华山古树名木衰败死亡原因及保护措施初探

通过对华山古树名木的调查,特别是对死亡古树名木的调查分析,阐明了影响华山古树名木衰弱死亡的原因是干旱、雷击及病虫危害,并提出了加强华山古树名木保护管理的对策和措施。     

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.     

河南省古树名木资源调查分析

采用实地现场调查为主,结合访问当地群众的方法,以县(市、区)为单位,对河南省的古树名木进行了逐株普查.结果表明:河南省古树名木分布范围广,各市种类数和株数有较大差异.全省古树共计528457株,名木211株,古树群617个,其中,散生古树29917株,隶属61科、147属、236种,树龄为100～299a、300～49...     

Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica III. Cycles of organic matter and nutrients

Models for cycles for organic matter and nutrients element (N, P, K, Ca and Mg) are presented for the agroforestry systems of cacao (Theobroma cacao) withCordia alliodora orErythrina poeppigiana in Turrialba, Costa Rica. For the models, system reserves (soil, humus, vegetation divided into leaves, branches, stems, fine roots, fruits) and transference between compartments (production and decomposition of litter residues) inputs (fertilizer, rainfall) and outputs (harvests) of the system are considered. The implications of the models are discussed in detail. Aspects of net primary production in the systems studied are considered. N fixation is calculated on the basis of balances. Analysis of soil water showed high variations that coincided with rainfall patterns and pruning of theE. poeppigiana. For part I see Vol. 4, No. 3, 1986 For part II see this issue Agroforestry Project, CATIE/GTZ (Tropical Agricultural Research and Training Center/Gesellschaft für Technische Zusammenarbeit), Turrialba, Costa Rica     

The dehesa: an agrosilvopastoral system of the Mediterranean region with special reference to the Sierra Morena area of Spain

A multidisciplinary team undertook a six-year investigation on the agro-ecological and socio-economic aspects of the dehesa system in the Sierra Norte area, a part of the Sierra Morena of the Sevilla Province, Western Andalusia, Spain. This paper summarizes its findings on the various agro-ecological features of the system and evaluates the system's functional aspects vis-a-vis the trends and developments in land use in the region over the past few centuries. The synergistic effects of tree cover on understorey grassland vegetation is discussed in terms of soil fertility build-up and favourable micro-climatic and hydrological features, and the potential use of this information in future research and development programmes to improve the dehesa system in the Mediterranean region is outlined.     

香港行道树管理优化探讨

结合实际情况,分析香港市区行道树安全管理在综合管理措施、规划设计建设、种植养护技术等方面存在的不足,其管理观念及技术已经不符合当前绿化生态的理念及发展。继而针对性提出健全管理机构、优化技术措施、加强各部门的宏观协作等建议。     

Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica

The agroforestry systems of cacao (Theobroma cacao) under laurel (Cordia alliodora) and cacao under poro (Erythrina poeppigiana) were studied at CATIE, Turrialba, Costa Rica. An inventory was taken of the organic matter and nutrients (N, P, K, Ca, and Mg) separating the species into their compartments (leaves, branches, trunks and roots). Studies of the litter and of the mineral soil (0–45 cm) yielded these results: Patterns of nutrient accumulation are discussed in relation to the characteristics of these agroforestry systems.     

泰山岱庙古树名木的现状与保护

为掌握泰山岱庙古村名木的生长状况，在进行调查的基础上分析了古树名木生长不利的因素，提出了泰山岱庙古树名木保护中存在的问题，并阐述了古树名木的保护措施。     

陕西省延川县孙家塬经济林土壤水分和水分平衡

对陕西省延川县孙家塬枣树林和苹果林4m深度土层水分的变化进行了研究,并对土壤水分有效性、土壤干层及其水循环等方面进行了分析。结果表明,枣树林地含水量平均为10.6%,还有4.5%的土壤水资源可以利用。苹果林地4m深度范围内平均含水量为7.4%,2.0—4.0m深度范围内土壤水资源基本耗尽。苹果林地土壤含水量自上向下呈现高—低—高分层变化特点,枣树林地土壤水分剖面垂向分层不明显。枣树林地和苹果林地土壤水分基本都呈难效水状态,但枣树林土壤水分接近中效水,土壤水分对苹果林生长具有严重的抑制作用,对枣树林的生长基本没有抑制作用。枣树林地2.0—4.0m深度范围仅有轻度干层发育,苹果林地土层2.0—4.0m深度范围有轻度干层、中度干层和重度干层发育。苹果林地和枣树林地土壤干层切断了深层水分与上层的联系。水循环主要表现为地表水循环,基本不存在地下水循环,形成了土壤—植物—大气的水分循环模式,属于异常水分循环类型。干层长期发展会导致该区地下水位的持续下降和地下水资源减少。该区土壤水分条件更适于发展枣树经济林。     

栗实蛾幼虫空间格局及抽样技术研究

对7个板栗园栗实蛾幼虫空间格局进行了研究.结果表明,栗实蛾幼虫在板栗园中的分布是遵循负二项分布的聚集分布,其中Iwao的m*-m回归模型为m*=3.532 3+1.071 0m,Taylor幂模型为lgv=0.591 3+1.130 4 lgm.对各聚集度指标的分析结果显示:在板栗园中的栗实蛾幼虫彼此之间互相吸引,分布的基本成分是个体群,个体群为聚集分布,且在任何密度下都是聚集的,聚集强度随着密度的升高而增大.导致栗实蛾幼虫在板栗园中呈聚集分布的原因是由该虫本身的习性和环境共同造成的.栗实蛾幼虫虫口密度调查的最适理论抽样数公式为n=t2/D2(4.532 3/m+0.071 0).