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1.
《Scandinavian Journal of Forest Research》2012,27(1-4):471-480
Ingestad's concept of relative addition rate was used to grow a range of seedling types, of both black (Picea mariana) (Mill.) B.S.P.), and white spruce (Picea glauca (Moench) Voss). Seedlings were grown for about 18 weeks in styrofoam containers under greenhouse conditions, and fertilized at exponentially increasing rates of either one, two, four or six per cent per day, following a one month pretreatment period. Pretreatment consisted of applying a nutrient solution proportionally low in nitrogen, but that had a relatively high conductivity compared to the initial solutions used in the exponentially increasing fertilizer treatments. Black spruce seedlings grew fastest, had significantly more root development or had a higher efficiency of nitrogen uptake when nutrients were applied at exponentially increasing amounts. In contrast, white spruce grew more rapidly when fertilized with a constant level of fertilizer (control treatment). Biomass allocation and nitrogen concentrations in seedlings of both species varied significantly with treatment, indicating that various levels of nitrogen stress had been achieved. It is suggested that different seedling stock types, which are acclimated to various levels of nutrient stress, can be produced by controlling the rate of nutrient addition. 相似文献
2.
P. J. Gregory 《Agroforestry Systems》1996,34(1):51-65
This review presents information about root systems of crops and trees and describes approaches that have been used to model uptake of water and nutrients in crops that may have application to agroforestry systems. Only a few measurements of the distribution of tree roots in agroforestry systems have been published and these are predominantly in alley cropping systems with young trees. Therefore, a major limitation to developing water and nutrient uptake models for trees is the lack of adequate measurements and conceptual models for describing the distribution of roots spatially and temporally. Most process-based modelling approaches to water and nutrient uptake integrate the activities of a single root over the whole root system. Several difficulties can be foreseen with applying these approaches to roots of older trees including the presence of mycorrhizal associations so that the root surface is not the site of uptake, the uncertainty as to whether all tree roots are active in taking up water and nutrients, and the fact that, unlike annual crops, trees have substantial reserves of nutrients that can be mobilised to support growth so that the notion of a plant demand regulating uptake may prove difficult to define. The review concludes that a programme of experimental measurements is required together with modelling using approaches both in which roots are implicit, and in which process-based models with roots allow competitive ability to be assessed. 相似文献
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4.
Budget studies have shown that internal cycling may contribute a large proportion of the annual nutrient supply required to support new growth in trees. Use of budgets to quantify internal cycling only quantifies the net transfer of nutrients within the plant. Differential partitioning of remobilized nutrients and current nutrient uptake could lead to errors in the interpretation of results from these studies. We have quantified the dynamic relationships among tree growth, nutrient uptake and internal cycling by labeling the current uptake of N in trees that received contrasting amounts of nutrient. Two-year-old seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.) were grown in sand culture in a greenhouse for one year. The trees received nutrients in a balanced solution at either a high (high-RAR) or a low (low-RAR) relative addition rate throughout the experiment. Current N uptake was labeled with (15)N from April 13 to July 25. Thereafter, trees were re-potted in clean sand and unlabeled N applied until November 13. Overall growth was sustained for approximately 10 weeks before treatment effects were observed. Initially, no differences in the partition of growth or remobilized N occurred, although partition of current uptake favored the roots of plants in the low-RAR treatment. After 6 weeks, the partition of both growth and remobilized N altered in favor of roots of plants in the low-RAR treatment. Nutrient supply had no effect on the amount or rate of N remobilization. No evidence was found to suggest that N taken up in the current season and partitioned to preexisting shoots or roots is remobilized late in the season to support growth of new shoots. However, some trees in the high-RAR treatment exhibited a second flush of growth later in the season that was partially sustained by remobilization of (15)N from current shoots formed earlier in the season. Use of (15)N demonstrated differential partitioning of current uptake and remobilized N. The results highlight the limitations of simple budget studies for quantifying internal cycling. 相似文献
5.
全营养施肥对桉树组培容器苗生长和营养状况的影响 总被引：2，自引：0，他引：2
在温室条件下对桉树组培容器苗进行全营养施肥与传统单施N肥比较试验,分析测定不同施肥处理对苗木生长、生物量以及养分含量的影响。结果表明,全营养施肥比单施N肥更有利于桉树苗木生长和营养平衡;在全营养施肥中,又以N50 mg.株-1处理优于N100 mg.株-1处理。在N50 mg.株-1基础上,实施全营养施肥是培育优质桉树苗的较佳施肥方案,可供桉树工厂化育苗推广应用。 相似文献
6.
《Scandinavian Journal of Forest Research》2012,27(1-4):347-354
Young birch (Betula pendula Roth) seedlings were grown in hydroponic cultures to which nutrients were added in amounts that increased exponentially over time. The nutrient additions were adjusted to give three different suboptimal, but stable, relative growth rates (RGR). Levels of glucose, fructose, sucrose and starch and the hormones 3‐Indolyl acetic acid (IAA) and abscisic acid (ABA) were determined in immature (sink) and mature (source) leaves and related to the measured RGR of the seedlings. The results show that ABA increased and IAA decreased in the sink leaves as the RGR of the plants decreased. This occurred in concert with a decrease in soluble sugar levels and starch accumulation in the source leaves. These observations suggest that ABA and IAA may be involved in source‐sink communication in the seedlings, although such causal relationships remain to be proven. 相似文献
7.
Pruning effects on root distribution and nutrient dynamics in an acacia hedgerow planting in northern Kenya 总被引：2，自引：0，他引：2
Tree pruning is a common management practice in agroforestry for mulching and reducing competition between the annual and perennial crop. The below-ground effects of pruning, however, are poorly understood. Therefore, nutrient dynamics and root distribution were assessed in hedgerow plantings of Acacia saligna (Labill.) H.L. Wendl. after tree pruning. Pruning to a height of 1.5 m was carried out in March and September 1996. In July and October 1996, the fine root distribution (< 2 mm) and their carbohydrate contents were determined at three distances to the tree row by soil coring. At the same time, foliar nutrient contents were assessed, whereas nutrient leaching was measured continuously. The highest root length density (RLD) was always found in the topsoil (0–0.15 m) directly under the hedgerow (0–0.25 m distance to trees). Pruning diminished the RLD in the acacia plots at all depths and positions. The relative vertical distribution of total roots did not differ between trees with or without pruning, but live root abundance in the subsoil was comparatively lower when trees were pruned than without pruning. In the dry season, the proportion of dead roots of pruned acacias was higher than of unpruned ones, while the fine roots of unpruned trees contained more glucose than those of pruned trees. Pruning effectively reduced root development and may decrease potential below-ground competition with intercropped plants, but the reduction in subsoil roots also increased the danger of nutrient losses by leaching. Leaching losses of such mobile nutrients as NO3– were likely to occur especially in the alley between pruned hedgerows and tended to be higher after pruning. The reduced size of the root system of pruned acacias negatively affected their P and Mn nutrition. Pruning also reduced the function of the trees as a safety net against the leaching of nutrients for both NO3– and Mn, though not for other studied elements. If nutrient capture is an important aim of an agroforestry system, the concept of alley cropping with pruning should be revised for a more efficient nutrient recycling in the system described here.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
8.
Steady-state nutrition of Pinus resinosa seedlings: response to nutrient loading, irrigation and hardening regimes 总被引：1，自引：0，他引：1
To test effects of fertilization on late-season growth and nutrient content of container-grown red pine (Pinus resinosa Ait.), seedlings were subjected to a factorial combination of two fertilization regimes (exponentially increasing concentrations providing 25 (1N) and 75 (3N) mg N seedling(-1), respectively) and two irrigation regimes (well-watered and water-stressed) followed by drought-hardening or nonhardening. The fertilization treatments gave rise to steady-state nutrition in the seedlings during the prehardening phase. The 3N treatment increased macronutrient uptake significantly more than dry matter production, particularly in the roots, giving rise to what has been called luxury consumption of nutrients, or nutrient loading. Nutrient loading was higher in well-watered seedlings than in water-stressed seedlings. Among well-watered seedlings, relative growth rate of nutrient-loaded seedlings was more sensitive to drought during the hardening phase than that of nonloaded seedlings. However, when watering was resumed at the end of the hardening treatment, the relative growth rate of the nutrient-loaded seedlings (421%) exceeded that of the nonloaded seedlings (213%). Nitrogen accumulation was also higher in nutrient-loaded seedlings than in nonloaded seedlings during the post-hardening phase. 相似文献
9.
Fiber farming utilizing fast growing trees provides a means to satisfy the increasing demand for hardwood fiber. To maximize growth during the establishment phase, it is important to understand the relationship between maximal growth rate, plant nutrient requirements, and the ability of the soil to supply nutrients. The objectives of this study were: (i) to use a steady state nutrition technique to establish threshold N, P, and K ratios associated with maximal growth and (ii) to use the Barber–Cushman nutrient uptake model as a means of coupling information on the nutrient supplying capacity of the soil with the optimum N:P:K ratio. Growth chamber and greenhouse studies, using Populus nigra×maximowiczii (NM-6), were conducted to determine maximal growth rate, optimal N, P, and K content, uptake kinetics, and soil supply characteristics. Maximal growth rate was 0.12 g g−1 per day at a whole plant ratio of 100N:11P:37K. The Barber–Cushman model was run using soil supply and root growth data from the greenhouse study. Nitrogen, P, and K uptake were simulated for a 105-day period in response to the addition of a slow release 17–6–12 fertilizer at rates equivalent to 0, 75, or 150 kg ha−1 of N. Model predictions of uptake improved as the amount of fertilizer added increased. Uptake estimates at the 150 level were 96, 120, and 98% of observed uptake for N, P, and K, respectively. The model predicted that the supply of N was not adequate to support sustained plant uptake throughout the study period. Plant uptake and soil supply observations confirmed that N uptake occurred primarily in the first half of the growth period and that soil N supply was quickly depleted. Model simulations of P uptake support earlier observations that uptake is not solely a function of supply. A 10-fold increase in simulated supply increased uptake by a factor of 6. Much more needs to be done before a soil supply model like Barber–Cushman can be used as a nutrient management tool in forestry applications. However, establishing optimum levels, ratios, and rates of nutrient addition provides a good starting point for further evaluation. 相似文献
10.
本文对杉木和马尾松林内、外雨树干茎流及迳流所含各种养分物质量进行了测定,其结果表明:林内雨的各种养分物质浓度显著地高于林外雨。林外雨的各养分物质含量是 N>Ca>K>Mg>P,杉木林内雨的各种养分物质量是 K>N>Ca>Mg>P。皆伐迹地迳流中养分流失量显著地高于林地的流失量。雨水养分含量与降雨量存在着半对数函数关系。由降雨输入的养分量显著地大于迳流输出的养分量。林内雨和树干茎流淋溶的养分量占还原养分总量的 48—53％。林内雨和树干淋溶的K、Mg、N的养分量超过凋落物归还的养分量。 相似文献
11.
Paulo Csar Teixeira Roberto Ferreira Novais Nairam Flix Barros Júlio Csar Lima Neves Jos Luiz Teixeira 《Forest Ecology and Management》2002,160(1-3):263-271
Lack of information concerning root growth of trees limits our knowledge of plant development and fertilizer response. The objective of this work was to study root growth dynamics of an E. urophylla forest after harvesting and the supply of nutrients from the roots and the soil to the new sprouts originating from the stumps. About 7-year-old eucalypt trees were felled and the sprouts and roots were sampled at 0, 60, 120, 180, 240, 330 days after harvesting. The roots were separated into fine roots (<1 mm), medium roots (1–3 mm), coarse roots (>3 mm), and taproot. Nutrient supply to sprouts from the old roots and the soil was calculated based on the change in nutrient content of the roots with time and accumulation of nutrients in the sprouts. Fine, medium and coarse root biomass increased with time after harvesting. However, the increase was more pronounced with fine roots. Between harvesting and day 60 of the new growth, all nutrients allocated to the sprouts, excluding potassium, were supplied by the soil. K was the nutrient most dependent on root reserves for the initial growth of sprouts. The contribution of the old roots to N, P, Ca, and Mg accumulation in the sprouts increased between day 60 and 120. At 330 days after harvesting, about 9.2, 23.9, and 12.6% of the N, K, and Mg, respectively, that had accumulated in the sprouts were supplied by the roots, while all P and Ca were supplied by the soil. 相似文献
12.
在我国亚热带毛竹(Phyllostachys pubescens Mazel ex H.de Lehaie)主要产区浙、赣两省的三块试验林中对毛竹林内降水的养分输入及其小流域迳流的养分输出进行了连续四年的观察研究。结果表明,林内降水中的养分物质浓度及其输入量的季节变化明显,且与林内降水量的季节变化密切相关。林内降水中各养分物质的浓度及输入量依大小顺序列为K~+>Ca~(2+)>Mg~(2+)>NH_4~+-N>NO_3~--N>PO_4~(3-)。迳流水养分输出量的季节变化动态与迳流水量的季节增减趋势相一致,其养分物质浓度及输出量高低顺序为K~+>Mg~(2+)>速效N>PO_4~(3-)。除作为养分移动载体的林内降水及迳流水外,毛竹生长发育特性、土壤生物活动及施肥、抚育等人力措施亦对毛竹林生态系统的养分输入与输出产生影响。文中建立了浙江省庙山坞试验林林内降水中养分元素钾的年输入量GM(1,1)预测模型。 相似文献
13.
Nutrients, moisture and productivity of established forests 总被引：1，自引：0，他引：1
The response of a forest to nutrient and moisture stresses is reflected in nutritional, physiological, and structural changes that include efficiency of nutrient use, translocation and cycling of nutrients, transpiration, retention of foliage, below-ground and above-ground allocation of carbon, as well as the structural development of the forest stand and its growth characteristics. This article reviews the relationship of forest ecosystems to nutrient and moisture stresses and addresses the means by which productivity can be enhanced by altering nutrient and moisture regimes.
Considerable research has focused on optimizing productivity by minimizing nutrient and moisture stresses. Research involved in nutrient additions has led to the use of commercial fertilizers to improve forest productivity. The results suggest that many forests are deficient in N and P and, to a lesser extent, S, K, Mg and trace elements. The duration of response for most nutrient additions is, however, relatively brief and the efficiency of the tree in using fertilizer is relatively poor. Long-term correction of nutrient deficiencies is seldom achieved with chemical fertilizers. However, N added through symbiotic fixation or, on a more limited scale, through addition of municipal and industrial waste by-products, can provide an excellent long-term growth response.
It is seldom feasible to change the moisture regime of a forest ecosystem through irrigation. However, field trials involving irrigation have demonstrated that moisture stress can limit productivity. There are various ways of minimizing moisture stress without irrigation, including mulching, removing ground-cover vegetation, and changing the spatial characteristics of the forest cover.
Research trials show that forest ecosystems will respond to moisture and nutrient additions; however, these responses and interactions between nutrients and moisture are typically poorly understood, and many questions remain unanswered: Does fertilization increase moisture-use efficiency of a forest or simply improve the nutrition of the site? Does improving the moisture regime of a site improve productivity primarily by decreasing moisture stress or by increasing nutrient availability and the rate of nutrient uptake? Is there a synergism in growth response with the addition of both nutrients and moisture? The linkages between nutrients and moisture appear inseparable and confound experimentation in this field. Answers to these questions and issues need to be found for the future development of plantation forestry. 相似文献
14.
Four shrub/tree species, Alchornea cordifolia, Pennisetum purpureum, Chromolaena odorata, and Calliandra calothyrsus were
evaluated for their potential contribution to soil fertility restoration after two years fallow. Standing biomass, root distribution,
nutrient content in the biomass, decomposition and nutrient release patterns, and association with mycorrhizae were the evaluation
parameters. Alchornea and Pennisetum produced thehighest above-ground biomass, 66 t and 54 t/ha respectively. Pennisetum had
more than 19 t/ha of root, 92% of which was in the 20 cm top soil. Alchornea had 74% of it roots in this soil layer, mostly
as coarse roots while Calliandra had a deeper root system. Alchornea fallow accumulated more N and Ca, and Pennisetum fallow,
more K than others, and mycorrhizae were mostly associated with Alchornea roots. The ranking of the different species for
the decomposition rate was: Chromolaena > Pennisetum > Calliandra = Alchornea. Also release of nutrients during decomposition
followed the order K > N > Ca. Alchornea and Pennisetum could be recommended as green manure species especially when high
quantities of material are needed for weed or erosion control. Calliandra and Chromolaena, because of the flush of nutrient
during early mass, loss can be used as mulch when the crop demand of nutrient is high. Alchornea decomposed slowly and therefore
could be used to improve Chromolaena mulch, thus contributing to the build up of soil organic N and providing both short-
and long-term nutrient release.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
Containerized red pine (Pinus resinosa Ait.) seedlings were grown over a 16-week rotation at different irrigation treatments to assess moisture stress on plant growth and nutrition, and to evaluate container capacity as a guide for irrigation. Wet, moist and dry moisture regimes were induced by watering trees to the container capacity weight of the growing medium after declining to respective 92, 73 and 57% of this reference weight. The seedlings received the same amount of fertilizer over the growth period. Maximum shoot and root growth was attained under the wet moisture regime, but biomass was reduced 21 and 43% for the moist and dry regimes. Plant nutrient concentrations were not significantly affected by watering treatment, and vector diagnosis of dry matter production and element composition indicated that macronutrients were non-limiting. Seedling nutrient uptake however, was significantly diminished by moisture stress which was attributed to decreased root growth and lower mass flow and diffusion of nutrients when moisture availability was reduced in the peat rooting media. Container capacity was found to be a sensitive reference for judging the watering requirements of greenhouse-grown containerized seedlings. The method can be relatively easily applied on an operational basis. 相似文献
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本试验通过5种营养液配方静置水培仙人球“层云”,并采用常规栽培作对照的方法,探讨仙人球“层云”在静置水培中生长和养分吸收的规律。结果表明:其生长速度要比基质栽培的快,但在水培中其根系生长量却显著低于基质栽培。“层云”对磷、钾的吸收量随营养液供应量的增加而增加,但养分供应量与生长量增加的关系不一致。综合认为配方三为最适合“层云”生长的营养液配方。 相似文献
18.
《Scandinavian Journal of Forest Research》2012,27(3):196-205
Growth and nutrition of hydroponically cultivated pine seedlings (Pinus pinaster Ait.) were investigated at various phosphorus (P) availabilities. P was added either with free access or at a relative addition rate of 0.02 and 0.04 day?1. Laboratory observations were compared with adult growth performances in the field in two sets of experiments: the first with three contrasting populations, the second with seven full-sib families within a population. Significant differences in P productivity (growth rate per unit P in the plant) and in maximal relative growth rate were observed in both experiments, but correlation with adult performances was restricted to populations. Selection for nutrient-related traits would thus be possible, but understanding of the relationship between growth and nutrition needs further evaluation. The minimum P concentration in the seedlings supporting maximum growth ([P]optimum) varied from 2.2 to 3.8 mg g?1 DM, which is in agreement with values obtained in other species. The root/shoot ratio increased with P limitation, with a marked tendency for the population with the highest adult height performance. Inversely, within families, seedlings identified as the best performers for adult growth invested more biomass in shoots than in roots with P stress. 相似文献
19.
通过对杉木、观光木混交林和杉木纯林细根的养分现存量动态进行研究 ,结果表明 ,混交林细根N、P养分现存量分别是纯林的 1.3和 1.2倍 ;年归还量分别是纯林的 1.2 3倍和 1.14倍 ,且分别占混交林凋落物N、P养分年归还量的 38.3%和 6 7.4 % ;年分解量分别是纯林的 1.2 6和 1.2 3倍 ,而年累积量分别是纯林的 1.2 3和 1.14倍 ,可见混交林细根具有比纯林更高的养分累积和周转能力。混交林和纯林群落中林下植被细根在群落细根N、P养分循环中占有重要地位 ,而杉木和观光木 <0 .5mm径级细根则是其细根养分循环功能的主体。混交林和纯林杉木活细根N养分现存量动态变化呈单峰型 ,P则呈双峰型 ;死细根N、P养分现存量动态变化均呈倒“S”型。混交林中观光木细根的N、P养分现存量动态变化与杉木的较相似 ,但其活细根P养分现存量动态变化呈单峰型。混交林与纯林中林下植被活细根N、P养分现存量动态变化均呈双峰型 ,而死细根的动态变化则呈单谷型 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(5):401-415
Norway spruce [Picea abies (L.) Karst.] and silver birch (Betula pendula Roth) seedlings were grown for one season under three different fertilization regimens in the forest nursery. During the first 50 days the seedlings were grown in a glasshouse, and thereafter outdoors until the beginning of September. Finally, the plants were exposed to 16 h nights in the glasshouse throughout September. When the seedlings were supplied with fertilizers at a rate adjusted to expected plant demand (RO), less than half as much of each nutrient was applied as in a conventional regimen (RC), in which equal amounts were supplied per unit time during the growth season, yet the plants still looked healthy. Utilization of N increased by almost 50% in spruce when supply was adjusted to plant demand. In the third treatment (RL), nutrients were supplied as in the RO treatment, but at a growth-limiting rate. These plants were loaded with nutrients at the end of the season and had higher root:plant ratios, i.e. root weight in relation to total plant weight, compared with the other treatments. The nutrient status of the plants was not growth limiting at the end of the growing season in any of the treatments. The plants given the different treatments differed in size at planting out, but they had similar heights after 3 yrs in the field. This indicates that the root:plant ratio may be important for growth performance, provided that nutrient status is not at a growth-limiting level. This study suggests that the use of fertilizers can be considerably reduced in Swedish forest nurseries. 相似文献