Fine root distribution of pruned trees and associated crops in a parkland system in Burkina Faso

Besides aboveground interactions, pruning of trees may also modify their rooting pattern for which a better understanding is needed for the optimisation of agroforestry systems. Thus, variation in fine root (d 2 mm) distribution of pruned trees and crops were assessed during three cropping seasons by sampling soil layers at 10 cm intervals up to 50 cm and at four distances from tree trunk. Three crown pruning treatments (totally-pruning, half-pruning and no-pruning) were applied to karité (Vitellaria paradoxa) and néré (Parkia biglobosa). In 1999, 59% (0.477 cm cm^–3) and 69% (0.447 cm cm^–3) of fine roots for karité and néré respectively occurred in the upper 20 cm with a significant decrease in root length density with soil depth. However, in 2000, totally-pruned trees of néré and karité showed 32% (0.051 cm cm^–3) and 34% (0.078 cm cm^–3) of their density in the upper 20 cm whereas root distribution in 2001 was similar to that of 1999. Thus, pruning to reduce belowground competition for the benefit of associated crops can be recommended in the light of the temporary reduction of root density in crop rooting zone and consequently the increase in crop production.This revised version was published online in November 2005 with corrections to the Cover Date.     

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.     

Karité (Vitellaria paradoxa) and néré (Parkia biglobosa) associated with crops in South Mali

The effect of two tree species, karité (Vitellaria paradoxa) and néré (Parkia biglobosa) on soil condition, development and production of cotton, sorghum and pearl millet, main crops in South Mali, has been investigated.The soil under the trees is slightly richer (organic matter content and several cations) compared to adjacent tree-less sites. Also tree-specific effects exist.Soil enrichment, however, is mainly a matter of redistribution of locally available nutrient resources.Of the six associations studied, only karité-cotton shows no tree-induced reduction in crop production. All other associations suffer greatly from reduced crop outputs caused by the trees, usually in the order of 60%.There are at least two reasons that explain tree-induced yield reduction. Because of increased humidity in the immediate surroundings of trees, in both soil and air, lower numbers of crop plants survive up to maturity, presumably because plants are attacked by fungi. Secondly, crop plants that mature show reduced output because of inter-specific competition for light and nutrients.In case of néré, in order to minimize the trees' negative influence lopping is advised. Such practice, however, is less suitable in case of karité, because of its assumed lower potential to regenerate, as compared to néré.     

Fatty acid and tocopherol patterns of variation within the natural range of the shea tree (Vitellaria paradoxa)

The shea tree, Vitellaria paradoxa, is one of the most economically and culturally important indigenous tree species in the Sudano-Sahelian region. Its seeds contain a vegetable fat, internationally known as shea butter, which is widely used in edible, cosmetic and pharmaceutical sectors. Based on samples from 456 trees distributed in 17 locations across the species natural range from Senegal to Uganda, the fatty acid and tocopherol variation, and its relationship with geographic and climatic variables, was assessed in order to address the pattern and the origin of this variation across the natural range. Significant differences between Western and Eastern regions for oleic, stearic acid, saturated–unsaturated acid ratio and γ-tocopherol were identified that it is postulated maybe a result of genetic drift due to the evolutionary history of shea tree populations. Within regions the difference among stands was significant for most constituents; however the major part of the variation was observed among trees within stand (53–90 %). Relationships with climatic variables were not verified, weakening evidence for clinal variation hypotheses suggested by previous studies.     

Mycorrhizal dependency of micropropagated argan tree (Argania spinosa): I. Growth and biomass production

The influence of V.A. mycorrhization was studied on two clones of in-vitro micropropagated plantlets ofArgania spinosa, a slow-growing tree of great importance in agroforestry systems in the semi-arid and arid zones of southwestern Morocco. Inoculation increased total shoot length, stem girth and biomass of the plants, when cultivated in controlled conditions with a phosphorus fertilization of 31 mgP·kg^–1 added to a substrate already containing 13.5 mg·kg^–1 available P (Olsen). The positive effect increased with time and, after 6 months, the above-ground dry matter production was 5 to 6 times higher for inoculated plants. The Relative Mycorrhizal Dependency Index, calculated on total dry matter, reached 77–78% at the end of experiment. Calculated on above-ground dry matter, the R.M.D.I. was 81–83%, placing the argan tree among the plants most dependent on mycorrhizal symbiosis. The root/shoot ratio was markedly (40–50%) reduced by inoculation, demonstrating the higher efficiency of a mycorrhizal root system.

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Résumé L'influence de la mycorhization V.A. a été étudiée chez l'arganier (Argania spinosa), arbre à croissance lente très important pour les systèmes agroforestiers des zones arides et semi-arides du Sud-Ouest marocain. Chez les plantules issues de micropropagation in vitro et cultivées en conditions contrôlées sur un substrat contenant 13.5 mgP·kg^–1 (Olsen) auquel on rajoute 31 mgP·kg^–1 par la fertilisation, l'inoculation accroit la longueur totale des axes, le diamètre au collet et la biomasse des plantes issus de multiplication in vitro. L'effet bénéfique augmente avec le temps et, après 6 mois, la matière sèche des parties aériennes était 5 à 6 fois plus élevée chez les plantes inoculées que chez les témoins non inoculés. L'Indice de Dépendence Mycorhizienne Relative, calculé sur la matière sèche totale, atteint 77–78% à la fin de l'expérience. Calculé sur la matière sèche des seules parties aériennes, l'I.D.M.R. est de 81–83%, situant l'Arganier parmi les plantes les plus dépendantes de la symbiose mycorhizienne. Le rapport racines/parties aériennes est nettement réduit (de 40 à 50%) par l'inoculation, mettant en évidence la meilleure efficacité d'un système racinaire mycorhizé.

     

Vegetative propagation of Vitellaria paradoxa by grafting

Vitellaria paradoxa or karité is a wild fruit-bearing tree species of sudano-sahelian parklands that plays an important socio-economic role in Sub-Saharan Africa due to the commercial and domestic value of the fruits. Principal constraints of karité fruit production are: long juvenile phase, slow growth, genetic variability and lack of knowledge regarding the cultivation of the species. To address these constraints and to enhance productivity and quality, five methods of grafting (side cleft, top cleft, tongue, chip budding and side veneer), two methods of pre-treatment of scions and rootstocks (washing with 10% sodium hypochlorite to wash off latex and sterilise and a control without washing), and two methods of protection of grafts against desiccation (covering with white plastic sheet and aluminium foil) were tested. The results showed decreasing success of survival of grafts 16 weeks after grafting for the five grafting techniques: side cleft (86.1%), tongue (80.9%), top cleft (78.1%), chip budding (38.1%) and side veneer (20.7%) grafting methods. The results also showed May to be the optimum time for grafting, with high rates of shoot growth and survival of grafts. The average annual growth rate of grafts was 12.6 cm. The pre-treatment of scions with 10% sodium hypochlorite, however, had no significant effect on survival of scions. There was also no significant difference in survival of scions between the two methods of protection of grafts against desiccation (aluminium foil and plastic sheet). Two grafts produced fruits two years after grafting using side veneer grafting.This revised version was published online in November 2005 with corrections to the Cover Date.     

Size class distribution and spatial pattern of Vitellaria paradoxa in relation to farmers' practices in Mali

The impact of human activities on size class distribution and spatial distribution of Vitellaria paradoxa (karité or shea butter tree) in the parklands of sub-Saharan Africa has not been reported in the literature. Two sites (Koumantou and Mperesso) in southern Mali and three treatments (cultivated field, fallow and forest) per site were involved in the present study. Results of a statistical test for random distribution showed that the spatial pattern of Vitellaria paradoxa became progressively aggregated from cultivated field to fallow and then to forest. A permanent aggregated pattern found at Koumantou was not found at Mperesso. A test of the independence of larger and smaller tree locations shows that size classes clump together at Koumantou but not at Mperesso. Results of the third test showed that in the cultivated field, auto-correlation was only observed at large scale. In the fallow the trend was towards negative correlation for both sites. In the forest, negative correlation was observed up to 20 m at Koumantou whereas at Mperesso, positive correlation was observed around 35 m and above 50 m. Site differences may be explained by the intensity of fruit production and recruitment, bound to rainfall and land use pressure. Greater regularity of the spatial pattern in cultivated field, then fallow, may be the result of human intervention.This revised version was published online in November 2005 with corrections to the Cover Date.     

Impact of tree coppicing on tree-crop competition in parkland and alley farming systems in semiarid Burkina Faso

The aim of this study was to evaluate the effects of tree coppicing on tree-crop competition in farmed parkland and in alley farming, both in semiarid Burkina Faso.Azadirachta indica A. Juss (neem) was studied in the parklands, while neem,Albizia lebbeck (L.) Benth. (albizia) andLeucaena leucocephala (Lam.) de Wit (leucaena) were investigated in the alley farming system. The crop was sorghum (Sorghum bicolor (L.) Moench) in both cases.Under non-coppiced neem trees in the parkland, the sorghum yield at 0–3 m distance from the tree (under the tree canopy) was 82% of open field yields at 6–9 m distance, but the difference was not significant (p=0.07). Close to trees (0–3 m distance) which had been coppiced before planting, the sorghum yield was 148% of open field yields. In alley farming, early coppicing was superior; sorghum yields were highest close to trees coppiced early and lowest close to trees coppiced late.

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Résumé La présente étude se propose d'évaluer les effets de la taille sur la concurrence entre arbres et cultures dans les parcs arborés et dans les cultures en couloir, en climat semiaride (Burkina Faso). Les espèces étudiées ont été:Azadirachta indica A. Juss (neem) dans les parcs et neem,Albizia lebbeck (L.) Benth. (albizia) ainsi queLeucaena leucocephala (Lam.) de Wit (leucaena) dans les cultures en couloir. Dans les deux cas la plante cultivée concerné a été le sorgho blanc (Sorghum bicolor (L.) Moench).Sous les neems non taillés des parcs, le rendement du sorgho cultivé de 0 à 3 m de l'arbre (sous le bouppier de l'arbre) a atteint 82% du rendement obtenu en plein champ, soit à une distance de 6 à 9 m de l'arbre (différence non significative,p=0.07). Une taille effectuée en début de campagne a entraîné un accroissement du rendement de 148% pour les cultures situées de 0 à 3 m de l'arbre, par rapport aux rendements en plein champ.Dans les cultures en couloir, on a constaté qu'une taille precoce est préférable, c'est à dire que les rendements de sorgho ont été supérieurs dans les lignes proches des arbres taillés tôt que dans celles proches des arbres taillés tard.

     

Effects of mulching withAzadirachta indica andAlbizia lebbeck leaves on the yield of sorghum under semi-aird conditions in Burkina Faso

From 1988 to 1990, leaves fromAzadirachta indica andAlbizia lebbeck were used as mulch on sorghum (Sorghum bicolor) in semi-arid Burkina Faso. Five different application modes, each representing a different combination of application timing and mulch composition, were evaluated. In one of the modes leaves were combined with sorghum straw. Leaf quantities applied corresponded to dosages of 25, 50 and 75 kg N ha^–1 in all five modes.Dosage had a significant influence on yield all three years. The mulching effect increased progressively over the years and was more pronounced the higher the dosage. Mean grain yields obtained with the highest dosage, relative to an unmulched control, were 203%, 364% and 422%, for the three years, respectively. Application timing had a significant influence on yields in 1988 and 1989, but the response was not consistent. Differences in response were attributed to variation in the rainfall distribution. Mulch composition did not have a significant influence on yield during any of the three years. Of the five modes evaluated, the ones producing the highest yields over the three-year period of study were azadirachta leaves applied (i) at sowing and (ii) 4–6 weeks after sowing. Yields decreased on both the treated and untreated plots between 1988 and 1989. On the treated plots, yield generally increased again in 1990. This increase was attributed to a residual effect of the mulch. The residual effect probably only explained part of the large difference in yield between treated and untreated plots. It is therefore suggested that most of the nutrients released from the mulch were used by the plants during the same season, which increased production. Furthermore, the mulch layer could have reduced evaporation and thus increased the retention of soil water.

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Résumé De 1988 à 1990, des feuilles d'Azadirachta indica et d'Albizia lebbeck ont été utilisées comme mulch sur une culture de sorgho blanc (Sorghum bicolor) au Burkina Faso, en climat semi-aride. Cinq modes d'application ont été évalués, chacun répresentant une compinaison différente en temps d'application et composition de mulch. Dans un des modes, les feuilles ont été combinées avec des tiges de sorgho. Les quantités de feuilles utilisées ont été équivalentes aux dosages de 25, 50 et 75 kg N ha^–1 et ceci dans tous les cinq modes.Le dosage a eu une influence significative sur la récolte pendant toutes les trois années. Leffet a augmenté progressivement d'année en année et a été plus prononcé pour le dosage le plus élevé. Les moyennes de rendement de graines par rapport au témoin sans mulch, obtenues avec la dose de 75 kg N ha^–1, ont été 203% pour la première année, 364% pour la seconde et 422% pour la troisième. Le temps d'application a eu une influence significative en 1988 et 1989, mais les résultats ont varié entre les années. Les différents résultats ont été attribués à la variation en distribution de la pluie. La composition de mulch n'a pas eu d'influence significative sur aucune des trois années. Parmi les cinq modes évalués, les deux qui ont assurés les récoltes les plus élevées sur la période entière de trois ans, étaient les feuilles d'azadirachta appliquées (i) au semis et (ii) 4–6 semaines après le semis. Les rendements ont baissés entre 1988 et 1989, tant sur les parcelles traitées que sur les parcelles non-traitées. Sur les parcelles traitées, les rendements ont de nouveau augmentés en 1990. Cette augmentation a été attribuée a un effet résiduel du mulch. Cet effet résiduel probablement n'explique qu'une partie de la grande différence en rendement entre les parcelles traitées et non-traitées. Il paraît donc que la plupart des élements nutritifs libérés par le mulch ont été utilisés par les plantes au cours de la même saison, et qu'ils ont ainsi augmenté la production. De plus, la couche de mulch a probablement réduit l'évaporation, résultant en une augmentation de la rétention d'eau dans le sol.

     

Nutritional status and genetic variation in the response to nutrient availability in Pinus pinaster. A multisite field study in Northwest Spain

The low nutrient availability of the acidic and sandy soils of Galicia (Northwest Spain) is probably the main environmental factor limiting forest primary productivity in the area. These particular edaphic conditions could have imposed selective pressures on maritime pine populations leading to specific local adaptations.We first assessed the nutritional status of 22 young contemporary Pinus pinaster plantations in Northwest Spain, and then analysed the response to fertilization in three family × fertilization trials, and how this response varied across sites and genotypes.Growth of P. pinaster in Northwest Spain appeared to be largely limited by nutrient availability, where most of the plantations showed severe nutrient deficiencies, especially in P and Mg. According to these deficiencies, a strong positive response to nutrient additions was observed in the three trials, with height increments of up to 30% compared with the unfertilized control. However, the response to fertilizers was very variable from site to site, and in some cases did not agree with the foliar nutritional diagnosis. The response to fertilization was also significantly affected by pine genotype, suggesting that the plastic response to nutrient additions within each environment was under genetic control. However, the family response to nutrient availability was not consistent across sites, and no significant differences among families were observed for the RDPI plasticity index – a single index that summarizes the phenotypic change in multiple environments – when analysed across environments.The strong environmental component modulating phenotypic responses to fertilization could impose an important obstacle to evolve specific adaptations to the local edaphic conditions, as well as to artificially select genotypes adapted to different environments and silviculture regimes.     

Über den natürlichen Gehalt kanzerogener polycyclischer Aromate in Nahrungspflanzen

Zusammenfassung Alle Pflanzen und Pflanzenteile beinhalten mindestens 8 polycyclische aromatische Kohlenwasserstoffe, von denen mindestens 5 kanzerogene Eigenschaften besitzen. Das am stärksten kanzerogene 3,4-Benzpyren findet sich in Mengen von 1–2 Gamma pro 100 g Pflanzentrockengewicht (=0,01–0,02 ppm).Der Gehalt an diesen Substanzen beruht nicht auf exogenen Verunreinigungen der Pflanzen, sondern entsteht — wie in Bilanzverzsuchen an Weizen-, Roggen-und Linsenkeimlingen gezeigt wurde—durch endogene Synthese im Pflanzenstoffwechsel.Düngungsversuche mit 3,4-Benzpyren und anderen polycyclischen Aromaten ergaben, daß sie bei Pflanzen eine Wachstumssteigerung bewirken und somit als Pflanzenwuchsstoffe oder deren Vorstufen angesehen werden können.Bedingt durch die Pflanzensynthese besteht in unserer Umwelt seit jeher ein naturgegebener Normalpegel dieser Substanzen, der für 3,4-Benzpyren im Bereich von 1–2 Gamma/100 g pflanzenorganischer Trockensubstanz liegt.

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Summary All plants and parts of plants contain a minimum of 8 polycyclic aromatic hydrocarbons of which at least 5 have carcinogenic qualities. The hydrocarbon showing the highest carcinogenity, i.e. 3,4-Benzpyren, has been found in quantities of 1 to 2 gamma per 100 g of dry vegetal substance (= 0.01 to 0.02 ppm).The content of these substances is not caused by exogenous contamination of plants but takes its rise from the endogenous synthesis in plant metabolism, as has been shown in balance experiments with seedlings of wheat, rye and lentils.It has been proved in fertilizing experiments with 3,4-Benzpyren and other polycyclic aromatic substances that these cause an increased plant growth and may, therefore, be considered as phytohormones or their primary stages.As a result of plant synthesis, a natural level of these substances exists ever since in our milieu, ranging from 1 to 2 gamma per 100 g of dry vegetal matter for 3,4-Benzpyren.

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Résumé Toutes les plantes et parties de plantes contiennent au moins 8 hydrogènes carburés polycycliques aromatisés, desquels au moins 5 présentent des qualités cancérigènes. L'hydrogène le plus cancérigène — le 3,4-Benzpyrene — se trouve en quantités de 1–2 gamma par 100 gr de matière végétale sèche (=0,01–0,02 ppm.)La teneur en ces substances n'est pas attribuable à des contaminations exogènes des plantes, mais résulte — comme il a été démontré par des essais de balance avec des plantules de blé, de seigle et de lentille — de la synthèse endogène du métabolisme des plantes.Des essais de fumure avec le 3,4-Benzpyrene et autres aromes polycycliques ont démontré qu'ils provoquent une croissance accrue des plantes, de manière qu'ils peuvent être considérés comme des phytohormones ou leurs phases préliminaires.Conditionné par la synthèse des plantes, il existe dans notre milieu depuis toujours un niveau normal de ces substances, qui pour le 3,4-Benzpyrene, se situe à 1–2 gamma/100 gr de matière organique végétale sèche.

     

Seasonal population dynamics of Typhlodromus pyri Scheuten (Acari, Phytoseiidae) in apple orchards in the region Meckenheim

Typhlodromus pyri Scheuten (Acari, Phytoseiidae) has been reported as the most important predator of the European red mite, Panonychus ulmi (Koch) (Acari, Tetranychidae) in apple culture. However, biological data on T. pyri was insufficient on important parameters like seasonal population dynamics and within-tree and on-leaf distribution in apple orchards in the region of Meckenheim, Germany. The purpose of the present work was, therefore, to obtain experimental data on these parameters of T. pyri from 2000 to 2002 in the apple orchards in this region. The results showed that overwintered females of T. pyri reactivate and start laying eggs between late March and early April. The mean daily number of the different stages of T. pyri per leaf peaked in July each year, where it ranged between 0.92–1.68 eggs, 0.81–1.41 nymphs, 0.64–1.32 females and 0.37–0.52 males. A significantly higher number of T. pyri individuals congregated in the bottom layer of trees (0.34–0.64 individuals/leaf) than in the middle and top layers (0.23–0.38 and 0.12–0.23 individuals/leaf, respectively). We found that 91.4–94.1% of the total eggs, 89.6–91.7% larvae, 73.0–76.5% nymphs, 60.5–64.6% adult females and 52.6–55.9% adult males concentrated their activities in the inner area of the leaf surface. More than 50% of the predatory mites congregated in the bottom layer in winter. Mean total density of the overwintering females in December of 2000,2001 and 2002 ranged between 10.6–14.2 females/5 cm twig in the bottom, 7.3–10.4 in the middle and 4.1–6.9 in the top layers of the apple trees. Mean total fecundity recorded over the 3 years was lowest in the overwintering generation with 31.8–37.6 eggs/female, highest in the June generation with 45.9–53.7 eggs/female, and intermediate in the August generation with 41.5–46.1 eggs/female. The overwintering generation was composed entirely of females, while the female to male ratio in the June generation was 2:1, and in the August generation 3:1. T. pyri overwinters as adult females in rough structures, cracks and crevices of twigs.     

Fodder production responses to pruning height and fodder quality of some trees and shrubs in a forest-savanna transition zone in southwestern Nigeria

Seasonal fodder production responses of five shrubs (Centrosema arenarium, Desmodium strigillosum, Desmodium velutinum, Phyllodium pulchellum, and Tadehagi triquetrum)and five trees (Albizia gummifera, Berlinia grandiflora, Albizia niopoides, Bauhinia monandra, and Inga edulis) to pruning heights ranging from 15 to 75 cm were evaluated during the main-wet, minor-wet, and dry seasons of 1993 and 1994 in the forest-savanna transition zone of West Africa. Fodder from the main-wet season was analysed for nitrogen (N) and phosphorus (P), and dry matter degradation characteristics after 6, 12, 24, 48, 72 and 96 h of incubation in rumen-fistulated N'Dama steers. In the minor-wet season, fodder production of all species increased in response to increasing pruning height with the exception of P. pulchellum and A. gummifera. Highest fodder production was attained at a pruning height of 45 cm for the Desmodium species, 50 cm for P. pulchellum, and 75 cm for the rest of the species. Concentrations of N and P varied significantly among the species; for N the ranges were 28.7–38.8 g kg^–1 (shrubs) and 25.3–44.5 g kg^–1 (trees), while for P the ranges were 3.26–7.04 g mg^–1 (shrubs) and 3.58–6.76 g mg^–1 (trees). Dry matter degradation characteristics differed significantly among shrubs and trees; ranges for shrubs were: soluble fraction (a), 128–185; degradable fraction (b), 664–703; potential degradability (PD), 793–857, as g kg^–1; rate of degradation (c), 0.0241–0.0308 as % h^–1 while for trees ranges were: (a), 139–160; (b), 651–826; (PD), 824–970, as g kg^–1; (c), 0.0143–0.0227 as % h^–1. Based on fodder production and quality, C. arenarium, D. strigillosum, D. velutinum, B. monandra, I. edulis, and A. niopoides were the most promising species for the development of animal agroforestry technologies in the west African forest-savanna transition zone and similar environments in the tropics.This revised version was published online in November 2005 with corrections to the Cover Date.     

Forest biomass and root–shoot allocation in northeast China

Temperate and boreal forests act as major sinks for atmospheric CO₂. To assess the magnitude and distribution of the sinks more precisely, an accurate estimation of forest biomass is required. However, the determinants of large-scale biomass pattern (especially root biomass) are still poorly understood for these forests in China. In this study, we used 515 field measurements of biomass across the northeast part of China, to examine factors affecting large-scale biomass pattern and root–shoot biomass allocation. Our results showed that, Picea & Abies forest and coniferous & broadleaf mixed forest had the highest mean biomass (178–202 Mg/ha), while Pinus sylvestris forest the lowest (78 Mg/ha). The root:shoot (R/S) biomass ratio ranged between 0.09 and 0.67 in northeast China, with an average of 0.27. Forest origin (primary/secondary/planted forest) explained 31–37% of variation in biomass (total, shoot and root), while climate explained only 8–15%, reflecting the strong effect of disturbance on forest biomass. Compared with shoot biomass, root biomass was less limited by precipitation as a result of biomass allocation change. R/S ratio was negatively related to water availability, shoot biomass, stand age, height and volume, suggesting significant effects of climate and ontogeny on biomass allocation. Root–shoot biomass relationships also differed significantly between natural and planted forests, and between broadleaf and coniferous forests. Shoot biomass, climate and forest origin were the most important predictors for root biomass, and together explained 83% of the variation. This model provided a better way for estimating root biomass than the R/S ratio method, which predicted root biomass with a R² of 0.71.     

Beeinflussen Insektizide die Photosynthese und Transpiration von Pappelblättern?

Summary By means of gas analyzers the gas exchange of leaves of black poplar was measured before and during 4 days after treatments with Gamalo (containing Lindane) and Perfekthion (Dimethoate). Photosynthesis and transpiration of Gamalo sprayed leaves fell to 40% and 60%, respectively, of the original value within an hour. Respiration was not affected measurably. Twenty hours later gas exchange was practically normal again. The observed effect is ascribed mainly to the volatile phase of Lindane which most likely caused a partial stomatal closure.The systemically acting Perfekthion caused but a slight, statistically not significant reduction of photosynthesis 2–4 days after treatment.With both treatments young leaves behaved like mature ones.

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Résumé On a mesuré les échanges gazeux chez des feuilles du Peuplier noir qui avaient été aspergées avec du Gamalo (contenant du Lindane) et du Perfekthion. Une heure après ie traitement avec du Gamalo, la photosynthèse et la transpiration des feuilles étaient réduites de moitié, alors que la respiration restait inchangée. Au bout de 20 heures, les échanges gazeux s'étaient à nouveau normalisés. L'effet observé est dû à la phase volatile du Lindane, qui vrais emblablement produisit la fermeture des stomates.L'insecticide systémique Perfekthion causa, 2 à 4 jours après l'application, une diminution de l'absorption en CO₂, changement dont la signification n'est cependant pas confirmée statistiquement.Les jeunes feuilles réagirent de la même manière que les feuilles adultes dans les deux cas.

     

Lästlinge und Schädlinge an Textilien

Zusammenfassung Während der entomologischen Arbeiten im Laboratorium für Textilzoologie wurden 51 unterschiedliche Tierarten an den 1961–1963 zur Untersuchung eingesandten Textilien gefunden. Von wirtschaftlich wichtiger Bedeutung sind jedoch nur die Wollschädlinge. Den 55 Textilschäden durch Tineiden-Larven stehen 110 beschädigte Textilien gegenüber, die von Dermestiden-Larven entwertet wurden. Wolltextilien werden heute in der Bundesrepublik Deutschland stärker von Käfer-als durch Mottenlarven bedroht.

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Summary In the course of applied entomological research at the Laboratory of Textile Zoology 51 different types of animals were determined during the years 1961–1963 on damaged textiles sent in. Of economic important are only the insects who eat wool. Today the actual main wool pests in the German Federal Republic are not the moths of the familyTineidae but the beetles of the familyDermestidae: the carpet beetles.

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Résumé Pendant le travail entomologique entre 1961 et 1963 dans le Laboratoire de Zoologie Textile 51 différentes sortes d'annimaux ont été trouvés dans des tissus endommagés. Seuls les insectes kératinophages: les Mites (microlépidoptères), les Anthrènes et les Attagènes (coléoptères) sont d'une importance économique. Mais pendant les années derniéres les larves des coléoptères anthrènes et attagènes ont causé plus de dommage dans l'Allemagne Fédéral que les mites.

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Herrn Dr. Adolf Herfs zum 70. Geburtstag gewidmet. ® — eingetr. Warenzeichen.     

Effects of press closing time on mat consolidation behavior during hot pressing and on linear expansion of particleboard

Mat consolidation behavior was investigated at various press closing times (PCTs) using hinoki (Japanese cypress) particle mats. The temperature in the core layer of the mat, press pressure, and platen distance were measured. At the plateau stage during hot pressing, the core temperature decreased with increasing PCT. The core temperature did not increase before the platen distance equaled the target board thickness in the PCT range of 4–50 s and rose slightly when the PCT exceeded 100s. There was a linear relation between the logarithm of PCT and the maximum press pressure. The density profile across board thickness was strongly affected by the PCT. As the PCT increased, the position of the peak density (PD) moved toward the core layer as the PD itself decreased. The effect of PCT on the linear expansion (LE) of the board is discussed in relation to the density profile. There was no difference in LE after high relative humidity treatment in the PCT range 4–50s. LE appeared to be related to the low density and the precured region of the board surface. The LE after drying treatment was around –0.1%, and the thickness swelling after high relative humidity and drying treatments increased with increasing PCT.Part of this report was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 1988     

Variation in relative palatability to sheep amongGliricidia sepium provenances

The cafeteria technique using three-year-old West African Dwarf sheep was used to determine relative palatability differences within 28 provenances ofGliricidia sepium collected from West Africa and Central America.Leucaena leucocephala andGuazuma ulmifolia were included as controls. Significant differences (P<0.05) in relative palatability index (RPI) were detected amongG. sepium provenances. Mexican ecotypes appeared to be of low relative palatability compared to those from Costa Rica. Based on their RPI, provenances were grouped into high (RPI>90%), medium (RPI 60–90%) and low (RPI<60%) preference rankings. The importance of the differences in relative palatability is discussed in relation to Gliricidia-based alley farming in the humid West African region.     

Estimation of drought-related limitations to mid-rotation aged plantation grown Eucalyptus globulus by phloem sap analysis

Previous research has shown that carbon isotope signatures (Δ¹³C) may correlate well with water status in 1–2 years old, plantation grown Eucalyptus globulus. Here we investigate this relationship for mid-rotation aged (5 years) trees and whether a simple field determination of phloem sugar concentrations is a reliable surrogate for Δ¹³C. We sampled six plantations covering much of the climatic range of E. globulus plantations in Australia (average annual rainfall 618–1094 mm). We found significant correlations between phloem Δ¹³C and phloem sugar concentrations across and within plantations. Both parameters were also correlated with a climate wetness index. We thus conclude that phloem sugar concentration is a useful surrogate for Δ¹³C and hence water status of mid-rotation E. globulus. We also observed strong correlations of phloem Δ¹³C and phloem sugar concentrations with growth across all plantations, providing some confirmation that water limits growth of E. globulus at a larger scale. This relationship was much weaker or absent within plantations, suggesting that factors other than water supply contribute significantly to growth limitations at smaller (within-plantation) scales.     

The effects of a heat treatment on the behaviour of extractives in softwood studied by FTIR spectroscopic methods

Scots pine battens were heat-treated at 100–240º C under saturated steam. Cross-sections of heat-treated battens were analysed using ATR and reflection FTIR microscopies. A typical absorption band of fats and waxes at 1740 cm^-1 was detected on the sapwood edges in the temperature range of 100–160º C, indicating that fats and waxes moved along the axial parenchyma cells to the surface of the sapwood during the heat treatment. At the elevated temperatures (above 180° C) fats and waxes disappeared from the sapwood surface and were no longer detected with FTIR spectroscopy. Resin acids were detected at temperatures between 100 and 180º C in the middle of the battens. IR spectra of these spots showed a characteristic absorption band of resin acids at 1697 cm^-1. At 200º C resin acids were not detected in the middle of the battens; however, resin acids were detected at distances of 500 and 600 mm from the midpoint of the battens and on the edges of battens. At temperatures above 200° C, resin acids had disappeared from the wood.