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1.
Growing concern for economic and environmental issues emphasizes the potential value of intercropping systems in temperate regions. However, the selection of relevant tree species to be associated with crops has been little documented. The growth and the nitrogen nutrition of two economically valuable species, wild cherry (Prunus avium L.) and hybrid walnut (Juglans nigra L.×Juglans regia L.), were compared over six years after plantation. These two species were associated with non-irrigated cereal crops in the agroforestry treatment or grown separately (weeded control and fallow). Intercropping increased diameter growth as soon as year 2 in the two species. Leaf biomass assessment using allometric models showed an earlier and greater leaf biomass increase in hybrid walnut than in wild cherry tree. After six years, the relative growth increase of the agroforestry trees with respect to the control trees varied with the parameter considered (diameter at breast height from +26 to +65%, leaf biomass from +54 to +142%) and with the tree species (higher relative growth for hybrid walnut trees). The beneficial effect on tree growth can be accounted for in terms of enhanced nitrogen nutrition. The tree–crop association in intercropping systems, which improves tree growth, might thus allow the planting of more demanding trees on soils of lower fertility.  相似文献   

2.
The coffee leaf-miner (CLM) (Leucoptera coffeella Guérin-Mèneville; Lepidoptera: Lyonetiidae), the main pest of coffee plants, occurs widely throughout the Neotropics where it has a significant, negative economic and quantitative impact on coffee production. This study was conducted in a rubber tree/coffee plant interface that was influenced by the trees to a varying degrees depending on the location of the coffee plants, i.e. from beneath the rubber trees, extending through a range of distances from the edge of the tree plantation to end in a coffee monocrop field. The most severe damage inflicted on coffee plants by the CLM (number of mined leaves) from April, which marks the start of the water deficit period, until September 2003 was in the zone close to the rubber trees, whereas the damage inflicted on plants in the monocropped field was comparable to that on coffee plants grown directly beneath the rubber trees, which received about 25–40 % of the available irradiance (Ir—available irradiation at a certain position divided by the irradiation received in full sunlight, i.e. in the monocrop). From May until July damage caused by the CLM nearly doubled in each month. In midwinter (July), the damage decreased perceptibly from the tree edge toward the open field. From September onward, with the rising air temperatures CLM damage in the coffee monocrop started to increase. Based on these results, we conclude that coffee plants grown in the full sun incurred the most damage only at the end of winter, with warming air temperatures. Coffee plants grown in shadier locations (25–40 % Ir) were less damaged by the CLM, although a higher proportion of their leaves were mined. The rubber trees probably acted as a shelter during the cold autumn and winter seasons, leading to greater CLM damage over a distance outside the rubber tree plantation that was about equal to the height of the trees. Future studies should attempt to relate leaf hydric potential to pest attack in field conditions. More rigorous measurements of shade conditions could improve our understanding of the relationship of this factor to CLM attack.  相似文献   

3.
Pedraza  R.A.  Williams-Linera  G. 《New Forests》2003,26(1):83-99
Four native tree species (Liquidambar styraciflua, Juglans pyriformis, Podocarpus matudae, and Carpinus caroliniana) were evaluated for their suitability in rehabilitating degraded areas of Mexican cloud forest. Plant survival and growth in height and diameter were determined in three mixed-experimental plantations with different land use histories; their performance was compared with two on-farm plantations started by landowners for forest restoration. Nearby forest fragments were controls for soil compaction. An experimental plantation with remnant trees had the highest plant survival (82%), height, basal diameter and relative growth rate. The plantation with the steepest slope had high plant survival (63%) and growth. The plantation characterized by dominance of grasses and compacted soils had the lowest survival (22%) and growth. On-farm plantations had good establishment of planted trees (5–10 species planted), and facilitated the recruitment of 9–11 woody species. Carpinus and Liquidambar appear to be suitable species for reforestation in all these areas. Podocarpus grew relatively slowly, although it performed well in two experimental sites. Juglans had high survival (76%) under the stressful conditions of the most adverse site, and therefore may be useful for rehabilitation of degraded sites. Differences among species and sites strongly suggest that species success depends on plantation site quality.  相似文献   

4.
Brazil accounts for about 20% of the world production of cocoa, and about 95% of cocoa produced in Brazil is from the southeastern part of Bahia State. Traditionally, cacao is grown in monoculture (though under the shade of various other species). But various crop combinations involving cacao have recently been undertaken by the farmers with encouragement from Brazilian government.As a part of the crop diversification programme in the traditional cacao growing areas and their surroundings, extensive areas are being planted to other plantation crops, mainly clove and rubber and, to some extent, coconut too. Crop combinations have been adopted in some of these new plantings and cacao is an important component of most of such combinations. Whereas several other crops are combined with clove trees, cacao is usually the only species grown with mature rubber trees. Young rubber trees are, however, interplanted with a number of other species. Productive coconut areas are found mostly in sandy soils along the coast so that there is little intercropping. However, scattered farms are found where coconuts are underplanted with guarana, black pepper, cacao, cashew, etc. as done commonly in other parts of Northeast Brazil.  相似文献   

5.
Abstract

An experiment was established in 1978 in two Norway spruce [Picea abies (L.) Karst.] plantations in southern Sweden to study yield after mortality in patches with and without supplementarily planted (SP) seedlings. Gaps of different sizes were created by removing the originally planted seedlings. The gaps were either left unplanted or a supplementary planting was performed with one of four species [Norway spruce, Scots pine (Pinus sylvestris L.), lodgepole pine (Pinus contorta Dougl.) or hybrid larch (Larix deciduas Mill×L. Leptolepis Gord.)] 2 (at Knäred) or 6 years (at Ullasjö) after the original plantation. In 2002, most of the SP Scots pine, lodgepole pine and hybrid larch seedlings were dead or severely damaged by roe deer and moose. Survival was high among SP Norway spruces, but they had slower growth than the originally planted spruces. Growth was lower at Ullasjö than at Knäred. In Ullasjö, growth was lower in small gaps than in large gaps. Trees in original regeneration in areas surrounding unplanted gaps were larger than trees surrounding gaps with SP seedlings, which in turn were larger than originally planted trees in plots without gaps. In conclusion, because the original plantation surrounding unplanted gaps used a large part of the open space and growth of SP seedlings was slow, supplementary planting resulted in an insignificant growth increase. However, supplementary planting may increase the timber quality of trees surrounding the gaps, although this effect remains to be quantified.  相似文献   

6.
Favouring Tetranychid mites by intercropping peanut plants on citrus plants and results of chemical control measures The mite populations ofT. cucurbitacearum (Sayed) andT. arabicus (Attiah) reached noxious levels on the peanut plants intercropped on orange trees, during July and August, when the increasing in temperature was accompanied with increasing in humidity. It seems that intercropping the peanut plants on fruit trees and cultural practices may affect as well peanut plant condition as the mortality of mites and consequently increase mite infestation.Regarding, the control experiments, it had been found that 5 acaricides used were very effective in decreasing Tetranychid populations on peanut plants.  相似文献   

7.
云南松天然林的种内和种间竞争   总被引：3，自引：2，他引：1       下载免费PDF全文
[目的]通过对云南松天然林内云南松种内和种间竞争强度的测定,分析揭示竞争强度在云南松群落内的动态变化规律及云南松种群的生态适应机制.[方法]在云龙天池自然保护区云南松天然林设置样方进行群落学调查的基础上,采用Hegyi单木竞争指数模型,以云南松为对象木,定量分析林分、对象木、竞争木的竞争强度,采用回归分析方法建立对象木胸径与林分、种内、种间竞争强度的函数模型.[结果]天池自然保护区云南松天然林的种内和种间竞争强度分别为80.16%和19.84%;云南松种内与主要伴生树种种间竞争强度大小顺序为:云南松种内> 水红木> 华山松> 米饭花> 大白花杜鹃> 槲栎> 马缨花> 旱冬瓜;云南松与整个林分、伴生树种以及种内的竞争强度与对象木胸径之间存在显著负相关关系,对象木胸径越大,其竞争能力越强.[结论]云南松天然林内云南松的竞争压力主要来自种内竞争;林分种内及种间竞争强度与对象木胸径间存在CI=AD-B形式的幂函数关系;胸径20 cm以上云南松的竞争压力变化趋于平缓,胸径20 cm以下的云南松中、幼林是抚育管理的重点林分.  相似文献   

8.
Soil samples were taken at different distances from the trunks of four- to five-year-old trees of six species planted on-farm in western Kenya. The tree species wereCordia africana, Croton megalocarpoides, Grevillea robusta, Acacia tortilis, Prosopis juliflora andSesbania sesban. Samples were also taken inside and outside a fenced plantation ofProsopis juliflora. Soil samples were analysed for total C%, total N%,13C abundance,15N abundance, extractable P and pH.The most sensitive indicator of effects of trees on soils was13C abundance, which reflected a shift in inputs of C from C4 grasses to C from C3 trees. All species except Prosopis lowered the13C abundance by 0.5–1 -units. This was equivalent to an increase of 3–5% of the percentage of C contributed by C3 species. Prosopis trees did not decrease the13C abundance because of the abundant grass-growth around them. Cordia, which had the most pronounced effects, raised the C%, N% and extractable P by 27%, 26% and 55%, respectively. Nitrogen and C were well correlated (r 2=0.97) in the whole material. Effects on soil pH were in both directions, i.e. it was raised under the Prosopis plantation by 0.33 units, while it was lowered under Acacia by 0.21 units.Effects of agroforestry trees were thus seen in as short time as five years in practical onfarm situations.13C abundance is recommended as a particularly sensitive indicator of the influence of trees on sites previously dominated by C4 crops and grasses.  相似文献   

9.
Enrichment planting is a technique that is gaining recognition for its potential to restore native forests. Due to the steep economic trade-offs involved and dearth of silvicultural and ecological knowledge about native flora, however, it remains unclear whether it has promise for widespread application. Focusing on growth performance, this study explores the restoration potential of twenty-one native tree species 3 years after planting in the understory of a rubber plantation in southern Bahia, Brazil. We tested the effects of slope, aspect, successional guild and basal area of the overstory rubber trees on the enriched species’ height, root collar diameter, and diameter at breast height. Height was the growth parameter that most differentiated species, with Parkia pendula, Sloanea monosperma, and Tachigali densiflora being three of the most successful species. Pioneer species grew faster than the non-pioneer species. Overstory basal area was the most important variable influencing the performance of the planted tree seedlings, while aspect and slope were less important. For every additional unit of basal area per hectare of rubber, there was an incremental decrease in the growth rates of the enrichment species. This suggests that the tree species are likely limited by available light, and that there are distinct trade-offs between overstory rubber density and understory tree species growth that are important to consider when accelerating forest recovery by using enrichment planting techniques.  相似文献   

10.
We investigated factors affecting the distribution of naturally regenerated broad-leaved trees in a 140-year-old Cryptomeria japonica plantation. We used path analysis to examine the relationship among microtopography, the biomass of planted trees, and the biomasses of canopy and subcanopy trees of broad-leaved species. The study plot was divided into three topographic types (ridge, slope, and valley), and we discuss how the different topographic types are affected. For all topographic types, the biomass of canopy trees of broad-leaved species decreased with convexity. For slope and valley topographies, the biomass of subcanopy trees of broad-leaved species also decreased with convexity. For ridge topography, the biomass of subcanopy trees of broad-leaved species increased with the biomass of planted trees, and decreased with the biomass of canopy trees of broad-leaved species. These results suggest the effects of microtopography on the biomass of subcanopy trees were much larger than the effects of canopy trees for slope and valley topographies, while the effects of microtopography were smaller for ridge topography.  相似文献   

11.
This study uses land expectation value (LEV) as a criterion to conduct economic analyses of natural rubber (Hevea brasiliensis) and tea (Camellia sinensis var. assamica) monoculture, and rubber-tea intercropping. We calculated LEV by using the Faustmann model that combines annual revenue flow from latex production with final timber harvest of rubber trees. Production and cost data were collected from Xinwei Farm in Hainan, China. We found that rubber-tea intercropping generated higher LEV than rubber and tea monoculture under current socio-economic circumstances. Sensitivity analysis has been conducted to examine the impacts on land expectation value by interest rate, prices of natural rubber and tea, and labor costs.  相似文献   

12.
Tree planting practices were investigated on a total of 95 homesteads in two communities in rural Swaziland. Information was also collected on socioeconomic characteristics of the homesteads. In both the study areas, Sigombeni and Bhekinkhosi, there was considerable variation amongst individual homesteads in size, relative wealth (as indicated by cattle and motor vehicle ownership), and amount and types of trees planted. Eighty-five percent of all homesteads in Sigombeni and 73 percent in Bhekinkhosi had planted at least one tree. Common forms of planting included small woodlots, fruit trees, and ornamentals. Virtually all the woodlots consisted of two introduced wattle species (Acacia mearnsii and A. decurrens). The most commonly planted fruit trees were avocadoes, bananas, and peaches. No complex or labor-intensive agroforestry practices (such as maize/leucaena intercropping) were observed. There was some evidence that the poorest and newest homesteads were the least likely to have planted any trees and that the richest homesteads were the most likely to have planted woodlots. The results indicate that forestry research and extension efforts should take into account homestead characteristics, and strive to offer a range of tree planting options that vary in input requirements, labor needs, and complexity.  相似文献   

13.
The last decades brought along a tremendous expansion of rubber plantations as well as respective socio-economic transformations. This paper reviews the historical development of rubber cultivation with special reference to intercropping and illustrates the major development steps. The agronomic challenges of intercropping are analyzed and a management classification scheme is suggested. Though the topic of labor always accompanied rubber management, it is nowadays of even higher relevance due to alternative income options, be it due to competing crops such as oil palm, or be it off-farm income opportunities. This development challenges labor intensive permanent intercropping systems. It can thus be concluded that the permanent integration of additional plants needs either to be highly profitable or at least be labor extensive to be adopted on a considerable scale. Given the large area of rubber plantations the latter seems to be more realistic. In this context timber trees might offer promising options if tree selection is properly adapted to site and plantation conditions. Nevertheless, without external interventions, such as land-use planning and implementation, or incentives, the development will be difficult to control.  相似文献   

14.
Perennial tree crops are often grown in complex multistrata systems that incorporate natural vegetation. These systems contribute simultaneously to sustaining rural livelihoods and to the conservation of biodiversity, but their productivity is usually low. Introduction of high yielding germplasm, usually selected in monocultural plantations, is a potential way to increase productivity, but a critical requirement is that such plants can be established in a competitive multispecies environment. The establishment of clonal planting stock in the jungle rubber agroforests of Indonesia was explored through participatory on-farm research. The trial involved four farmers who grew clonal rubber trees in a total of 20 plots, constituting five replicate experimental blocks spread across four farms. Unexpectedly, vertebrate pest damage by monkeys (Presbytis melalophos nobilis) and wild pigs (Sus scrofa) was the most important influence on establishment, explaining almost 70% of the variation in rubber tree growth. The amount of labour invested in weeding was also positively correlated with rubber tree growth. Farmers generally decided to completely cut back vegetation between rows of rubber trees, including potentially valuable trees, rather than weeding within the rows and selectively pruning trees in the inter-row. Farmers thought that the inter-row vegetation would harbour vertebrate pests and compete with the clonal rubber, and they had access to fruits, firewood and other non-timber forest products from other land. Thus, contrary to expectations, when offered clonal germplasm, farmers opted to use plantation monoculture methods to protect what they considered a valuable asset, rather than maintain the traditional multispecies strategy they use with local germplasm. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

15.
Eucalyptus globulus is the predominant exotic hardwood plantation species in Western Australian (WA), and is often planted adjacent to native eucalypt forests. The increase in number of Mycosphaerella species associated with Mycosphaerella leaf disease (MLD) in E. globulus plantations in WA in the past decade has raised concern about the possible movement of pathogens between the native forests and plantations. In order to determine whether the introduction of new E. globulus genetics into WA may have further exacerbated this situation, juvenile and adult foliage were taken from a genetics trial near Albany, WA consisting of 60 full-sib families and Mycosphaerella species identified using morphological and molecular tools. Eleven species of Mycosphaerella were identified from one plantation: Mycosphaerella fori (Pseudocercospora fori) and Mycosphaerella ellipsoidea are new records for Australia; Mycosphaerella tasmaniensis (Passalora tasmaniensis) and Mycosphaerella suttoniae (Kirramyces epicoccoides) are new records for WA; and Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella marksii, Mycosphaerella molleriana, Mycosphaerella lateralis, Mycosphaerella aurantia and Mycosphaerella parva, previously recorded for WA. The most frequently isolated species from juvenile foliage was M. marksii (77%) followed by M. nubilosa (33%). M. nubilosa was most frequently isolated from adult leaves (88%) followed by M. parva (7.5%). Three species, M. molleriana, M. lateralis and M. cryptica, were only isolated from adult leaves while M. ellipsoidea was only isolated from juvenile leaves. These records increase the number of known Mycosphaerella species from eucalypts in WA from 10 to 13. The increase in the number, distribution and impact of Mycosphaerella species contributing to MLD in WA is of concern both to the potential productivity of the plantations and the biosecurity of native WA Eucalyptus species. Continued monitoring of the plantation estate is required to understand the dynamics of the host–pathogen interactions.  相似文献   

16.
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17.
Natural rubber (Hevea brasiliensis) is one of the major plantation crops of the state of Kerala in India and intercropping is practised during the initial gestation period of the crop. In this paper a to bit model was used to study the decision making behaviour of farmers in adoption and extent of adoption of intercropping in three regions of Kerala. The availability of family labour and the type of intercrops were found significant in explaining the adoption behaviour in all three regions. The perception of profitability of intercropping was also found to influence decision on adoption. The probability of adoption of intercropping was highest for three intercrops, banana (Musa spp.), cassava (Manihot esculenta) and pineapple (Ananas comosus). Targeting extension efforts to groups of farmers with available family labour and popularising selected intercrops may result in higher rates of adoption of intercropping in all three regions of the state.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

18.
Climate warming has resulted in rapid range shifts of plant species, but it is not well known how species with different natural distribution ranges adapt to increase in temperature through physiological adjustment. We experimentally imposed a 1.8 °C increase of air temperature to the cuttings of two common poplar species Populus yunnanensis and Populus szechuanica naturally growing in southwest China using open-top chambers. Populus yunnanensis is distributed along a narrower elevation range compared with P. szechuanica. We determined some key physiological parameters and plant growth regulator activities during the growing season without soil water limitation. Our results showed that a 1.8 °C increase in air temperature increased shoot growth of P. szechuanica through an extension of its growth period but did not affect the growth of P. yunnanensis. Malondialdehyde content, guaiacol peroxidase activities and abscisic acid content increased while indoleacetic acid content decreased in P. yunnanensis. Our results suggest that the two common poplar species in southwest China should be able to adapt to the moderate increase in temperature projected for future climate. The growth of P. szechuanica may benefit through phenological adjustment but a further increase in temperature may inhibit the growth of P. yunnanensis. For poplar plantation management, selecting species with a wide natural distribution range could provide an adaptive alternative for buffering anthropogenic induced increase in temperature and help in sustaining productivity for the long term.  相似文献   

19.
在橡胶林下种植望天树、羯布罗香、格木、铁力木、降香黄檀、高阿丁枫等雨林树种,进行7种配置模式的种植试验,通过调查不同配置模式的生物量和碳贮量与橡胶纯林对比,选择出最佳的配置模式,结果表明:橡胶林下种植以格木为最佳模式,同时可以适当配置羯布罗香、望天树和铁力木。  相似文献   

20.
The objective of this study was to evaluate how competition would affect the physiology, and thus productivity of American beautyberry (Callicarpa americana L.), wax myrtle [Morella cerifera (L.) Small] and inkberry [Ilex glabra (L.) A. Gray] when intercropped in a longleaf pine (Pinus palustris Mill.) plantation in the southeastern United States. The effect of competition was assessed via comparisons of mortality, biomass, light transmittance, gas exchange and soil moisture between intercropping and monoculture (treeless) treatments. Overall, shrubs in the intercropping treatment performed worse than those in the monoculture, with higher mortality, and reductions in biomass of 75.5, 50.6, and 68.7% for C. americana, M. cerifera and I. glabra, respectively. Root–shoot ratios for all species were significantly higher and soil moisture during dry periods was significantly lower in the intercropping treatment. Light transmittance below the pine canopy was high (57.7%) and I. glabra was the only species that exhibited reduced A max when belowground resources were not limiting. These results suggest that the effect of shading is minimal and belowground competition is likely the most important determinant of productivity in this system.  相似文献   

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