Silviculture in African moist forests : do we have new answers to old questions?

The silviculture of African tropical moist forests has a long history punctuated with (few) successes and (many) failures. The European foresters in charge of managing forests in the African colonies realized early - e.g. 1900 in Nigeria - that they were facing a complex ecosystem with a low volume per ha of commercial timber. Somewhat a different situation than the one faced by foresters in South-East Asia where forests were rich in commercial timber of the Dipterocarpaceae family. Confronted to a highly dispersed, highly valuable timber resource and entrenched in their temperate forester culture they worked on ways to produce ?the greatest timber volume, as homogenous as possible?. Two main schools of thought confronted one another, promoting respectively natural regeneration vs artificial regeneration techniques. In the 1970's, realizing the many difficulties and costs linked to enrichment planting, French foresters decided to focus on silvicultural operations targeted at future crop trees, rather than trying to actively favor regeneration. But they came quickly to consider that logging will in most cases be the only economically feasible silvicultural operation in the course of a felling cycle. Attention shifted to establishing simple logging rules supposedly ensuring long-term timber production. Today, we face what foresters in the 30's and 40's had anticipated: the "picking" of a small number of valuable light demanding trees through highly selective logging is slowly but surely exhausting these populations as canopy is not opened enough to allow regeneration. In countries where industrial logging started early, several important commercial species like Assamela - Pericopsis elata - and most species of Entandrophragma are becoming rare and some logging companies are beginning to turn to silviculture, thus demonstrating the modernity of old questions and the urgency of finding answers. We went back over 64 years of publications on silvicultural trials in the journal Bois et Forêts des Tropiques to highlight the conditions of success, and to propose ways forward. (Résumé d'auteur

European Mixed Forests: definition and research perspectives

peer-reviewedAim of study: We aim at (i) developing a reference definition of mixed forests in order to harmonize comparative research in mixed forests and (ii) briefly review the research perspectives in mixed forests. Area of study: The definition is developed in Europe but can be tested worldwide. Material and methods: Review of existent definitions of mixed forests based and literature review encompassing dynamics, management and economic valuation of mixed forests. Main results: A mixed forest is defined as a forest unit, excluding linear formations, where at least two tree species coexist at any developmental stage, sharing common resources (light, water, and/or soil nutrients). The presence of each of the component species is normally quantified as a proportion of the number of stems or of basal area, although volume, biomass or canopy cover as well as proportions by occupied stand area may be used for specific objectives. A variety of structures and patterns of mixtures can occur, and the interactions between the component species and their relative proportions may change over time. The research perspectives identified are (i) species interactions and responses to hazards, (ii) the concept of maximum density in mixed forests, (iii) conversion of monocultures to mixed-species forest and (iv) economic valuation of ecosystem services provided by mixed forests. Research highlights: The definition is considered a high-level one which encompasses previous attempts to define mixed forests. Current fields of research indicate that gradient studies, experimental design approaches, and model simulations are key topics providing new research opportunities.The networking in this study has been supported by COST Action FP1206 EuMIXFOR

Aspects of precommercial thinning in heterogeneous forests in southern Sweden

The overall objective of the work underlying this thesis was to suggest and evaluate possible strategies for the tending of young heterogeneous stands of Norway spruce, Scots pine and birch in southern Sweden. Heterogeneity was defined as variation in species composition, height distribution and spatial arrangement of the trees. The influence of stand density after precommercial thinning and timing of thinning on the diameter of the thickest branch was studied for naturally regenerated Scots pine. The branch diameter was found to decrease with increasing number of remaining stems after precommercial thinning. However, leaving very dense stands (> 3000 stems ha-1) resulted only in a minor reduction of the branch diameter. Late precommercial thinning, compared to early, reduced the branch diameter. The influence of the precommercial thinning regime on the crown ratio (living crown length/tree height) was also analysed. To be able to simulate the influence of different management options on the development of the young forest, single-tree growth models was developed for Scots pine, Norway spruce and birch. Height growth and diameter was estimated as a function of tree height, stand and site variables. Growth reduction due to competition was estimated using individual, distance independent indices as well as expressions of the overall stand density. In the third study the influence of stand structure after precommercial thinning on the development of mixtures between Norway spruce and silver birch was simulated. The aim was to identify mixtures that allowed both species to develop well until the first commercial thinning. By leaving birches with an average height slightly greater than spruce at precommercial thinning, a large proportion of competitive birches were available at first commercial thinning, at the same time as the relative diameter distribution of spruce in the mixture was equal to that of a pure spruce stand of the same density. The height difference between the species as well as the species proportion had a decisive impact on volume production. In the fourth study different precommercial thinning strategies were identified and applied to a heterogeneous stand including Scots pine, Norway spruce and birch. Stand development and economical returns over a rotation was estimated using a set of empirical models. The aim of the long-term strategies was: (i) a conifer dominated stand with focus on high production, (ii) a conifer dominated stand with focus on high timber quality, (iii) to preserve the heterogeneous stand structure, (iv) a mosaic pattern by tree species, (v) to reduce the precommercial thinning cost, without jeopardizing the future stand development. The difference in total volume production was found to be relatively small between the strategies. The lowest production was found for the strategies promoting species mixture at tree level (iii) and group level (iv). The net present value was highest for the strategy aiming at high production (ii) and lowest for the strategy aiming at preserved heterogeneity (iii). The minimal precommercial thinning (v) was a less profitable alternative, mainly because of an expensive first commercial thinning. Differences in timber quality were not considered in the simulations. The case study illustrates the possibilities for influencing the structure of a heterogeneous stand through precommercial thinning, as well as the limitations imposed by the initial stand structure

Rapid silviculture appraisal to characterise stand and determine silviculture priorities of community forests in Nepal

Published online: 7 September 2016Community forestry in Nepal is an example of a successful participatory forest management program. Developments in community forestry in four decades have focused on the social and governance aspects with little focus on the technical management of forests. This paper presents a silviculture description of community forests and provides silviculture recommendations using a rapid silviculture appraisal (RSA) approach. The RSA, which is a participatory technique involving local communities in assessing forests and silviculture options, is a simple and costeffective process to gather information and engage forest users in the preparation of operational plans that are relevant to their needs. The RSA conducted on selected community forests in Nepal’s Mid-hills region shows that forests are largely comprised of dominant crowns of one or two species. The majority of studied community forests have tree densities below 500 stems per hectare as a consequence of traditional forest management practices but the quality and quantity of the trees for producing forest products are low. Silviculture options preferred by forest users generally are those which are legally acceptable, doable with existing capacities of forest users and generate multiple forest products. For sustainable production of multiple forest products, the traditional forest management practices have to be integrated with silviculture-based forest management system.Edwin Cedamon, Ian Nuberg, Govinda Paudel, Madan Basyal, Krishna Shrestha, Naya Paude

Conservation, genetic improvement and silviculture of rattan species in south east Asia. Six month progress report on the activities of the participants to the project N°TS3-CT94-0285

Rattan is a forest product with a high value for local economy of South East Asia. The rattan trade represents S 5 billions, 90 % of which being concentrated in Indonesia and Malaysia. In spite of this, the knowledge about rattan biology, silviculture and the geographic partitioning of genetic diversity is still very limited. In 1994, a number of public and private organisations working in the region decided to join their research efforts on these topics within the present project, supported by the "Science and Technologies for Development" programme of the EEC. The list of the organisations involved is the following: 1) CIRAD-Forêt, HQ in France, Regional Office in Sabah, Malaysia 2) Forest Research Institute Malaysia, Malaysia (FRIM) 3) Forestry Department Sabah, Sabah, Malaysia (FD) 4) Innoprise Corporation Sdn Bhd, Sabah, Malaysia (ICSB) 5) Royal Botanical Garden, United Kingdom (RBG) The Official Commencement Date of the EEC project was the first of October 1994. The associated contracts between CIRAD-Forêt and the other participants were signed from December 1994 to April 1995. This six-months progress report refers therefore to a period from January 1995 and June 1995.According to the decisions taken during the First Workshop among Participants to the EEC Project on Rattans (Tawau, 23-27 January 1995, related in a previous document), the major activities during the first six-months period were subdivided among research, documentation, purchase of new equipments, recruitment of researchers, participation in international congress, and seed collections. These activities are briefly resumed in the following paragraphs and detailed in the participants' papers

Fallows, agroforests and forests: should tropical silviculture go beyond the forest margin?

Over the recent years, studies on small scale, chainsaw logging in a number of countries of West and Central Africa have documented the gap between timber production as recorded in official statistics vs. actual national production. The latter includes both the large-scale, industrial, export-oriented, forestry sector and the small-scale, artisanal one, largely feeding domestic and regional timber markets. In countries such as Ghana and Cameroon preliminary findings indicate that timber informally harvested in a range of agricultural land use units, such as fallows and cocoa-agroforests, contributes to about half of national production. We present the preliminary results of a series of studies conducted in two regions of Cameroon to assess timber stock and production in the rural mosaic and assess the sustainability of present exploitation practices. Results indicate that timber harvesting intensely focuses on, and is rapidly depleting, a handful of useful trees that farmers traditionally maintained on the rural land. Density, diameter distribution and basal area vary significantly by species and across the various agricultural units. Some species regenerate, in particular in the fallow units, but fuel wood extraction and pole production combined to field preparation practices seriously mine the reconstitution of the timber stock and its preservation across the fallow cycles. We conclude that models to join production of forestry and agricultural crops should be developed at the landscape level with a particular focus on the integration of the land uses that represent the largest portion of the rural mosaic, i.e. those with fallows, agroforests and secondary forests. Production and management tradeoffs (e.g. fallow length versus trees growth rates, damages to main crops, competition), and the factors that could enable the adoption of those models (e.g. land and trees tenure, options for alternative land uses) have to be carefully assessed. (Résumé d'auteur

Digital Preservation and Access of Natural Resources Documents

Digitization and preservation of natural resource documents were reviewed and the current status of digitization presented for a North American university. It is important to present the status of the digitation process for natural resources and to advocate for increased collections of digital material for ease of reference and exchange of information. Digital collections need to include both published documents and ancillary material for research projects and data for future use and interpretation. The methods in this paper can be applied to other natural resource collections increasing their use and distribution. The process of decision making for documents and their preservation and inclusion in ScholarWorks is presented as a part of the Forest Sciences Commons as a subset of the Life Sciences Commons of the Digital Commons Open Network launched and maintained by bepress. Digitization has increased the roles and skillsets needed for librarians and from libraries. This creates new challenges and opportunities for the library as publisher and as an advocate for open access. Digital curation melds together digitization and knowledge management and enhances community engagement. Digitization of collections are reviewed and natural resource documentation presented for faculty publications, Research Projects and Centers, eBooks, Journals, Galleries and electronic Theses and Dissertations (ETDs). Recommendations are made to increase the digital curation of the collection by encouraging community participation and use. Digital archives are important to natural resource professionals as society-ready natural resource graduates need to deal effectively with complex ecological, economic and social issues of current natural resources management. Natural resource research for the future needs to ensure that professionals have a greater breath of knowledge as they interpret and apply new knowledge, understanding, and technology to complex, transdisciplinary social and biological issues and challenges

Ingenuity, diversity, vision and adaptability of farmers producing timber and NTFP in western Cameroon

Most development workers, involved in farm forestry in southern countries, act on the basis of paradigms such as: ?poor farmers only consider the short-term production, their traditional agroforestry systems are immutable or being abandoned, we can offer them only well-established techniques, including simple and standardized fast-growing exotic species plantation methods for live-fences, fodder-banks or production of poles?. The study of the practices of farmers in western Cameroon, on the contrary, shows that there is a wide range of behaviour concerning the silviculture. Farmers show ingenuity to adapt traditional systems or integrate external technologies and adapt them to their current needs and their ability, while looking at different uses, sometimes over several generations. Thus, for private Eucalyptus plantations, they integrated the system used by state departments and projects, innovating in the following areas: plant production and direct seeding, spacing, association with crops, coppice selection, and diversity of products. By cons, for Pinus, also encouraged by the state and projects, very few farmers' plantations were carried out, mainly because of lack of markets for products at different ages of stands. Regarding the traditional live-fences, we find that species that have no current use are eliminated in favour of new species. These are selected, on the base of family needs and local market opportunities. For example, near the art centre of Foumban, Polyscias are planted because wood can be sold to the sculptors of masks. The Canarium multipurpose species (fruit and timber), with an average growth, is largely retained and planted. It is surprising to see a small number of farmers planting hedges with local species producing timber after more than 50 years, as Podocarpus or Entandrophragma, while the state itself does not. Rather, the state or municipal plantations burn in a general indifference, despite the best efforts of their managers. The question is whether the aid credits for public reforestation would not be used more effectively as an aid for private reforestation (Résumé d'auteur

The use of heart rate indices and subjective questionnaires in the determination of fatigue in motor-manual tree felling and delimbing operations in New Zealand exotic plantation forests : a thesis presented in partial fulfilment of the requirements for the degree of Master of Business Studies in Ergonomics at Massey University

This study assessed the use of heart rate indices and subjective questionnaires in the determination of fatigue in motor-manual tree felling operations in New Zealand exotic plantation forests. The research design consisted of a causal study utilising an amalgamation of both observational and ex post facto data collection techniques employing a cross sectional case study approach within a field study research environment. Findings from the research indicate that motor-manual tree felling and delimbing are tasks not necessarily analogous with excessively high levels of fatigue, even though the physiological measures categorised motor-manual felling and delimbing as being moderate to heavy workload tasks. Chronic fatigue was avoided, and acute fatigue mitigated by the effective use of the fallers self-pacing mechanism, combined with both structured and spontaneous rest breaks analogous with the work method adopted by motor-manual fallers. Consequently, production was not negatively affected by the progression of the working day. Poor work postures commonly adopted by the fallers encourage the progressive development musculo-skeletal damage. Hazards encountered by the subjects followed national trends for felling and trimming. Significant decreases in thermal comfort and sensation ratings occurred, accompanied by an increase in the skin wettedness rating and higher thermal regulation ratings for the majority of the fallers. No discernible increase in mental fatigue could be identified during the study. The ambient thermal environment and work site terrain had minimal effect on the subjects performance levels or physiological and psycho-physiological loadings

Occurrence and management of oak in southern Swedish forests

This article describes the current proportions of forest types with oak (Quercus robur and Q. petraea) in southern Sweden, provides an overview of oak distribution over time and reviews literature about oak regeneration relevant for the region. Further we discuss silvicultural possibilities to maintain and promote oak in Scandinavia. In Götaland pure oak forest covers 1% of the forest area and mixed forest types with > 10% oak proportion cover approximately 10% of the area. Common types of mixture are spruce-oak and pine-oak forest. Both mixtures are frequent in mature forest, especially pine-oak. Additionally, about one third of spruce-oak mixtures can be found in medium-aged forest. Intensive management would be necessary to promote single oak trees in old pine stands or spruce plantations, but the proportion of oak in coniferous forest provides some potential to maintain additional oak trees. The distribution of acorns by Jays, enhanced measures against browsing, and the release of single oak trees from competing tree species could help to maintain more oak trees for nature conservation. However, regarding management of oak for timber production, conventional methods are recommended. Planting after clear cutting of coniferous forest, or short shelter periods after mast years in oak stands, are established methods to regenerate pure oak stands. Another possibility to develop mature oak forest are mixed oak-spruce plantations, as traditionally practised in a small region in southern Sweden. The different approaches of oak management in Sweden were presented in April 2012 on the annual meeting of the section silviculture of DVFFA (German Union of Forest Research Organizations) in Wermsdorf near Leipzig to give an overview and access to recent forest research in Sweden