木麻黄与根系微生物关系研究进展

木麻黄是我国沿海防护林基干林带中的主栽树种,与土壤中的微生物可以形成共生关系,提高自身耐干旱、抗贫瘠、抗盐碱等适应恶劣环境的能力。土壤中的细菌和真菌能够与木麻黄根系形成稳定的相互作用的微生态系统,其中微生物主导的物质代谢循环是植物获取营养的主要来源之一,反之木麻黄的根系分泌物可以为微生物的生长提供养分。文中综述了木麻黄与根系微生物之间相互作用的相关研究,尤其是接种弗兰克氏菌（Frankia）及菌根菌提高木麻黄抗逆性方面的研究进展,对木麻黄与根系微生物体系的促生、抗逆机制进行了探讨和展望。     

热带四种按树人工林的土壤指标对氮肥反应的评价

较低氮利用性经常会导致桉树人工林的减产.为检验氮矿化的土壤指标的利用并预测桉树对添加氮肥的响应,研究四种桉树人工林(印度海岸低洼地2种细叶桉人工林和和喀拉拉邦高地的2种巨桉人工林)对添加氮肥和相关季节性氮矿化以及其他氮利用率指标的响应,测定几种生化指标对氮肥的响应,包括全氮,土壤C:N比和在厌氧、有氧孵化过程中释放的氮.结果表明,在4块实验地里,增加氮肥可以相应的提高生产率7%至70%;在有氧孵化过程中,释放的氮与氮肥间有最显著相关性(R2=0.92,p<0.01).与有氧孵化过程中释放的氮相比,季节性土壤氮矿化作用是一个较差的肥料响应的指标.虽然有的指标有很好的应用价值,但在广泛应用之前还需验证测试.     

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.     

Soil fertility management for reclamation of Imperata grasslands by smallholder agroforestry

Imperata cylindrica grasslands are widely believed to indicate poor soil fertility. Soil fertility improvement may have to be an important component of a reclamation strategy. Data for Sumatra, Indonesia indicate, however, that Imperata occurs on a broad range of soil types and is not confined to the poorest soils. A direct role of Imperata in soil degradation cannot be ascertained. In many instances, however, Imperata soils are low in available P and effective N supply. The use of rock phosphate in combination with erosion control (fertility traps) and legume cover crops can be effective in restoring soil fertility. Case studies for a number of sites in Sumatra have confirmed the practical possibility of reclaiming grasslands for food and tree crops.     

Tropical red gums — a source of 1,8-cineole-rich Eucalyptus oil

Tropical provenances of Eucalyptus camaldulensis Dehnh. and E. tereticornis Smith were studied, in their natural habitat in Australia and in a 3.75-year-old progeny trial in Zimbabwe, for their potential to produce medicinal-grade essential oils. Substantial interand intra-specific variation in the contents of five prominent monoterpenes, 1,8-cineole, -pinene, -pinene, limonene and p-cymene was found. Plantations of E. camaldulensis established in the wet/dry tropics using seed from Petford in northern Queensland offer immediate potential for oil production. Other widely-planted Queensland provenances with oil potential are Gilbert River Bridge E. camaldulensis and, after some genetic improvement, E. tereticonis from Morehead and Kennedy Rivers. Select individual trees at Petford provide oil of enhanced quality, at about double the yield of average trees.     

Biomass and production of fine and coarse roots of trees under agrisilvicultural practices in north-east India

An understanding of the rooting pattern of tree species used in agroforestry systems is essential for the development and management of systems involving them. Seasonal variation, depth wise and lateral distribution of biomass in roots of different diameter classes and their annual production were studied using sequential core sampling. The investigations were carried out in four tree species under tree only and tree+crop situations at ICAR Research Farm, Barapani (Meghalya), India. The tree species were mandarin (Citrus reticulata), alder (Alnus nepalensis), cherry (Prunus cerasoides) and albizia (Paraserianthes falcataria). The contribution of fine roots to the total root biomass ranged from 87% in albizia to 77% in mandarin. The bulk of the fine roots (38% to 47%) in the four tree species was concentrated in the upper 10 cm soil layer, but the coarse roots were concentrated in 10–20 cm soil depth in alder (46%) and albizia (51%) and at 0–10 cm in cherry (41%) and mandarin (48%). In all the four tree species, biomass of both fine- and coarse-roots followed a unimodal growth curve by showing a gradual increase from spring (pre-rainy) season to autumn (post rainy) season. Biomass to necromass ratio varied between 2 to 3 in the four tree species. The maximum (3.2) ratio was observed during spring and the minimum (2) in the rainy season. In alder and albizia, the fine roots were distributed only up to 1 m distance from the tree trunk but in the other two species they were found at a distance up to 1.5 m from the tree trunk. The annual fine root production varied from 3.6 Mg ha^–1 to 6.2 Mg ha^–1 and total production from 4.2 to 8.4 Mg ha^–1 in albizia to mandarin, respectively. Cherry and mandarin had a large number of woody roots in the surface layers which pose physical hindrance during soil working and intercultural operations under agroforestry. But the high biomass of roots of these two species may be advantageous for sequential or spatially separated agroforestry systems. However, alder and albizia have the most desirable rooting characteristics for agroforestry systems.This revised version was published online in November 2005 with corrections to the Cover Date.     

Pasture floristic composition in different Eucalyptus species plantations in some parts of northern Guinea savanna zone of Nigeria

In view of the recurrent drought and human population pressures which have drastically reduced the density of pasture species within the Nigerian savannas, the nomadic herdsmen rely mostly on silvipastoralism, grazing their herds in Eucalyptus plantations. In this study, the population of understorey forage and non-forage speicies and the relative light intensities on the forest floors of two Eucalyptus species, viz: E. citridodora, and E. camaldlensis were compared with those of open savanna lands at Kabama, Samaru and Guga, all within the Northern Guinea savanna zone.At normal 3 m by 3 m spacing between trees, the herbages were fewer in the plantations and the E. citridora plantation had only about half the number of species observed under E. camaldlensis in the same and other sites despite similarities in light intensity levels in all the plantations. This information forms a guideline in using eucalyptus silvo-pastoral farms.     

Effect of the inoculation and distribution of mycorrhizae in <Emphasis Type="Italic">Plathymenia reticulata</Emphasis> Benth under monoculture and mixed plantation in Brazil

This paper investigates the distribution of arbuscular mycorrhizal fungi (AMF) spores and AMF colonization in a field study in southeastern Brazil. Response to AMF and rhizobial inoculation was studied in monocultures of Plathymenia reticulata and mixed plantations with both Tabebuia heptaphylla and Eucalyptus camaldulensis in a sandy soil during two consecutive years. P. reticulata height and diameter and mycorrhizal colonization and AMF diversity were measured in dry and rainy periods. The inoculated treatment of E. camaldulensis, T. heptaphylla and P. reticulata mixed plants showed higher height and diameter growth of P. reticulata used as well as increased root colonization and AMF spore numbers. Spore populations were found to belong to five genera: Acaulospora, Entrophospora, Glomus, Gigaspora and Scutellospora, with Glomus dominating. Agroforestry practices including use of leguminous tree P. reticulata effectively maintained AMF spore numbers in soils and high AMF colonization levels compared with monocultures, proving an efficient system for productivity and sustainability.     

Moisture extraction and crop yield as a function of distance from a row of Eucalyptus tereticornis

A study was made on the effect of an east-west tree line of years old Eucalyptus tereticornis on soil physical parameters and adjoining mustard and wheat crops as a function of distance from the tree-crop interface in north- and south-facing sides. Maximum soil temperature, pan evaporation, moisture extraction, number of plants/m², and yields of mustard and wheat did not differ significantly on the two sides of plantation. Plant growth parameters decreased linearly with distance from the plantation. Mustard yield, Y (kg/ha) was linearly related to moisture extraction, ME (mm) as Y = 1914–120.3 ME. Eucalyptus tereticornis was found to extract 5 times more water than mustard from 0–150cm soil profile. Mustard and wheat yield reductions in adjoining 10 meter strips on both sides of the plantation were 47 and 34 per cent, respectively. Eucalyptus tereticornis is, therefore, not a suitable species for row plantations in agro-forestry systems in deep water table conditions of semi-arid regions.     

Effect of rhizobial inoculation methods and host plant provenances on nodulation and growth of <Emphasis Type="Italic">Acacia senegal</Emphasis> and <Emphasis Type="Italic">Acacia nilotica</Emphasis>

The purpose of this work was to determine the most efficient methods of inoculation to significantly improve nodulation and growth of Acacia senegal and Acacia nilotica, grown under greenhouse conditions. Our results showed that inoculation using dissolved alginate beads containing rhizobia significantly improved the growth of both acacia species better than the growth of plants in other treatments. The experiment with A. nilotica was conducted in two unsterilised soils from different areas. Plants grown in soil from Bel Air were well-nodulated and showed better growth than plants grown in soil from Sangalkam. However, no difference between these soils was shown between the several methods of inoculation and their effect on the nodulation and growth of plants. An interaction between A. senegal and A. nilotica provenances and the effect of inoculation with rhizobia was also demonstrated. Bel Air provenance of A. senegal, Dahra and RIM provenances of A. nilotica grew best of several provenances tested. These results suggest that (1) it may be possible to improve growth and yield of A. senegal and A. nilotica by careful selection of each symbiotic partner; and (2) nursery-grown seedlings of A. senegal and A. nilotica should be inoculated, just after sowing, with dissolved alginate beads containing a mixture of selected rhizobia. Résumé. Lobject de notre travail était de déterminer la méthodologie dinoculation la plus efficace pour améliorer significativement la nodulation et la croissance dAcacia senegal et dAcacia nilotica poussant dans des conditions de serre. Nos résultats ont montré que linoculation utilisant des billes dalginate dissoutes améliorait significativement la croissance des deux espèces dAcacia par rapport à celle des plantes des autres traitements. Lexpérience avec A. nilotica a été faite dans deux types de sol non stériles. Nous avons observé que les plants poussant dans le sol de Bel Air étaient plus nodulés et mieux développés que ceux poussant dans le sol de Sangalkam. Cependant, aucune différence significative entre les deux sols na été mise en évidence en termes deffet des différentes méthodologies dinoculation sur la nodulation et la croissance des plantes. Il a aussi été démontré lexistence dune interaction entre les provenances dA. senegal et dA. nilotica et leffet de linoculation avec rhizobium. Cest ainsi que les provenances Bel Air dA. senegal, Dahra et RIM dA. nilotica ont le mieux poussé parmi les différentes provenances testées. Lensemble de ces résultats suggèrent: ⁽¹⁾ il devrait être possible daméliorer la croissance et la production dA. senegal et dA. nilotica par une sélection des deux partenaires symbiotiques; ⁽²⁾ Les jeunes plantules dA. senegal et dA. nilotica produites en pépinière devraient être inoculées juste après le semis avec des billes dalginate dissoutes contenant un cocktail de souches sélectionnées.     

Evaluation of native tree species for the rehabilitation of deforested areas in a Mexican cloud forest

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.     

Organic matter amendments to a calcareous forest nursery soil

Organic amendments were added to a southwestern United States forest nursery sandy loam soil to determine the effects on soil nutrient reserves and subsequent growth of 1.5+0 ponderosa pine (Pinus ponderosa Laws.) seedlings. Treatments included irradiated sewage sludge, peat moss and pine bark each at 67 t/ha, sawdust at 43 t/ha, and a control that received no organic matter. Sludge caused immediate increases in soil nutrients, especially N and P. Sawdust resulted in near complete N immobilization 45 d after application. Peat moss and bark did not significantly alter soil nutrients. All treatment effects disappeared within 6 months of application.Amendments did not significantly alter seedling survival, biomass or yield (caliper 3 mm). Seedling biomass was positively correlated with early soil nutrient status, but growth was not significantly improved. The modest, short-term nutritional benefits indicate single applications of organic amendments are ineffective in improving the nutrient status of sandy nursery soils of the Southwest.     

Soil properties and nitrogen availability in silvopastoral plantings of Acacia melanoxylon in North Island, New Zealand

Acacia melanoxylon, a N₂-fixing timber tree occurring naturally in eastern Australia, is now promoted as a component of silvopastoral systems; but the interaction of the tree with pasture and soils has not been adequately studied. This study investigated the effects of Acacia melanoxylon on soil nitrogen (N) levels, N availability, soil pH, bulk density, organic carbon, C:N ratios and soil moisture in three separate silvopastoral sites with contrasting soil types in the North Island of New Zealand. At each site four tree stocking rates were studied (0, 500, 800, and 1700 stems ha^–1). The trees were nine years old at the time of the study. Soil samples from each study site were taken once at three depths (0 to 75 mm, 75 to 150 mm, and 150 to 300 mm), with three replicates per tree stocking rate. Soil analyses showed that although there were differences between soil types, few statistically significant differences occurred due to tree stocking rate. A greenhouse pot trial growing ryegrass (Lolium multiflorum L. cv. Concord) in soil from the A horizon of each soil type from under the trees and the open pasture found that ryegrass yield, N uptake and N supply increased with increasing tree stocking rate. Increased N supply under the trees, coupled with greater soil moisture compared to the open pasture may have accounted for the higher pasture yield under Acacia melanoxylon compared to non dinitrogen fixing tree species. This study suggested that Acacia melanoxylon in a silvopastoral system had the potential to increase soil N availability.This revised version was published online in November 2005 with corrections to the Cover Date.     

Planting frozen conifer seedlings: Warming trends and effects on seedling performance

In temperate climates, conifer seedlings are often held in frozen storage (–2 °C) for extended periods and then placed in cool storage (+2 °C) so the root plug can thaw prior to outplanting. Two plug temperature treatments were used to test the hypothesis that thawing seedlings prior to outplanting may be unnecessary: seedlings were planted with frozen root plugs (frozen seedlings) and with thawed root plugs (thawed seedlings). The experiment was conducted under two watering regimes (irregular, regular) and with three conifer species (lodgepole pine [Pinus contorta var. latifolia], western larch [Larix occidentalis], interior spruce [Picea glauca × engelmannii]) to increase the generality of the results. The warming of root plugs after planting was examined. Thawed root plugs warmed to soil temperature rapidly (about 30 min) while frozen root plugs took longer (to 2 h) because ice in the plug had to melt before temperatures rose. Larger root plugs took longer to warm to soil temperature. Several aspects of seedling field performance were also assessed. For all species, variable fluorescence did not differ between frozen and thawed seedlings. Bud break was faster for thawed than frozen western larch seedlings but did not differ between frozen and thawed seedlings for either lodgepole pine or interior spruce. Height increment differed significantly between frozen and thawed seedlings that received the irregular watering regime; this effect was likely a response to the positioning of irrigation nozzles, which resulted in sporadic and non-uniform irrigation patterns. Height increment did not differ between frozen and thawed seedlings that received the regular watering regime. Root collar diameter and volume increments were not significantly affected by plug temperature treatment under either watering regime. Planting seedlings with frozen root plugs did not hinder field performance over one growing season under these watering regimes.     

Litter of an alien tree, <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis>, inhibits seed germination and initial growth of a native tree on the Ogasawara Islands (subtropical oceanic islands)

We investigated the effects of the accumulation of litter of an alien tree, Casuarina equisetifolia, on the initial establishment of Schima mertensiana, a tree native to the Ogasawara (Bonin) Islands, in the northwestern Pacific Ocean, in field and greenhouse experiments. The field experiment compared emergence of seedlings in forests dominated by C. equisetifolia with those in native forests, with and without litter removal. The greenhouse experiment compared seedling germination and biomass among 12 treatments that included two soil types (collected from the C. equisetifolia and native forests), two litter types (C. equisetifolia and native litter), and three amounts of litter (5, 15, or 45 g/pot). Significantly fewer S. mertensiana seedlings emerged at sites dominated by C. equisetifolia than at sites of native species in the field experiment. Litter removal tended to increase seedling emergence. Fewer and smaller S. mertensiana seedlings germinated with greater litter cover regardless of soil type or litter type in the greenhouse experiment. Our results demonstrate that C. equisetifolia litter suppresses germination and initial growth of S. mertensiana, and that the main cause of the suppression is the greater amount of litter accumulated under C. equisetifolia forest floor rather than factors such as the nature of the soil or litter between native and alien species.     

Indigenous livelihood systems in industrial tree-plantation areas in West Kalimantan, Indonesia: Economics and plant-species richness

An integrated tree plantation approach combining indigenous livelihoods and industrial wood production is being implemented in West Kalimantan, Indonesia. In this study the economics of land-use was investigated in villages within the plantation scheme. The effect of three alternative land-use scenarios and costs and benefits of each land-use type were studied using linear programming. The scenarios were based 1) on the current land-use, 2) on the integrated tree plantation system with incentives and government regulations, and 3) on a financially optimal land-use distribution. Additionally, plant species richness in different land-use types was surveyed. The scenarios had different kinds of effects on villages varying in respect to their possibilities for land-use intensification. In villages with extensive land use, establishment of tree plantations without any land-use regulations increased the potential economic return on land, resulting in conversion of natural and man-made semi-natural forests into swidden fields. In villages with more sedentary agriculture, the plantation scheme did not create pressures towards remaining forests even in the case of financially optimal land-use distribution. Incorporation of land-use regulations prevented further deforestation but also decreased households' economic returns. The results also showed that conversion of Imperata grasslands to any other land-use increased species richness. Incentives, restrictions or regulations aiming at conserving natural and semi-natural forests are needed to ensure conservation of biodiversity and long-term improvements in local livelihoods. It can be concluded that tree plantations can be combined with other land-use practices: They can improve the economic return on land without further degradation of the environment.This revised version was published online in November 2005 with corrections to the Cover Date.     

Selection of efficient VA mycorrhizal fungi for Casuarina equisetifolia—second screening

An investigation was carried out to screen and select efficient vesicular arbuscular mycorrhizal (VAM) fungi for inoculating the forest tree species, Casuarina equisetifolia. The seedlings were inoculated with 10 different VAM fungi, obtained from various sources. Inoculated seedlings generally had greater plant height, stem girth, biomass and P content than uninoculated plants. They also had more mycorrhizal root colonization and spore numbers in root zone soil. C. equisetifolia seedlings responded best (in biomass) to inoculation with Glomus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, closely followed by Acaulospora laevis Gerdemann and Trappe and G. fasciculatum (Thaxter Sensu Gerdemann) Gerdemann and Trappe; all the three being statistically on par with each other.     

Growth,nutrient, water relations,and gas exchange in a holm oak plantation in response to irrigation and fertilization

Eighty 6-years-old Quercus ilex L. subsp. ballota seedlings planted on a former agricultural land were subjected during two growing seasons to one of four treatments: fertilization and irrigation, irrigation, fertilization, and control. Seasonal and between-treatment variations on water relations, gas exchange parameters, growth and nutrient status were analyzed. Water potential () was related to climatic conditions. Thus, the frequent rain storms during the summer allow seedlings to maintain relatively high values, joined to moderate photosynthetic activity. Differences on , photosynthesis and stomatal conductance due to irrigation were shown at the onset and end of growth, related with lower water availability. Fertilization had a greater effect on growth than irrigation. Both fertilization and irrigation positively affected the relative increment on leaf nutrient concentration at the end of the second year. The results indicate that water availability was not a limited factor, thus irrigation is not justified; while fertilization improve growth.     

Provenance and family variation in growth performance of Eucalyptus tereticornis (Sm.) in a provenance cum progeny trial in Midnapore, India

Eucalyptus tereticornis Sm. is an important species for agroforestry and commercial plantations in India. Results of a combined provenance–progeny trial of E. tereticornis laid out in 2002 at Midnapore (West Bengal) located in eastern tropical region of India are reported and discussed. Twelve provenances representing 70 families from Australia and Papua New Guinea were evaluated up to the age of 3 years. As a local seed source open-pollinated seed collected from a land race, i.e., Mysore gum (commonly known as Eucalyptus hybrid) was used to serve as check material (control). Significant variation in plant height, clean stem height, girth at breast height (GBH) and field survival was observed due to provenances, as well as families within provenances. This offers an ample scope to a breeder for increasing the growth and productivity in E. tereticornis through selection of provenances and families having potential for higher productivity. Heritability (narrow sense) values were appreciable for growth traits. Within provenance individual tree heritability estimates for height, clean stem length, GBH and number of branches at age 3 years were 0.318, 0.215, 0.269 and 0.231, respectively (assuming a coefficient of relationship of 0.4 for open-pollinated families of E. tereticornis). Provenance of Walsh River, Queensland Australia performed best for plant height, clean stem height, GBH, number of branches and field survival. Apart from this, the provenance from Oro bay to Emo, Papua New Guinea and Burdekin river, Queensland also showed good performance. Provenance from Yurammie, SF from New South Wales performed poorest for growth and survival. Correlations on growth traits were high and statistically significant, indicating that substantial gains could be achieved through indirect selection for one trait based on the direct selection for another. Age–age genetic correlations between age 1 and 3 years for the growth traits were highly significant and positive. Geographic clinal variation pattern was observed as latitude was negatively correlated with height and GBH (P < 0.05); longitude with number of branches (negative, P < 0.05). Fair differences were observed between phenotypic and genotypic coefficient of variability.