Field-scale influence of karité (Vitellaria paradoxa) on sorghum production in the Sudan zone of Burkina Faso

Sorghum (Sorghum bicolor L. Moench) production in 15 transect blocks, each with a karité (Vitellaria paradoxa C. F. Gaertn.) tree at each end, was evaluated on-farm in a village of southern Burkina Faso in a season of below-average rainfall. Under tree crowns, plant height and grain yield were significantly lower, by a factor of 16% for grain yield, than elsewhere in transects. In addition, mean plant height, and mean biomass and grain production per area as well as per plant were higher at the outside edge of tree crowns than in the middle of the field. Soil moisture content decreased significantly with increasing distance from the tree in the 0–20 cm soil layer. Top soils were also richer in organic carbon and potassium around tree crowns than in the middle of blocks. Sorghum performance in the zone under and around canopies was projected at field scale and compared to central transect controls. Grain production in karité parklands was higher with trees of mean crown radii of 225 to 275 cm, average densities of 12 and 31 trees/ha than in areas without trees. Therefore, farmers do not improve cereal production by reducing parkland tree densities below these levels. When nut production is included in the analysis, maintaining trees in fields can be economically advantageous at all densities.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effect of shading by baobab (Adansonia digitata) and néré (Parkia biglobosa) on yields of millet (Pennisetum glaucum) and taro (Colocasia esculenta) in parkland systems in Burkina Faso, West Africa

An experiment was conducted in Nobéré, Burkina Faso to assess the effect of shade of two indigenous fruit trees, Adansonia digitata (Baobab) and Parkia biglobosa (Néré), on a shade-tolerant crop called taro (Colocasia esculenta) in comparison with millet (Pennisetum glaucum) a shade-intolerant crop. Photosynthetically active radiation (PAR) and performance of crops under trees and in the open field were assessed during three cropping seasons. Millet performed better under baobab (806.1?±?121.48?kg?ha^?1) compared to the control plot (595.8?±?83.43?kg?ha^?1) and néré (320.2?±?59.91?kg?ha^?1). In contrast, the yield of taro was higher under néré (4124.0?±?469.05?kg?ha^?1) compared to the control plot (2336.9?±?617.04?kg?ha^?1) and baobab (2738.3?±?595.61?kg?ha^?1). There was a strong relationship between the amount of PAR intercepted by trees and crop yields under trees. As PAR decreased the yield of millet decreased whereas the yield of taro increased. Hence, it was concluded that parkland productivity could be enhanced by cropping taro under néré where light reduction was 83, 56 and 18% in zones A, B and C, respectively. An efficient association of baobab with crops could be the production of taro in zone A and millet in zones B and C where PAR reduction was 62, 38 and 15%, respectively.     

The characteristics of financing arrangements for the production and marketing of shea (Vitellaria paradoxa) butter in Tamale in the Northern Region of Ghana§

Shea (Vitellaria paradoxa) butter is an important internationally recognised economic commodity because of its food and medicinal potentials. However, access to finance for small-scale forest enterprises such as shea butter production and marketing remains a fundamental problem, which affects the growth and performance of these enterprises. This study, therefore, assessed the financing schemes and delivery mechanisms available for the production and marketing of the product in Tamale, Northern Region of Ghana. It also identified the financial structures available to shea butter producers, including constraints of the financial delivery mechanisms. Using a social survey, the study purposively selected and interviewed 83 women who engaged in shea butter processing. Of these, 86% were full-time processors of shea butter and 14% were involved in other businesses, such as petty trading, groundnut and rice processing. The study revealed low patronage of financial services as only 18% of the respondents took loans. A high proportion (82%) of the respondents were under contract financing with companies that purchased the shea butter. This financing arrangement made it difficult for the women to expand their activities as they usually were unable to negotiate and receive competitive prices for their shea butter. Non-governmental organisations and some financial organisations were involved in providing technical support services to the producers. However, there was an absence of continuous support services in credit management. The high illiteracy rate (97%) of shea butter producers made it challenging for the women to access formal training programmes to make them aware of opportunities that exist for financing their business. There is the need for targeted collaboration among stakeholders to improve existing financing schemes. In the long term, there should be policies to standardise the activities of the shea butter industry to improve access to credit, which could lead to the sustainable growth of these enterprises.     

The potential of Vachellia kosiensis (Acacia kosiensis) as a dryland forestry species in terms of its water use,growth rates and resultant water-use efficiency§

The potential of the country’s numerous indigenous tree species to address challenges facing the commercial forestry industry in South Africa is under-explored. Relevant issues include the rising demand for timber and non-timber forest products due to population and economic growth, minimal available land for expanding traditional commercial forestry operations, and known streamflow reduction impacts associated with introduced plantation tree species. However, little is known about the water use and corresponding growth rates of indigenous tree species, and consequently their potential as an alternative form of forestry and sustainable resource use. In this study, the water use, growth rates and resultant water-use efficiency of Vachellia kosiensis (Acacia kosiensis) (dune sweet thorn) were quantified within a mature stand of these trees situated on rehabilitated dune mining land in the Richards Bay area of South Africa. Hourly sap flow rates were measured over a two-year period in five trees, and tree heights and stem circumferences were recorded periodically throughout the monitoring period, to derive biomass increments. Rates of growth and water use were used to calculate water-use efficiency, defined as mass of utilisable (stem) wood produced per unit of water transpired. Results were compared with similarly sampled data for introduced plantation species, including Eucalyptus, Pinus and Casuarina. Results showed that the indigenous V. kosiensis trees used less than half the water used by introduced plantation species. The growth rates of individual V. kosiensis trees were unable to compete with introduced species; however, their higher tree density nevertheless yielded a mean annual increment of 10.3 m³ ha^?1 y^?1 (7.2 t ha^?1 y^?1). Furthermore, their correspondingly low water-use rates indicated that the indigenous trees had similar biophysical water-use efficiency values compared with genetically improved introduced tree species and highlighted their potential as an attractive land-use option in appropriate locations within water-constrained or dryland areas.     

Early recognition of graft compatibility in <Emphasis Type="Italic">Uapaca kirkiana</Emphasis> Müell Arg. clones,provenances and species

Examination of callus micro-grafts in Uapaca kirkiana Müell Arg. was carried out with the objective of determining early signs of graft compatibility. Leaves from U. kirkiana, U. nitida and Jatropha curcas trees were used for callus induction. Two pieces of callus were co-cultured on Murashige and Skoog (MS) medium with different supplements. Co-cultured calli were embedded in paraffin wax and dissected. The specimens were stained in safranin and fast green before viewing under a light microscope. Results showed that MS medium with 0.1 mg l⁻¹ thidiazuron (TDZ) and 0.5 mg l⁻¹ naphthaleneacetic acid (NAA) or 1.0 mg l⁻¹ dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l⁻¹ NAA was effective for callus induction. There were no necrotic layers at the unions within U. kirkiana clones and provenances, but a differential growth (irregularity) between U. kirkiana and U. nitida co-cultured calli. Phenol deposits were observed at the union interfaces of U. kirkiana combinations and were high on calli derived from mature trees. Phenol deposits were absent at the union of J. curcas heterografts. Necrotic layers developed at the unions of U. kirkiana and J. curcas micro-grafts and indicating an outright graft incompatibility. Accumulation of phenol deposits at the union interfaces inhibited graft compatibility in many U. kirkiana combinations. Callus fusion technique can be used to identify partners with an outright graft incompatibility, especially for distant related plant species.     

Phosphorus,copper and zinc supply levels influence growth and nutrition of a young Populus trichocarpa (Torr. & Gray) × P. deltoides (Bartr. ex Marsh) hybrid

Growth and nutrient responses of a P.trichocarpa × P. deltoides hybrid to phosphorus(P), copper (Cu) and zinc (Zn) were examined in a 4P× 3Cu × 3Zn factorial experiment conducted in anunheated greenhouse from 20 May until 25 August, 1997. Increase of growth medium P concentration from 37 to356 mg kg^-1 resulted in a mean increase in treedry weight of 53%, and increase of P concentrationfrom 37 to 500 mg kg^-1 was associated with a stemvolume increase of 47%. Increase from 0 to 0.32 µM Cu in solution applied thrice weekly wasassociated with a 61% increase in tree dry weight anda 59% increase in stem volume. There was also asmaller increase in stem volume (9.4%) resulting fromincrease in concentration of Zn from 0 to 0.31 µMin nutrient solution. Mean minimal leafconcentrations for satisfactory stem growth were foundto be 2.5 g kg^-1 P, 2.4 mg kg^-1 Cu and 74 mgkg^-1Zn. Visual deficiency symptoms wereassociated with mean leaf P concentrations below 1.6 gkg^-1, and Cu concentrations below 1.7 mgkg^-1. Increase in leaf P concentration wasassociated with decreases in leaf Cu and Znconcentrations, and high leaf Zn appeared tocompensate in some degree for low leaf Cu. Totalplant dry weight was satisfactorily predicted by stemvolume (r² = 0.85), but not by mean leaf weightor area.     

Elevated temperature effects on germination and early growth of European aspen (Populus tremula), hybrid aspen (P. tremula × P. tremuloides) and their F2-hybrids

This study aimed to understand the interaction between temperature and genotype in terms of the effect on early seedling development of European aspen (Populus tremula) and various F₂-aspen hybrids. We evaluated the response of 16 different European aspen and F₂-hybrid families on seed germination, survival rate and seedling height in one- and two-family trials under three different temperature regimes. In one-family trials, higher germination and higher survival rates were observed in higher temperature (C1700), leading to taller seedlings. European aspen × hybrid aspen individuals (Asp × Hyb) had a higher survival rate and taller seedlings than Asp, Hyb × Asp or Hyb × Hyb individuals. The difference between Asp × Hyb and Hyb × Asp was pronounced. Both growth conditions and genotype (i.e., hybrid cross) had strong effects on germination, survival rate and height of European aspen and F₂-hybrid seedlings. However, the interaction of genotype and growth conditions also had a significant influence on survival rate and seedling height, but not on germination. Two-family trials involving European aspen and F₂-hybrids led to significant negative effects on germination and survival rate and also facilitation effects on seedling height. Similarly, genotype had strong effects on germination and survival rate. Different genotypes and traits affected survival rate and seedling height differently in different growth conditions. These differences were more pronounced in the warmest environment, i.e., 1,700 degree days. We conclude that introgression between F₂-hybrids and local European aspen is likely in the current climate, and any warming will likely favor certain F₂-hybrids, especially the most probable types (P. tremula × (P. tremula × P. tremuloides)).     

Light quality and intensity of light-emitting diodes during pre-cultivation of Picea abies (L.) Karst. and Pinus sylvestris L. seedlings – impact on growth performance,seedling quality and energy consumption

Three different LED lamps with continuous spectra were compared against commonly used fluorescent lights. The lamps were characterized by light output, energy consumption and spectral quality for plant growth. The biological effects of light quality were compared by pre-cultivating seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. under each spectrum for 35 days in a growth chamber with controlled temperature, humidity and photoperiod. The seedlings were then transplanted and cultivated for one vegetation period at the nursery, then planted outdoors on a forest field trial and followed for three years. The seedlings showed similar growth performance for all spectra tested. LED lamps have several advantages to fluorescent light such as energy consumption, longer life span and adjustable light intensity. Regarding light intensity the effects on growth performance were studied for both species using the most promising LED spectra. The photosynthetically active radiation (PAR) was maintained at 50, 100, 200 and 400 μmol?m^?2?s^?1. Unlike energy consumption, seedling development did not display a linear relationship to light intensity. Instead, the results show an optimum light level between 100 and 200?μmol?m^?2?s^?1 for the shade tolerant Picea abies seedlings and a level of around 200?μmol?m^?2?s^?1 for the more shade intolerant Pinus sylvestris seedlings.     

Effect of combined stress (salinity + hypoxia) and auxin rooting hormone addition on morphology and growth traits in six Salix spp. clones

New Forests - Willows plantations development could be an alternative for hydro-halomorphic soils but it is limited by combined stress salinity?+?hypoxia (main stressor under...     

Intraspecific variation in growth and allocation patterns in seedlings of Pinus pinaster Ait. submitted to contrasting watering regimes: can water availability explain regional variation?

? Interpopulation variation in key functional traits of Pinus pinaster Ait. is well recognized. However, the relative importance of drought tolerance to explain this regional variation in the species remains elusive.

? Here, we raise the question whether water availability constitutes a likely driver of regional variation in biomass allocation, growth and morphological traits of ten populations that cover the distribution range of P. pinaster. We carried out an experiment where seedlings of five families per population were submitted to two contrasting watering treatments.

? The effects of water availability and population were significant for relative diameter and height growth rate, biomass allocation and number of lateral stems and dwarf shoots. Total dry mass significantly differed between watering treatments but it did not among populations. Populations could be clustered into four main groups. Root mass fraction explained most of the variation and significantly correlated to altitude but not to aridity.

? The geographical pattern of genetic variation found in morphology and biomass allocation did not translate into population differences in drought tolerance or phenotypic plasticity to water availability, indicating that water availability is not a likely driver of the regional variation observed in the studied traits of P. pinaster at the seedling stage.

     

Economic,environmental and social impact of alternative forest management in Baden-Württemberg (Germany) and Västerbotten (Sweden)

The forest sector is important for the German Federal State of Baden-Württemberg (BW) and the Västerbotten (VB) County in Sweden. Their forestry wood chains (FWCs) are of similar magnitude and supply forest industries. This study provides a regional comparison of the performance of FWCs from roundwood harvesting, including hauling, to mill gate concerning the factors that impact sustainability and assess different sustainability indicators for alternative supply chains, in particular fully mechanized chains in comparison to motor-manual operations. The harvest volumes are similar but operational conditions differ. Analysis of sustainability indicators demonstrated that the total costs for roundwood to industry are similar. Higher harvesting costs in BW are compensated for by lower transport costs to the mills. Employment per unit is higher in BW because of the high share of labour in felling. Due to smaller machinery and shorter transport distances in BW, energy use and greenhouse gas emissions per unit are lower than in VB. Areas for improvement are the technologies for logging in BW and the logistics of timber transport in VB.     

Classification and distribution of Comastoma (Gentianaceae) in Helan Mountains in China by floristic, ecological and geographical approaches

Four species of the Comastoma genus (Geianaceae) in Helan Mountains between Inner Mongolia and Ningxia Province in China have been recognized by morphological and geographical taxonomy. These four species are C. falcatum (Turcz.) Toyokuni, C. polycladum (Diels et Gilg) T. N. Ho, C. tenellum (Rottb.) Toyokuni and C. acutum (Michx.) Y. Z. Zhao et X. Zhang. Among them, C. tenellum (Rottb.) is a new recorded species and C. acutum (Michx.) Y. Z. Zhao et X. Zhang is a new combination. The floristic, ecological and geographical distribution of each species was analyzed and then a new key of Comastoma in Helan Mountains and the distribution maps have been generated, which will provide a reference for the revision of this genus and the analysis of the flora in Helan Mountains.     

Spatial variability of nutrient stocks in the humus and soils of a forest massif (Fougères, France)

In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones).