The vertical distribution of fine roots of five tree species and maize in Morogoro,Tanzania

In order to assess the possibility of root competition in agroforestry, the vertical distribution of fine roots (< 2 mm in diameter) of five tree species in pure two-year-old stands was compared to that of mature maize.Cassia siamea, Eucalyptus tereticornis, Leucaena leucocephala andProsopis chilensis had a rooting pattern similar to that of maize, i.e. a slow decline in fine root mass from 0–100 cm soil depth.Eucalyptus camaldulensis had its roots evenly distributed down to 100 cm. On an average, the fine root biomass of the tree species was roughly twice as that of the maize. We conclude that the studied tree species are likely to compete with maize and other crops with a similar rooting pattern for nutrients and water.     

Studies on root distribution of five multipurpose tree species in Doon Valley,India

Observations on the growth performance, rooting behaviour and distribution of fine roots of five tree species viz., Bauhinia purpurea, Grewia optiva, Eucalyptus tereticornis, Leucaena leucocephala and Ougeinia oojeinensis (Family: Papilionaceae) are being presented here. Roots were exposed at the time of planting, 6 months, 16 months, and 28 months after planting. Total root weight and root volume were highest in Eucalyptus tereticornis and lowest in Bauhinia purpurea. Major part of the root system confined within 90–120 cm soil depth in case of Bauhinia purpurea, Grewia optiva and Leucaena leucocephala but Eucalyptus tereticornis and Ougeinia oojeinensis strike their roots to deeper depths. Bauhinia purpurea had its roots evenly distributed down to 120 cm. In general, the vertical distribution of fine roots (< 2 mm in diameter) of the five species indicate that more the depth, fewer the number of roots. The observations on soil binding capacity, indicated that Ougeinia oojeinensis had the maximum and Eucalyptus tereticornis had the minimum binding value. Due to leaf shading and other litter fall significant increase of nutrient components in soils under the tree canopies has been observed. The study indicates that bulk of the roots of the five tree species are found near the surface, but observation on soil moisture and nutrient content does not indicate variation under the tree canopies and in open, hence there may not be root competition in initial years of plantation.Authorised for publication by the Institute as contribution No.3311/239/89.     

Growth and yield of maize alley cropped with Leucaena leucocephala and Faidherbia albida in Morogoro, Tanzania

This study examined the effect of alley cropping of Leucaena leucocephala and Faidherbia albida on wood biomass, maize grain yield and soil nitrogen status. The treatments were: trees planted alone at 1 × 5 m spacing; trees intercropped with maize and a sole maize crop. Mulch biomass averaged 6.18 and 0.97 t ha⁻¹ for L. leucocephala and F. albida, respectively. Corresponding wood production was 1.71 and 1.11 t ha⁻¹. Both total N and inorganic N (NO ₃ ⁻ –N plus ₄ ⁺ –N) were higher under F. albida and lowest under L. leucocephala. Similarly, foliar N concentration in maize was higher in plots intercropped with F. albida and least in L. leucocephala intercropping. Maize grain yield was little affected by the tree intercrop as competition for resources was reduced through periodic pruning and clean weeding. There was no gain in maize grain yield due to the presence of L. leucocephala and F. albida. These results suggest that alley cropping in Gario is justified for wood production but not for increasing maize grain yield. This revised version was published online in June 2006 with corrections to the Cover Date.     

Fine root biomass,distribution, and production in young pine-hardwood stands

Patterns of fine root biomass, production, and distribution were estimated for pure stands and mixtures of three-year-old loblolly pine (Pinus taeda L.) with red maple (Acer rubrum L.) or black locust (Robinia pseudoacacia L.) on the Virginia Piedmont to determine the role of fine roots in interference between pine and hardwood tree species. Estimates were based on amounts of live and dead fine roots separated from monthly core samples during the third growing season after planting. Live and dead fine root biomass and production varied by species, but mixtures of loblolly pine and black locust generally had greater fine root biomass and fine root production than pure stands or loblolly pine-red maple mixtures. Hardwood species had greater live fine root biomass per tree in mixtures with pine compared to pure stands. Greater live fine root biomass in pine-locust stands may be attributed to differential utilization of the soil volume by fine roots of these species. For all stands, approximately 50% of live five root biomass was located in the upper 10 cm of soil.     

Interspecific competition impacts on the morphology and distribution of fine roots in European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.)

Morphology and vertical distribution patterns of spruce and beech live fine roots (diameter ≤2 mm) were studied using a soil core method in three comparable mature stands in the Solling: (1) pure beech, (2) pure spruce and (3) mixed spruce–beech. This study was aimed at determining the effects of interspecific competition on fine root structure and spatial fine root distribution of both species. A vertical stratification of beech and spruce fine root systems was found in the mixed stand due to a shift in beech fine roots from upper to lower soil layers. Moreover, compared to pure beech, a significantly higher specific root length (SRL, P<0.05) and specific surface area (SSA, P<0.05) were found for beech admixed with spruce (pure beech/mixed beech SRL 16.1–23.4 m g⁻¹, SSA 286–367 cm² g⁻¹). Both indicate a flexible ‘foraging’ strategy of beech tending to increase soil exploitation and space sequestration efficiency in soil layers less occupied by competitors. Spruce, in contrast, followed a more conservative strategy keeping the shallow vertical rooting and the root morphology quite constant in both pure and mixed stands (pure spruce/mixed spruce SRL 9.6/7.7 m g⁻¹, P>0.10; SSA 225/212 cm² g⁻¹, P>0.10). Symmetric competition belowground between mixed beech and spruce was observed since live fine roots of both species were under-represented compared to pure stand. However, the higher space sequestration efficiency suggests a higher competitive ability of beech belowground.     

Biomass of fine roots and its relationship with water-stable aggregates in a composite ecosystem of triploid Populus tomentosa in the conversion of farmland to forest

A study on the biomass of fine roots and its relationship with water-stable aggregates (WSA) was conducted in two herbaceous models, triploid Populus tomentosa + Lolium multiflorum (TL) and triploid P. tomentosa + natural grass (TN). Both of the model triploid P. tomentosa stands were four years old converted from agriculture. Unconverted steep slope farmland was used as a control site. Results showed that the biomass of fine roots (⩽ 1 mm) in different layers varied in the following descending order: upper layer, middle layer and lower layer, at approximate ratios of 50:30:20. The average annual biomass of fine roots in ryegrass was twice that of the mixed natural grass-forest land. The total amount of natural grass roots was 4.4 times that of the ryegrass model. Water-stable aggregates of the upper, middle and lower layers and the unconverted farmland did not show any significant differences, whereas the amounts of water-stable aggregates of big-particles in the upper and middle layers were much larger than those of unconverted lands. The amounts of water-stable aggregates of natural grass-forest lands (TN model) were higher than those of managed grass-forest lands (TL model). Two-way analysis of variance indicated that fine roots (≤ 1 mm) could significantly enhance water-stable aggregates and total water-stable aggregates. We conclude that the program of converting agricultural lands to forest-grass lands is an effective way in improving soil anti-erosion capability. __________ Translated from Scientia Silvae Sinicae, 2007, 43(5): 24–29 [译自:林业科学]     

Nutrient use efficiency and biomass production of tree species for rotational woodlot systems in semi-arid Morogoro,Tanzania

Frequent nutrient removals accompanying wood and crop harvests from rotational woodlot systems may contribute to declining site productivity and sustainability because of soil nutrient depletion. However, selecting for nutrient-efficient tree species may well sustain productivity under this system. To test this hypothesis, a randomized complete block experiment was adopted to assess effects of five tree species on soil nutrients status, nutrient use efficiency and wood yield in semi-arid Tanzania. After 5 years rotation, top soils under Gliricidia sepium (Jaqua), Acacia polyacantha Willd. and Acacia mangium Willd. were the most fertile with soil organic carbon and exchangeable cation status raised close to those in natural Miombo systems. Soil inorganic N and extractable P levels reached sufficiency levels for subsequent maize culture. Wood productivity in tree fallows averaged three times higher than that of Miombo woodlands indicating the high potential of the woodlot system to supply fuelwood, and consequently relieve harvesting pressures on the natural forests. Acacia crassicarpa A. Cunn. ex Benth. produced the most wood (51 Mg ha⁻¹) at low nutrient “costs” presumably due to high nutrient use efficiency. Wood yield of this species was 42 and 120% greater than that of A. polyacantha and A. nilotica, respectively, but contained comparatively less nutrients (42–60% less for P, K, and Ca). Gliricidia sepium and A. polyacantha returned the largest amount of nutrients through slash at harvests. Of all test species, A. crassicarpa exhibited the most promise to sustain wood production under rotational woodlot systems due to relatively high productivity and low nutrient export at harvest.     

A model for vertical distribution of fine roots in Robinia pseudoacacia plantations on the Loess Plateau

Based on a detailed investigation of vertical distributions of fine roots in Robinia pseudoacacia plantations at the Ansai Soil and Water Conservation Station, Shaanxi Province, a model was developed for the deep distribution of fine roots of R. pseudoacacia, which reflects the growth of fine roots affected by the mixed process of infiltration water and deep soil water. The maximum depth of the distribution h _max and the depth of the highest fine root density (FRD) h _p were determined and the maximum depth of infiltration water supplied for fine root growth h _q could also be calculated, h _q was considered as the approximate boundary between infiltration water and deep soil water in support of the growth of fine roots. According to the model, the soil water of R. pseudoacacia woodland in the profile could be classified into three layers: the first layer from the soil surface to h _p was the active water exchange layer, very much affected by precipitation; the second was the soil water attenuation layer, between h _p and h _q and largely affected by the vertical distribution of fine roots; the third was the relatively stable soil water layer below h _q, below which soil water did not change much. The percentage of infiltration water supplied for the growth of fine roots reached a level of 88.32% on the shaded slopes and 85.21% on sunny slopes. This indicated infiltration of precipitation played a crucial role in the growth of R. pseudoacacia in the gully region of the Loess Plateau. The research of interaction between the distribution of fine roots and soil water in the profile will help to explain the reasons for the complete drying out of soils and provide a theoretical basis for continuing the policy of matching tree species with sites on the Loess Plateau. Translated from Scientia Silvae Sinicae, 2006, 42(6): 40–48 [译自: 林业科学]     

Spatial distribution characteristics of fine roots of Populus euphratica in a desert riparian forest

The soil-plant system is a very important subsystem of the soil-plant-atmosphere continuum (SPAC). The water uptake by plant roots is an important subject in the research on water transport in this SPAC and is also the most active study direction in the fields of ecology, hydrology and environment. The study of the spatial distribution pattern of fine roots of plants is the basis of constructing a water absorption model of plant roots. Our study on the spatial distribution pattern of fine roots of Populus euphratica in a desert riparian forest shows that the density distribution of its root lengths can be expressed horizontally as a parabola. The fine roots are concentrated within the range of 0–350 cm from the tree trunk and their amount accounts for 91.9% of the total root mass within the space of 0–500 cm. In the vertical direction, the density distribution of the fine root lengths shows a negative exponential relation with soil depth. The fine roots are concentrated in the 0–80 cm soil layer, accounting for 96.8% of the total root mass in the 0–140 cm soil layer. __________ Translated from Chinese Journal of Ecology, 2007, 26(1): 1–4 [译自: 生态学杂志]     

Above-ground biomass of seedling and semi-mature Sesbania sesban,a multi-purpose tree species,estimated using allometric regressions

Above-ground biomass production in seedling and semi-mature individual plants of Sesbania sesban varieties were compared to non-destructive measurements of stem allometrics. The results indicate that measurements of stem characteristics (diameter and total height) are suitable for estimating biomass of S. sesban varieties and therefore useful in the selection of particular varieties for inclusion in short-rotation agroforestry systems in arid- and semi-arid regions. Less labour-intensive methods for accurately assessing the productivity of agroforestry species, such as the use of allometric regressions, could significantly increase the number of individual plants that could be screened in any particular trial. A multiple polynomial regression accurately estimated above-ground biomass in all plants ranging in age from six weeks to eighteen months (r ²=0.99;p<0.001).     

Root biomass and distribution of five agroforestry tree species

Knowledge of the quantitative assessment and structural development of root systems is essential to improve and optimize productivity of agroforestry systems. Studies on root biomass recovery by sieves of different mesh sizes (2.0, 1.0, 0.5 and 0.25 mm) and root distribution for four-year-old individuals of five agroforestry tree species viz.; Acacia auriculiformis A. Cunn. ex Benth, Azadirachta indica A. Juss, Bauhinia variegata L., Bombax ceiba L. and Wendlandia exserta Roxb. were conducted at the research farm of Rajendra Agricultural University, Pusa, Bihar, India. The results indicated that the 0.5 mm sieve was adequate for recovery of the majority of roots. All the tree species exhibited a large variation in root depth and horizontal root spread four years after planting. The maximum root depth was recorded in W. exserta (2.10 m) and minimum in B. variegata (1.00 m). Horizontal root spread was 2.05 m in B. ceiba and 8.05 m in A. auriculiformis. Root spread exceeded crown cover for all species. The primary roots were more horizontal than the secondary roots. The length and diameter of the main root were highest in A. indica (108.3 cm) and B. ceiba (23.2 cm), respectively. Highest length and diameter of lateral roots were recorded in B. variegata (201.6 cm) and A. indica (1.8 cm), respectively. Total root biomass among different species accounted for 18.2–37.9% of the total tree biomass. Results of this study infer that although all the species have potential to conserve moisture and improve fertility status of the soil, A. auriculiformis is the most effective for promoting soil fertility. The deep rooted W. exserta and A. auriculiformis will be preferred for cultivation under agroforestry systems and could reduce competition for nutrients and moisture with crops by pumping from deeper layers of soil.     

Water and nitrogen dynamics in rotational woodlots of five tree species in western Tanzania

The objective of this study was to compare the effects of woodlots of five tree species, continuous maize (Zea mays L.) and natural fallow on soil water and nitrogen dynamics in western Tanzania. The tree species evaluated were Acacia crassicarpa (A. Cunn. ex Benth.), Acacia julifera (Berth.), Acacia leptocarpa (A. Cunn. ex Benth), Leucaena pallida (Britton and Rose), and Senna siamea (Lamarck) Irwin & Barneby). The field experiment was established in November 1996 in a completely randomized block design replicated three times. Maize was intercropped between the trees during the first three years after planting and thereafter the trees were allowed to grow as pure woodlots for another two years. Transpiration by the trees was monitored when they were 3 years old using sap flow gauges. Soil water content was measured using the neutron probe approach between November 1999 and March 2001. Soil inorganic N profiles were measured when the trees were four years old in all treatments. The results indicated that the trees transpired more water than natural fallow vegetation during the dry season. The difference was apparent at a depth of 35 cm soil, but was more pronounced in deeper horizons. The water content in the entire soil profile under woodlots and natural fallow during the dry period was 0.01 to 0.06 cm³ cm⁻³ lower than in the annual cropped plots. This pattern was reversed after rainfall, when woodlots of A. crassicarpa, A. leptocarpa, A. julifera, S. siamea and L. pallida contained greater quantity of stored water than natural fallow or continuous maize by as much as 0.00 to 0.02, 0.01 to 0.04, 0.01 to 0.04, 0.01 to 0.03 and 0.00 to 0.02 cm³ cm⁻³, respectively. Natural fallow plots contained the lowest quantity of stored water within the entire profile during this period. Transpiration was greatest in A. crassicarpa and lowest in L. pallida. All tree species examined were `scavengers' of N and retrieved inorganic N from soil horizons up to 2-m depth and increased its concentration close to their trunks. This study has provided evidence in semi-arid environments that woodlots can effectively retrieve subsoil N and store more soil water after rains than natural fallow and bare soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

Diversity,abundance, and structure of tree communities in the Uluguru forests in the Morogoro region,Tanzania

Uluguru forests are globally recognized as important biodiversity hotspots, but anthropogenic pressure threatens their value. This study examined species diver-sity, abundance, and structure of trees i...     

Coating nursery containers with copper carbonate improves root morphology of five native Australian tree species used in agroforestry systems

Seedlings of the native Australian tree species Acacia holosericea, Casuarina cunninghamiana, Eucalyptus argophloia, E. camaldulensis and Melaleuca bracteata, were raised in nursery containers which were coated with CuCO₃ (50 g l^-1, in a water-based paint solution) or left uncoated for three months. Seedling growth of all species in the nursery was generally less in treated containers, although differences were relatively small. More importantly, CuCO₃ treatment reduced the occurrence of lateral roots growing down or coiling around container walls for both three- and six-month-old seedlings. Twenty-four months after planting both three- and six-month-old seedlings on a semiarid site in subtropical southeast Queensland, there was no effect of CuCO₃ treatment on height or basal diameter development of seedlings. However, sample excavations of root systems showed that the poor root morphology exhibited by untreated seedlings when in the nursery had persisted in the field. As such poor root form has the potential to reduce tree growth and wind firmness in the longer term, these results suggest that chemical root-pruning is a helpful nursery practice when raising seedlings for dryland afforestation, and in circumstances where it may be necessary to retain seedlings in the nursery for longer than normal to take advantage of infrequent rainfall events. This revised version was published online in June 2006 with corrections to the Cover Date.     

江南油杉细根生物量空间分布及其对土壤水分的响应

[目的]探明广西不同栽培区江南油杉细根生物量的空间分布共性及其对土壤水分的响应机制.[方法]以广西3个栽培区江南油杉人工幼林为研究对象,采用根系全株分层挖掘和根系形态结构分析法,定量分析江南油杉幼树不同径级细根生物量密度、根长密度和表面积密度的空间分布特征.[结果]1)江南油杉幼林期细根生物量在垂直方向上主要分布在0～...     

Growth of ten multipurpose tree species on acid soils in Sangmelima,Cameroon

Ten multipurpose tree species were planted both in monoculture and intercropped withArachis hypogea (groundnut) in a randomized complete block with three replications. The vigrou, biomass, nutrient content, and coppicing percentage of the trees were evaluated. Intercropping with groundnuts during the establishment phase did not affect subsequent growth and development of the species.Acacia mangium, Acacia auriculiformis, Cassia siamea, Calliandra calothyrsus andParaserianthes falcataria established well, when compared toGliricidia sepium, Leucaena leucocephala, Dialum guineense, Dubocia macrocarpa andMilicia excelsa. A. mangium, A. auriculiformis, C. calothyrsus, C. siamea andP. falcataria produced the highest leaf (4 to 20 t ha^–1) and wood (12 to 37 t ha^–1) biomass yield (primary growth) at one to three years after planting. Coppicing percentage ofA. mangium A. auriculiformis andP. falcataria were relatively low (35 to 50%).C. calothyrsus andC. siamea showed the highest coppicing percentage (95 to 100%) and produced the greatest coppice biomass (9 to 13 t ha^–1). Total nitrogen and organic matter percentage of soils from under the stands of these two species were also significantly higher than that of the rest. The two species may thus be considered for use in agroforestry technologies for soil improvement on acid soils, which are typical of the moist tropics.     

Endemism of plants in the Uluguru Mountains,Morogoro, Tanzania

A survey was conducted to determine richness of Vascular Endemic Plants of the Uluguru Mountains in Morogoro, Tanzania. Strict and near-endemic species were identified and their habits, habitats and altitudinal ranges were indicated. About 108 strict endemic plant species were identified in the Uluguru Mountains. Most of the endemic species are shrubs followed by herbs, trees and climbers, and are confined to the families Rubiaceae (38 species in 11 general), Orchidaceae (13 species in 7 general) and Balsaminaceae (11 species in 1 genus). The major habitat for endemic species is the montane rain forest on the windward side ranging between 1200 and 2450 m a.s.l. The major areas where the Uluguru endemics are concentrated are the forests of Bondwa/Lupanga followed by Lukwangule/Chenzema and then Bunduki and Mgeta. These areas are therefore the major hotspots for the endemism in the Uluguru Mountains. The information presented in this paper will contribute to the conservation and management of the biodiversity of the Uluguru Mountains.     

水曲柳落叶松混交林中细根空间分布

采用根钻取样方法对年生水曲柳落叶松混交林中细根空间分布状况进行了研究。结果表明,水曲柳落叶松地下生物量的空间分配差异显著。在林分水平上,水曲柳的根生物量密度高于落叶松(分别为4442.3和2234.9g/m3)。两树种在相邻区域中分配的细根生物量较高,表明种间根系竞争较弱。落叶松行间的水曲柳细根生物量密度和根长密度均高于水曲柳行间的落叶松细根,表明水曲柳地下部分具有较强能力。根系的空间分布有利于混交林中水曲柳的生长。图1表4参19。     

Structural root form and fine root distribution of some woody species evaluated for agroforestry systems

Fine root distribution and structural root characteristics of four-years-old multipurpose woody species with potential for use in agroforestry systems were investigated on an Alfisol in the forest savanna transition zone of south-western Nigeria. Rooting patterns of woody species studied differed considerably. Lonchocarpus sericeus had the lowest percentage (21%) of total fine roots confined to the upper (0 to 30 cm) soil layer, compared to 84% with Tetrapleura tetraptera. Despite the superior tap root system of Enterolobium cyclocarpum and the fine root form of Nauchlea latifolia however, their extensive distribution and very large lateral woody root volume density may pose a major problem for seedbed preparation and tillage operations in simultaneous agroforestry systems. Lonchocarpus sericeus appears to have the most desirable structural and fine root architecture among the species studied for simultaneous agroforestry systems. The total root density below the underlying distal soil layers was linearly related to the sum of square of tap root diameter and the corresponding soil depths. This revised version was published online in June 2006 with corrections to the Cover Date.     

植物细根生产和周转研究进展

细根是植物根系最重要的组成部分,作为衡量植物生产力的重要因素,对森林生态系统生产力具有重要影响。前人研究表明,细根的生产与周转对细根的寿命、分解和生物量估算具有重要意义,并且会影响森林生态系统碳、养分和水循环过程。文中系统阐述了细根生产和周转的研究进展,介绍了细根的3种主要研究方法（根钻法、内生长法和微根管法）,进一步分析细根生产和周转的影响因素,即除了受植物内在因子（细根构型、根序和化学组成）的制约外,细根生产和周转还受到纬度、海拔、气候、土壤条件、土层深度等环境因子及生物因子的影响;探讨了在植物细根研究中存在的问题,并对今后的发展趋势进行了展望,以期为植物细根深入研究和根系生态学学科发展提供参考。