and Bogor Agricultural University, sponsored by the Japan Society for the Promotion of Science (JSPS). The authors would like to express their thanks to Prof. Sumiaki Iwamoto, the University of Tokyo, for his kind help. Correspondence to:M. Inoue     

Current status and predicted impact of climate change on forest production and biogeochemistry in the temperate oceanic European zone: review and prospects for Belgium as a case study

Reviews of the current statuses of forests and the impacts of climate change on forests exist at the (sub)continental scale, but rarely at country and regional levels, meaning that information on causal factors, their impacts, and specific regional properties is often inconsistent and lacking in depth. Here, we present the current status of forest production and biogeochemistry and the expected impacts of climate change on them for Belgium. This work represents a case study for the temperate oceanic zone, the most important bioclimatic zone in northwestern Europe. Results show that Belgian forests are mainly young, very productive, and have a high C-sequestration capacity. Major negative anomalies in tree vitality were observed in the 1990s and—as result of disturbances—in the last decade for sensitive species as poplars and European beech. The most severe disturbances were caused by extreme climatic events, directly (e.g. storms) or indirectly (e.g. insect outbreaks after a mild autumn with an early/severe frost). Because of atmospheric deposition and soil fertilization (due to the previous use of the land), nutrient stocks of Belgian forests are likely to sustain the future enhancement in productivity which is expected to follow the increase in atmospheric CO₂ concentration that will occur in years to come. However, in the long term, such (enhanced) forest production is likely to be limited by nutrient deficiencies at poor sites and by drought for sensitive species such as beech and (particularly) Norway spruce. Drought conditions will likely increase in the future, but adverse effects are expected on a relatively limited number of tree species. The potential impacts of windstorms, insects and fungi should be carefully investigated, whereas fires are less of a concern.     

Farmers' perspectives on slash-and-burn as a land clearing method for small-scale rubber producers in Sepunggur, Jambi Province, Sumatra, Indonesia

On September 10, 1997, Indonesian President Soeharto renewed a ban on the practice of burning forests to clear land. At that moment a thick haze caused by land-clearing related fires in Kalimantan and Sumatra, Indonesia, blanketed large parts of Indonesia, Malaysia, Singapore, Brunei, the Philippines and Thailand. These fires, aggravated by the El Niño weather pattern and described as the worst in Southeast Asian history, renewed a long-term debate on slash-and-burn (S&B) as a method of land clearing.

Acceptable alternatives to S&B should address both the problems and the benefits of the use of fire. In depth knowledge and a clear diagnosis of the problems that rise with S&B and its alternatives are needed. A social/economic/agronomic survey was therefore conducted among 37 small-scale rubber producers in Sepunggur, Jambi Province, Sumatra, Indonesia. Our objectives were to: (1) characterize S&B techniques; (2) characterize farmers' perspectives on land clearing methods related to agronomic/economic factors (soil fertility, plant growth, production); and (3) evaluate alternatives to S&B that would be acceptable to individual farmers at present and in the near future. Small rubber producers (average farm size ≈5 ha) were selected because rubber gardens are the major land use type in this area, small producers are the main contributors, and most of the forest that is presently converted for agricultural use is being planted with rubber seedings.

Farmers generally start slashing in March and burn in the month of August. Burning takes place in two steps: broadcast burn followed by pile-and-burn. The five advantages of using fire as mentioned by the farmers were: (1) burning creates space (51%); (2) ash acts as a fertilizer (23%); (3) burning improves soil structure enabling faster establishment of seedlings (15%); (4) burning reduces weed/tree competition (5%); and (5) burning reduces the occurrence of pests/diseases (3%).

Alternatives to S&B should be economically acceptable. Mulching does not provide an alternative to any of the benefits of burning. Slash-and-remove-wood addresses only the first advantage and requires a tremendous effort in labor. If forced to accept either alternative, farmers expect a reduction in income due to difficulties in establishing new rubber gardens, reductions in yield, and an increase in labor costs.

At present, small quantities of wood with economic value are sold on the local market. Slash-sell-and-burn is an alternative that could maintain the advantages of using fire while supplying the farmer with extra income and the initiative to remove and not burn the trees. Even though forest is rapidly being converted to rubber gardens, land clearing will remain in practice to rejuvenate the old rubber gardens or to convert them to other land use systems. By selling rubberwood, farmers could cover costs of land clearing and earn enough to cover some of the costs of buying higher-yielding clones for rubber planting. This alternative has benefits similar to using fire and could significantly reduce pollution problems, but a change in local trade regulations and taxes is required for its successful adoption.     

Effect of complete competition control and annual fertilization on stem growth and canopy relations for a chronosequence of loblolly pine plantations in the lower coastal plain of Georgia

Stem growth, developmental patterns and canopy relations were measured in a chronosequence of intensively managed loblolly pine stands. The study was located on two distinct sites in the lower coastal plain of Georgia, USA and contained a factorial arrangement of complete control of interspecific competition (W) and annual nitrogen fertilization (F). The W treatment increased growth rate for several years, while the F treatments led to sustained growth increases. The combination of the W and F treatments resulted in more than 180 Mg ha⁻¹ stem biomass production at age 15 which is more than double the production of control treatment. Stem biomass production is continuing to increase through age 15 as indicated by the current annual increment in stem biomass continuing to exceed the mean annual increment in stem biomass. The F treatment decreased wood quality by decreasing whole tree latewood specific gravity from 0.565 to 0.535 and by lengthening the transition from juvenile to mature wood from 4 to 5 years. Increased rates of stem growth in response to cultural treatments were largely mediated by increased leaf area, with strong functional relationships between leaf area index and current annual increment. However, growth efficiency (stem production per unit of leaf area) decreased with stand age. These results indicate that nutrient amendments are necessary for sustaining high rates of stand development on relatively nutrient poor lower coastal plain soils.