Productivity of four sesbania species on two soil types in Ethiopia

In Ethiopia, lack of quality forage in adequate quantities is a major constraint to livestock productivity. Fast growing N₂ fixing Sesbania have shown great promise both as high quality fodder and green manure. The objective of this study was to evaluate and select among the species S. macrantha, S. rostrata, S quadrata and S. sesban for fodder yield, quality and green manure potential. The field experiment was conducted on a light soil (loam, Alfisol) and a heavy soil (cracking type clay, Vertisol) at Debre Zeit (9° N and 39° E, 45 kms SE of Addis Ababa). There were two cutting treatments: cutting once at ground level or cutting twice at 50 cm (first, 65 days after sowing; second, 40 days later). A two-factor factorial in randomized block design was used. S. macrantha performed better on the light soil producing the highest dry matter (DM) yields of leaf (2.8 t/ha), stem (6.3 t/ha) and total nitrogen (151 kg/ha) in 105 days than the rest of the species. Most species performed poorly on the heavy soil. S. quadrata, however, showed better adaptability to the heavy soil (5.5 t/ha DM) than any of the other species. The lowest DM yield was recorded for S. rostrat which could be due to poor nodulation. Cutting twice over the 105 days growth period caused a drastic reduction in DM yield, but resulted in higher leaf-to-stem ratio and total N yield. The nutritional composition of all the species was within an acceptable range for livestock requirements. N content (4%) and IVDMD (over 70%) were high. S. macrantha had superior overall performance and seems promising both as high quality fodder and green manure crop. Under rain-fed conditions, cutting once was better than cutting twice particularly for S. macrantha. This revised version was published online in June 2006 with corrections to the Cover Date.     

Enhancement of seed germination in Macaranga peltata for use in tropical forest restoration

We used pre-sowing treatments v/z., soaking seeds in concen- trated sulphudc acid （CSA）, gibberellic acid （GA）, combined treatment of CSA ＋ GA and mechanical scarification to overcome seed dormancy and enhance synchronous germination of Macaranga peltata seeds. We analysed percent seed germination data by logistic regression and con- finned that except in GA treatment, time and acid concentration together were crucial for enhancing germination. The combination treatment of CSA and GA resulted in higher percent germination （up to 74%） than either treatment used separately, but produced defective seedlings （26%）. Mechanical scarification of seed coat had the greatest impact in enhanc- ing germination （78%） and reducing imbibition time （6 days） against the control （0%）. Germination studies and SEM analysis confirmed that seed germination in M. peltata was inhibited by seed coat dormancy.     

Establishment patterns of woody species in low intensity-grazed pastures after the cessation of intensive agricultural use

Low intensity grazing with large herbivores is increasingly used to steer the development of mosaic landscapes (including wood-pastures) and woodland expansion on former agricultural land. We studied the establishment and early growth pattern of woody species in grasslands (formerly used for high intensity summer cattle grazing) in which a low intensity-grazing regime was set up between 4 and 11 years ago. We tested whether the developing vegetation patches, consisting of tall herbs and scrub, influenced this pattern. Further, we investigated if increased susceptibility to trampling disturbance by large herbivores on wet soils in floodplains influenced sapling establishment.Formerly intensively used grasslands were studied at six sites, four in floodplains and two in interfluvial zones on nutrient rich, heavy soils. In total, we sampled 141 plots with grassland, tall herb or scrub vegetation and recorded individuals of established tree and shrub species, their height, diameter, browsing damage and distance to potential seed sources. In the floodplains, we recorded soil disturbance by large herbivores (hoofprints) in wet and moist soils.Sapling frequencies, with Fraxinus excelsior as the most common species (>50% of all individuals), were two to three times higher in tall herb and scrub patches compared to grassland. Only the spiny Crataegus monogyna established in higher frequencies in grassland plots. In floodplains, we found two to three times more established woody saplings in wet tall herb plots, compared to moist and wet grassland plots and moist tall herb plots.Browsing reduced sapling height in grassland and tall herb patches. Only in scrub patches did average height (±2.5 m) reach above the browse line. We found 30–70% less browsing damage to saplings in scrub compared to damage in grassland and tall herb plots. In particular, damage to the apical shoot was strongly reduced.Our findings show that tree establishment occurs in spatial association with non-grassland patches that offer protection against browsing. Fast growing spiny shrubs like Rubus sp. offer protection for palatable saplings, allowing establishment and growing out beyond the browse line. Alternatively, increased establishment occurs in wet tall herb patches, where soil disturbance by moderate trampling favours germination and, subsequently, saplings are protected at least temporarily against browsing by unpalatable tall herbs.     

An ecophysiological evaluation of the suitability of Eucalyptus grandis for planting in the tropics

Water use by eucalypts has received a lot of attention in tropical countries during the past decade because of the large-scale introduction of these trees for afforestation. Eucalyptus grandis, widely used as a plantation item in tropical southern India, is the subject of a detailed ecophysiological study in this paper. A 4-year-old coppiced plantation was used for measurements. Microclimate data collected above the canopy were used along with stomatal conductance measurements to estimate the transpirational water loss by the Penman-Monteith equation assuming a two-layer canopy model. Leaf photosynthesis was measured diurnally and seasonally to understand the limitations in photosynthesis in the field. Results show that the water loss from the plantation ranges between 2.5 and 6.5 mm day⁻¹ depending on the season. When suitably extrapolated, this amounts to 1181 mm annually in the study location, where annual rainfall averages 1302 mm. The stomatal conductance measurements showed that the increase in atmospheric vapour pressure deficit induced stomatal closure. This was probably regulated by the leaf water potentials also. Based on the above results it is concluded that E. grandis need not be a high water consumer because of its good stomatal control of transpirational water loss, especially during the dry season when the atmospheric vapour pressure deficit is high. The photosynthesis measurements led to a conclusion that the dry period experienced in the study location does not seriously affect the photosynthetic rate of the trees on a leaf unit area basis.     

常绿阔叶林择伐伐区作业综合评价优化模型

以最大净收益与对林地破坏最小为目标 ,综合考虑了采伐作业对林地破坏、林木损伤、生产成本等因素 ,建立常绿阔叶林最优择伐模型。     

Cutting management of alley cropped leucaena/gliricidia-Guinea grass mixtures for forage production in southwestern Nigeria

A study was conducted at Fasola (7°45 N and 3°5 E) in southwest Nigeria to determine the best tree cutting scheme for forage production and the effects of hedge configurations on tree, grass and total forage productivity of 6–8-year-old leucaena (Leucaena leucocephala Lam. de Wit) and gliricidia (Gliricidia sepium Walp.)-Guinea grass (Panicum maximum Jacq. cv. Ntchisi) mixture. After a uniform cut at the end of January 1990 (mid-dry season), the trees were cut according to the following cutting regimes: one cut after a 12-month regrowth (12M); two cuts after three- and nine-month regrowth (3–9M); two cuts every six months (6-6M); two cuts after nine- and three-month regrowth (9-3M); three cuts, two cuts every three months and the third cut after a six-month regrowth (3-3-6M), and four cuts every three months (3-3-3-3M). Grass was cut every six weeks between April and October followed by a cut in January. The hedge configuration was either one or three hedgerows of mixed stands of leucaena and gliricidia. There were twice as many trees and one-third less grass in the triple than in the single hedgerow hedge configuration.The 3-3-3-3M, 9-3M and 3-3-6M cutting regimes produced the highest total forage (tree foliage + grass) dry matter yields (DM) of 6.54, 5.80 and 5.77 t DM ha^–1 annum^–1, respectively. The magnitude of the difference between the tree forage yields of the triple and single hedgerow plots (16%) did not reflect the theoretical difference in the number of trees (33%) in the two arrangements.     

豆腐柴扦插生根条件的初步研究

用不同浓度的吲哚乙酸和赤霉素处理不同年龄的豆腐柴插条,插条栽培在河沙和黑壤土基质中,选择促进插条生根和成活的最佳条件。结果表明,豆腐柴的多年生枝条比1年生枝条扦插的成活率高,土培插条比砂培插条的生根率高,100×10-6以下浓度的吲哚乙酸和赤霉素能显著促进插条的生根和根系发育,50×10-6的低浓度时赤霉素对2~3年生插条的效果更明显。     

西北地区水土保持林建设的三大热点问题研究

与西北地区水土保持林建设密切相关的土壤干燥化、有害生物防治和水土保持林建设质量问题为西北地区水土保持林建设的三大热点问题。本文分别论述三大热点问题的研究现状和发展趋势,并对西北地区水土保持林建设质量的内涵和提高途径进行探讨。提出水土保持林建设质量问题是三大热点问题的核心。水土保持林建设质量的持续提高不仅要依靠水土保持林...     

湿地松采穗圃修剪促萌技术研究初报

本试验针对湿地松采穗圃的修剪高度、修剪时间、施肥量3个因素采用正交设计开展试验,结果表明：湿地松采穗圃穗条的萌芽时间和修剪时间、修剪高度有关,修剪时间早,萌芽较晚,保留母株高度越高,萌芽时间越早;采穗圃母株的修剪高度对穗条的数量有显著影响,以12 cm的修剪高度获得的穗条数量最多;采穗圃的修剪时间对穗条长度有显著影响,3月22号修剪的母株萌发的穗条最长;采穗圃的修剪时间、修剪高度、施肥量对穗条粗度均无显著影响.     

日光温室内作物干物质积累预测新方法研究

介绍了一种有效结合神经网络和作物生长模型预测目光温室内作物干物质积累的方法，该方法既解决了经验模型的解释性和广适性差的缺点，又解决了机理模型难以理解和使用、输入多而输出欠稳定的不足。以有效光照积累和有效积温作为输入参数，以作物的干物质积累作为输出参数建立神经网络，利用大量实测数据对神经网络结构进行训练，建立作物干物质积累与有效光照累积和有效积温之间的关系，从而对干物质积累进行预测。并以目光温室内黄瓜为例，采用此方法对其进行干物质积累的预测，与实际测量结果相比较，误差率不超过10％。     

Selected physical and chemical properties of mechanically extracted neem seed oil sourced as a preservative for ligno-cellulose in southwestern Nigeria

Most of the seeds produced by neem (Azadirachta indica A. Juss) trees in Nigeria are currently underutilized. Hence, relevant literature provides only limited information concerning many of the seed oils from this country, especially where it concerns the potential applications of these oils as preservatives for ligno-cellulose against bio-deterioration. Using standard procedures therefore, this study was carried out to evaluate and document selected physical and chemical properties of neem seed oil (NSO), mechanically extracted using a cold press at 31.03 N·mm -2 pressure and a room temperature of 25 ± 2℃. The results show that oil yield was 38.42% with a specific gravity of 0.91 ± 0.01. The amount of acid was 18.24 ± 1.31 mg KOH·g -1 and that of iodine 93.12 ± 2.01 g·100 g -1 , while saponification and peroxide values were 172.88 ± 2.06 and 1.42 ± 0.04 mg·g -1 respectively. The implication of the values obtained, particularly those for the chemical properties, as they concern the potential application of NSO as a preservative for ligno-cellulose, is likely that it may be useful in this regard since the values may support some of the documented anti-microbial properties of the oil, although other physical and chemical properties that may affect this potential are recommended for investigations. Conclusions and other recommendations follow in line with the results of the study.     

解决胶园干胶准确定产的途径探讨

干胶的准确定产始终是困扰橡胶林木资产承包经营管理的一大难题。本文从影响干胶定产的因素、理由、办法等进行阐述,提出建立橡胶资产科学评估体系。     

Initial agronomic evaluation of Parkia biglobosa in the humid zone of Nigeria

Parkia biglobosa is an important traditional economic tree legume of considerable multipurpose potentials that has not been well researched. It is used for fodder, human food, fuel wood, timber, green manure, medicine, provides shade for forage grasses and livestock and protects soil from heat and it is important in soil nutrient cycling.The objective of this study was to determine the effect of management regimes (cutting frequency and height) on the coppicing ability, fodder production, and nutritive value potentials of cultivated Parkia trees. This initial study has shown that the tree has a potential as fodder for livestock as well as human food and should be further studiedto fully understand its biology, agronomy and feeding value under various agroforestry or silvopastoral systems of humid tropics in West Africa.     

尖峰岭热带山地雨林群落呼吸量初步测定

用密闭吸收法测定了海南岛尖峰岭热带山地雨林主要树种的树干、树枝、树叶、树根等组分的呼吸速率，根据ＰｉｐｅＭｏｄｅｌ理论，测出主要树种木质器官的直径频度分布模型，树干、树枝及树根的呼吸速率与直径呈良好的幂函数关系：求出了单株林木呼吸总量与胸径之间的经验公式，计算森林群落（乔木层）月呼吸量，树干１．６９－１．７３、树枝０．７８－０．７９、树叶０．８１－０．８３、树根０．２４－０．２５，总计为３．５－３     

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。     

太寺森林公园建设适宜度等级评价与发展模式研究

本研究是在对太寺森林公园风景资源进行全面系统普查的基础上,依据《中国森林公园风景资源质量等级评定〉标准（GB／T18005—1999）,从森林公园森林资源评价,生态建设适宜度和敏感度评价等三个方面对太寺森林公园旅游资源进行等级评价,评价结果不仅为太寺森林公园发展模式提供参考,同时带动了区域生态、经济、社会三者之间协调发展。     

杉木种子园截杆更新技术研究初报

通过截杆进行杉木种子园更新技术研究。结果表明：第二（或第一）活枝处截杆、平切口、薄膜盖顶，复壮率达１００％，更新后２年就可挂果。     

氯化钠胁迫对廊坊杨苗木生长特性的影响

为了选择抗盐性较强的树种,合理利用盐碱土,以廊坊杨3个无性系和其亲本之一山海关杨的1a生扦插苗为试验材料,用不同浓度的氯化钠溶液处理,分析了盐胁迫对苗木生长特性的影响。结果表明:盐胁迫下各无性系苗高随盐浓度的增加,单位时间内高生长量减小,各无性系苗高增长率随盐浓度的增加而逐渐减小。在浓度0.9%的氯化钠溶液处理下按相对增长率以廊坊杨3号最高,比对照山海关杨高3倍;盐胁迫抑制各无性系叶面积的扩展,但廊坊杨3号幼叶生长受影响最小;盐胁迫下各无性系总生物量逐渐减少且根、茎、叶生物量的分配比例发生了明显的变化,廊坊杨3个无性系根系生物量所占比例均增加,廊坊杨3号增加最多,而山海关杨的根、茎、叶分配比例变化不明显。     

Potentials of Millettia thonningii and Pterocarpus santalinoides for alley cropping in humid lowlands of West Africa

This study was conducted to assess the suitability of two fallow species that are indigenous to West Africa, M. thonningii (Schum and Thonn) and P. santalinoides (L'Her), for alley cropping with maize and their effect on soil chemical properties. It was carried out during the rain-fed cropping season at Ibadan, Nigeria and Mbalmayo, Cameroon in 1993 and 1994. Total dry matter of P. santalinoides prunings was higher at the two sites than that of M. thonningii by about 35% to 37%. Maize grain yield in plots supplied with prunings was significantly higher (P > 0.05) than in control (no prunings or fertilizer application) at Ibadan. Grain yield in plots supplied with prunings plus 40 kg ha⁻¹ urea fertilizer gave significantly higher yields than plots supplied with 80 kg N ha⁻¹ urea fertilizer only. At Mbalmayo, there was no significant difference between grain yield in plots supplied with 80 kg N ha⁻¹ and plots supplied with prunings plus 40 kg N ha^-1 urea fertilizer though the latter had higher yields. Grain yield was also higher in the middle rows than in rows adjacent to the hedgerows and these were not significantly different. Weed dry matter was reduced by 27% to 43% when Pterocarpus prunings were applied and 13% to 31% with application of Millettia prunings. Weed flora in both locations changed from grasses to broad leaved. Soil chemical changes at soil depth 0 to 10 cm showed significant increases (pH, C, N, P and Ca) after two cropping seasons in plots supplied with prunings or prunings plus fertilizer than the initial values. At Mbalmayo, K was lower after cropping in treatments than the initial values while at Ibadan, K and Mg were lower except in plots supplied with Pterocarpus prunings only. P. santalinoides and M. thonningii have significant potential for agroforestry in this sub-region. This revised version was published online in June 2006 with corrections to the Cover Date.     

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.