商溪公社油桐生产调查报告(摘要)

商溪公社山多耕地少,是发展用材林、经济林的好地方。现有油桐林19134亩,占总面积的17.24%;占有林地面积的44.62%,年产桐油15—20万斤,平均亩产8—10斤。一、油桐林的经营方式和现状(一)油桐在人民生活中的位置。油桐生产是当地人民的主要经济来源。过去群众吃饭、穿衣和小孩读书都靠桐油。现     

油桐良种化工程及实施效果

参加全国油桐良种化工程系列研究和实施的有13个省区218个单位的530位专业技术人员,研究工作范围包括油桐分布区的66个地区233个县市,面积约70万km.自1977-1989年历时13年的研究成果,基本查清了全国184个地方品种,两批共选优树1846株。评选出全国71个油桐主栽品种,选育出全国油桐优良品种39个;收集油桐种质资源1849号,建立全国油桐基因库5处,地方基因库19处;应用数量分类方法,将全国油桐品种科学地划分为 7个品种类群;营建母树林14785亩,实生种子园、无性系种子园、杂交种子园共9123.6亩,采穗圃940.6亩,年产良种种子90110万kg,接芽1000万只以上,良种的生产能力已超过全国年造林150-200万亩的总需要量水平;良种的推广面积184.01万亩(占全国1600万亩投产桐林的11.5％),良种平均年产桐油0.2934亿kg(占全国年总产量1.06亿kg的27.6％),良种平均亩产桐油15.9kg(为全国平均6.6kg的2.4倍),良种推广年创产值2.05亿元,6年期间共产桐油1.76亿kg,计创总产值12.32亿元.     

油桐低产的原因与改造技术

油桐是我国特有的工业油料树种。解放以来,我省油桐生产发展很快,南阳、信阳、许昌、洛阳等地区有三十多个县有油桐分布,面积已达150万亩,但单产很低。从1981年产量看,南阳地区结果桐林63万亩,平均亩产桐油6.8斤;许     

油桐丰产栽培综合技术的研究

油桐是我国的特产。我省陕南山区有25个市、县种植油桐,栽培历史悠久,栽培面积较大,是全国主要产区之一,1988年栽培面积达9.6ha,年产桐油569万kg,油桐产区桐油收入约占林业总收入的20％,白河等主产县桐油年产值占林业总产值的50％以上,长期以来陕南山区的桐油还是沿用传统的生产方式,栽培品种混杂,良莠不齐,栽培技术落后,单位面积产量低,平均亩产桐油仅3.9kg,只是全国亩产桐油7kg的55％。为了改变陕南山区油桐低产的面貌,我们自1986年～1990年五年间研究出一套油桐丰产栽培综合技术,应用于生产,使产量有了大幅度提高。     

发挥山区优势,科学种植油桐

湖北省郧县油桐生产历史悠久,素称“油桐之乡”,历年桐油收购量居全省第二位,属全国油桐基地之一。近年来油桐生产发展更快,1983年全县油桐面积已发展到17.4万亩,比1979年的12万亩增长35％,比建国初期的4.5万亩增长四倍。桐油年产量现已达到238万斤,平均亩产桐油19.8斤(投产面积12万亩),为全省最高水平。桐油收购量增长较快,1980年全县     

广西油桐群体遗传改良及效益评价

一、引言 广西是我国桐油主产区之一。30-40年代,桐林面积16.6-26.67万ha,产油1万t上下,最盛时(1939年)栽培面积达33.33万ha,产油1.95万t。第二次世界大战使广西油桐生产受到严重摧残,直到1949年后才又得到一定恢复:1957年,全区桐林面积恢复至16.67万ha,桐油产量恢复到历史常年年产量(即1万t)。1958年至十一届三中全会前,极“左”的农村政策,导致广西油桐产量再一次严重滑坡,1958-1984年(良种桐林投产前一年)27年间平均年产桐油仅5073t,比1957年的产量(亦即历史常年产量)下降50％。     

谈谈我省油桐生产的前景

油桐是我省三大经济林木(核桃、油茶、油桐)树种之一。由于桐油质地优良,用途极广,在国民经济领域直接或间接用途达千种以上,又是传统的出口商品。因此,各级政府都很重视油桐的发展。我省曾于1964年在全省掀起了大战“五果”的高潮,大大推动了油桐生产的发展。桐林面积从1949年的6万亩,发展到1984年的98万亩,桐油年总产量达1千多万斤。初步缓和了我省桐油的供需矛盾,为国家提供了一部分外贸桐     

积极发展油桐生产 加快油桐发展步伐——在全省油桐生产会议上的讲话(摘要)

一、我省油桐生产的历史和现状 建国以来,我省从一九五二年开始就成片营造油桐林,至一九六五年全省桐林保存面积有十五万亩,桐籽产量一九六八年达到一万四千多担。但是由于林彪、“四人帮”的干扰破坏,价格降低,奖售取消,到一九七五年时只剩了七千多亩,我省油桐生产处于奄奄一息的状态。一九七八年国务院召开了全国桐油会议,要求我省到八五年桐林面积恢复到历史上十五万亩的最高水平,并确定高淳、溧水、溧阳、句容、江宁县为我省的油桐基地县。此后,我省在收购价格上进行了一些调正,在造林投资上作了重点支持,桐林面积又开始恢复。但是,收购价格还是偏低,种植油桐收入太少,所以近两年来的发展情况仍     

耕作改制 油桐增产

我社盛产桐油,桐林面积37800多亩,每人平均2.4亩多.过去,我社的油桐生产是一个旧摊子,一套老办法,产量低,总产不稳定.从1972年冬起,我们连续抓了几个冬春的垦复、中耕、补造、新造和抚育,全社共垦复老荒桐林8千多亩,新造桐林2千多亩,中耕抚育补造2万多亩.同时认真执行了垦复补助、交售奖励等政策,制定了维护油桐生产的奖惩办法,充     

油桐造林技术经济效益分析

我们从1979年承担林业部与省林业厅联营的油桐良种繁育基地的建设任务以来,针对低丘红壤有机质缺乏、土壤粘重、酸性强等不利于油桐生长的条件,进行了一系列速生丰产造林技术措施的探讨,初获成效。现已造林的900多亩桐林,二年生就开花结实,三年生平均亩产湿桐籽37.96公斤。其中浙林选5号品种20.9亩与浙林选8号品种17.89亩,平均亩产桐籽     

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.     

油桐大面积丰产栽培综合技术的研究

对传统的油桐林通过淘汰老树劣种,更换优良品种,调整林分结构;修石坎梯地,种龙须草,保持水土;合理施肥,促进油桐高产稳产;农桐间作,以耕代抚;积极防治病虫害;适时采果等技术措施,使72ha 油桐林由1985年平均每公顷产桐油53.4kg,提高到1989年平均每公顷产320.7kg,提高了5.01倍。     

油茶系统选择方法及其效果的研究

在油茶天然林分中进行群体选择,评选出优良母树,并营造示范林。在此基础上利用个体选择评出33个优株,连续4年进行无性系测定,选育出12个高产优良无性系,亩产油量达51.76kg,各项指标均表现优良。     

林下植被对杉木林地力影响的研究*

本文研究了林下植被对杉木林地力的影响,结果表明在正常的经营水平下,林下植被生长迅速。0.7的林分郁闭度,4～5年后生物量积累达4～5 t/ha;营养元素达80～100kg/ha。丰富的林下植被能促进养分的有效化,并且在一定程度上能起到改善土壤肥力的作用,因此对防止杉木林地力衰退具有一定的意义。     

Optimizing Tapping-Tree Density of Rubber (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis>) Plantations in South China

Tapping-tree density in rubber plantations affects the production of dry rubber. Farmers can estimate rubber productivity when they know with certainty the number of tapping trees within a plantation and can therefore increase productivity through optimized planting schematics. Historical data on planting distance between trees and between rows, planting density (trees/ha) and tapping-tree density (number of trees under tapping for latex harvest per hectare) from 1952 to 2014 have been collected for plantations in the Hainan, Yunnan and Guangdong provinces of South China. A plantation survey was conducted to collect more detailed data on current tapping tree and planting densities in various plantations in the three provinces. Planting density and row spacing are found to have increased with rubber tree planting time and plant spacing to have declined from 1952 to 2014. Tapping-tree density of rubber plantations from 1955 to 1995 in South China ranges from 270 to 345 tree/ha, averaging 300 trees/ha. Strong typhoons and cold snaps are important drivers of fluctuations in tapping-tree density. The factors driving tapping-tree density are similar across the three provinces but the degree of change differs between provinces. Tapping panel dryness (due to tapping beyond the natural limit of the rubber tree productivity), severe wind damage and cold damage are the major factors resulting in loss of tapping trees in plantations in South China. These results suggest that a combination of environmental management for extreme weather and targeted breeding could improve tapping-tree density in rubber plantation and therefore dry rubber yield per unit area.     

Availability of residual phosphorus fertilizer for loblolly pine

Fertilizing pine plantations with phosphorus has been a common practice on the Coastal Plain since the 1960s. A decision to fertilize a second or subsequent rotation must take into consideration the availability of residual phosphorus fertilizer. We tested the efficacy of phosphorus applied in a first rotation loblolly pine stand to support the growth of the subsequent second rotation stand. Phosphorus rates applied in 1967 at the time of planting of the first rotation were 0, 28 and 56 kg/ha. Retreatments included the application of 45 kg/ha P at midrotation in 1978, and the application of 45 kg/ha P at the beginning of the second rotation in 1991. The field trial had a split-block design with the three initial P rates crossed by five retreatments, and replicated four times. The first rotation 28 kg/ha P treatment had 91% and the 56 kg/ha P treatment 101% of the volume at age 5 of all the treatments fertilized with P in the second rotation. Foliar P levels, in the second rotation, were elevated at age 2 relative to ages 3 and 5, presumably due to effective competition control. Twenty-nine percent, 40% and 75% of the trees fertilized with 28 kg/ha P in 1967, 56 kg/ha P in 1967, and 45 kg/ha P in 1991, respectively, had foliar P concentrations of 0.10% or above at age 3. Based on foliar analyses, we recommend refertilizing stands fertilized with 45 kg/ha P in the first rotation by age 3 in the second rotation.     

Carbon sequestration in the trees, products and soils of forest plantations: an analysis using UK examples

A carbon-flow model for managed forest plantations was used to estimate carbon storage in UK plantations differing in Yield Class (growth rate), thinning regime and species characteristics. Time-averaged, total carbon storage (at equilibrium) was generally in the range 40-80 Mg C ha(-1) in trees, 15-25 Mg C ha(-1) in above- and belowground litter, 70-90 Mg C ha(-1) in soil organic matter and 20-40 Mg C ha(-1) in wood products (assuming product lifetime equalled rotation length). The rate of carbon storage during the first rotation in most plantations was in the range 2-5 Mg C ha(-1) year(-1).A sensitivity analysis revealed the following processes to be both uncertain and critical: the fraction of total woody biomass in branches and roots; litter and soil organic matter decomposition rates; and rates of fine root turnover. Other variables, including the time to canopy closure and the possibility of accelerated decomposition after harvest, were less critical. The lifetime of wood products was not critical to total carbon storage because wood products formed only a modest fraction of the total.The average increase in total carbon storage in the tree-soil-product system per unit increase in Yield Class (m(3) ha(-1) year(-1)) for unthinned Picea sitchensis (Bong.) Carr. plantations was 5.6 Mg C ha(-1). Increasing the Yield Class from 6 to 24 m(3) ha(-1) year(-1) increased the rate of carbon storage in the first rotation from 2.5 to 5.6 Mg C ha(-1) year(-1) in unthinned plantations. Thinning reduced total carbon storage in P. sitchensis plantations by about 15%, and is likely to reduce carbon storage in all plantation types.If the objective is to store carbon rapidly in the short term and achieve high carbon storage in the long term, Populus plantations growing on fertile land (2.7 m spacing, 26-year rotations, Yield Class 12) were the best option examined. If the objective is to achieve high carbon storage in the medium term (50 years) without regard to the initial rate of storage, then plantations of conifers of any species with above-average Yield Classes would suffice. In the long term (100 years), broadleaved plantations of oak and beech store as much carbon as conifer plantations. Mini-rotations (10 years) do not achieve a high carbon storage.     

Silvicultural and economic aspects of pure and mixed native tree species plantations on degraded pasturelands in humid Costa Rica

Reforestation of degraded land in tropical regions provides one means of restoring ecosystems and improving rural livelihoods. Most plantations in humid tropical regions are established in pure plots, including few species of high commercial value, generally exotics. The present study compares growth and economic viability of 15–16 year-old trees of native species in pure and mixed plantations on degraded pasturelands at La Selva Biological Station, Costa Rica. The species with the best growth were Vochysia guatemalensis, Virola koschnyi, Jacaranda copaia, Terminalia amazonia, and Hieronyma alchorneoides. The mixed plantations performed better than pure plantations for all growth variables considered, including height, diameter at breast height, volume, and aboveground biomass. Mixed plantations outperformed pure plantations economically, with Net Present Value (NPV) of 1,124 to1,124 to 8,155/ha and Internal Rate of Return (IRR) of 7.7–15.6% depending on the species mixture. The most profitable pure plantations were those of Vochysia guatemalensis, with NPV and IRR of $6,035/ha and 14.3%, respectively; Hieronyma alchorneoides ($6,035/ha and 14.3%, respectively; Hieronyma alchorneoides (2,654 and 10.8%); and Virola koschnyi ($1,906/ha and 9.22%). These are the estimated benefits that would be accrued at harvest. These projections are realistic since the decision to harvest is generally mandated not just by profit maximization but by economic necessity, thus many small- to medium-scale farmers in Costa Rica harvest plantations prior to the completion of the rotation length. Mixed plantation may be the preferred system for reforestation with native species designed for timber production or carbon sequestration because this system is more economically viable and productive than pure plantations.     

Afforestation of savannah with cocoa agroforestry systems: a small-farmer innovation in central Cameroon

Cocoa cultivation is generally considered to foster deforestation. Contrary to this view, in the forest–savannah interface area in Cameroon, farmers have planted cocoa agroforestry systems on Imperata cylindrica grasslands, a soil-climate zone generally considered unsuitable for cocoa cultivation. We undertook a survey to understand the agricultural and ecological bases of this innovation. Age, cropping history and marketable cocoa yield were assessed in a sample of 157 cocoa plantations established on grasslands and 182 cocoa plantations established in gallery forests. In a sub-sample of 47 grassland cocoa plantations, we inventoried tree species associated with cocoa trees and measured soil organic matter levels. Marketable cocoa yields were similar for the two types of cocoa plantations, regardless of their age: 321?kg?ha^?1 in cocoa plantations on grasslands and 354?kg?ha^?1 in cocoa plantations in gallery forests. Two strategies were used by farmers to eliminate I. cylindrica prior to the establishment of cocoa plantations, i.e., cropping oil palms in dense stands and planting annual crops. Farmers then planted cocoa trees and fruit tree species, while preserving specific forest trees. The fruit tree and forest tree densities respectively averaged 223 and 68 trees?ha^?1 in plantations under 10?years old, and 44 and 27 trees?ha^?1 in plantations over 40?years old, whereas the cocoa tree density remained stable at 1,315 trees?ha^?1. The Shannon–Weaver index increased from 1.97 to 2.26 over the same period although the difference was not statistically significant. The soil organic matter level was 3.13?% in old cocoa plantations, as compared to 1.7?% in grasslands. In conclusion, our results show that the occupation of grasslands by cocoa agroforestry systems is both an important example of ecological intensification and a significant farmer innovation in the history of cocoa growing.