Guava (Psidium guajava L.) trees in a pasture: population model,sensitivity analyses,and applications

A preliminary demographic model is presented for a population of guava (Psidium guajava L.) trees in a pasture. In this paper special attention is devoted to describing both the calculation and testing of the parameters of the model. Some applications of the model are described. It is predicted that the guava population will gradually decline; low seedling survival (due to chemical control of pasture weeds) seems to be the factor governing this trend. Preliminary analyses of total gross energy production and economic income, with and without the guavas, favours the presence of the trees in pastures.     

Contractile effect of the aqueous extract of Psidium guajava leaves on aortic rings in rat

Aqueous leaves extract of Psidium guajava significantly and dose-dependently (0.25-2 mg/ml) contracted aorta rings. The effect was evaluated also in presence of nifedipine and phentolamine. The sensitivity of the aortic rings to cumulative doses of P. guajava was significantly enhanced in the presence of phentolamine suggesting that the effect of P. guajava was to a large extent mediated by activation of alpha-adrenoceptor and to a lesser extent by acting via calcium ion channel.     

Pasture growth and floristic composition under the shade of guava (Psidium guajava L.) trees in Costa Rica

Guava (Psidium guajava L.) trees in naturalized, unimproved pastures produce valuable firewood, fruit, shade, and other benefits. The effects of guavas on pasture growth and floristic composition were evaluated. Shaded and non-shaded pastures are floristically very similar. Total growth under shade is 49–63% of that in the open.Axonopus compressus andPaspalum conjugatum were the most prominent grasses in both sun and shade.     

Pasture growth and floristic composition under the shade of guava (Psidium guajava L.) trees in Costa Rica

Guava (Psidium guajava L.) trees in naturalized, unimproved pastures produce valuable firewood, fruit, shade, and other benefits. The effects of guavas on pasture growth and floristic composition were evaluated. Shaded and non-shaded pastures are floristically very similar. Total growth under shade is 49–63% of that in the open.Axonopus compressus andPaspalum conjugatum were the most prominent grasses in both sun and shade.     

孟加拉国Dinajpur农林复合区内不同树种和作物种中丛枝菌根分布和孢子群落多样性的研究

从孟加拉国Dinajpur地区采集了不同农林复合区内树种和作物种,对采集植物的丛枝菌根多样性进行了研究.在3个取样地采集了18种植物的根和根际土,取样地和被采取植物分别为：取样地Dashmail为黄豆树 （Albizia procera Benth.）、小指椒 （Capsicum frutescens L）、姜黄（Curcuma domestica Vahl）、印度黄檀 （Dalbergia sissoo Roxb.） 和大叶桃花心木（Swietenia macrophylla）5种植物; 取样地Kantaji为姜黄（C.Domestica）、印度檀 （D.Sissoo）、赤桉 （Eucalyptus camaldulensis Dehnn.）、石梓（Gmelina arborea （Roxb） DC） 和水稻 （Oryza sativa L.） 5种植物; 取样地Ramsagar为姜黄（C.Domestica）, 印度檀 （D.Sissoo）, Litchi chinensis Sonn.和水稻.在取样地Dashmail,植物丛枝的分布范围在36%-79%,其中分布最高的是小指椒,达到79%,而C.Domestica仅占36%.取样地 Kantaji丛枝的分布范围在33%-70%之间,其中分布最高的是石梓,达到79%,而O.Sativa分布最低,仅36%.取样地 Ramsagar丛枝的分布范围在35%-70%之间,印度檀丛枝分布在该地最高, 达70%,而水稻丛枝在该地的分布最小,仅35%.在采样地Dashmail,每100克干土中所含采样植物丛枝菌根孢子群落54-140个;孢子群落最多的是印度檀（140/100g dry soil）,最低的是姜黄（C.Domestica） （40/100g dry soil）.在采样地Kantaji,孢子群落在63-221/100g dry soil,石梓具有的群落最高,为221/100g dry soil;印度檀为63/100g dry soil.在采样地Ramsagar, 所具有的最高和最低群落分别是 160/100g dry soil （D.Sissoo）和69/100g dry soil（L.Chinensis）.土壤Ph值与土壤中丛枝分布和菌根孢子群落无显著相关性.Simpson多样性指数和Shannon多样性指数在取样地Kantaji 的印度檀土壤中最高;而在取样地Ramsagar的水稻土壤中最低.研究表明孟加拉国Dinajpur地区丛枝菌根的存在、树种和作物种中的营养性质、丛枝菌根的必要性和贡献以及复合农林植物生长与丛枝?     

The infestation of Vicia faba L. (Fabaceae) by Aphis fabae (Scop.) (Homoptera: Aphididae) under the influence of Lamiaceae (Ocimum basilicum L. and Satureja hortensis L.)

Abtract The system Vicia faba–Aphis fabae fabae was studied under the influence of Ocimum basilicum (basil) and Satureja hortensis, in a wind tunnel, in the greenhouse and in field experiments. In the wind tunnel at 20°C both Lamiaceae were deterrent for A. fabae, and S. hortensis proved to be more deterrent than O. basilicum. In experiments in the greenhouse at low temperatures (average minimum 14.6°C, average maximum 24.1°C), A. fabae colonised first and significantly more intense Vicia fabae (field beans) not surrounded by O. basilicum or S. hortensis. At high temperatures (average minimum 18.0°C, average maximum 38.5°C) this relation was inverted: Vicia faba surrounded by the two Lamiaceae were preferred for colonisation (Ocimum basilicum significantly). It showed that pots with Lamiaceae were no obstacle for the aphids to reach Vicia faba. In strip cropping in the field, the repellent effect of Ocimum basilicum proved to be stronger than of Satureja hortensis. In 2002 there was observed only a tendency of lower aphid attack of field beans intercropped with Lamiaceae, while in 2004 and 2005 the infestation of Vicia faba by Aphis fabae was significantly lower in plots intercropped with basil. In plots with Satureja hortensis as intercrop, Vicia faba were significantly lower infested, after 3 weeks. The differences between the results of the wind tunnel/greenhouse at low temperatures, and the field experiments concerning the deterrence by Satureja hortensis cannot be explained. But basing on our results with Ocimum basilicum and those published by other authors, it is recommended to follow up intercropping, after a sincere analysis in every case, in favour of agronomists.     

Virtual trees and light capture: a method for optimizing agroforestry stand design

In agroforestry systems, the distribution of light transmitted under tree canopies can be a limiting factor for the development of intercrops. The light available for intercrops depends on the quantity of light intercepted by tree canopies and, consequently, on the architecture of the tree species present. The influence of tree architecture on light transmission was analysed using dynamic 3D architectural models. The architectural analysis of Acacia mangium and Tectona grandis was performed in Indonesian agroforestry systems with trees aged from 1 to 3 years. 3D virtual trees were then generated with the AmapSim simulation software and 3D virtual experiments in which tree age, planting density, planting pattern and pruning intensity varied were reconstructed in order to simulate light available for the crop. Canopy closure of trees was more rapid in A. mangium than in T. grandis agroforestry systems; after 3 years the quantity of light available for A. mangium intercrops was three times lower than under T. grandis. Simulations with A. mangium showed that practices such as pruning and widening tree spacing enable to increase the total transmitted light within the stand. On T. grandis, modification of the tree row azimuth resulted in changes in the spatial and seasonal distribution of light available for the intercrops. These results are discussed in terms of agroforestry system management.

Butt rot ofChamaecyparis obtusa (Sieb. et Zucc.) Endlicher trees caused byPerenniporia subacida in Shikoku district, Japan: Pathogen, distribution of damaged trees in the stand, and soil investigation

The rot ofChamaecyparis obtusa (hinoki) trees was studied in the northern part of Kagawa Prefecture, Japan. Among 158 hinoki examined, butt rot was found in 28.6, 58.3, and 100% of trees in the 29, 30, and 34-year-old stands, respectively. All trees with butt rot, and 11 trees without it had rotted roots. Thirteen hinoki were peeled byCervus nippon (sika deer) and all of them were infected with butt rot. The maximum height of rot in deer-damaged trees was 2.6 m from the ground level, but was 1.9 m in undamaged trees. About eighty-two percent of rotted trees showed rotted areas of less than 40 cm² on the cross section of stems at the ground level. White mycelia and black flecks sometimes appeared in the rotted wood. Basidiocarps of polyporaceous fungus were often found on felled logs and rotted stumps of hinoki and identified asPerenniporia subacida. Basidiomycetous fungus was isolated frequently from rotted wood of roots and stems, and determined to beP. subacida by comparative study on cultural characteristics. An inoculation experiment and wood-decay test proved that the fungus was the cause of the rot of hinoki. Few absorbing roots of living trees were found in the clayey subsurface soil of the high dry bulk density and the less soil aeration. Some absorbing roots had root rot and the rot spread from the base of the absorbing root to the central part of the woody root. This is the first report on the rot of hinoki caused byP. subacida in Japan.     

Regeneration ecology and population status of a critically endangered and endemic tree species （Ilex khasiana Purk.） in north-eastern India

Detailed studies on population structure and regeneration ecology of Ilex khasiana were carried out at five representative natural populations i.e. Mylliem (Population - I), Upper Shillong (Population - II), Shillong Peak (Population - III), Laitkor (Population - IV) and Nongpiyur (Population - V) to probe into the responsible affecting factors for its population structure and regeneration ability in these populations. Experimental observation under three controlled light conditions (full sunlight (100%), intermediate sunlight (50%) and low sunlight (30%)) showed that the growth status and survival rates of seedlings under intermediate and low light were better than those under the high light condition. The density-diameter distribution in population of adult trees (≥5cm dbh) exhibited a typical character of a regenerating population. A higher seedling mortality rate in natural populations of I. khasiana was most probably due to increase in light intensity following vegetation destruction and other anthropogenic disturbances that cause opening of forest canopy. The findings of the present study would be of immense value in formulating appropriate conservation measures for the species.     

A population genetic study in a scattered forest species, wild service tree [Sorbus torminalis (L.) Crantz], using RAPD markers

Wild service tree [Sorbus torminalis (L.) Crantz] is a forest tree widespread in Europe, characterized by a scattered distribution. Its hermaphroditic flowers are pollinated by insects, and outcrossing is the prominent mating system, also due to the presence of gametophytic self-incompatibility. Genetic diversity and differentiation of 22 populations from northwestern Italy were investigated by means of variation scored at 53 polymorphic RAPD (Random Amplified Polymorphic DNA) loci. Populations differed in genetic variation, with Shannon diversity index ranging from 0.166 to 0.469. According to Analysis of Molecular Variance (AMOVA), most of the genetic variation was found within populations (61.78%) with a significant proportion of variance attributable to genetic differences between regions (23.60%) and between populations (14.62%). Evidence for isolation by distance was found in the set of populations sampled. The effect of habitat fragmentation on genetic variation was also evaluated. The efficacy of RAPD markers in analysing genetic variation, and the contribution of the results in terms of the preservation of biodiversity are discussed.     

Root competition for phosphorus between coconut, multipurpose trees and Kacholam (Kaempferia galanga L.) in Kerala, India

The magnitude of root competition 17 year-old coconut palms suffer from three year-old inter-planted multipurpose trees, Vateria indica L., Ailanthus triphysa (Dennst.) Alston. or Grevillea robusta A. Cunn. and kacholam (Kaempferia galanga L.), a herbaceous medicinal plant, was evaluated based on the extent of absorption of applied ³²P by the palms in sole and mixed crop situations. The multipurpose tree (MPT) species were grown under two planting geometries (single row and double row). The hypothesis that, when grown together, widespread root proliferation of coconut and multipurpose trees occurs in the well-fertilised kacholam beds was tested by root excavation. Interplanted MPTs substantially altered absorption of ³²P by coconut. Both Ailanthus and Vateria exerted a modest depressing effect, while Grevillea enhanced ³²P uptake by coconut. Single rows of MPTs also favoured ³²P recovery by coconut, presumably because of the increased root densities in the subsoil. Ailanthus, Vateria and Grevillea absorbed substantial ³²P. Overall, high ³²P absorption in the coconut-Grevillea plots indicates complementary root-level interactions between these species. ³²P absorption by MPTs was generally higher closer to the trees owing to the greater root concentration of the MPTs, which in turn suggests possible root interference between MPTs and coconut. Hence selection of tree species with low root competitiveness and/or trees with complementary root interaction is of strategic importance in agroforestry. Kacholam showed substantial ³²P content in its foliage. This ³²P appears to have been translocated by coconut into the kacholam beds where new coconut roots were abundant. This revised version was published online in June 2006 with corrections to the Cover Date.     

Litter production and nutrient cycling in coffee (Coffea arabica) or cacao (Theobroma cacao) plantations with shade trees

The relative importance of N fixation, organic material inputs and nutrient inputs in litterfall, as justifications for including shade trees in plantations of coffee or cacao, is discussed. According to existing data, N fixation by leguminous shade trees does not exceed 60 kg.N/ha/a. However, these trees contribute 5,000–10,000 kg. organic material/ha/a.Comparisons are made between the leguminous shade tree Erythrina poeppigiana and the non-leguminous timber tree Cordia alliodora. The former, when pruned 2 or 3 times/a., can return to the litter layer the same amount of nutrients that are applied to coffee plantations via inorganic fertilizers, even at the highest recommended rates for Costa Rica of 270 kg.N, 60 kg.P, 150 kg.K/ha/a. The annual nutrient return in this litterfall represents 90–100 percent of the nutrient store in above-ground biomass of E. poeppigiana, and hence the consequences of competition with the crop should not be a serious limitation. In the case of C. alliodora, which is not pruned, nutrient storage in the tree stems, especially of K, is a potential limiting factor to both crop and tree productivity.It is concluded that, in fertilized plantations of cacao and coffee, litter productivity is a more important shade tree characteristic than N fixation.An early version of this review was presented at the CATIE-IUFRO meeting Los Arboles de Uso Multiple en Sistemas Agroforestales, June 1985, Turrialba, Costa Rica.     

Scots pine (Pinus sylvestris L.) plantations contribute to the regeneration of holly (Ilex aquifolium L.) in mediterranean central Spain

The aim of this study is to evaluate the recruitment possibilities of holly (Ilex aquifolium L.) populations under Pinus sylvestris plantations in the mountains of Central Spain. Population recruitment of holly under P. sylvestris L. plantations was studied at two localities. We sampled holly seed rain, seed bank, and seedling emergence and survival (of both emerged and planted seedlings) in both localities. Seed germination was analysed by randomly sowing Ilex seeds and their subsequent recollection and analysis over the following 3 years (only in one locality). Seed rain, seed bank and emerged seedling densities did not differ between localities. Seed bank density was between 10 and 20 seeds m⁻², considerably higher than the observed seed rain (0.4–1.2 seeds m⁻²), and also higher than the emerged seedling density (0–4 seedlings m⁻²). But Ilex is not very efficient in germinating under pine forests (29.1% germination after 3 years). This may indicate a seed accumulation process of at least 5 years. Seedling survival for the first year differed among the studied sites (50–60 vs. 17%). Nevertheless these survival rates are higher than those found for the same seedling populations in different forest habitats (not Scots pine forests) from near locations. Differences in summer water stress between the study sites are proposed as the main cause of the observed differences in seedling survival. It is concluded that P. sylvestris forests may provide one of the best regeneration habitats for holly in the Mediterranean area, where this species is close to the Southern limit of its distribution.     

Effects of Gliricidia sepium (Jacq.) Steud and Leucaena leucocephala (Lam.) de Wit on growth and development of Imperata cylindrica (L.) Raeuschel.

Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30 cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing speargrass.     

Seed dormancy in bay laurel (Laurus nobilis L.)

The germination of bay laurel (Laurus nobilis L.) seeds wasexamined both in the laboratory and in the field during twoyears. Seeds were collected from a grove in a garden in the townof Drama, Northern Greece, by mid November in the first year andby late November in the second year. The seeds with and withoutpericarp were given a warm-moist (20 °C day/12 °C night) oncold-moist (4±1 °C) treatment in peat or sand. After treatment theseeds were placed in the germinator along with controls. Thegermination of seeds with and without pericarp was alsoinvestigated in the field (late fall sowing). It was found thatthe pericarp caused dormancy. In seeds without pericarp,cold-moist and warm-moist stratification both proved to besuccessful in breaking embryo dormancy (100% and 96% successrespectively). The required stratification duration was 50 daysfor the warm-moist and 60 days for the cold-moist treatments.During the cold-moist stratification no germination was observed.On the other hand, seeds started to germinate during thewarm-moist stratification by about the 50th day. In the fallsowing germination was 20% for seeds with pericarp and 41% for seeds without pericarp. Drying bay laurel seeds caused areduction of the seed germination.     

Arthropod diversity in alley cropped black walnut (Juglans nigra L.) stands in eastern Missouri, USA

Knowledge of the complex interactions among trees, crops and their associated fauna is necessary to determine the viability of a particular agroforestry practice. Information is lacking concerning these interactions, particularly in temperate agroforestry practices. We examined the effects of two forages on the growth, nut production, and arthropod communities of alley cropped eastern black walnut, Juglans nigra L. Experimental plots of eastern black walnut, intercropped with alfalfa, Medicago sativa L., smooth bromegrass, Bromis inermis Leyss., or no vegetation were sampled with sweep nets prior to each cutting date for the forages. Comparisons were made between treatments and sampling dates. Tree growth measurements, nut yield and other nut quality measurements were taken at the end of each growing season. There were no differences in tree growth among alleyway treatments. The first season's nut yield was greater from trees with vegetation-free alleyways; otherwise nut production did not differ among the treatments. Arthropods were more numerous and diverse in alley cropped alfalfa than in alley cropped bromegrass or in the vegetation-free controls. Alley cropped bromegrass supported a more diverse population of arthropods than did the vegetation-free control. Arthropod diversity in the tree canopies did not differ among treatments. Alley cropped forages supported a more diverse and even arthropod fauna than did adjacent monocropped forages. We conclude that alley cropped forages had a relatively minor impact on the growth and nut yield of walnut trees.This revised version was published online in November 2005 with corrections to the Cover Date.     

Long-term growth analyses of Japanese cedar trees in a plantation: neighborhood competition and persistence of initial growth deviations

The individual growth of tree diameter at breast height (dbh) is analyzed in an even-aged plantation of Cryptomeria japonica from stand age of 45 to 94 years, to examine how the growth of individual trees has been affected by the changes in spacing resulting from thinning operations. At any age, a significant proportion (0.37–0.46) of the variation in dbh growth during a 5–11-year period was explained by dbh at the beginning of the period, probably due to greater leaf mass of larger trees. Next, either one-sided or two-sided competition was added to the model, by calculating the basal area (BA) of neighboring trees around each tree within a given radius or BA for trees having larger dbh than the focal tree within the radius. After preliminary analyses, a radius of 8 m was selected as the critical range for tree competition. Although both types of competition explained a significant proportion (0.09–0.43) of growth variation, one-sided competition was not significant at ages greater than 54 years. Based on the model at 45 years of age, the initial deviation of growth rate for each tree from the predicted rate was calculated and added to the models as a third variable. This raised the coefficient of determination up to 0.50–0.74. These findings have practical significance for forest plantation management, particularly for controlling the growth of standing trees via thinning, to produce high-quality timber in the future.     

Durian trees (Durio zibethinus Murr.) in Javanese home gardens: their importance in informal financial systems

Home gardens used to be an important source of income and wealth for many Javanese rural households. In the wake of economic development and income diversification processes, their role is increasingly linked to credit needs. People borrow money by pawning (gadai) trees from home gardens. The tree harvest is at the disposal of the lender during the loan period. Analysis of more than 80 oral gadai contracts on durian trees in West Java demonstrates that the real interest rate is not usurious and can be compared to other formal and informal credit interest rates. It also shows that distributions of loan rates and loan amounts do not differ according to their final use (consumption or investment) or to the family relationship between the two partners of the transaction.     

Report of a 60 month study on litter production,changes in soil chemical properties and productivity under Poplar (P. deltoides) and Eucalyptus (E. hybrid) interplanted with aromatic grasses

Quantity of litter fall, its chemical composition, nutrient addition and changes in chemical constituents of soil were studied under agroforestry systems involving Populus deltoides and Eucalyptus hybrid tree with intercrops of Cymbopogon martinii Wats and Cymbopogon flexuosus Wats in the tarai tract of Kumaon hills of U.P. India. P. deltoides had significantly more diameter (63%) as compared to E. hybrid. There was decrease in herb (5.4%) and oil yield (15.4%) of grasses due to trees, but both the grasses did not affect the performance of trees. On an average, dry litter production of P. deltoides was 5.0 kg tree⁻¹ year⁻¹ where as of E. hybrid 1.5 kg tree⁻¹ year⁻¹. The litter of P. deltoides contained 1.3 times more N and 1.5 times P and K of E. hybrid. Addition of N, P and K through P. deltoides litter was 36.6, 91.6, and 69.9 per cent more than E. hybrid litter, respectively. Under these two canopies soil organic carbon was enhanced by 33.3 to 83.3 per cent, available N by 38.1 to 68.9 per cent, available P by 3.4 to 32.8 per cent and available K by 5.8 to 24.3 per cent over control (no tree canopy) in 0—15cm layer. P. deltoides plantation was superior to E. hybrib in enriching the soil.     

Cajanus cajan (L.) Millsp. as a potential agroforestry component in the Eastern Province of Zambia

Farmers in the Eastern Province of Zambia are faced with problems common to other parts of the tropics: increased pressure to expand food production leading to accelerated forest clearing, decrease in traditional fallow periods, increased soil erosion, and reductions in soil fertility. Of special concern are shortages of labor during their growing season, a shortage of staple foods during January through March, pest (termite) problems, and seasonal fires. Alleycropping appears able to solve some of the farmers' problems. Both on-farm and experiment station trials were initiated to screen potential agroforestry species. Perennial pigeonpea, Cajanus cajan (L.) Millsp., a species indigenous to the Province, showed particular promise. Cultivars grew over 3 m tall and produced up to 4.8 tons/ha dry matter (in 7 months after pruning) for green manure. Farmers reacted favorably to their experience with the on-farm trials. Ease of establishment and production of food (green pod and grain) make perennial pigeonpea a special agroforestry option in the Province, deserving additional research.