Analysis of root fractal characteristics in remote areas of the Taklimakan desert, China

Fractal geometry is a potential new approach to analyze the root architecture, which may offer improved ways to quantify and summarize root system complexity as well as yield ecological and physiological insights into the functional relevance of specific architectural patterns. Fractal analysis is a sensitive measure of root branching intensity and fractal dimension expresses the ＂space filling＂ properties of a structure. The objective of this study was to find out the fractal characteristics of root systems in a remote area of the Taklimakan desert in China. The entire root system of two naturally occurring species were excavated and exposed with shov- els in 2007. The species were Tamarix taklamakanensis and Calligonum roborovskii. A one-factorial ANOVA with species as factor showed statistically a highly significant difference in fractal dimensions, indicating differences in their pattern of root branching. There was no relationship between root diameter and two parameters of fractal root models a and q, representing general characteris- tics of root systems, for either species （a： the ratio of the sum of root cross-sectional areas after a branching to the cross-sectional area before root division; q： the distribution of the cross-sectional areas after branching）. We have found significant linear relation- ships between the diameter after branching and root length and biomass respectively, because of the self-similarity of root branching. Branching rules are the same for roots of all sizes and lengths. Root biomass for the root systems of entire trees can be estimated by measuring the diameter of each root at the base of the trunk or the diameter after branching. We have shown that the diameter of each root at the base of the trunk and the diameter after branching are effective indices that can be measured easily in order to estimate the root lengths, biomass and other parameters of root architecture.     

民勤沙区梭梭人工接种肉苁蓉栽培技术

从种子采收、种子处理、接种技术、病虫鼠害防治、采挖管理等方面介绍了民勤沙区梭梭人工接种肉苁蓉栽培技术。     

提高荒漠滩地梭梭植苗造林成活率的综合措施

通过梭梭苗木的假植、造林地整地、造林定植后浇水量的试验,优选出了提高荒漠滩地梭梭植苗造林成活率的方法,提出了提高荒漠滩地梭梭植苗造林成活率的综合措施。     

石羊河下游干旱荒漠区梭梭人工林病害发生种类及防治对策

通过对石羊河下游干旱荒漠区梭梭人工林病害的调查,结果表明:梭梭人工林发生的各类病害有7种,其中:叶部病害有白粉病和枯萎病2种,枝干病害有枝枯病、瘤锈病、黑枯病和干桔病等4种,根部病害有根腐病1种.危害梭梭人工林主要病害有白粉病和枝枯病,有针对性地提出了防治对策.     

黑河流域荒漠地区水分胁迫对梭梭苗木影响的试验研究(英文)

梭梭(HaloxylonAmmodendronBge,一种C4灌木)苗种植在15升的容器中,给予不同的水分胁迫处理,研究了其水分关系和气体交换特征。结果表明:当土壤水分含量大于11%时,梭梭苗有高的蒸腾量;土壤水分含量低于6%时,苗木就不能从土壤中吸取水分;很好供水的苗木的蒸腾量与潜在蒸发量成线型相关。气体交换测定发现,随着土壤水分含量的下降,造成了不同程度的气孔导度、叶蒸腾强度和光合作用的下降。对同一苗木而言,由于这个地区有高的水气压亏缺(VPD),很好和中度供水的苗木在气孔反应方面有较宽的范围,气孔在决定光合作用方面起着较小的作用,二者没有明显的线型相关关系。虽然水分胁迫使蒸腾速率比光合速率下降的更快,提高了水分利用效率,而较高的蒸发需求增加了蒸腾量,限制了光合作用,但是总的趋势是光合作用和蒸腾强度成线型相关。图6表2参15。     

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.     

Using isotopic labeling to investigate root water uptake in an alley cropping system within Taklimakan Desert Oasis,China

Agroforestry Systems - Intercropped trees are becoming popular as an ecological protection screen for a desert oasis from wind-blown sand and sand erosion. However, trees also consume a...     

秋季巴丹吉林沙漠东南缘人工梭梭林水分来源

2009 年秋季( 9 月份) 在巴丹吉林沙漠东南缘的绿洲 - 荒漠过渡带,选择栽植 2,5,10,20 和 30 年的人工梭梭林,测定 20,30,50,100,150 和 200 cm 土深的土壤含水量,应用稳定氧同位素方法研究人工梭梭林的水分来源。结果表明: 梭梭林 20 ～ 30 cm 土层含水量显著高于 150 ～ 200 cm 土层; 土壤浅层的水分来自夏末和秋初的自然降雨; 随林龄增加,梭梭对地下水的利用比例逐渐增加,而对浅层土壤水分的利用比例逐渐降低; 2 年生梭梭依次主要利用 100,20,30,50 和 200 cm 土壤水分,5 年生梭梭依次主要利用地下水以及 200,150,100 和 30 cm 土壤水分,10 年生梭梭依次主要利用地下水以及 200,150,30 和 20 cm 土壤水分,20 年生梭梭依次主要利用地下水以及200 和 150 cm 土壤水分,而 30 年生梭梭依次主要利用 50,100,150,200,30 和 20 cm 土壤水分; 在巴丹吉林沙漠东南缘,随着林龄增加,梭梭对降雨补充的土壤浅层水分的利用能力降低,而对土壤深层水分与地下水的利用又不足以维持其正常生长需要,这可能是导致人工梭梭林大面积退化的一个原因。     

Benefit-cost analysis of raising Pinus wallichiana seedlings in different capacities/sizes of root trainers in the nursery

Modern nursery methods of seedling production in different sized root trainers,were compared by raising seedlings of Pinus wallichiana involving costs incurred and benefits received. In order to provide a common basis for the comparisons,the study involved the raising of 1000 seedlings annually on a continuous basis for seven years. A relative economic analysis of raising P. wallichiana seedlings in 300,150 and 100 cm3 root trainers was carried out and we estimated that the root trainers of 300 cm3 capacity...     

Variations of root hydraulic conductance of Fraxinus mandshurica seedlings in different concentrations of NH4NO3 solution

Absorbing water from soil by roots in vascular plants is an important physiological function and plays an essential role on their water balance. The root hydraulic conductance (L _P) determined by radical water transport inside the root is a major influence on the shoot water status, plant growth, and development. However, a few studies have focused on the effect of different substances on L _P of roots, and the role of radical water transport was poorly understood. Based on the pressure-flux approach, this study used the roots of Fraxinus mandshurica seedlings with different treatments, i.e., distilled water, NH₄NO₃ solution, and HgCl₂ to determine the effect of various substances on L _P of roots. The objectives are: 1) to evaluate the difference in L _P occurred between distilled water and NH₄NO₃ solution with various concentrations; and 2) to examine the changes of L _P under distilled water and NH₄NO₃ solution with various concentrations after HgCl₂ treatment. The results showed that L _P of roots were 18.85×10⁻⁸ m/(s·MPa) in distilled water, 31.25–34.15×10⁻⁸ m/(s·MPa) in four NH₄NO₃ solutions (2, 4, 8 and 16 mmol/L), 14.69×10⁻⁸ m/(s·MPa) in distilled water after HgCl₂-treated, and 9.63–13.57×10⁻⁸ m/(s·MPa) in four NH₄NO₃ solutions after HgCl₂-treated, respectively. Aquaporins play an important role in regulating water uptake and transport in roots. NH₄ ⁺ and NO₃ ⁻ could stimulate activity of aquaporins, and L _P of roots in NH₄NO₃ solution was distinctly 77% higher than in distilled water. Nevertheless, Hg²⁺ can inhibit activity of aquaporins, and and L _P of roots decreased 22% in distilled water and 68% in NH₄NO₃ solution after treatment by HgCl₂ respectively. These evidences suggested that both Hg²⁺-sensitive aquaporins and ion channels existing in the protoplasm and vacuole membranes could regulate root water uptake, transport, and integral plant water balance. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(5): 706–712 [译自: 植物生态学报, 2005, 29(5): 706–712]     

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.     

高速公路生态边坡灌木根系垂直分布特征

选择高速公路生态边坡8种灌木根系,从根长、根量、根系削弱系数3个参数对其根系垂直分布特征进行研究,结果表明根系垂直分布大体呈现出由土壤表层至深层逐渐下降的趋势。但不同灌木根长、根量和根系削弱系数均在不同径级、不同土层中存在着较为明显的垂直分布差异。     

Spatial heterogeneity of fine root biomass of Pinus massoniana forests in the Three Gorges Reservoir Area, China

Environmental heterogeneity is a constant presence in the natural world that significantly affects plant behavior at a variety of levels of complexity. In order to estimate the spatial pattern of fine root biomass in the Three Gorges Reservoir Area, the spatial heterogeneity of fine root biomass in the upper layer of soils (0-10 cm) in three Masson pine (Pinus massoniana) stands in the Three Gorges Reservoir Area, China, was studied in 30 m × 30 m plots with geostatistical analysis. The results indicate that 1) both the live and dead fine root biomass of stand 2 were less than those of other stands, 2) the spatial variation of fine roots in the three stands was caused together by structural and random factors with moderate spatial dependence and 3) the magnitude of spatial heterogeneity of live fine roots ranked as: stand 3 > stand 1 > stand 2, while that of dead fine roots was similar in the three stands. These findings suggested that the range of spatial autocorrelation for fine root biomass varied considerably in the Three Gorges Reservoir Area, while soil properties, such as soil bulk density, organic matter and total nitrogen, may exhibit great effect on the spatial distribution of fine roots. Finally, we express our hope to be able to carry out further research on the quantitative relationship between the spatial heterogeneous patterns of plant and soil properties.     

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.     

The dependance of root growth potential on light level,photosynthetic rate,and root starch content in jack pine seedlings

Number of new roots (root growth potential or RGP), new root length, photosynthesis, total nonstructural carbohydrate content of needles and roots, terminal bud condition, and shoot elongation were measured on jack pine container seedlings for 4 weeks at weekly intervals under greenhouse conditions of 100%, 20%, and 10% sunlight to simulate competition-induced, lower light levels in the field. Both lower light levels significantly reduced photosynthetic rate, RGP, new root length, total nonstructural carbohydrate (especially starch) content of needles and roots, speed of terminal bud flush, and shoot growth. Both light level and photosynthetic rate were positively correlated with RGP and new root length, indicating that jack pine seedlings may use current photosynthate as an energy source to support new root growth. RGP and new root length were also both negatively correlated with root starch content suggesting that jack pine seedlings may also use stored carbohydrates as a potential carbon source for root initiation and initial root growth.     

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.     

Early root morphology of jack pine seedlings grown in different types of container

Abstract

This study compared the effects of container type on early root system morphology of jack pine (Pinus banksiana Lamb.) seedlings to determine impacts of container type on root characteristics that may be important for tree stability. Seedlings were grown for one season in Multipots®, Ventblocks®, Copperblocks®, Starpots® and Jiffy® pellets, and for a second season in sand culture in pots. After the first growing season, roots that had grown between Jiffy plugs were cut using a knife, either “early”, in September, or “late”, in November. Seedlings produced in non-pruning containers, Multipots and Ventblocks, had more vertical structural roots, less even root distribution and high shoot:root mass after a second season. Seedlings grown in pruning containers, Copperblocks, Starpots and Jiffy pellets, had more horizontal structural roots and more evenly distributed roots. Jiffy seedlings had high shoot:root mass after pruning, but ratios decreased to low levels similar to Starpots and Copperblocks after a second season in pots. Early pruning of Jiffy seedlings removed less root mass than late pruning, but total live root mass of early and late pruned seedlings was similar after the potting trial. Pruning containers thus produced structural root forms with more desirable characteristics for tree stability. These characteristics were evident after the first season and persisted after the second season in the potting trial.     

Benefit-cost analysis of raising Pinus wallichiana seedlings in different capacities/sizes of root trainers in the nursery

Modern nursery methods of seedling production in different sized root trainers, were compared by raising seedlings of Pinus wallichiana involving costs incurred and benefits received. In order to provide a common basis for the comparisons, the study involved the raising of 1000 seedlings annually on a continuous basis for seven years. A relative economic analysis of raising P. wallichiana seedlings in 300, 150 and 100 cm³ root trainers was carried out and we estimated that the root trainers of 300 cm³ capacity recorded the highest total input cost of Rs. 35571 and Rs. 40018 for 1000 seedlings produced annually at discount rates of 12% and 6%. Seedlings raised in 100 cm³ root trainers recorded the lowest total input cost of Rs. 23390 and Rs. 27737 per 1000 seedlings annually at discount rates of 12% and 6%. Hence, returns per rupee invested in raising seedlings in the 100 cm³ root trainers accounted for the maximum benefit-cost ratio (i.e., 1.56 and 1.61) at discount rates of 12% and 6%. Thus seedlings raised in 100 cm³ and 150 cm³ root trainers were found to be most cost effective when compared with seedlings grown in 300 cm³ root trainers. The results can be attributed to the larger number of cells per tray (higher growth density) in the 100 and 150 cm³ root trainers, compared to the number of seedlings in the 300 cm³ root trainers.     

华北落叶松人工林的生物量估算参数

分析华北落叶松人工林4个典型区域(关帝山、五台山中山区、五台山盆地区和塞罕坝)的生物量估算参数(生物量转扩因子、生物量扩展因子和根茎比)及其区域分异。结果表明:关帝山林区和五台山林区(中山区和盆地区)的生物量转扩因子平均值间无显著差异(P>0.05)且都大于塞罕坝林区(P<0.05);关帝山林区、五台山盆地区和塞罕坝林区的生物量扩展因子平均值间无显著差异(P>0.05)且都小于五台山中山区(P<0.05);生物量转扩因子和生物量扩展因子随林龄、平均胸径和蓄积量的增加而减小并趋于稳定;4个区域的根茎比平均值间无显著差异(P>0.05);根茎比随林龄和平均胸径的增加而增加(P<0.01),但与林分密度和蓄积量无显著相关性(P>0.05)。由于不同区域的生物量转扩因子和生物量扩展因子平均值间存在显著差异,故而建议按区域选择它们的值,并尽可能利用它们与林分测量指标的函数关系来确定。     

Relationships between the root system size and its hydraulic properties in white spruce seedlings

Seedlings grown under different N supply were examined for relationships between root system size attributes and its hydraulic properties. These relationships were also studied on seedlings of different stock types (grown in different container types). Measurements with root pressure probes were taken at various times after germination, under applied hydrostatic pressure and non-limiting soil moisture. Different N-treatments and stock types were used solely to produce seedling of different sizes, especially root system sizes. Specific root hydraulic conductivity (Lp_r) typically declined with an increasing root system size and correlations between Lp_r and the root system size attributes were often negative. The flow of water through the root system correlated well with root system size attributes only in young (3–4 month old) seedlings but the correlations were inconsistent among different N treatments and stock types. Neither the root system surface area nor dry weight reliably reflected its ability to absorb and conduct water. Generally, the amount of water delivered through the root system and available for transpiration per unit or leaf surface area or unit of leaf dry weight correlated poorly or negatively with the root system size. Practical and scientific implications of the findings are discussed. *Paper presented at Forest Seedling Root Development Conference: From the Nursery to the Field, Eugene, Oregon, May 12–13, 2004.