Agroforestry for water management in the cropping zone of southern Australia

Agroforestry has been advocated as a means of managing excess water that has accumulated in the agricultural landscape of southern Australia since clearing of native vegetation. This article examines the feasibility and profitability of agroforestry systems designed to manage rising, saline watertables. A framework for Australian conditions is described that considers the interactions between trees, crops and their below ground environment and how they influence water use, crop yield and profitability. Data is presented from a study of a commercial scale agroforestry system under ideal conditions where trees have access to a shallow fresh water table. The discussion is then broadened to encompass soil, relief and ground water conditions more typical of the southern Australian cropping zone. The relative merits of segregating, integrating and rotating trees with crops are then examined. It is concluded that, in most cases, trees would need to be widely dispersed over a significant proportion of the landscape to manage deep drainage and salinity. Agroforestry is therefore only likely to be an effective solution to water management where trees can compete directly on commercial terms with conventional agriculture. Given the generally low rates of biomass accumulation in semi-arid woody species, this presents a significant challenge for agroforestry in the cropping zone of southern Australia. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of shelter on temperate crops: a review to define research for Australian conditions

The fact that the shelter created by windbreaks can have a significant, positive effect on crop production is supported by eight decades of research from many countries around the world. Although the concept of planting windbreaks to enhance crop production has general currency in Australia, the practice is not as wide as it could be. This review of the last decade of windbreak literature defines the research needed to encourage wider utilisation of windbreak technology. After outlining the principal mechanisms behind the effect of shelter on temperate crops, the review discusses relevant literature of the past decade especially that from Australia. The main mechanisms discussed are: the protection of crops from physical damage; soil conservation; the direct augmentation of soil moisture; and the alteration of the crop energy balance and plant water relations. Also discussed are the elusiveness of the shelter effect, competition from windbreak trees, and the modelling of windbreak systems. Suggestions for future research in Australia include: quantifying the competition of various windbreak species and the effect of root pruning on both crop and tree; a model of crop energy and water relations at the tree-crop interface; an economic model and a farmer-oriented decision support tool. This revised version was published online in June 2006 with corrections to the Cover Date.     

The role of agroforestry in industrialized nations: the southern hemisphere perspective with special emphasis on Australia and New Zealand

Agroforestry in Australia and New Zealand is dominated by silvopastoralism. Farmers may employ combinations of shelterbelts, shade trees, widely spaced trees over pasture, or more densely planted woodlots. In addition to wood production and shelter, erosion control, amenity and landscape planting, and conservation of natural forest are often important. Many farm forestry people show considerable innovation.In temperate wetter areas of Australia, eucalyptus and, to a lesser extent,Pinus radiata (radiata pine) dominate agroforestry tree plantings for wood, shade, shelter, and salinisation and erosion prevention. The One Billion Tree Program, initiated by the Australian Federal Government, provides limited funding for tree planting. Joint farmer ventures with the State or local industry are also common. Most State governments also provide advice, and planting is tax deductible. Local landcare groups, formed to encourage sustainable agriculture, often promote tree planting, particularly where soil degradation is a problem. Melbourne University and other Techncial Institutes offer training in agroforestry.In New Zealand, a third of the farms require trees for soil conservation. This, together with the growing recognition of the financial benefits of planting trees, has resulted in small landowners doing most of the current planting of 80,000 to 100,000 ha yr^–1. Most farmers plant radiata pine, but eucalyptus and other hardwoods, including willows and poplars, are also widely used. There are almost no government incentives for tree planting in New Zealand. The Farm Forestry Association is the major extension organization. Lincoln University has an important teaching and research commitment, and the New Zealand Forest Research Institute Limited has developed very useful management models.     

Tree Performance and Root-Zone Salt Accumulation in Three Dryland Australian Plantations

Doubts exist about the effectiveness of establishing trees near saline discharge areas on farmland to manage dryland salinity. These centre on low rates of water uptake from saline water tables, salt accumulation in tree root zones and the consequent poor growth and survival of trees. Despite this, trees still survive in many plantations established adjacent to saline discharge areas and land-holders often favour such locations, as they do not compete for arable land such as that occurs with plantings in recharge areas. Tree performance and salt accumulation were assessed in three experimental plantations established adjacent to saline discharge areas 20–25 years ago. These were all in the 400–600 mm rainfall zone of south-western Australia. Mean soil salinity, within 1 m of the surface, ranged from 220 to 630 mS m⁻¹, while permanent ground-waters occurred within 2–5 m of the surface and had electrical conductivities ranging from 175 to 4150 mS m⁻¹. The study confirmed the low growth rates expected for trees established over shallow, saline water tables in a relatively low rainfall environment, with estimated wood volumes in Eucalyptus cladocalyx, E. spathulata, E. sargentii, E. occidentalis and E. wandoo of between 0.5 and 1.5 m³ ha⁻¹ yr⁻¹. Values of up to 3 m³ ha⁻¹ yr⁻¹ were obtained on soils with low salinity (<200 mS m⁻¹). The excellent survival (>70%) of several Eucalyptus species confirms that discharge plantations species can persist, despite increasing soil salinity. However, the long-term sustainability of such plantings (50–100 years) without broader landscape treatment of the present hydrological imbalance must be questioned.     

变色牵牛扦插繁殖和垂直绿化应用初步研究

变色牵牛（Pharbitis indica）是旋花科常绿藤本，具有适应性强，生长快，花色艳丽，花期长的特点，是热带亚热带地区极具应用前景的垂绿化植物。近年深圳将其用于垂直绿化，本文报道了该植物的生物学特性、扦插繁殖技术及其在立交桥美化的应用的生长表现，并提出栽培技术措施建议。     

Short-term responses to salinity of seabuckthorn (Hippophae rhamnoides L.) seedlings in the extremely cold and saline Qinghai region of China

The investigation of the mechanisms of plant adaptation to stressor action is one of the leading directions of current biological studies. To understand the mechanism of salt tolerance of seabuckthorn (Hippophae rhamnoides L.) and identify its ability to cope with the salinity effect in the saline and extremely cold region of Qinghai, China, a test was conducted with two-year-old seedlings subjected to 0, 200, 400 and 600 mmol·L–1 NaCl solutions for 30 d. The results show that with an increase in salinity, the biomass of H. rhamnoides seedlings clearly decreased. Leaf water potential (Ψw) and relative water content (RWC) were significantly reduced under salinity, with severe water shortages appearing in leaves. At the same time, the total chlorophyll content declined markedly. When salinity increased and stress time prolonged, the net CO2 assimilation rate (A) significantly declined. Intercellular CO2 concentration (Ci) declined at first and was then followed by an increase over the stress time. We conclude that H. rhamnoides grown in the extremely cold and saline region of Qinghai has a certain resistance to salt, which can be planted at appropriate salinity levels.     

Enhanced transpiration in response to wind effects at the edge of a blue gum (Eucalyptus globulus) plantation

In Australia, tree planting has been widely promoted to alleviate dryland salinity and one proposed planting configuration is that of strategically placed interception belts. We conducted an experiment to determine the effect of tree position in a belt on transpiration rate. We also assessed how much the effect of tree position can be explained by advection and environmental conditions. Daily transpiration rates were determined by the heat pulse velocity technique for four edge and 12 inner trees in a 7-year-old Tasmanian blue gum (Eucalyptus globulus) plantation in South Australia. Various climatic variables were logged automatically at one edge of the plantation. The relationship between daily sap flow and sapwood area was strongly linear for the edge trees (r2 = 0.97), but only moderately correlated for the inner trees (r2 = 0.46), suggesting an edge effect. For all trees, sap flow normalized to sapwood area (Qs) increased with potential evaporation (PE) initially and then became independent as PE increased further. There was a fairly close correlation between transpiration of the edge and inner trees, implying that water availability was partially responsible for the difference between inner and edge trees. However, the ratio of edge tree to inner tree transpiration differed from unity, indicating differences in canopy conductance, which were estimated by an inverse form of the Penman-Monteith equation. When canopy conductances were less than a critical value, there was a strong linear relationship between Qs of the edge and inner trees. When canopy conductances of the edge trees were greater than the critical value, the slope of the linear relationship was steeper, indicating greater transpiration of the edge trees compared with the inner trees. This was interpreted as evidence for enhancement of transpiration of the edge trees by advection of wind energy.     

棕榈藤的研究和发展

棕榈藤是热带和南亚热带森林宝库中的多用途植物资源,原藤是仅次于木材和竹材的重要林产品,具有重要的经济价值.概述了国内外棕榈藤物种资源天然分布及其利用状况;阐述了国内外棕榈藤的研究和发展现状;提出今后的研究和发展方向.并简要论述了主要优良商品藤种的生态生物学特性和发展种植业的关键技术,及原藤产后加工利用技术,预测产品市场的发展动向.     

Investigation of salinity impacts on germination and growth of two forest tree species at seedling stage

Soil salinity is becoming an increasingly serious constraint to plant growth in many parts of the world;this is particularly common in semi-arid and arid zones. This study was conducted to evaluate the...     

Effects of agroforestry-pasture associations on groundwater level and salinity

Stream and land salinisation brought about by rising groundwater levels due to the clearing of native forest for agricultural development is a major environmental and resource problem in Western Australia and several other semi-arid regions of the world. One potential approach to reclamation with simultaneous economic benefits is agroforestry. To determine the effects of agroforestry on groundwater level and salinity, two experiments were carried out in Western Australia. In Experiment I a pinius-pasture agroforestry covering 58% of the cleared area with final stem densities of 75–225 stems ha⁻¹ was successful in lowering a saline groundwater table. Over the period 1979–1989, groundwater levels decliend by 1.0 m relative to groundwater levels beneath a nearby pasture site. In Experiment II the eucalyptus-pasture agroforestry covering 57% of farmland at a final density of 150–625 stems ha⁻¹ was found to successfully lower the yearly minimum groundwater level by 2.0 m relative to a pasture site over seven years. The salinity of the groundwater beneath agroforestry decreased by 9% and 6% for Experiments I and II respectively, which was contrary to some early expectations. The design of agroforestry for controlling saline groundwater tables needs further evaluation with respect to species, stem densities and proportion of cleared area planted.     

植物耐盐机理与耐盐植物选育研究进展*

文中结合对植物耐盐生理基础的讨论，综述了耐盐植物，尤其是耐盐树木的选育研究进展。植物对盐分胁迫的反应和适应是一个复杂的生理过程，既有蛋白质、核酸、碳水化合物等结构和能量物质的代谢，还有酶、激素等生长调节物质的合成与激话。在这一系列的反应过程中包含着离子交换与逆向运输，信号刺激与传递．基因活化与合成，其中渗透调节起着关键作用；在渗透调节过程中，离子如K^ 、Ca^2 等在浓度和时空上的变化对渗透调节的启动，调节速率和调节能力都有着重要作用。此外，脯氨酸、脯氨酸甜菜碱、甘氨酸甜菜碱等作为可配伍溶质在调节渗透势变化、整合盐分离子方面有着无可代替的作用。Ca^2 |作为第二信使的一个重要组成部分．在胁迫信号传递方面的功能正受到日益重视。激素如ABA在渗透调节和胁迫基因的诱导方面发挥了重要作用。胁迫基因目前主要是指渗透调节基因。首先在细菌中被发现，后来在高等植物中也相继分离克隆出来。有许多不同的方法用来选育耐盐植物，包括选、引、育等常规育种方法和基因工程，突变体育种等生物工程方法。它们各有特点．都发挥了各自的作用。对植物耐盐机理有限的认识以及高等植物结构与功能的高度复杂性制约着耐盐植物选育工作的进展。     

改土排盐工程措施成功应用——盘锦船舶工业基地四号路绿化

盘锦船舶工业基地土壤盐碱化极其严重,因此对于该工业基地的四号路绿化项目,面临的最大困难不是景观设计,而是如何做好盐碱地土壤改良、采取何种排盐措施、选择哪些耐盐碱植物以及如何栽植养护管理的问题。文章在借鉴一些成功案例的基础上,结合四号路绿化项目设计和施工的实际经验,详细阐述了四号路的立地条件以及排盐技术措施,以期与业内同行切磋。       

The development of reforestation options for dryland farmland in south-western Australia: a review§

Current forest industries in south-western Australia are based on regrowth natural eucalypt forests and Pinus and Eucalyptus spp. plantations, and restricted to areas with >600 mm y^?1 annual rainfall. Dryland farming systems have been developed across 20 million ha in a zone with 300–600 mm y^?1 annual rainfall and a Mediterranean climate. This zone is beset with land degradation problems, such as salinity and wind erosion, and there has been considerable effort in the last three decades to develop reforestation options to stabilise the landscapes. Traditional forestry approaches using pulp wood or sawlog production in this zone have been limited by unfavourable economics driven by modest tree growth rates, large transport costs to processing and export facilities, and high labour costs. Given that salinity results from a disruption of the landscape water balance, reforestation has represented a major component in attempts to tackle the problem. Issues with reforestation include (1) obtaining sufficient scale of activity to impact watershed water balances, (2) obtaining a hydrological response without displacing farm production and rural communities and (3) gaining payment for non-forest benefits. This paper reviews the approaches that have been used to integrate trees into the dryland farming (300–600 mm y^?1 annual rainfall) systems of south-western Australia, and have resulted in at least 113 286 ha of reforestation. These included both traditional (pine and eucalypt sawlogs) and new (sandalwood, biodiversity restoration and carbon mitigation through bioenergy and carbon sequestration) projects. Ongoing investment has centred on carbon sequestration as this represents one of the few profitable options for the management of dryland salinity in this region. Approaches developed in this region to encourage farmland reforestation will be applicable in other dryland regions, particularly with the interest in using the land-sector to meet climate mitigation targets.     

Trends in global wildfire potential in a changing climate

The trend in global wildfire potential under the climate change due to the greenhouse effect is investigated. Fire potential is measured by the Keetch-Byram Drought Index (KBDI), which is calculated using the observed maximum temperature and precipitation and projected changes at the end of this century (2070–2100) by general circulation models (GCMs) for present and future climate conditions, respectively. It is shown that future wildfire potential increases significantly in the United States, South America, central Asia, southern Europe, southern Africa, and Australia. Fire potential moves up by one level in these regions, from currently low to future moderate potential or from moderate to high potential. Relative changes are the largest and smallest in southern Europe and Australia, respectively. The period with the KBDI greater than 400 (a simple definition for fire season in this study) becomes a few months longer. The increased fire potential is mainly caused by warming in the U.S., South America, and Australia and by the combination of warming and drying in the other regions. Sensitivity analysis shows that future fire potential depends on many factors such as climate model and emission scenario used for climate change projection. The results suggest dramatic increases in wildfire potential that will require increased future resources and management efforts for disaster prevention and recovery.     

Principles and Practice of Forestation in Saline Soil in China

China is the most populated country in the world, andits land area is not the largest, especially its cultivatedland is gradually declining with socio-economicdevelopment. In order to meet the demand to grain,vegetable and so on, wasteland must be reclaimed(Zhang Jianfeng, 2004). In China there is a large scaleof salt-affected land, e.g. in Lop Nur 5 000 km2, inTurfan almost the same, in Quidam Basen 20000 km2 (Gong Hongzhu, et al, 1984). Owing toadverse conditions crops growing in salty s…     

Salt tolerance of frost-resistant eucalypts

Nineteen frost-resistant Eucalyptus species were screened for salt tolerance under glasshouse conditions. This study was undertaken in order to determine the potential of these species for planting on dryland salt-affected sites in the frost-prone Tablelands of south-eastern Australia. Seedlings were established in sand-filled pots and exposed to a step-wise increase in NaCl concentration to a maximum of 500 mol m^–3. Salt tolerance was assessed on the basis of mortality, leaf damage and height growth. All species in the subgenus Symphyomyrtus , particularly those in the Section Maidenaria Series Ovatae, were moderately salt-tolerant (no mortality at 300 mol m^–3 NaCl) whereas those in the subgenus Monocalyptus proved to be very salt-sensitive (no survival at 300 mol m^–3 NaCl). Eucalyptus camaldulensis, E. tereticornis and E. occidentalis were the most salt-tolerant species of those included in this study. Salt-sensitive species had shoot Na⁺ and Cl^– concentrations of up to 2.25 mmol g^–1 dry wt.

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Recent trends in nursery practice in New Zealand

The plantation resource in New Zealand is now 1.73 million hectares, of which 90% is Pinus radiataD. Don (radiata pine). The resource has been expanding at over 50,000 ha per year since 1992, although new planting is currently declining. In 1998, new planting and restocking of previously clear-felled areas was 81,100 ha. Initial stocking rates vary, but are typically in the range of 800–1000 plants per hectare, requiring around 80 million nursery plants to be raised per year.Sufficient open-pollinated seed is produced for New Zealand requirements. An increasing proportion of more expensive control-pollinated seed is being used to increase genetic gain. This has led to increased use of vegetative propagation by cuttings and tissue culture, providing more than 25% of current planting stock. These propagules, especially cuttings, often have better early performance compared with seedlings, perhaps because of their larger size. Clonal forestry options are also now being evaluated.Seedling quality specifications have been well defined for bare-root radiata pine, but not well quantified for more recent plant types such as vegetative propagules or container-grown plants. Both root system quality and physiological age can be important for vegetative propagules. These propagules, especially cuttings with a physiological age of less than 4 years, have performed as well as seedlings for growth, and have been better than seedlings for stem form and early stability. Container-growing of planting stock is being introduced with this more valuable genetic material, and issues of plant quality are being raised, as it is expensive to grow large stock in containers. More research should be done to determine what plant quality standards are required to ensure successful establishment with these stock types.     

The role of shelter in Australia for protecting soils,plants and livestock

The purpose of this review is to examine the current knowledge of the role of trees in providing shelter for pastures, crops, and livestock, for controlling erosion of soils and improving productivity and sustainability of agricultural production in Australia — and the extent to which this knowledge has been applied.Land degradation — tree loss and associated soil salinity, water and wind erosion, soil acidification, soil structural decline and nutrient degradation — is evidence that our primary production systems are not sustainable. We have sought increased production without proper consideration of the ecological context of that system. About half of Victoria's crop and pasture lands are affected or at risk, and in Western Australia about 25% of the cleared agricultural land is wind-eroded and 60% is potentially susceptible, salinity affects 0.43 m ha and half of the divertible surface water is affected by salinity. Similar problems occur in other States. At least 43 m ha or 13% of our rangelands are seriously degraded by wind erosion caused by overgrazing, often coinciding with drought or a run of drier years.Minimum tillage and stubble management for erosion control in cropping has been a major extension and research activity in Australian agriculture. Severe weather, combined with imperfect adoption of appropriate grazing and crop management systems, shows the weakness of complete reliance on these methods of erosion control. An effective system must accommodate the impact of extreme events, which are the most damaging. However, the complementary use of windbreaks to reduce soil erosion is rare, and their establishment has not been promoted, despite the wide-spread adoption of this technology by other countries.In the cropping and higher rainfall grazing areas, the systematic planting of 10% of the land in a net of shelterbelts/timberbelts/clusters could achieve a 50% windspeed reduction; this would substantially improve livestock and pasture production in the short and long-term. Wind erosion could be dramatically reduced and crop production probably increased by the use of windbreaks. Wheat and oat yield at Rutherglen (Victoria), and lupin yield at Esperance (Western Australia), were increased in the sheltered zone by 22% and 47%, and 30%, respectively.In semi-arid and dry temperate areas, planting of 5% of the land to shelter could reduce windspeed by 30–50% and soil loss by up to 80%. This planting would also contribute substantially to achieving other objectives of sustainable agriculture. Agroforestry — particularly timberbelts applications — will be important in the long-term strategy for achieving revegetation. If some of the trees yield a marketable product then the adoption of the system will be more readily achieved.In the arid (pastoral) areas there is an urgent need to promote the ethic that preservation and improvement of the perennial grass and shrub vegetation is critical for the protection of the soil and maintenance of land capability. Control of animal grazing remains the sole means of preventing erosion in much of this zone. While satellite imagery allows us to assess the condition of leasehold lands, we have failed to achieve stocking policies that will halt the degradation of our rangelands.     

Socio-economic factors affecting smallholder tree planting and management intentions in Leyte Province,Philippines

Survey data have been collected from four rural communities in Leyte Province, the Philippines, on household tree planting and management intentions, as well as the socio-economic characteristics, attitudes to tree planting and management, farming practices and the number of trees planted. In relation to intended tree planting and management activities, respondents were asked a series of structured questions as to what tree species they intend to plant, how many individual trees of each of those species they plan to plant, and for what purpose they propose to plant each of the tree species. This paper reports the results of analyses of the stated tree management intentions of households in the four communities and identifies the socioeconomic factors that influence householders’ tree management intentions. Respondents were generally enthusiastic about the possibility for further tree planting on their land, 75% indicating they would undertake planting. About 60% indicated an interest in commercial tree farming, with no significant differences in this level of interest between communities. It was found that a number of socio-economic variables indicating higher levels of land ownership and previous experience in the forestry industry are related to the intention to plant trees to produce timber for sale. These include the use of materials from public lands, participation in community organisations and community forestry programs, and the present management of trees to produce timber for sale.     

珠海淇澳岛的杨叶肖槿引种育苗试验

在珠海淇澳-担杆岛省级自然保护区,开展了半红树植物杨叶肖槿(Thespesia populnea)引种育苗试验。结果表明:温室盆栽条件下,杨叶肖槿在盐度≤3‰的土壤中可正常生长,土壤盐度≥6‰,将不利于生长;2009年2月寒害调查表明,与其他半红树植物(银叶树、水黄皮和海芒果)相比,杨叶肖槿苗期的抗寒性稍差;种植于高潮滩后,杨叶肖槿苗(0.5年生)的越冬保存率为78.3%,1年生苗均高27.4cm,长势良好、无病虫害。杨叶肖槿在珠海淇澳岛具有较好的适应性和生长性状,引种栽培潜力较大。