Defining the poor by the rural communities of Burkina Faso: implications for the development of sustainable parkland management

Parklands are mixtures of trees and shrubs that farmers select for certain functions. In the Sahel, parklands are cultivated together with staple food crops, such as millet and sorghum. Parkland trees are sources of foods, including fruits, fats, oils, leafy vegetables, nuts and condiments that complement food crops in the local diet. Despite their socio-economic and ecological role, many studies have shown that the parklands are degrading very rapidly. Therefore, there is a need to undertake restoration actions that are based on a clear understanding of the livelihood context, such as the wealth status of the farmers, in which these agroecosystems are evolving. Thus, we conducted a wealth survey with rural communities in two different farming systems of Burkina Faso that are the cereal-based system in the “Plateau Central” and the cotton-based system in the “Boucle du Mouhoun”. A total of twelve villages were sampled, six villages for each system. The Participatory Analysis of Poverty and Livelihood Dynamics (PAPoLD) method was used by rural farmers to rank farmer households of their communities according to their wealth status. The results revealed that 70% of households in the Plateau Central and 56% in the “Boucle du Mouhoun” managed to escape poverty, and became wealthy. However, 2% of households of the villages in the Plateau Central and 6% in “Boucle du Mouhoun” fell into poverty in the same period whereas 9 and 12% remained poor in these zones, respectively. The main causes associated with households getting out of poverty are subsidies for cotton, external revenues from relatives working in towns and gardening activities. Death of spouse, illness, high number of people in the household and indebtedness are the main causes that lead into poverty. The implications of these findings in designing appropriate policies and management options for a sustainable management of agroforestry parklands under different land use systems were finally discussed.     

Agroforestry systems and biodiversity conservation in arid zones: the case of the Tehuacán Valley,Central México

The role of agroforestry systems in biodiversity conservation was investigated in the semiarid Tehuacán Valley, Central México. Richness and diversity of native plant species were compared between agroforestry systems (6 sampling sites) and the following forests (6 sampling sites) dominated by columnar cacti: (i) “chichipera” dominated by Polaskia chichipe; (ii) “jiotillal” dominated by Escontria chiotilla; and (iii) “garambullal” dominated by Myrtillocactus schenckii. Our information on genetic variation of dominant arboreal species in the study sites was reviewed and included in the analysis. Factors influencing household’s decisions to maintain vegetation cover were compiled through a survey and interviews and analyzed. All the samples of the agroforestry systems studied maintained on average nearly 59% plant species and 94% genetic variation of dominant cacti occurring in the forests, although their ability to preserve endemic rare species is limited. Social factors favoring maintenance of perennial species in agricultural plots include collective rules, households traditions, use of the plants maintained in the systems, and the environmental information gathered from NGOs, the local Biosphere Reserve, and researchers. However, agroforestry systems are losing their capability to maintain vegetation cover, mainly because of (i) decreasing amount of land managed by households, determined by a progressive fragmentation of the land area given to new families, (ii) adoption of technologies to intensify agriculture, and (iii) governmental programs penalizing the presence of vegetation patches within agricultural lands since they are considered “useless” areas. Necessary policies to stop degradation of the agroforestry systems and to improve their conservation capacity are discussed.     

Ethnicity, land use and woody vegetation: a case study from south-western Burkina Faso

Woody vegetation in cultivated landscapes in Burkina Faso is influenced by agricultural activities that are in turn influenced by institutional arrangements. Research was undertaken in a village in south-west Burkina Faso to investigate the relationship between species composition, diversity, density, species accumulation and land use category. Additionally the relationship between number of trees, size of farmed land and farmer ethnicity was investigated. Indigenous Tiéfo farmers had on average more than double the number of large (>4 m) trees of Vitellaria paradoxa Gaertn. f., Parkia biglobosa (Jacq.) R. Br. Ex G. Don and Anacardium occidentale L. than farmers belonging to other ethnic groups, but this was partly explained by a larger area being available. Differences between ethnic groups were not significant when expressed per ha. Botanical inventories of fallows more than 4 years old, cultivated parklands and plantations of Mangifera indica L. and A. occidentale showed that tree density and Simpson’s index of diversity for trees were highest in the fallow. Simpson’s index was not significantly different for regeneration, but sample-based species accumulation curves indicated that species accumulation in parklands was faster than in plantations when expressed per individual. The average regeneration density was 12,605, 1,995 and 6,772 seedlings ha^-1 for fallow, parklands and plantations, respectively. This low density for parklands means that species accumulation is slow compared to the other land uses when expressed per unit area. Fallow seems the most efficient way of keeping tree diversity in the agricultural landscape.     

Indigenous market-oriented agroforestry: dissecting local diversity in western Amazonia

This paper reports on a study of local diversity and variation in indigenous agroforestry practices among Amazonian peasants in a traditional community near Iquitos, Peru. Data were gathered through in-depth interviews with agroforestry-reliant households n = 36) on farming practices, demographic characteristics, income-expenditures and household wealth. Visits to crop fields and forest fallows n = 329) allowed the reconstruction of extensive cropping histories. More in-depth assessments of crop occurrence, density and diversity were conducted on 83 fields. Our results indicate considerable variation in field characteristics, agroforestry-cycles, and household agroforestry portfolios. Agroforestry practice is found to be strongly related to access to land within the community: households holding more land use both potentially more sustainable and more lucrative swidden-fallow agroforestry systems. Our results question the view of indigenous agroforestry systems as intrinsically ‘stable, equitable, and sustainable’, and underscore the importance of studying local variation in indigenous agroforestry practices. Promising avenues are discussed for future research on the factors related to the successful adoption of sustainable agroforestry systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

Traditional agroforestry systems and biodiversity conservation in Benin (West Africa)

In the past, the conservation of biodiversity has been mostly understood in terms of the management of protected areas and natural forests, ignoring the possible role of farm areas and the ways through which rural communities have promoted biodiversity in their subsistence agricultural production systems. The present study focused on the floristic diversity within traditional agroforestry parkland systems around the Pendjari Biosphere Reserve in Benin and showed the diversity of tree species in the area as well as socio-economic factors which affect the practice of this farming system. We used questionnaires and interviewed a total of 118 households to collect data. Respondents were interviewed on their farms and during the interview; we inventoried the number of tree on the farm and determined the farm size. Twenty-one tree species belonging to 14 botanical families were recorded during the surveys and the average stand density of the woody component of farmlands was 7.97 ± 5.43 stems/ha. A number of both native and exotic tree species occurred in the parkland agroforestry systems with dominance of indigenous tree species. Species richness varied with the size of household where households with small land holding conserve more tree species in their field than households with large land holdings. 64% of households surveyed were making deliberate efforts to plant tree species on their farmlands. The most important reasons which determined household ambitions to conserve woody species on farmland were tree products contribution to food and medicine. Results also showed that respondents who noticed that trees were decreasing in the wild conserve more tree species on their farmlands. This research highlights the role of traditional agroforestry practices to support tree species richness and provides evidence of the farms’ role as biodiversity reservoirs.     

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     

Household decision-making in agroforestry parklands of Sudano-Sahelian Mali

This study examines farmers’ knowledge and management of soil fertility and vegetation in Vitellaria paradoxa and Cordyla pinnata dominated agroforestry parklands in a Sudano-Sahelian region of Mali. Qualitative data from a series of semi-structured interviews were used to construct an empirically based typology of farmer practices. These interrelated practices center on famers’ agroecological knowledge, decision-making, and cropping strategies and are conceptualized as variable and adjustable socioecological responses to environmental and socioeconomic contingencies. The typology categorizes farmers in terms of their capacity for managing parkland soil and tree resources in an ecologically sustainable manner while negotiating livelihood challenges. It identifies the ideal farmer as one who practices the following: (1) use of environmental knowledge that considers multidimensional relationships among ecological and social components of parkland systems, (2) agricultural techniques that adaptively combine aspects of intensive and traditional extensive agriculture, and (3) natural resource decision-making that explicitly includes women’s environmental knowledge and livelihood strategies.     

Contribution of trees to soil carbon sequestration under agroforestry systems in the West African Sahel

Consequent to recent recognition of agricultural soils as carbon (C) sinks, agroforestry practices in the West African Sahel (WAS) region have received attention for their C sequestration potential. This study was undertaken in the Ségou region of Mali that represents the WAS, to examine the extent of C sequestration, especially in soils, in agroforestry systems. Five land-use systems were selected in farmers’ fields [two traditional parkland systems, two improved agroforestry systems (live fence and fodder bank), and a so-called abandoned land]. Soil samples taken from three depths (0–10 cm, 10–40 cm, and 40–100 cm) were fractionated into three size classes (2,000–250 μm, 250–53 μm, and <53 μm) and their C contents determined. Whole-soil C contents, g kg⁻¹ soil, across three depths ranged from 1.33–4.69 in the parklands, 1.11–4.42 in live fence, 1.87–2.30 in fodder bank, and 3.69–5.30 in abandoned land; and they correlated positively with silt + clay content. Using the ¹³C isotopic ratio as an indicator of relative contribution of trees (C3 plants) and crops (C4 plants) to soil C, more tree-origin C was found in larger particle size and surface soil and indicated that long-term tree presence promoted storage of protected C in deeper soil. Existing long-standing agroforestry practices of the region such as the parklands seemed to have little advantage for sequestering additional C, whereas improved agroforestry practices such as live fence and fodder bank introduced in treeless croplands seemed to be advantageous.     

Effect of management and spatial characteristics on plant species richness of Castanea sativa Mill. woodlots in the NW Iberian Peninsula

This paper analyzes the effect of the spatial characteristics and intensity of land use on vascular plant species richness in Castanea (Chestnut) woodlots of the northwestern Iberian Peninsula included in the category “9260 Castanea sativa woodland” (Annex I, DC 92/43 European Community). Digital maps were used to characterize 30 woodlots for which land use intensity was estimated and all plants found were inventoried. The results show that woodlot shape and land use intensity have a significant effect on vascular plant richness and indicator species number. However, an analysis of the interaction between woodlot characteristics and land use intensity suggests that the response of vascular plant species to land use intensity does not exhibit a uniform pattern and that it is modulated by the shape of the woodlots. We conclude that restricting the use of these types of woods to traditional practices must be determined in keeping with the specific characteristics of each woodlot, since the moderate management of Castanea sativa woodlots of the northwest Iberian Peninsula may continue to play an important role to maintaining plant species diversity in this area.     

Smallholder Teak and Agrarian Change in Northern Laos

Smallholder teak (Tectona grandis) plantations have become increasingly prominent in the landscape of Luang Prabang Province, Lao PDR. While the global market for teak-wood is attractive, investment has been driven by a range of factors, including changes to land legislation, land-use planning, taxation incentives, and government and non-government programs and promotions. The establishment of teak stands provides a labour-saving land use for households, potentially freeing up household resources for other farm and non-farm opportunities. However, the degree to which households can participate in the industry varies within and between villages. This paper reviews some of the underlying incentives for the expansion of teak plantations, examines the livelihood activities of both teak and non-teak producers in five case study villages in Luang Prabang, and explores the differential outcomes emerging from the expansion of smallholder teak production. The survey revealed that teak planting has been more extensive among households with a longer history of settlement, where the household head is older and better educated, where household members have off-farm sources of income, and where the household has access to paddy land and is thus more likely to be self-sufficient in rice. Households that depend on shifting cultivation for their livelihoods, without access to alternative productive land or income sources, will continue to have difficulty planting teak or holding on to the land they do manage to plant. The paper concludes that the establishment and improvement of teak plantations, like other apparently technical interventions aimed at providing a ‘pathway out of poverty’, need to be seen in the context of wider processes of agrarian change and differentiation to appreciate the resultant impacts on livelihood trajectories.     

Patterns of genetic diversity that result from bottlenecks in Scots Pine and the implications for local genetic conservation and management practices in Bulgaria

As one of the principal coniferous species of commercial importance in Bulgaria, Scots Pine has been subjected to strict management, which has posed a challenge for the conservation and management of its gene pool. In this study, we measured genetic diversity and population structure using 6 microsatellite loci in 12 populations from Bulgarian mountain ranges. Our analysis showed good intrapopulation divergence (18.22%; AMOVA) and genetic evidence of bottlenecks. “NJ-IAM” and “non-admixing” clusters divided the populations into 3 large groups. Our microsatellite analysis was consistent with the documented “mountain effect” influence on genetic diversity. Two methods—the Coalescent Bayesian model and M-stat analysis—implicated recent bottlenecks for all populations, suggesting that the genetic structure of Bulgarian Scots Pine was shaped over a long period (one thousand generations; i.e. 20,000 years) by the interaction of genetic and autoecological processes. Our results suggest that conservation and management practices should strive to maintain this genetic differentiation, specifically by emphasizing reforestation efforts with stocks from local provenances to avoid nonlocal introductions.     

Complementary labor opportunities in Indonesian pulpwood plantations with implications for land use

This analysis suggests important considerations for assessing social impacts of large-scale pulpwood production in Indonesia, emphasizing the extremely limited conditions under which pulp plantations may complement, rather than threaten, livelihoods of existing communities in their vicinity. Pulpwood plantations are expanding rapidly in Indonesia to feed major new pulp mills. Though officially developed on “unproductive forest lands”, pulpwood monocultures are commonly established at the expense of natural forests and indigenous agroforestry systems in Sumatra and Kalimantan. Based on a South Sumatra case study, this article analyzes how pulpwood plantations may be combined with more traditional land uses to improve livelihoods for local populations, considering the potential for “complementary” labor opportunities. This analysis is built on two assumptions: (1) village smallholder activities represent a first choice for village-based workers and smallholders, with relatively high financial returns per hectare; and (2) seasonal variations in labor requirements for village-based livelihoods open opportunities for complementary labor and land uses such as industrial plantations. Applying our model to a Sumatra case study highlights an upper limit to “complementary labor” for industrial timber plantation land use at a ratio of 5:1 (no more than 5 ha of pulpwood to each 1 ha remaining in intensified local agriculture and agroforestry). Other conditions required to minimize risks for local livelihoods include: flexible timing of company operations; priority to local employment; cautious determination of plantation sites; more transparent government licensing of plantation concessions and pulp mills recognizing local and customary land and resource rights.

Phylogenetic analysis of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Hemiptera: Aleyrodidae) populations from cotton plants in Pakistan,China, and Egypt

Bemisia tabaci is a species complex, of which the B and Q biotypes are globally distributed. B. tabaci feeds on more than 600 plant species including cotton, which is one of the main crops in Pakistan. In this study, the biotypes/haplotypes of B. tabaci populations collected from cotton plants in Pakistan, China, and Egypt were identified, and their phylogenetic relationships were investigated. None of the populations from Pakistan or Egypt belonged to the B or Q biotype: all 16 samples from Pakistan belonged to haplotype “PCG-1” and it is a group of unresolved populations all from Pakistan, while all three populations from Egypt belonged to unresolved haplotype “ECG.” The three populations from China belonged to the B biotype. Phylogenetic analysis indicated that the PCG-1, ECG, and B biotypes clustered into different clades even though they share the same cotton plant species as their host. The association between the outbreaks of cotton leaf curl disease and the occurrence of the PCG haplotype of B. tabaci in Pakistan is discussed.     

Growth and ecological impacts of traditional agroforestry tree species in Central Himalaya, India

A number of multipurpose tree species are conserved as scattered trees in settled farms on terraced slopes by the traditional farmers in Central Himalaya, India. Knowledge on growth rates and ecological impacts of these tree species is limited. Ten locally valued multipurpose tree species, viz., Albizzia lebbek, Alnus nepalensis, Boehmeria rugulosa, Celtis australis, Dalbergia sissoo, Ficus glomerata, Grewia optiva, Prunus cerasoides, Pyrus pashia and Sapium sebiferum, were established as mixed plantations at a degraded community forest land site and an abandoned agricultural land site in a village at 1200 m altitude in District Chamoli, India. At the abandoned agricultural land site, annual food crops were grown, along with planted trees, providing supplemental irrigation and organic manure following traditional farming practices. Survival, height, stem circumference, crown depth and width, number of branches, above-ground biomass and soil physico-chemical characteristics were monitored up to five years of plantation growth. Above-ground tree biomass accumulation at the abandoned agricultural land site was 3.9 t ha⁻¹ yr⁻¹ compared with 1.1 t ha⁻¹ yr⁻¹at the degraded forest land site. B. rugulosa, C. australis, F. glomerata, G. optiva, P. cerasoides and S. sebiferum showed more prominent differences in growth at the two sites compared with A. lebbek, A. nepalensis, D. sissoo and P. pashia. A. nepalensis and D. sissoo showed best growth performance at both the sites. A significant improvement in soil physico-chemical characteristics was observed after five years at both of the sites. Carbon sequestration in soil was higher than that in bole biomass. This revised version was published online in June 2006 with corrections to the Cover Date.     

Woody Plants Diversity and Possession,and Their Future Prospects in Small-Scale Tree and Shrub Growing in Agricultural Landscapes in Central Highlands of Ethiopia

Woody plants diversity and possession in small-scale tree and shrub growing practices among farmers of central highland Ethiopia were assessed by using a complete census of the trees and shrubs existing on farmers’ lands. The future prospects of diversity and possession of woody plants in the agricultural landscapes were also investigated by using the farmers’ species preferences and seedling demands as indicators. Comparisons were made across wealth classes, proximity clusters to a nearby state forest and land uses. It was found that 27 tree and 21 shrub species exist on lands of the studied households. With increasing wealth status of the households, the tree and shrub species richnesses increased. Tree and shrub species richnesses were highest in boundary plantings and homesteads respectively. Small-scale woodlots had the highest number of tree stems while homesteads contained the highest number of shrub stems. The number of tree stems a household possesses is strongly influenced by distance from the state forest, family size, educational level of the household head and number of iron-roofed houses owned. And, the shrub stems possession is significantly influenced by wealth status, distance from the state forest, land holding size, family size, livestock holding, age of wife and possession of off-farm income sources. The species preference analysis and seedling demand computations indicated that the woody species diversity is less likely to change in the future because there is no difference between the currently existing species and the preferred ones. Nonetheless, the number of tree and shrub stems on the farmers’ holdings could increase if the seedling demands of the preferred woody species are met.     

Evaluation of sustainability in Eastern Amazon under proambiente program

This study evaluates the sustainability of the innovative practices of smallholders who have extended their traditional farming and backyard gardening to other production parcels, such as agroforest systems in Eastern Amazon, Northeast Pará, under the PROAMBIENTE Program at Capim River Pole. According to these smallholders, these practices have assured food supplies and yields with the inclusion into the consumer market through produce diversity obtained by agroforest arrangement and increased purchase of material goods to the system. The smallholders’ perceptions also permit the evaluation of the sustainability of their experiences through the “Amoeba” method, which consolidates economic, social, cultural, and environmental indicators.     

Transitioning from wild collection to forest cultivation of indigenous medicinal forest plants in eastern North America is constrained by lack of profitability

The forest flora of eastern North America includes many herbaceous plant species traded in domestic and international medicinal markets. Conservation concerns surrounding wild-collection exist and transitioning to cultivation in agroforestry systems has potential economic and ecological benefits. Costs and revenues associated with adopting forest cultivation were modeled for eight North American medicinal forest plants. Sensitivity analysis examined profit potential in relation to (1) discount rates; (2) propagation methods; (3) prices; (4) growing period; (5) production costs; and (6) yields. Results indicate that intensive husbandry of six of eight species would be unprofitable at recent (1990–2005) price levels. Exceptions are American ginseng (Panax quinquefolius L.), and under certain circumstances (e.g., maximum historic prices, low production costs) goldenseal (Hydrastis canadensis L.). Direct marketing to consumers and retailers might improve grower profits, but is undermined by the availability of cheaper, wild-collected product. We suggest that the North American medicinal plant industry could play a key role in facilitating any transition from wild to cultivated product, perhaps through development of a certification and labeling program that brands “forest cultivated” products. This could generate price premiums, to be passed along to growers, but must be accompanied by aggressive consumer education. A “forest cultivated” certification and labeling program has potential to benefit industry and consumers if assurances regarding product identity and quality are a central feature. Plant species that are not viable candidates for commercial cultivation due to limited consumer demand (i.e., species with “shallow,” erratic markets) are best addressed through proactive government and industry initiatives involving targeted harvester education programs.     

Non-operator landowner interest in agroforestry practices in two Missouri watersheds

Land tenure has long been considered a critical factor in determining the adoption and long-term maintenance of agroforestry practices. Empirical evidence from non-US settings has consistently shown that secure land tenure is positively associated with agroforestry adoption. In the US, over 40% of private agricultural land is farmed by someone other than the owner. Given the importance of land tenure in agroforestry decisions in other countries and the magnitude of non-operator landownership in the US, there has been surprisingly little focus on land tenure in the temperate agroforestry literature. Using data from a 1999 survey in Missouri, this study explores factors associated with non-operator landowner interest in agroforestry. Results suggest that differences in farming orientation are linked to interest in agroforestry. Closer ties to farming, stronger financial motivations for landownership, and higher proportion of land planted to row crops were negatively related to interest in agroforestry among non-operator landowners. Environmental or recreational motivations for landownership and contacts with natural resource professionals were positively associated with interest in agroforestry. These results, consistent with earlier qualitative research suggesting that farm operators who have a strong “conventional farming identity” were less interested in agroforestry, point to a divide between landowners for whom environmental and recreational values play an important role in ownership motivation and those for whom financial considerations take precedence. The findings imply that agroforestry development programs in the US should take non-operator landowners and their farming and ownership orientations into account when designing research and outreach efforts.

The host range of the Eucalyptus Weevil, <Emphasis Type="Italic">Gonipterus “scutellatus”</Emphasis> Gyllenhal (Coleoptera: Curculionidae), in South Africa

• Introduction   

The Eucalyptus Weevil (Gonipterus “scutellatus” Gyllenhal) is a notorious pest of eucalypt plantations around the world, but its host range differs across its area of introduction, which may be due to it being a complex of several cryptic species.     

Volatile composition analysis by solid-phase microextraction applied to oak wood used in cooperage (Quercus pyrenaica and Quercus petraea): effect of botanical species and toasting process

The purpose of this study was to investigate the sorption of selected volatile substances from oak wood-chip samples (Quercus pyrenaica Willd. and Quercus petraea L.) subjected to different toasting levels, namely, without toasting, with medium toasting, and with strong toasting, through the use of solid-phase microextraction (SPME). The main volatile compounds identified as a function of the toasting level and botanical species were furfural, hexanal, α-pinene, d-limonene, decanal, vitispirane, ethyl hexanoate, cis-3-methyl-γ-octalactone (“oak lactone” or “whisky lactone”), α-terpineol, p-xylene, and nonanal. Considering the data obtained from the toasted woods (medium and strong intensity) in comparison with those of nontoasted woods, it can be pointed out that the average peak area and the number of compounds identified in the gas chromatogram decreased during the toasting process. In general, regarding the compounds analyzed, quantitative differences were found between the two oak wood species under study. High values of volatile compounds were found in Quercus pyrenaica oak wood chips. In addition, for the number of compounds identified in oak wood extracts and directly extracted from solid oak wood chips by SPME, it is concluded that the best extraction process for volatile compounds from oak wood is the use of oak wood-chip liquid extracts.