Survival, growth, timber productivity and site index of Cordia alliodora in forestry and agroforestry systems

Matching tree species to appropriate site conditions and stand management is crucial for sound agroforestry production. In this study, survival, growth and site index for laurel (Cordia alliodora (Ruiz and Pavón) Oken.) were measured between 1987–1999 in two forestry (line plantings and pure plantations) and four agroforestry systems (taungya and three laurel – cacao (Theobroma cacao L.) systems) in the lowland humid tropics of Costa Rica and Panama. Mortality ranged between 2 and 52% at age nine years. Poor drainage, flooding and high water tables resulted in low laurel survival on some sites. At age 5, laurel site index was 21 m in cacao – plantain (Musa AAB) – laurel associations (CLP), but only 15 m in line plantings. Diameter at breast height at that age was 28.5 cm in CLP and only 15.6 cm in pure plantations. Laurel growth and site index were high when planted in association with intensively managed crops (e.g., cacao, plantain or taungya sequences).     

Timber harvest,damage to crop plants and yield reduction in two Costa Rican coffee plantations with Cordia alliodora shade trees

Both model and field estimations were made of the damage inflicted to coffee plants due to the harvest of timber shade trees (Cordia alliodora) in coffee plantations. Economic analyses were made for different coffee planting densities, yields, and both coffee and timber prices.Damage due to tree felling and log skidding should not be a major limitation to the use of timber shade trees in coffee plantations. The timber price that would balance all discounted losses and benefits to zero, for scenarios with and without trees ranged between 8–20 US $/m³ (current overbark log volume at the saw mill yard is US$ 66/m³). There will be lower margins for coffee damage in high yielding plantations, specially in years of good coffee prices. Nevertheless, the use of timber shade trees is recommended even in these scenarios.     

Pure and mixed forest plantations with native species of the dry tropics of Costa Rica: a comparison of growth and productivity

In Costa Rica, most reforestation trials with native species were established in the tropical humid regions. In the dry tropics, research on the performance of native species in forest plantations is incipient and trials comparing pure and mixed designs are limited. This paper presents the results of two experimental plantations with native trees in pure and mixed plots in the dry tropics of Costa Rica. The growth and productivity of 13 native species in pure and mixed plantations was compared with Tectona grandis (L.f.) Lam., an exotic species broadly used in the region. In a plantation of relatively slower growing species, measurements taken at 68 months of age resulted in Samanea saman (Jacq.) Merril. and Dalbergia retusa Hemsl. demonstrating the best growth, followed by Astronium graveolens Jacq. and Swietenia macrophylla King. Measurements in a plantation of relatively faster growing species, at 68 months of age, showed that growth of Schizolobium parahyba (Vell.) Blake was greatest in the pure and mixed plots, followed by Terminalia oblonga (Ruiz & Pav.) Steud., Anarcadium excelsum (Bert. & Balb. ex Kunth) Skeels and Pseudosamanea guachapele (Kunth) Harms. The native species grew better in the mixed plots. The pure plots of T. grandis (L.f.) Lam. were the most productive, compared to all species and the mixture of species. Plantations of T. grandis (L.f.) Lam. seem to be well adapted to the region and are certainly a commercially interesting alternative. Nevertheless, mixed plantations with native species would contribute more to sustainable management, because while single-species plantations do not provide a great range of goods and services when compared to the natural forest, mixed plantations are likely to increase this range of benefits.     

Sustainable timber production from uneven-aged shade stands of Cordia alliodora in small coffee farms

A model was developed to estimate the stable timber output from shade stands of Cordia alliodora in coffee farms. The model predicts, for stand densities between 120–290 trees/ ha, timber yields of 9–24 and 6–15 m³/ha/yr of total and commercial overbark volumes, respectively. Current harvest rates in four sample farms are below these figures.The model is used to describe the transient trajectory (in terms of timber output over time) of Cordia alliodora stands with different initial DBH distributions. Practical recommendations are derived as to how farmers should manage their trees to achieve stable timber outputs in the shortest time possible.     

不同林龄桉树林下植被结构与物种多样性

依据野外样方调查数据,对广东省德庆县三叉顶自然保护区不同林龄桉树林下植被作了研究,用Margale丰富度指数、Simpson优势度指数、Shannon—Wiener指数、Pielou均匀度指数分析其物种组成与结构。结果表明：三叉顶自然保护区1年生桉树林共记录维管束植物52科94属113种,3年生桉树林共记录维管束植物56科99属121种,林下植被优势种是盐肤木、山苍子、广东蛇葡萄、断肠草、买麻藤、鬼灯笼、芒、芒萁等;1年生和3年生桉树林各样地的各项多样性指标差别不大;3年生桉树林物种多样性指数总的来说比1年生桉树林的物种多样性指数大,说明桉树人工林的物种多样性指数有随着林龄增加而增大的趋势。     

Biodiversity Conservation in the La Amistad Biosphere Reserve

Abstract

The AMISCONDE Initiative was created and promoted by Conservation International (CI). This paper analyzes the approach to biodiversity conservation of the Costa Rican portion of the Initiative in the context of CI's mission statement. Global, national and local challenges to biodiversity conservation are briefly reviewed. Then, the implementation of the AMISCONDE Initiative is examined. To provide a basis for comparison, two other well-known Costa Rican conservation programs are summarized. The Initiative differs from these other programs in its central emphasis. AMISCONDE focuses on community development, apparently prioritizing development above biodiversity protection. The paper concludes with several recommendations: that the Initiative place far greater emphasis on biodiversity through education, employment opportunities and collaboration with other organizations interested in the biota of the region; and that the program evaluate its impact on the protected area's biota. This would enable CI to determine the degree to which the impacts of the Initiative are consistent with its mission.     

林下植被多样性、生物量及养分作用研究进展

林下植被是森林生态系统的重要组成部分,对森林生态系统的稳定性、生产力及养分循环具有重要影响,因此研究林下植被具有重要意义。但是以往由于研究方法、研究时限以及研究尺度等方面存在许多缺陷,对林下植被的认识还不统一,研究结论不够深刻。如何正确测定林下植被多样性及其生物量,合理评价林下植被对森林生态系统的作用,科学制定林下植被的管理措施,这些问题都值得进一步深入研究。文中对林下植被多样性、生物量及其养分作用3个方面的研究进行了分析总结,以期为今后林下植被研究、林下植被管理和森林可持续经营提供参考。     

Vegetation response to intensity of herbaceous weed control in a newly planted loblolly pine plantation

Growth of loblolly pine (Pinus taeda L.) seedlings through three growing seasons after planting increased with intensity of herbaceous weed control using herbicides. Weed control had no effect on pine survival. Two years of complete herbaceous weed control (CHC, control throughout the first two growing seasons after planting) and operational herbaceous weed control (OHC, sulfometuron at 0.42 kg ai/ha at the beginning of the first growing season), resulted in lower biomass of weeds plus trees than with no herbaceous weed control (NHC) during the first growing season. Differences in total biomass during the first year were due to differences in biomass of herbaceous weeds. Total biomass on CHC and OHC plots was at least as great as NHC the second year, and greater by the third year, as pines assumed dominance as a result of increased growth from reduction of herbaceous weeds. The operational herbicide treatment had no significant impact on overall herbaceous weed biomass and cover, and little effect on species composition compared to no herbaceous weed control two and three growing seasons after treatment. The CHC treatment significantly reduced herbaceous weed biomass, cover and composition through three growing seasons.     

桂西南岩溶区不同恢复模式群落生物量及林下植物多样性

[目的]研究桂西南岩溶区不同恢复模式群落的生物量及其林下植物多样性的特点,为该区域的生物多样性保护、生态功能恢复效果评价积累基础数据。[方法]以桂西南岩溶区4种不同恢复模式为研究对象,采用样方法对林下植物多样性进行研究;采用收获法研究灌木层与草本层的地上、地下生物量及凋落物层现存量;采用异速生长模型来估算乔木层的地上生物量,并参考IPCC根茎比来量化乔木的地下生物量。[结果]表明:共调查记录林下植物85种,隶属于46科,81属,其中,灌木植物25科,46属,50种;草本植物21科,35属,35种;不同恢复模式群落生物量的变化趋势为自然恢复林(166.66 t·hm-2)任豆林(48.61 t·hm-2)吊丝竹林(36.54 t·hm-2)灌草坡(0.96 t·hm-2)。[结论]不同恢复模式灌木层物种丰富度差异不显著,最高的为灌草坡(16种),其次为任豆林(15种),最低为自然恢复林(12种);草本层物种丰富度最高的为任豆林(12种),其次为灌草坡(10种),最低为自然恢复林(4种)。自然恢复林乔木不同组分生物量与任豆林、吊丝竹林之间差异显著(P0.05);灌草坡的灌木、草本地上生物量与吊丝竹林、任豆林、自然恢复林之间差异显著(P0.05)。吊丝竹林、任豆林的灌草生物量表现为草本层灌木层,而灌草坡与自然恢复林的灌草生物量则表现为灌木层草本层。     

竹林林下植物多样性与土壤水分入渗关系的研究

研究分别以浙江安吉县的4种林分类型(毛竹纯林(A)、毛竹+乔木(B)、毛竹+灌草(C)、乔木+灌草(D))以及湖南炎陵县3种林分类型(毛竹+乔木、毛竹+灌草、乔木+灌草)为对象,探讨了不同类型竹林林下植物多样性与其下不同深度土壤根系重量之间的关系,以及土壤渗透速率与不同土层根系重量和土壤含水量的相关性.结果表明:(1)上述4种植被类型0 ～40 cm根系生物量约为40～80cm的3倍,各类型林下植物多样性与其不同土层的根系重量相关性不显著;(2)浙江安吉4种植被类型中,0～40 cm与40～80 cm土层的渗透性指标以毛竹+乔木较好,初渗率、稳渗率和平均渗透率平均分别为:15.38、5.26和8.8 mm·min-1;毛竹纯林上述3项指标较低,平均分别为:5.83、3.03和4.45mm·min-1;湖南0～40 cm土层毛竹+乔木渗透性最好,上述三项指标分别为:16.72、12.23和9.13mm/min,40～ 80 cm各植被类型渗透性相差不大;(3)浙江毛竹+乔木、乔木+灌草土壤含水量均随土壤深度增加而降低,毛竹纯林与毛竹+灌草土壤含水量随土壤深度增加而先降低到18％后逐渐升高最终稳定在19％;(4)土壤入渗速率与不同深度土层根系重量显著相关,但根系重量不是决定土壤渗透性能的主要因素;(5)0 ～40cm土层的累计入渗量和土壤初始含水量呈典型的负相关,而40～80 cm土层的累计入渗量和土壤初始含水量没有明显的相关关系.     

Status of floor vegetation under some monoculture and mixculture plantations in North India

A study conducted to assess the floor vegetation shows the presence of 17 species underPopulus deltoides in comparison to 28, 29 and 35 underAlbizia lebbeck, Dalbergia sissoo and mix-culture plantations, respectively. Further, the biomass and density of floor vegetation is considerably reduced underP. deltoides compared to other plantations. In addition, the indices for species richness, evenness, dominance and diversity are also reduced underP. deltoides showing some inhibitory mechanism being operative under these plantations. Based on available literature, allelopathy is speculated to be responsible for this reduction.     

华北落叶松人工林侵蚀沟内植物多样性研究

为进行林下侵蚀沟的植被恢复与生态保育,以冀北山地典型的华北落叶松人工林为研究对象,对林下侵蚀沟内植物多样性进行了研究。结果表明:侵蚀沟内平均物种丰富度约为13.03,低于沟外,物种组成主要为耐干旱瘠薄物种,无明显优势种;沟内群落密度为131.3株/m2,明显低于沟外的211.6株/m2;沟内物种均匀度指数高于沟外,但两者的物种多样性指数无明显差异。对比侵蚀沟两侧坡面多样性可知,半阴坡耐阴喜湿植物重要值较高,丰富度和多样性均高于半阳坡,而均匀度指数无明显差异。     

相思人工林生物量分配格局与林下植被多样性分析

对位于漳州平和7年生的3种相思人工林生物量的分配格局和林下植被多样性进行研究,结果表明:马占相思林下植被Shannon-Wiener多样性指数最高(3.0936),黑木相思其次(3.0649),卷荚相思最低(2.2430);而与物种数目无关的Shannon均匀度指数则以黑木相思最高,表明其物种组成比较均匀;3种相思人工林林下植被群落相似性指数均在0.5~0.75之间,表现为中等相似;在3种相思人工林单株各器官生物量组成中,干材生物量所占的比例最大(55.30%~68.28%),其它组分依次为:根(14.72%~19.30%)>皮(10.59%~10.82%)>枝(3.96%~9.19%)>叶(2.42%~8.39%);3种相思人工林林下植被生物量大小顺序为:卷荚相思(6.69 t.hm-2)>马占相思(6.24 t.hm-2)>黑木相思(4.21 t.hm-2);3种相思人工林林分生物量的大小顺序为卷荚相思(75.21 t.hm-2)>黑木相思(49.19 t.hm-2)>马占相思(48.22 t.hm-2)。对3种相思人工林生物量分布格局的比较研究表明:卷荚相思生产力高,适宜在闽南山地营林生产实践中推广。     

不同林龄桉树林下植被多样性分析

以广东省信宜市中部山区不同林龄（3 a 生和 5 a 生）桉树人工林为研究对象,通过样地调查, 统计和分析了桉树林下植被结构特征（种类组成、结构与分布）和物种多样性（Margale 丰富度指数、 Simpson 优势度指数、Shannon-Wiener 指数和 Pielou 均匀度指数）。结果表明：（1）3 a 生桉树林下植被共 记录维管束植物23 科 31 属 33 种,5 a 生桉树林林下植被共记录维管束植物 24 科 32 属 35 种,不同林龄 桉树林下植被结构与分布特征差异较大,乔木幼苗、灌木层和草本层的优势种均明显不同;（2）林龄对 桉树林下植被丰富度影响相对较小,但对优势度和均匀度影响较大;随着林龄的增加,桉树林下灌木层 和草本层植被物种多样性均明显下降,其中灌木层下降幅度大于草本层。总体而言,林龄对林下植被的 种类组成影响相对较小,但对林下植被的结构与分布以及物种多样性有显著影响。     

广东高要南部低丘桉树人工林下植被物种多样性分析

对广东高要南部低丘桉树（Eucalyptus spp．）人工林林下植被物种进行了调查分析。结果表明,林下植被物种最少有156种以上,分属56科和103属,乔木21种,灌木59种,藤本20种,草本36种,总体Shannon-Wiener指数为2．26。种群数目大于5％的优势种均为草本植物,其中芒箕（Dicranopteris dichotoma）占绝对优势（46．2％）,这是林下植被物种丰富度较高而多样性偏低的主要原因。林下植被物种组成、丰富度和多样性在不同地域之间均有显著的差异,但在林分龄级之间则没有明显的变化。     

The R. R. Reynolds Research Natural Area in Southeastern Arkansas

The R. R. Reynolds Research Natural Area is a 32-ha pine-hardwood forest in southeastern Arkansas, U.S.A., that originated from diameter-limit cutting of the virgin forest before 1915. In 1935, these 32 ha were reserved from timber management. Between 1937 and 1993, eight inventories were taken of all living trees > 9-cm DBH, using 2.5-cm DBH classes within three species groups: Pinus spp., Quercus spp., and other hardwoods. In 1994, all standing dead snags of pines and hardwoods > 9-cm DBH were inventoried by 2.5-cm DBH classes. During 56 years, thc overstory pine-hardwood ratio remained stable in terms of relative basal area, but pine density decreased with a commensurate increase in hardwood density. In 1993, pines represented 63% of basal area but only 23% of stem density. Just before the 1993 inventory, a pine bark-beetle infestation developed on the area, and within one year the pines lost about 2.5 m2/ha in basal area and had 180% more snags than were contributed by hardwoods. The overstory pine component is decreasing in density as a result of natural senescence and the allogenic effects of bark beetles. Hardwood species are expected to eventually dominate the forest because shade-intolerant pine regeneration will not develop to maturity beneath the closed hardwood canopy which can be altered only by catastrophic natural disturbances or anthropogenic intervention.     

哥斯达黎加热带雨林国家公园及乡土景观植物的应用

通过调查中美洲有"小亚马逊"之称的哥斯达黎加热带雨林国家公园及其首都周边主要景观植被,详细记录了沟谷雨林、山地雨林和平原河岸雨林以及海滨及岛屿砂生环境中主要的植物种类;其城市绿化植物种类多样,首都圣荷西有"花城"美誉。热带特种作物及果树丰富,咖啡、香蕉等成为该国重要产业。调查研究发现,哥斯达黎加拥有如此丰富的植被资源是由于当地政府和原住民对其领地的物种和自然景观严加保护而留存至今的。     

广东山区3种不同人工林林下植物多样性初步研究

人工林林下植物多样性发展有利于提高人工林地力、维持群落健康和提高生态系统的稳定性。应用样方调查法,比较研究了广东山区马尾松林、湿地松林和杉木林等3种人工针叶林群落的林下植物多样性。结果表明,杉木林的林下植物丰富度较高,共记录了138种林下植物;马尾松林次之,林下植物共有135种;湿地松林的林下植物种类最少,仅53种。物种多样性指数总的变化趋势为杉木林>马尾松林>湿地松林。3种人工林群落之间的相似性系数均较低,表明这些人工林群落的林下植物种类差异明显。基于以上研究结果,文章探讨了影响人工林植物多样性的主要因素和提高人工林植物多样性的途径。     

Effects of active pasture,teak (Tectona grandis) and mixed native plantations on soil chemistry in Costa Rica

In this study soil samples were taken from the O/A and B horizons of undisturbed forest, active pasture, and 8- to 12-year-old teak and mixed native plantations. Samples were analyzed for K, Ca, Mg, soil organic carbon, pH, exchangeable acidity, bulk density, and compared with a fertility equation. Bulk density was significantly lower in the undisturbed forest than other land uses, suggesting that after approximately 10 years of growth neither plantation lowered bulk density significantly from that of the active pasture. Teak plantations had significantly higher Mg and K (B horizon) and Ca (O/A horizon) concentrations than the undisturbed forest. This trend suggests that exchangeable base concentrations increase when land use changes from undisturbed forest to pasture, then pasture to plantation, with the most pronounced effect of this in teak plantations exhibiting more high fertility plots than other land uses. Soil organic carbon concentration was similar for all land uses except for a significantly lower concentration in teak plantations than in active pasture (O/A horizons). These results suggest that teak plantations may be advantageous for increasing soil fertility but, with respect to restoration of undisturbed forest conditions, present significant deviations in soil chemistry. Options for improved plantations soil management are discussed.