Fine-root dynamics of coffee in association with two shade trees in Costa Rica

Fine-root dynamics (diameter < 2.0 mm) were studied on-farm in associations of Coffea arabica with Eucalyptus deglupta or Terminalia ivorensis and in a pseudo-chronosequence of C. arabica-E. deglupta associations (two, three, four and five years old). Coffee plants were submitted to two fertilisation types. Cores were taken in the 0–40 cm soil profile two years after out-planting and subsequently in the following year in depth layers 0–10 and 10–20 cm, during and at the end of the rainy season, and during the dry season. Fine root density of coffee and timber shade trees was greater in the coffee fertilisation strip as compared to unfertilised areas close to the plants or in the inter-rows. Coffee fine roots were more evenly distributed in the topsoil (0–20 cm) whereas tree fine roots were mostly found in the first 10 cm. Although the two tree species had approximately the same fine root length density, lower coffee / tree fine root length density ratios in T. ivorensis suggest that this shade tree is potentially a stronger competitor with coffee than E. deglupta. Coffee and tree fine root length density for 0–10 cm measured during the rainy season increased progressively from two to five-year-aged associations and coffee fine root length density increased relatively more than E. deglupta fine root length density in the four and five-year-aged plantations suggesting that contrary to expectations, coffee fine roots were displacing tree fine roots.     

Species and site selection for timber production on farm boundaries in the humid Atlantic Lowlands of Costa Rica and Panama

In 1987–89 the CATIE-GTZ Agroforestry Project set up experiments with five timber tree species planted in single lines on twelve farm boundaries in cooperation with local farmers. When the trees were five years old, their height, diameter and total stem volume were: Acacia mangium 17 m, 19 cm and 67 m³ km^–1, Cordia alliodora 14 m, 20 cm and 46 m³ km^–1, Eucalyptus deglupta 22 m, 24 cm and 85 m³ km^–1, Tectona grandis 17 m, 20 m and 64 m³ km^–1, Terminalia ivorensis 18 m, 23 cm and 104 m³ km^–1. Considering these excellent growth rates, planting of Cordia alliodora, Eucalyptus deglupta and Tectona grandis in lines on farm boundaries should be promoted. T. ivorensis and A. mangium are not recommendable for sites with impeded drainage because of mortality caused by root rot, mostly due to Rosellinia sp.     

A provisional growth model with a size–density relationship for a plantation of <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> derived from measurements taken over 2 years in Pare,Indonesia

A growth model for a plantation of Paraserianthes falcataria was provisionally derived from measurements of 32 permanent plots taken over a period of 2 years in Pare, Indonesia. This model first predicts height growth with the polymorphic site index equation. Then density-related growth and mortality, that is, diameter and stand density, are calculated to satisfy the mathematical relationship for the reciprocal and self-thinning equations, both of which were based on the maximum size–density line with the slope of −1.759 identified in this study. Cumulative predictions on diameter and stand density, starting with each of three age classes, 3, 4, and 5 years after planting, and continuing for the next 2 years, agreed well with the observations of age-class mean. An exception was for stands that were 7 years old, which were marginal, but closest to the rotation age of 8 years. Contrasting height/diameter relationships among the three age classes were described reasonably well with this model, and the predicted basal growth area was found to agree fairly well with observations. These results suggest that the growth model presented here has good potential for applying size–density control for plantations of P. falcataria. However, measurements for an additional few years might be necessary to derive a model that will more accurately predict diameter size at the rotation age.     

Modelling growth behaviour in monoculture in subtropical eastern Australia of two eucalypt species that differ in shade tolerance

Growth behaviour of the relatively shade-intolerant species Eucalyptus dunnii and the rather more shade-tolerant Corymbia citriodora was considered during several growth periods over 8–14 years of age in experimental plantation monoculture in subtropical New South Wales. Larger trees dominated growth in any stand; this was consistent with the principle that inter-tree competition in such forests is for light and is asymmetric in that larger trees shade smaller trees but the reverse does not occur. Once competition was established, competition-induced mortality of C. citriodora was less than that of E. dunnii. A model relating tree diameter growth rate to tree diameter, competitive position in the stand and stand basal area was developed. The model showed that smaller, hence partially shaded, trees in stands of C. citriodora were better able to maintain their growth rates than equivalent trees in stands of E. dunnii. It is hypothesised that this reflects the greater shade tolerance of C. citriodora. This pattern of growth led to a more even distribution of tree size classes across the stand in the more shade-tolerant species.     

The effect of competition on individual tree basal area growth in mature stands of Pinus cooperi Blanco in Durango (Mexico)

In this paper, we evaluated how well-selected distance-dependent and distance-independent competition indices explain individual tree basal area growth of trees, growing in mature and even-aged stands of Pinus cooperi Blanco. A total of 18 competition measures were analyzed of which six do not need tree location (distance-independent) and 12 that utilize tree location (distance-dependent). The competition situation of a stand and/or an individual tree was studied using 11 different competitor selection methods. The mean square error reduction relative to no-competition was used to judge the performance of each competition index. It was found that the best distance-independent competition indices performed as well as the best distance-dependent competition indices. It was concluded that the BALMOD-index would be a good competition index to be incorporated into further individual tree basal area growth models for the study area.

Initial growth of pioneer timber tree species in a Taungya system in the humid lowlands of Costa Rica

The temporary association of annual crops in juvenile tree plantations (Taungya system) can reduce or offset the initial costs of reforestation and hence provide incentives for tree planting on private farms. A replicated systematic spacing design, derived from a Nelder-fan design, was used to study the effects of tree-crop distance on growth and development of the timber species salmwood (Cordia alliodora) or eucalyptus (Eucalyptus deglupta), associated with maize (Zea mays) or cassava (Manihot esculenta), during the first year after transplanting the trees on two sites on alluvial soils in the humid lowlands of Costa Rica. Association with maize did not affect mean tree growth. However, mean eucalyptus and salmwood heights of 7–8 m and 3–4 m, respectively, after one year in pure plantation or associated with maize, were only 4.7 m and 1.4 m, respectively, when associated with cassava. Wider tree – crop spacings were more important for initial salmwood growth than for eucalyptus. It was concluded that the shoot growth characteristics (continuous or episodical growth) of the timber species is a very important consideration when selecting associated agricultural crop species and tree-crop distances.     

A Comparison of the Utility and Agronomic Traits of Indigenous and Exotic Trees in the Mount Kenya Region

On-farm indigenous (Cordia africana) and exotic (Grevillea robusta) tree species were compared in terms of the quality of their utility and their agronomic traits in the Meru Central district of Kenya. These two species are the most common indigenous and exotic trees, respectively, among the recorded 117 trees on farms. Interviews with farmers and collected documents on tree felling and planting showed that farmers considered C. africana to be more useful than G. robusta. However, farmers wanted to plant more G. robusta than C. africana because the easily established and fast growing G. robusta has a higher short-term contribution to the household economy. The advantages of C. africana, however, should be redefined in terms of its long-term contribution to farmers; C. africana contributes to farming more effectively than does G. robusta. The lower growth performance and relative difficulty in the establishment of C. africana can be compensated for by its higher timber quality and coppicing ability.     

Stand structure and composition of a 60-year-old larch (Larix kaempferi) plantation with retained hardwoods

Tree retention is understood as a key practice in creating complexity, leading to heterogeneity in resources and habitats in managed stands. In this article, we clarify the long-term effects of tree retention on stand structure and tree-species composition in a 60-year-old Larix kaempferi plantation in central Japan. In our study plot (1.5 ha) there were 18 stems/ha of retained trees (determined by tree-ring analysis), mostly Quercus crispula. We conducted spatial analyses and tested the hypothesis that tree abundance, size structure, and species composition and diversity change with distance from the retained trees. Near the retained trees, L. kaempferi showed a reduction of 40%–60% in basal area, due presumably to the shading effect. In contrast, the nearby area showed greater species diversity in the canopy layer. The retained trees created patches of different species composition in the understory. The spatial gradient of shade and colonization opportunity provided by retained trees greatly affect the distribution of the colonized species, according to their shade tolerance and seed-dispersal ability, which resulted in the stand structure with a heterogeneous shrub-layer vegetation. Retention proved particularly important for the enhancement and long-term maintenance of structural and compositional complexity in L. kaempferi plantations.     

Effects of Eucalyptus obliqua (L'Herit) density on young stands of even-aged Pinus radiata (D. Don)

In a 10-year-old Pinus radiata plantation, increasing densities of Eucalyptus obliqua, a woody weed species, caused reductions in the canopy leaf area and total stem volume of P. radiata. As the density of E. obliqua increased stand volume (the sum of stem volumes of the two species) was constant, but the sum of projected leaf area of the two species decreased. Higher E. obliqua density also resulted in higher mean height to diameter ratio of P. radiata. With increasing E. obliqua density the size distribution of P. radiata became more positively skewed and the size hierarchy of P. radiata increased. The effects of E. obliqua density on P. radiata are more likely due to below-ground competition than competition for light above-ground. Understanding the effects of E. obliqua density on the characteristics of P. radiata can benefit weed control programs and subsequent management of plantations with naturally regenerated E. obliqua.     

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.     

Growth and nut production of black walnut in relation to site, tree type and stand conditions in south-central United States

Black walnut (Juglans nigra) is a prime tree species for agroforestry practices in the United States providing highly prized wood and nuts for human consumption and wildlife. In 54 black walnut stands in south central United States, the site index (i.e., mean dominant height [DH], at age 25 years) ranged between 5.2 and 21.4 m, and was independent of stand density. There were no differences in height and stem diameter (DBH) growth rates between stands with improved varieties and native stock. Most stands were in a “free growth” stage because of either early age or wide spacing. Mean annual increments in DBH and height were positively related both for improved varieties and native stock. Understory competition had a substantial detrimental effect on DH. In a 26 year-old stand, trees growing within Kentucky blue grass (Poa pratensis) had a site index 5 m greater than trees growing within tall fescue (Festuca arundinacea). Predicted nut yields in 2002 varied between 0 and 1370 kg of hulled nuts per ha. Improved varieties had, in general, higher nut yields than predicted from a nut yield-DBH equation developed for individual trees. Nut yields were highly variable both within and among stands, and were related to DBH in native stock but not in improved varieties.     

The potential of alley cropping im improvement of cultivation systems in the high rainfall areas of Zambia II. Maize production

Theee trials to evaluat the potential of alley cropping in maize production on the low fertility, acidic soils in Northern Zambia are described. Leucaena leucocephala, Gliricidia sepium, Sesbania sesban, Albizia falcataria, Fleminga congesta, and Cassia spectabilis, were grown in alley crops with hybrid maize and soybean. All trials received recommended rates of P and K fertiliser; N fertiliser was applied at three rates as a subplot treatment. One trial received lime before establishment.Only in the limed trial was there a significant improvement in maize yields through alley cropping; when no N fertiliser was applied, incorporation of Leucaena leucocephala prunings resulted in an increase of up to 95% in yields, with a smaller improvement being produced by Flemingia congesta. There was a significant correlation between the quantity of prunings biomass applied and the proportional increase in maize yields over the control treatment. It is suggested that the lack of effect of most of the tree species on crop yields was due to low biomass production.An economic analysis showed that alley cropping with limed Leucaena was only profitable when fertiliser costs were high in relation to maize prices. However, lime is both expensive and difficult to obtain and transport for most small scale farmers in the region, and is therefore not a practical recommendation. It is suggested that future alley cropping research should focus on screening a wider range of tree species, including other species of Leucaena, for acid tolerance and higher biomass production.     

Dry matter production and nutrient cycling in agroforestry systems of cardamom grown underAlnus and natural forest

A study on dry matter production and nutrient cycling in agroforestry systems of cardamom grown under N₂-fixingAlnus and mixed tree species (non-N₂-fixing) was carried out in the Sikkim Himalaya. The stand total biomass, and tiller number, basal area and biomass of cardamom crop was much higher under the influence ofAlnus. Annual net primary productivity ofAlnus trees was slightly higher than mixed tree species in spite of lower stand density ofAlnus. The agronomic yield of cardamom increased by 2.2 times under the canopy ofAlnus. Litter production and its disappearance rates were also higher in theAlnus-cardamom stand. Nitrogen and phosphorus concentrations of different components ofAlnus were higher than those of mixed tree species, whereas their back translocation from leaf before abscission was lower inAlnus. The cardamom based agroforestry system under the influence ofAlnus was more productive with faster rates of nutrient cycling. The poor nutrient conservation and low nutrient use efficiency ofAlnus, and malleability of nutrient cycling under its influence make it an excellent association which promotes higher availability and faster cycling of nutrients.     

基于树冠因子的林木竞争指数研究

[目的]以湖南省黄丰桥国有林场杉木纯林为研究对象,进行树木竞争指数的研究,基于Hegyi简单竞争指数的形式,提出包含反映树冠特征因子的树冠竞争指数。[方法]将树冠竞争指数和Hegyi简单竞争指数分别与胸径增长量进行相关分析。[结果]Kendall's tau-b系数、Spearman's rho系数和相关系数R²均显示树冠竞争指数与林木生长量的相关性高于Hegyi简单竞争指数。[结论]该结果表明树冠竞争指数与林木生长量有更强的相关性,可以更好地体现树冠在树木生长中的作用,能作为模拟林分生长量的依据。     

Nitrogen fixation capacity in the component species of contour hedgerows: how important?

The choice of an appropriate hedgerow species is one of the most critical decisions in exploiting the value of a contour hedgerow system. The implications of hedgerow species with nitrogen (N)-fixation capacity on hedgerow-crop competition and crop productivity have been widely debated. We examined the agronomic significance of N-fixation by comparing the performance of species representing three classes of hedgerow vegetation: A nitrogen-fixing tree legumeGliricidia sepium), a non-nitrogen fixing tree (Senna spectabilis syn.Cassia spectabilis), and a forage grass (Pennisetum purpureum). The 4-year study investigated the hedgerow biomass and nutrient yields, and their relative effects on the performance of two annual crops commonly grown in alley farming systems, with emphasis on hedgerow-crop interference. The work was done on an Ultic Haplorthox (pH 4.8, organic C 1.9%, total N 0.18%).Senna produced 46% more pruning biomass on an annual basis than didGliricidia; N supplied to the alley crops was similar toGliricidia in the first year of observation, but 20–30% higher in the succeeding years. Upland rice and maize grain yields and total dry matter were unaffected by tree species, but the nitrogen-fixing tree exerted less competitive effects on the annual crops growing in adjacent rows. Grass hedgerows reduced maize yields 86% by the second year, indicating an unsustainable drawdown of nutrients and water. We conclude that hedgerow systems composed of a nitrogen-fixing tree did not exert significant advantages compared to a non-fixing tree species, and that factors other than N-fixation were more important determinants for the choice of hedgerow species.     

Basal area growth and mortality of Betula maximowicziana affected by crown dieback in a secondary forest in Hokkaido, northern Japan

Since the late 1990s, decline of B. maximowicziana Regel has been observed in mature secondary forests in various parts of Hokkaido, northern Japan. To develop a method of thinning for large-timber production of B. maximowicziana, we measured basal area growth and the mortality of 217 trees during a four-year period (1999–2003) in a 90-year-old secondary forest with serious tree damage. We analyzed growth and mortality in relation to the degree of crown dieback (DC), symmetric and asymmetric competition from neighbors, and initial tree size. Individual basal area growth decreased with increasing DC, with increasing symmetric (two-sided) competition, and with decreasing initial tree size. During the four-year period, 4.1% of the observed trees died. Logistic regression analysis revealed that mortality rate increased with increasing DC and with increasing symmetric competition. These results suggest that both growth and mortality rates were affected by the same factors (i.e., DC and symmetric competition). We concluded that the resource for which individuals were competing at the study site was underground, most likely water. Modeled growth and mortality rates can be used to improve the management of damaged forests. A management plan for the damaged study site is proposed.     

杉木人工林单木断面积生长动态模拟

应用面板数据固定效应模型对杉木人工林单木断面积生长规律进行模拟,在模拟过程中,将胸径(DBH)和活冠比例(LCR)作为自变量,又分别加入密度因子和不同类型的竞争指数,同时引入立地条件和林龄效应来解释单木断面积生长过程中的异质性。结果表明:虽然密度因子与竞争指数有较强的相关性,但是在单木断面积生长中都具有不可忽略的重要影响。立地条件与林龄对单木断面积的拟合偏差在不同的林分密度下略有不同,随立地指数或者林龄增加,其对平均单木断面积拟合偏差的影响也增大。     

Growth and yield prediction models for Acacia mangium grown in the plantations of the central region of Bangladesh

Acacia mangium is a very fast growing species belonging to the family Leguminosae that has been introduced in the plantations in Bangladesh for its faster growth and wide range of adaptability. The present study aimed at development of growth and yield prediction models for the species using simultaneous equation method. Models were selected for the species to estimate stand dominant height, stand diameter, stand basal area per hectare and total volume yield per hectare. Paired t-test, 45-degree line test, percent absolute deviation and biological principle of stand development were used for the validation of chosen models. The results suggest that the models derived were statistically and biologically acceptable and could be satisfactorily used for stands of Acacia mangium of ages 4–7 yrs based on a base age of 6 yr.     

小陇山锐齿栎天然林结构动态分析

[目的]为了解锐齿栎天然林群落动态变化过程。[方法]采用每木定位监测样地重复观测的方法,对甘肃小陇山林区百花林场王安沟营林区内的锐齿栎天然林进行研究,从树种组成及多样性结构、径级结构、空间结构等几方面分析了锐齿栎天然林群落的结构动态特征。[结果]表明:2次调查群落树种组成和优势树种的重要值排序变化不大,有2个稀少种退出群落,死亡林木40株,死亡率8.3%;群落乔木层的物种丰富度和树种空间多样性下降,优势树种的集中性变大,物种个体数目分配的均匀程度下降。林分径级结构由典型的反"J"型分布变化为左偏的单峰状曲线;群落的空间结构没有发生显著变化,林木分布格局仍为随机分布,中林层和上林层林木个体增加,垂直结构更趋复杂;树种隔离程度下降,建群种锐齿栎的优势度增强,膀胱果、白桦和青榨槭种群的优势度下降。[结论]锐齿栎天然林群落组成和结构变化是一个复杂和缓慢的过程,6年间仅发生了一些微小的波动。     

Prescribed burning and hexazinone herbicide as release treatments in a sapling hardwood-loblolly pine stand

To compare release treatments, a randomized complete block study was established in a 7-year-old hardwood-loblolly pine (Pinus taeda L.) stand in central Louisiana established using chopping and burning. There were 5 blocks of 3 treatments each: (1) check, (2) hexazinone applied once, and (3) prescribed backfiring applied twice. The first burn in December 1985 (7 years after site preparation) had a fire intensity of 90 kJ/s/m. The hexazinone herbicide was applied in April 1986 (the 8th year after site preparation) with a metered spotgun applicator at a rate of 3.0 kg active ingredient/ha. The second burn in March 1989 (the 11th year after site preparation) had a fire intensity of 106 kJ/s/m.The two prescribed burns increased the number of stems less than 1.5 m tall from 1,380 to 2,960/ha red maple (Acer rubrum L.), blackgum (Nyssa sylvatica var. bifora), and sweetgum (Liquidambar styraciflua L.). Burning reduced the number of loblolly pines less than 2.0 m tall, which resulted in a significant increase in average loblolly pine height and diameter. Loblolly pine comprised 62 and 59% of the basal area on the check and burn treatments, respectively, 11 years after site preparation. Hexazinone reduced the number of blackgum, sweetgum, and oak (Quercus spp.) from 6,100 to 4,560 stems/ha and resulted in significantly less hardwood tree basal area than found on the check or burn treatments. Therefore, the herbicide treatment resulted in principally a loblolly pine stand (over 80% of the total tree basal area was pine) four years after hexazinone application.