Survival,growth and productivity of tree species under evaluation for agroforestry to control salinity in the Western Australian wheatbelt

Survival and growth were investigated for 10Eucalyptus species and 2 fodder tree species planted for salinity control in the wheatbelt of Western Australia. After two years of growth the trees were harvested to determine fodder biomass production and yields of cineole from the eucalyptus leaf oil. Subsequent harvests were conducted at three and five years after planting.At each harvest, biomass production from fodder species was greater than from most species of eucalypts. Biomass yields from eucalypts were variable, and there were no consistent trends in the productivity of the different species for the three harvests.Leaf cineole concentrations and cineole yields were low after two years of growth, but after three and five years cineole yields were generally higher from all species.E. kochii subspp.plenissima andkochii, E. horistes, E. radiata andE. angustissima produced consistently high cineole yields after three and five years. These species appear to have potential for the production of high grade eucalyptus oil in the wheatbelt of Western Australia.     

Initial growth of pioneer timber tree species in a Taungya system in the humid lowlands of Costa Rica

The temporary association of annual crops in juvenile tree plantations (Taungya system) can reduce or offset the initial costs of reforestation and hence provide incentives for tree planting on private farms. A replicated systematic spacing design, derived from a Nelder-fan design, was used to study the effects of tree-crop distance on growth and development of the timber species salmwood (Cordia alliodora) or eucalyptus (Eucalyptus deglupta), associated with maize (Zea mays) or cassava (Manihot esculenta), during the first year after transplanting the trees on two sites on alluvial soils in the humid lowlands of Costa Rica. Association with maize did not affect mean tree growth. However, mean eucalyptus and salmwood heights of 7–8 m and 3–4 m, respectively, after one year in pure plantation or associated with maize, were only 4.7 m and 1.4 m, respectively, when associated with cassava. Wider tree – crop spacings were more important for initial salmwood growth than for eucalyptus. It was concluded that the shoot growth characteristics (continuous or episodical growth) of the timber species is a very important consideration when selecting associated agricultural crop species and tree-crop distances.     

Effects of Morus alba leaf extract on the production of nitric oxide, prostaglandin E2 and cytokines in RAW264.7 macrophages

Morus alba leaf methanolic extract and its fractions (chloroform, butanol, and aqueous fractions) were found to inhibit NO production in LPS-activated RAW264.7 macrophages without an appreciable cytotoxic effect at concentration from 4 to 100 microg/ml. LPS-induced PGE2 production was significantly reduced only by butanol fraction. In addition, M. alba leaf extract and its fractions significantly decreased the production of TNF-alpha. These findings suggest that M. alba leaf extract seems to be able in suppressing inflammatory mediators. Moreover, the inhibitory activities on COX-2 and iNOS of its butanol fraction are warranted for further elucidation of active principles for development of new antiinflammatory agents.     

Schima superba as a fuelbreak: Litter combustibility of three tree species with five water content levels using a cone calorimeter

To determine the suitability of Schima superba Gardn. et Champ as a fuelbreak, we compared and analyzed the flammability characteristics of tree litter from three trees commonly grown in south China, i.e., Pinus massoniana Lamb., Cunninghamia lanceolata (Lamb.) Hook., and S. superba, using a cone calorimeter at five different water content levels. Water content levels of 10%, 15%, 20%, 25% and 30% for the litter were manually produced with a new technique of adding water to dry litter. The cone calorimeter utilized a radiant heat intensity for leaf litter of 20 kW/m² (510°C) and for twig litter of 30 kW/m² (608°C). Results show that fixing the water content level by adding water with a pipette was an acceptable technique. For S. superba, compared to P. massoniana and C. lanceolata, 1) the heat release rate (HRR) was slower and lower; 2) the total heat released (THR) from the material was lower and started later in the burning process; and 3) except for the 10% water content, pkHRR/TTI was less. These results show that overall, S. superba was the best of the three species to be used as a fuelbreak in south China. __________ Translated from Scientia Silvae Sinicae, 2008, 44(5): 96–101 [译自: 林 业科学]     

Dry matter production and nutrient cycling in agroforestry systems of mandarin grown in association with Albizia and mixed tree species

A study on dry matter production and nutrient cycling in agroforestry systems of mandarin grown in association with N₂-fixing Albizia and mixed tree species (non-N₂-fixing) was carried out in the Sikkim Himalaya. A site with Albizia was referred asAlbizia-mandarin stand and the other site with mixed tree species as mandarin stand. The stand total biomass, net primary productivity and mandarin fruit production was higher under the influence of Albizia. Agronomic yield of crops remained nearly the same in both the stands. Nitrogen and phosphorus concentrations of different components of Albizia were higher than those of mixed tree species, whereas their back translocation from leaf to branch before abscission was lower inAlbizia. The mandarin-based agroforestry is a highly nutrient-exhaustive system evaluated in terms of nutrient exit through the removal of agronomic yield. This system, under the influence of Albizia, was more productive with faster rates of nutrient cycling. Nutrient use efficiency increased under the influence of Albizia, in contrary to the hypothesis that efficiency should decrease with increasing rate of uptake. The poor nutrient conservation of Albizia, and malleability of nutrient cycling under its influence make it an excellent association which promotes higher availability and faster cycling of nutrients.Albizia should be utilised more extensively in the management of mandarin-based agroforestry systems.     

Seed viability of selected tree,shrub, and vine species stored in the field

Seeds from 10 species were collected, sealed in fiberglass screen pouches, and stored under hardware-cloth cages on both a forest and cleared site for up to five years. At each site, half of the pouches were placed under leaf litter and the other half were planted in mineral soil. Liquidambar styraciflua and Callicarpa americana seeds had high germination rates under all conditions. Quercus falcata, Sassafras albidum, Rhus copallina, and Vaccinium arboreum required planting in mineral soil to ensure germination. Planted Myrica cerifera and Vitis aestivalis seeds germinated well on both sites. Myrica cerifera also germinated well if placed under litter on the forest floor and Vitis aestivalis if placed under litter on the cleared site. Germination of Crataegus uniflora seeds was erratic. Most Lonicera japonica were unsound when collected. Germination rates generally decreased over time, but some Sassafras albidum, Myrica cerifera, and Vaccinium arboreum seed germinated after four years, and Rhus coppalina, Callicarpa americana, Crataegus uniflora, and Vitis aestivalis seeds germinated after five years in the field.     

Coffee yields and soil nutrients under the shades of Inga sp. vs. multiple species in Chiapas, Mexico

For many decades, simplification of traditionally shaded coffee-production systems has been an idealised model for increasing yields. In Mexico, coffee producers have been interested in replacing diverse natural shade with Inga species monocultures due to this practice having the supposed advantages of producing higher coffee yields than diverse shade. However, the effect of different shade systems on yields is little known. The purpose of this study was to evaluate the effect of two types of shaded-coffee systems on coffee yields and soil nutrient content; the first shade system is mainly dominated by Inga latibracteata Harms and the other composed of species-rich natural vegetation. The investigation took place in producer plots in the Francisco I. Madero Community, Municipality of Jitotol, Chiapas, Mexico. Collected data included species richness, shade-tree density, number of strata, tree diameter, tree height, shade-cover percentage, direct and diffused light, coffee yields, soil-nutrient concentrations (N, P, K, Ca and Mg), soil-organic matter and pH. Evaluated shade type did not have an effect on grain yield or soil nutrients. The perceived advantage of the Inga shade system is reduced weed emergence, saving farmers one annual weed-clearing. There was no significant correlation between total N and organic matter. The presence of fewer products and services in comparison to the multiple shade system was thought to be an additional disadvantage to the Inga dominated system. Organic matter in the multiple shade system correlated positively with total N. Due to its complex structure and diversity, the multiple shade system could be certified as shade or bird-friendly coffee. This revised version was published online in June 2006 with corrections to the Cover Date.     

Litterfall,litter decomposition and the use of mulch of four indigenous tree species in the Atlantic lowlands of Costa Rica

Litterfall, forest-floor litter biomass and nutrients, short-term litter decomposition and the effects of leaf mulches on initial growth of maize were studied for four indigenous tree species with agroforestry potential:Stryphnodendron microstachyum Poepp. et Endl.(S. excelsum), Vochysia ferruginea Mart,Vochysia guatemalensis Donn. Sm. (V. hondurensis) andHyeronima alchorneoides (O), growing in a young experimental plantation in the Atlantic humid lowlands of Costa Rica. Total annual leaf litterfall was higher inV. ferruginea plots, followed byS. microstachyum, V. guatemalensis andH. alchorneoides; all with values comparable to those reported for other tree species grown in agroforestry combinations in humid tropical regions. Forest-floor litter accumulation was highest underV. ferruginea andV. guatemalensis. Both litterfall and forest-floor litter material had similar patterns in nutrient concentrations: N was higher inS. microstachyum, Ca was higher inV. guatemalensis, K was higher inH. alchorneoides; Mg was higher inV. guatemalensis andH. alchorneoides; H. alchorneoides andV. guatemalensis had the highest P.V. ferruginea litter decomposed more slowly, whileS. microstachyum apparently decomposed faster than the other species. The twoVochysia species showed increases in N and P concentration in decomposing litter after seven weeks in the field,H. alchorneoides showed an increase in litter N and a decrease in litter P, andS. microstachyum showed a net decrease in both N and P over the same time period. The patterns found in the litter bag study were confirmed by results obtained in a tethered-leaves experiment.S. microstachyum andV. ferruginea litters lost more weight when mixed in a 11 proportion than either of them alone. Maize seedlings growing in plots mulched withS. microstachyum andH. alchorneoides leaves showed greatest initial growth, confirming patterns found in decomposition and nutrient release studies. The results show that these species could be used in agroforestry combinations with different advantages according to the specific objectives desired, whether these are soil protection, nutrient recycling, or enhancement of the growth of associated crops.     

Effects of alley cropped Calliandra calothyrsus and Cliricidia sipium hedges on weed growth,soil properties,and taro yields in Western Samoa

Field experiments were conducted on a tropical Inceptisol at Apia, Western Samoa to evaluate the effects of alley cropping on soil characteristics, weed populations, and taro yield. Taro yields were compared from Calliandra calothyrsus and Gliricidia sipium alleys, spaced at 4 m, 5 m, and 6 m, and a no tree control. Measurements were made for soil moisture and temperature, weed growth, hedge biomass production, and taro growth and yield. Data was analyzed over 4 consecutive years from 1988 to 1991.Hedge biomass yields ranged from 5.1 to 16.1 t/ha/yr dry weight over the 4 years of the trial, with Calliandra and Gliricidia performing equally well. Biomass yields decreased by about 2 mt/ha with increasing alley width from 4 to 6 m alleys. Weed populations were significantly lower in the 4 m alleys compared to the 5 m, 6 m, and control plots. The 6 m alleys supported the significantly highest weed populations. Soil from alley plots held significantly more water in the 0.3 to 1 bar range than soils from the controls. Four years of mulch application measurably improved soil water holding capacity and bulk density. However, no improvement was seen in nitrogen, phosphorus, potassium, calcium, magnesium and organic carbon content in the alley plots compared to the controls. There was no positive yield effect of alley cropping on taro yield. Yields in the 5 m and 6 m alleys were not significantly different from the control, while the 4 m alleys produce significantly lower yields than the control. Thus, alley cropping did not prove a viable alternative to traditional shifting cultivation after 4 years of continuous cropping, in this trial.     

Phosphorus fractions of fertiliser-derived P in an allophanic soil under Pinus radiata seedlings grown with broom and ryegrass

Changes in phosphorus (P) fractions in a P deficient allophanic soil under P. radiata seedlings grown with broom (Cytisus scoparius L.) and ryegrass (Lolium multiflorum) in pots were studied 14 months after the application of triple superphosphate at the rates of 0, 50, and 100 μg·g⁻¹, to determine the fate of fertiliser-derived P in the rhizosphere soils. Application of P fertiliser increased NaOH-P_i, NaOH-P_o, and H₂SO₄-P_i concentrations in the soil, but decreased the residual-P concentration. The resin-P_i concentration, which is extremely low in this soil (1 to 3 μg·g⁻¹), remained the same. The majority of the added fertiliser P was however recovered in the NaOH-P_i fraction (40%–49%). This is due to the high P fixation in this soil (92%). The second highest P recovery was in NaOH-P_o fraction (7%–19%). Under P deficient condition or addition at the rate of 0 μg·g⁻¹, the NaOH-P_i concentration in the radiata rhizosphere soil was lower than that in the bulk soil and broom and grass rhizosphere soils. This may be due to higher oxalate production by the roots and mycorrhiza under P deficient conditions which released some of the P fixed to the soils in the rhizosphere, which needs to be tested in future studies. Foundation project: This work was supported by Centre for Sustainable Forest Management at Forest Research Institute, New Zealand.     

Agroforestry in the Bolivian Altiplano: evaluation of tree species and greenhouse growth of wheat on soils treated with tree leaves

Severe environmental problems encountered in the highlands of Bolivia may be remedied through the adoption of agroforestry systems, never before studied adequately in this region. As a first step, seven tree species were tested for growth, survival and health at two elevations in the Bolivian altiplano. Species responded variably with Buddleja coriacea Remy., Pinus radiata D. Don. and Eucalyptus globulus Labill. (at the higher elevation) and E. globulus, Baccharis spp., Robinia pseudoacacia L. and B. coriacea (at the lower elevation), displaying high survival, growth and health. In a related greenhouse study, grain yields of wheat planted in soils amended with incorporated foliage of B. coriacea, P. radiata and E. globulus increased three-fold (0.3 g·plant⁻¹ to >1.0 g·plant⁻¹) over grain yields in unamended soils (B. coriacea > P. radiata = E. globulus). Grain nitrogen (mg·plant⁻¹) increased equally in soils amended with P. radiata and B. coriacea foliage (18 mg N⋅plant⁻¹ to 20 mg·plant⁻¹) but decreased in soils amended with foliage of E. globulus (18 g·plant⁻¹ to 9 g·plant⁻¹). This revised version was published online in June 2006 with corrections to the Cover Date.     

Soil CO2 efflux in an Afromontane forest of Ethiopia as driven by seasonality and tree species

Variability of soil CO₂ efflux strongly depends on soil temperature, soil moisture and plant phenology. Separating the effects of these factors is critical to understand the belowground carbon dynamics of forest ecosystem. In Ethiopia with its unreliable seasonal rainfall, variability of soil CO₂ efflux may be particularly associated with seasonal variation. In this study, soil respiration was measured in nine plots under the canopies of three indigenous trees (Croton macrostachys, Podocarpus falcatus and Prunus africana) growing in an Afromontane forest of south-eastern Ethiopia. Our objectives were to investigate seasonal and diurnal variation in soil CO₂ flux rate as a function of soil temperature and soil moisture, and to investigate the impact of tree species composition on soil respiration. Results showed that soil respiration displayed strong seasonal patterns, being lower during dry periods and higher during wet periods. The dependence of soil respiration on soil moisture under the three tree species explained about 50% of the seasonal variability. The relation followed a Gaussian function, and indicated a decrease in soil respiration at soil volumetric water contents exceeding a threshold of about 30%. Under more moist conditions soil respiration is tentatively limited by low oxygen supply. On a diurnal basis temperature dependency was observed, but not during dry periods when plant and soil microbial activities were restrained by moisture deficiency. Tree species influenced soil respiration, and there was a significant interaction effect of tree species and soil moisture on soil CO₂ efflux variability. During wet (and cloudy) period, when shade tolerant late successional P. falcatus is having a physiological advantage, soil respiration under this tree species exceeded that under the other two species. In contrast, soil CO₂ efflux rates under light demanding pioneer C. macrostachys appeared to be least sensitive to dry (but sunny) conditions. This is probably related to the relatively higher carbon assimilation rates and associated root respiration. We conclude that besides the anticipated changes in precipitation pattern in Ethiopia any anthropogenic disturbance fostering the pioneer species may alter the future ecosystem carbon balance by its impact on soil respiration.     

The performance of selected leaf mulches in temperature reduction and moisture conservation in the upper soil stratum

This paper reports on the effect of the leaf mulches of Leucaena leucocephala, Gliricidia sepium and Flemingia macrophylla on moisture content and temperature in the first 5 cm of the soil. The mulches were applied at a standard quantity of 5,000 kg ha^–1 DM.In order to characterise a mulch material two parameters are distinguished; the initial impact (I _i ) and the effective lifetime (T _e ) of a mulch material. I is expressed in terms of percentage surplus moisture or degrees Celsius average temperature reduction. T quantifies the duration of the effect. Of the three mulch materials that of Flemingia macrophylla performs best in terms of moisture retention and lowering soil temperatures as well as in terms of longevity of the effect. Leucaena leucocephala mulch shows the smallest impact, over the shortest period.     

Improving the Traditional Acacia Senegal-Crop System in Sudan: The Effect of Tree Density on Water Use, Gum Production and Crop Yields

The traditional Acacia senegal bush-fallow in North Kordofan, Sudan, was disrupted and the traditional rotational fallow cultivation cycle has been shortened or completely abandoned, causing decline in soil fertility and crop and gum yields. An agroforestry system may give reasonable crop and gum yields, and be more appealing to farmers. We studied the effect of tree density (266 or 433 trees ha⁻¹) on two traditional crops; sorghum (Sorghum bicolor) early maturing variety and karkadeh (Hibiscus sabdariffa), with regard to physiological interactions, yields and soil water depletion. There was little evidence of complementarity of resource sharing between trees and crops, since both trees and field crops competed for soil water from the same depth. Intercropping significantly affected the soil water status, photosynthesis and stomatal conductance in trees and crops. Gum production per unit area increased when sorghum was intercropped with trees in low or high density. However, karkadeh reduced the gum yield significantly at high tree density. Yields of sorghum and karkadeh planted within trees of high density diminished by 44 and 55% compared to sole crops, respectively. Intercropping increased the rain use efficiency significantly compared to trees and field crops grown solely. Karkadeh appears to be more appropriate for intercropping with A. senegal than sorghum and particularly recommendable in combination with low tree density. Modification of tree density can be used as a management tool to mitigate competitive interaction in the intercropping system.     

Assessing the impacts of species composition, top height and density on individual tree height prediction of quaking aspen in boreal mixedwoods

In this study we developed an individual tree height prediction model for quaking aspen (Populus tremuloides Michx.) grown in boreal mixedwood forests in Alberta using the nonlinear mixed model (NLMM) approach. We examined the impacts of density, species composition, and top height on aspen height predictions. Statistically significant stand level variables were incorporated into the base height–diameter model to increase the predictive ability and accuracy of the model at both the population and subject-specific levels. Our analyses showed that top height and density impacted height growth, but species composition did not. More importantly, we found that the inclusion of additional variables into the base model, despite improving model fitting statistics on the modelling data, did not improve the model's predictive ability and accuracy when cross-validated and when tested on an independent testing data set. Under the NLMM framework the base model performed as well as or better than the expanded models that contained other stand level variables. This has important theoretical and practical implications because, other than for biological reasons, more accurate local tree height predictions for aspen can be achieved simply by using the base height–diameter model fitted with the NLMM approach without the inclusion of other variables.     

Frequency, species composition and efficiency of Ips typographus (Col., Scolytidae) parasitoids in infested spruce forests in the National Park “Bavarian Forest” over three consecutive years

During the summers of three consecutive years (2002, 2003 and 2004) the parasitoid fauna of the spruce bark beetle Ips typographus was investigated in the national park “Bavarian Forest”. In the central part of this forest no human influence in the population dynamics is allowed, whereas, in the surrounding no bark beetle attacks are accepted and all infested wood is removed consequently. Species frequency and species composition did not differ much in 2002 and 2003, when Coeloides bostrichorum and Roptrocerus sp. was most numerous. But in 2004 species composition changed with the increase of R. tutela and the decrease of C. bostrichorum. We found that C. bostrichorum reached very high numbers of individuals, but its frequency did not exceed 31% during 3 years while the pteromalid wasps were not so numerous, but had very high frequencies. For Roptrocerus, we found 55, 82 and 85% and for R. tutela 41, 67 and 85% frequency. In 2004, mean parasitization was higher (8.5) as in 2003 (5.8%). The highest parasitization in one sample was 92.2% in 2002 caused by C. bostrichorum, 73.5% in 2003 caused by C. bostrichorum and R. tutela and 59.8% in 2004 caused by R. tutela and Roptrocerus. Our hypothesis that the influence of parasitoids on the population dynamics of I. typographus is greater in natural forests than in normal treated forests could not be corroborated.