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1.
Clonal Plasticity in Response to Reciprocal Patchiness of Light and Nutrients in the Stoloniferous Herb Glechoma longituba L. 总被引:1,自引:0,他引:1
Yu Chu Fei-Hai Yu Ming Dong 《植物学报(英文版)》2006,48(4):400-408
Interconnected ramets of clonal plants can functionally specialize in the uptake of resources from aboveground and/or underground sources. Ramet pairs of the clonal stoloniferous herb Glechoma Iongltuba L. were grown In spatially heterogeneous environments with complementary availability of light and nutrients. Plasticity with respect to root-shoot ratio, fitness-related traits (biomass, number of ramets and dry weight per ramet), morphological traits (lamina area, root length) were experimentally examined. The aim was to understand the adaptation of G. Iongltuba to an environment with reciprocal patchiness of light and soil nutrients by plasticity In Its root-shoot ratio and clonal morphology. The results showed that the performance of ramets growing In patches with high light Intensity and low soil nutrients into the adjacent opposite patches was Increased in terms of fitness-related traits. However, the performance of those from patches with low light Intensity and high soil nutrients into the adjacent opposite patches was not changed. The root-shoot ratio and clonal morphology were plastic. Morphological traits such as lamina area and root length were altered In a way that enhanced the capture of light resources and soil nutrients. Apparent reciprocal resource transport between the ramets In an environment of reciprocal patchiness of resources can enhance the growth of ramets with complementary resource deficiencies. 相似文献
2.
Physiological integration facilitates clonal plants to deal with heterogeneous resources. However, little is known about how
nutrient patchiness affects its use and stoichiometry in clonal plants. We conducted an experiment with Cynodon dactylon, Glechoma longituba, and Potentilla reptans to address the effects of physiological integration on nutrient use efficiency and N:P ratios. For C. dactylon, the effects of nutrient patchiness on N use efficiency (NUE), P use efficiency (PUE), and N:P ratio were stronger in daughter
ramets than in parent ramets; for G. longituba, nutrient patchiness affected PUE and N:P ratio of parent and daughter ramets, but not NUE; for P. reptans, nutrient patchiness decreased NUE, PUE, and N:P ratio, regardless of parent or daughter ramets. PUE was associated with
N:P ratios in three clonal plants and this association of NUE with N:P ratios varied with species. Our findings suggest that
physiological integration alters nutrient use efficiency and N:P ratios of clonal plants under patchy nutrients and that these
effects are linked to clonal species identity. 相似文献
3.
Source–sink relationships determine the transfer of resources among interconnected ramets of clonal plants and these relationships depend on resource regimes experienced by ramets. We hypothesized that if ramets growing in nutrient-richer patches support ramets in nutrient-poorer patches, then this support would weaken the performance of supporters themselves. This hypothesis was tested in an experiment, in which two interconnected ramet-groups of Glechoma longituba were subjected to four levels of nutrient-patch contrast. For nurse ramets, midday leaf water potential, net photosynthetic rate, fluorescence yield, specific root length, biomass, and root weight ratio remained unchanged along the gradient of patch contrast, indicating that no damage occurs to these ramets. Nitrogen use efficiency and phosphorus use efficiency of nurse ramets significantly increased with increasing patch contrast, suggesting that these increases may allow nurse ramets from habitats higher in patch contrast to have a greater capacity for export of nutrients than those ramets from habitats lower in patch contrast. In addition, we discuss the likely implications of these findings. 相似文献
4.
Mingjun Liao Feihai Yu Minghua Song Shumin Zhang Jinzheng Zhang Ming Dong 《Acta Oecologica》2003,24(5-6):231-239
Clonal fragments of the stoloniferous herb Glechoma longituba were subjected to a complementary patchiness of light and soil nutrients including two spatially homogeneous treatments (SR–SR and IP–IP) and two spatially heterogeneous treatments (IP–SR and SR–IP). SR and IP indicate patches (shaded, rich) with low light intensity (shaded, S), high nutrient availability (rich, R) and patches (illuminated, poor) with high light intensity (illuminated, I) and low nutrient availability (poor, P), respectively. Plasticity of the species in root–shoot ratio, fitness-related traits (biomass, number of ramets and dry weight per ramet) and clonal morphological traits (length and specific length of stolon internodes, area and specific area of laminae, length and specific length of petioles) were experimentally examined. The aim is to understand adaptation of G. longituba to the environment with reciprocal patches of light and soil nutrients by plasticities both in root–shoot ratio and in (clonal) morphology. Our experiment revealed performance of the clonal fragments growing from patches with high light intensity and low soil nutrient availability into the adjacent opposite patches was increased in terms of the fitness-related characters. R/S ratio and clonal morphology were plastic. Meanwhile, the capture of light resource from the light-rich patches was enhanced while the capture of soil nutrients from either the nutrient-rich or the nutrient-poor patches was not. Analysis of cost and benefit disclosed positive effects of clonal integration on biomass production of ramets in the patches with low light intensity and high soil nutrient availability. These results suggest an existence of reciprocal translocation of assimilates and nutrients between the interconnected ramets. The reinforced performance of the clonal fragments seems to be related with specialization of clonal morphology in the species. 相似文献
5.
Clonal growth allows plants to spread horizontally and to experience different levels of resources. If ramets remain physiologically integrated, clonal plants can reciprocally translocate resources between ramets in heterogeneous environments. But little is known about the interaction between benefits of clonal integration and patterns of resource heterogeneity in different patches, i.e., coincident patchiness or reciprocal patchiness. We hypothesized that clonal integration will show different effects on ramets in different patches and more benefit to ramets under reciprocal patchiness than to those under coincident patchiness, as well as that the benefit from clonal integration is affected by the position of proximal and distal ramets under reciprocal or coincident patchiness. A pot experiment was conducted with clonal fragments consisting of two interconnected ramets (proximal and distal ramet) of Fragaria orientalis. In the experiment, proximal and distal ramets were grown in high or low availability of resources, i.e., light and water. Resource limitation was applied either simultaneously to both ramets of a clonal fragment (coincident resource limitation) or separately to different ramets of the same clonal fragment (reciprocal resource limitation). Half of the clonal fragments were connected while the other half were severed. From the experiment, clonal fragments growing under coincident resource limitation accumulated more biomass than those under reciprocal resource limitation. Based on a cost-benefit analysis, the support from proximal ramets to distal ramets was stronger than that from distal ramets to proximal ramets. Through division of labour, clonal fragments of F. orientalis benefited more in reciprocal patchiness than in coincident patchiness. While considering biomass accumulation and ramets production, coincident patchiness were more favourable to clonal plant F. orientalis. 相似文献
6.
Aims
The purpose of this study was to test the hypotheses that soil nutrient patchiness can differentially benefit the decomposition of root and shoot litters and that this facilitation depends on plant genotypes.Methods
We grew 15 cultivars (i.e. genotypes) of winter wheat (Triticum aestivum L.) under uniform and patchy soil nutrients, and contrasted their biomass and the subsequent mass, carbon (C) and nitrogen (N) dynamics of their root and shoot litters.Results
Under equal amounts of nutrients, patchy distribution increased root biomass and had no effects on shoot biomass and C:N ratios of roots and shoots. Roots and shoots decomposed more rapidly in patchy nutrients than in uniform nutrients, and reductions in root and shoot C:N ratios with decomposition were greater in patchy nutrients than uniform nutrients. Soil nutrient patchiness facilitated shoot decomposition more than root decomposition. The changes in C:N ratios with decomposition were correlated with initial C:N ratios of litter, regardless of roots or shoots. Litter potential yield, quality and decomposition were also affected by T. aestivum cultivars and their interactions with nutrient patchiness.Conclusions
Soil nutrient patchiness can enhance C and N cycling and this effect depends strongly on genotypes of T. aestivum. Soil nutrient heterogeneity in plant communities also can enhance diversity in litter decomposition and associated biochemical and biological dynamics in the soil. 相似文献7.
The response of clonal growth and ramet morphology to water depth (from 60 to 260 cm) and sediment type (sand versus organic
clay) was investigated for the stoloniferous submersed macrophyte Vallisneria natans in an outdoor pond experiment. Results showed that water depth significantly affected clonal growth of V. natans in terms of clone weight, number of ramets, number of generations, clonal radius and stolon length. V. natans showed an optimal clonal growth at water depths of 110–160 cm, but at greater depths clonal growth was severely retarded.
A high allometric effect was exhibited in ramet morphology. Along the sequentially produced ramet generations, ramet weight
and plant height decreased while stolon length and the root:leaf weight ratio increased. When using ramet generations as covariate,
sediment type rather than water depth more strongly affected the ramet characteristics. For plants grown in clay, ramet weight,
ramet height and stolon length were greater, and plants exhibited lower root:leaf weight ratio. These data suggest that water
depth and sediment type have differential effects on clonal growth of V. natans: Water depth appears primarily to affect numerical increase in ramets and spatial spread, whereas sediment type mainly affects
biomass accumulation and biomass allocation.
Handling editor: S. M. Thomaz 相似文献
8.
Patch contrast, defined as the difference between patches, isamong the basic traits of environmental heterogeneity (Kolasa and Pickett 1991;Stuefer 1996). Clonal plants, especially those with long spacers,usually experience certain patches with different nutrient-patchcontrasts (de Kroon et al. 2005; Stuefer 1996). Clonal integrationhas been recognized as a basic strategy, by which clonal plantscan effectively cope with patchy resources and increase theirfitness in such habitats (de Kroon et al. 2005; Zhang et al. 2007).Glechoma longituba is distributed 相似文献
9.
Chang-Cheng Liu Yu-Guo Liu Ke Guo Da-Yong Fan Li-Fei Yu Rui Yang 《Acta Physiologiae Plantarum》2011,33(1):93-102
The karst habitats of southwestern China are characterized by a highly heterogeneous distribution of water resources. We hypothesized
that the clonal integration between connected ramets of the clonal vine Ficus tikoua was an important adaptive strategy to the patchy distribution of water resources in these habitats. We grew ramet pairs (each
consisting of a parent and an offspring ramet) in both homogeneously and heterogeneously watered conditions. The offspring
ramets were well-watered, whereas their connected parent ramets were randomly assigned to four water treatments: well-watered,
mild water stress, moderate water stress, and severe water stress. Increasing water stress decreased leaf water potential,
relative water content, net assimilation rate, maximum quantum yield of PSII (F
v/F
m), and biomass of the parent ramets. Subjecting the parents to water stress significantly increased root biomass and root
mass ratio (RMR) of their offspring ramets. Exploitation of plentiful water resources through the increased adventitious roots
connected to another soil patch permitted the complete restoration of water relations and photosynthetic capacity of offspring
ramets after an initial depression. Water relations and gas exchange of the parents were not affected by the water supply
to their connected offspring ramets, suggesting that offspring ramets hardly exported water to the stressed parents. However,
net assimilation rate and proline content of the offspring ramets increased when they were connected to water-stressed parents.
The compensatory photosynthetic responses of offspring ramets connected to stressed parents revealed an increasing trend as
the experiment progressed. Morphological and physiological plasticity of F. tikoua in response to heterogeneous water resources allow them to adapt to karst habitats and be suitable candidates for vegetation
restoration projects. 相似文献
10.
Reciprocally patchy environments, where the availability of two resources are patchily distributed and negatively correlated in each patch, are common in many ecosystems. Interconnected ramets of clonal plants can specialize in the uptake of locally abundant resources. Ramet pairs of the stoloniferous herb Duchesnea indica were grown in reciprocally patchy environments i.e., one ramet of a pair was grown in the high light but low water patch (high light patch) and the other in the low light but high water patch (high water patch). Biomass allocation pattern (root-shoot ratio), morphological traits (leaf area and root length) and physiological traits (photosynthetic rate and chlorophyll content) were altered in a way that potentially enables ramets to enhance the capture of the locally abundant resource (i.e., increase the capture of light resource in the high light patch and of water in the high water patch). As a result,biomass and number of ramets in the connected ramet pairs were greatly improved. Functional specialization of ramets, modified by clonal integration, may have contributed greatly to the growth increase of D. indica in the reciprocally patchy environment. 相似文献
11.
模拟在喀斯特异质生境下,通过随机区组实验,研究三叶鬼针草(Bidens pilosa L.)在两种土壤生境(浅而宽、深而窄)和3种水分处理(对照、减水50%、减水70%)下植物的地上和地下生长关系及生物量分配格局。结果显示:(1)两种生境中三叶鬼针草的地上生长(株高、地径、叶面积、叶生物量)与地下根系生长(根长、根表面积、根体积、根生物量)均随着施水量的减少而降低;叶面积比率随着施水量的减少而增加;根质量比在浅而宽土壤生境中呈先增后减的趋势,而在深而窄土壤生境中呈增加趋势。(2)两种生境中三叶鬼针草的地上生物量与地下根系生物量、叶面积与根长、叶面积与各层根系生长均呈显著正相关关系。但在浅而宽土壤生境中,三叶鬼针草的地上生物量与各土层根系生物量均呈显著正相关,而在深而窄土壤生境中,地上生物量仅与中上土层根系生物量呈显著正相关。研究表明三叶鬼针草在不同生境中均具有较好的地上地下协同生长对策,在增强对地下资源获取的同时也增强了对地上资源的获取。在浅而宽土壤生境中,三叶鬼针草通过协调根系的横向拓展能力与植物叶片的生长来应对快速的干旱缺水;在深而窄土壤生境中,植株能较好地协调根系向下拓展能力与地上叶面积的生长,更好地利用土壤深层的水分资源。 相似文献
12.
Islands within islands: two montane palaeo‐endemic birds impacted by recent anthropogenic fragmentation 下载免费PDF全文
Anthropogenic habitat fragmentation of species that live in naturally patchy metapopulations such as mountaintops or sky islands experiences two levels of patchiness. Effects of such multilevel patchiness on species have rarely been examined. Metapopulation theory suggests that patchy habitats could have varied impacts on persistence, dependent on differential migration. It is not known whether montane endemic species, evolutionarily adapted to natural patchiness, are able to disperse between anthropogenic fragments at similar spatial scales as natural patches. We investigated historic and contemporary gene flow between natural and anthropogenic patches across the distribution range of a Western Ghats sky‐island‐endemic bird species complex. Data from 14 microsatellites for 218 individuals detected major genetic structuring by deep valleys, including one hitherto undescribed barrier. As expected, we found strong effects of historic genetic differentiation across natural patches, but not across anthropogenic fragments. Contrastingly, contemporary differentiation (DPS) was higher relative to historic differentiation (FST) in anthropogenic fragments, despite the species’ ability to historically traverse shallow valleys. Simulations of recent isolation resulted in high DPS/FST values, confirming recent isolation in Western Ghats anthropogenic fragments and also suggesting that this ratio can be used to identifying recent fragmentation in the context of historic connectedness. We suggest that in this landscape, in addition to natural patchiness affecting population connectivity, anthropogenic fragmentation additionally impacts connectivity, making anthropogenic fragments akin to islands within natural islands of montane habitat, a pattern that may be recovered in other sky‐island systems. 相似文献
13.
Background and Aims Enhanced availability of photosynthates increases nitrogen (N) mineralization and nitrification in the rhizosphere via rhizodeposition from plant roots. Under heterogeneous light conditions, photosynthates supplied by exposed ramets may promote N assimilation in the rhizosphere of shaded, connected ramets. This study was conducted to test this hypothesis.Methods Clonal fragments of the stoloniferous herb Glechoma longituba with two successive ramets were selected. Mother ramets were subjected to full sunlight and offspring ramets were subjected to 80 % shading, and the stolon between the two successive ramets was either severed or left intact. Measurements were taken of photosynthetic and growth parameters. The turnover of available soil N was determined together with the compostion of the rhizosphere microbial community.Key Results The microbial community composition in the rhizosphere of shaded offspring ramets was significantly altered by clonal integration. Positive effects of clonal integration were observed on NAGase activity, net soil N mineralization rate and net soil N nitrification rate. Increased leaf N and chlorophyll content as well as leaf N allocation to the photosynthetic machinery improved the photosynthetic capability of shaded offspring ramets when the stolon was left intact. Clonal integration improved the growth performance of shaded, connected offspring ramets and whole clonal fragments without any cost to the exposed mother ramets.Conclusions Considerable differences in microbial community composition caused by clonal integration may facilitate N assimilation in the rhizosphere of shaded offspring ramets. Increased N content in the photosynthetic machinery may allow pre-acclimation to high light conditions for shaded offspring ramets, thus promoting opportunistic light capture. In accordance with the theory of the division of labour, it is suggested that clonal integration may ameliorate the carbon assimilation capacity of clonal plants, thus improving their fitness in temporally and spatially heterogeneous habitats. 相似文献
14.
E. A. Irlandi 《Oecologia》1994,98(2):176-183
Landscape ecology, predominantly a terrestrial discipline, considers the effect of large-scale (tens of meters to kilometers) spatial patterns of habitats on ecological processes such as competition, predation, and flow of energy. In this study, a landscape-ecology approach was applied to a marine soft-sediment environment to examine rates of predation and transfer of secondary production in and around vegetated habitats. Seagrass beds naturally occur in a variety of spatial configurations from patches 1–10s of meters across with interspersed unvegetated sediments (i.e., patchy coverage) to more continuous coverage with little or no bare sediment. I designed experiments to address how percent coverage of seagrass in a 100-m2 area of seafloor, and the spatial arrangement (degree of patchiness or fragmentation) of an equal area (100 m2) of vegetation affected predation (lethal) and siphon nipping (sublethal) intensity on an infaunal bivalve, Mercenaria mercenaria (hard clam). Measures of seagrass density and biomass with different percent coverage of seagrass were also made. When clams were placed in both the vegetated and unvegetated portions of the seafloor nearly twice as many clams were recovered live with 99% seagrass cover than with 23% seagrass cover, while survivorship was intermediate with 70% cover. Cropping of clam siphons from both the vegetated and unvegetated sediments was also affected by the amount of seagrass cover in a 100-m2 area of seafloor: mean adjusted siphon weights were approximately 76% heavier from the 99% seagrass cover treatment than from the 70% or 23% cover treatments. Survivorship of clams placed within an equal area of seagrass in very patchy, patchy, and continuous spatial configurations was 40% higher in the continuous seagrass treatment than in either of the two patchy treatments. This study demonstrates that transfer of secondary production in the form of predation and cropping on an infaunal organism is altered as the percent cover of seagrass changes. While large-scale changes in the amount and spatial patterning of vegetation may affect habitat utilization patterns and foraging HGLoopbehavior, increased seagrass density and biomass with increased percent coverage of seagrass limit any conclusions concerning predator foraging behavior and feeding success in response to patch shapes and sizes. Instead, local changes in seagrass characteristics provide the most compelling explanation for the observed results. 相似文献
15.
Peter Alpert 《Oecologia》1999,120(1):69-76
In plants, only species with clonal growth are able to directly transfer resources between otherwise independent units of
the same genetic individual. A simple conceptual model of plant performance as a function of internal resource supply and
environmental resource availability suggests that resource sharing between ramets within clones is likely to be disadvantageous
in uniform habitats and advantageous in patchy ones. It was therefore hypothesized that clones in populations from relatively
uniform habitats will have been selected for low rates of resource sharing between ramets compared to clones in populations
from patchier habitats. In coastal northern California, the clonal herb Fragaria chiloensis is common both in grasslands, where resources are relatively uniform, and on sand dunes, where resources are more patchy.
It was predicted that clones from a grassland population of Fragaria would have “selfish” ramets with low rates of resource sharing compared to clones from an adjacent dune population. Ramets
were subjected to contrasting light levels with and without connection between ramets. Patterns of biomass accumulation were
consistent with the prediction. This appears to be the first report of genetically based variation in patterns of resource
sharing in clonal plants. It supports the idea that these patterns are locally selected to increase plant performance in habitats
with different patterns of resource availability.
Received: 19 August 1998 / Accepted: 4 March 1999 相似文献
16.
Hao-qin Xiong 《Journal of Plant Ecology》2010,3(2):131
Aims Most plants are clonal in nature. Clonal ramets can share water, nutrients and photosynthate, especially when they experience patchy resources. Patch contrast (i.e. a difference in resources among patches) and patch direction (i.e. source–sink relations) are among the basic attributes of spatial patchiness. Here, I hypothesize that young established ramets in nutrient-rich patches support old ramets in nutrient-poor patches when ramets are subjected to different patch contrasts and patch directions.Methods In a greenhouse experiment, old and young ramets of Glechoma longituba were grown in four combinations consisting of patch contrast and patch direction. Minus patch direction refers to a patch combination in which parent ramets grow in nutrient-rich patches while connected daughter ramets grow in nutrient-poor ones and plus patch direction is the opposite direction. I measured photosynthesis and fluorescence traits, harvested all ramets, took morphological measures, weighed their dry mass and determined their nutrient uptake and use.Important findings For parental ramets of G. longituba, patch contrast and patch direction and their interactions had no significant effects on net photosynthetic rate, maximal fluorescence yield, photochemical quenching (quenching refers to any process which decreases the fluorescence intensity of a given substance), non-photochemical quenching, nutrient uptake, biomass and stolon weight ratio. Patch direction alone significantly affected root weight ratio. Large patch contrast enhanced N use efficiency (NUE) and P use efficiency (PUE); plus patch direction decreased NUE, but increased PUE; the patch contrast by patch direction interaction affected PUE and K use efficiency (KUE). There were significant interactions between patch direction and patch contrast on PUE and KUE. It is concluded that soil nutrient patchiness may influence nutrient use strategies, but not nutrient uptake, photosynthesis and growth of parent ramets of G. longituba connected to daughter ramets, and that patch contrast and patch direction jointly affect PUE and KUE. 相似文献
17.
Different behaviour of small groups of stomata on a single leaf blade (stomatal patchiness) is reviewed. The occurrence of stomatal patchiness depends on plant species, age, leaf position, environmental conditions,etc. The possibility of errors in conventional evaluation of stomatal and non-stomatal (biochemical) limitations of photosynthesis resulting from patchy stomatal closure is analysed. The consequences of stomatal patchiness for leaf and plant photosynthesis and water economy are discussed. A brief survey of the techniques currently used for detection and quantification of stomatal patchiness is presented. 相似文献
18.
Resource sharing in heterogeneous environments has been shown to increase growth and survival of clonal plants. In addition,
plants in harsh climates have been suggested to have higher levels of resource sharing than plants in milder climates. We
experimentally investigated the level of resource sharing in plants from garden and forest habitats from two regions with
contrasting climates. The clonal herb Aegopodium podagraria reaches its northern distribution limit in central Sweden. South of that it grows in both patchy and dynamic light climate,
as a natural component of deciduous forest, as well as in more homogeneous light climates as a garden weed. Since heterogeneity
and habitat harshness have both been suggested to increase resource sharing, we hypothesized (1) integration and sharing of
resources to be higher in plants from forest than in plants from garden habitats and (2) integration and sharing of resources
to be higher in plants from the northern region that encounter a harsher climate than in plants from the southern region.
Clonal fragments of A. podagraria were collected and multiplied in the greenhouse. Ramet pairs were then planted in adjacent pots, with one ramet shaded. Rhizome
connection was either left intact or severed to prevent resources sharing. Plants from forest habitats were more negatively
affected by the severance treatment than plants from garden habitats. Although region alone had no significant effect on biomass,
the interaction between rhizome severing, shading and regional origin was close to significance. We conclude that A. podagraria from forests are more dependent on resource sharing than those from gardens. These results concur with previous studies that
suggest that local adaptation for different degrees of resource sharing can occur in clonal plants. 相似文献
19.
Environmentally-induced functional specialization for locally abundant resources in the stoloniferous herb Duchesnea indica 下载免费PDF全文
Reciprocally patchy environments, where the availability of two resources are patchily distributed and negatively correlated in each patch, are common in many ecosystems. Interconnected ramets of clonal plants can specialize in the uptake of locally abundant resources. Ramet pairs of the stoloniferous herb Duchesnea indica were grown in reciprocally patchy environments i.e., one ramet of a pair was grown in the high light but low water patch (high light patch) and the other in the low light but high water patch (high water patch). Biomass allocation pattern (root-shoot ratio), morphological traits (leaf area and root length) and physiological traits (photosynthetic rate and chlorophyll content) were altered in a way that potentially enables ramets to enhance the capture of the locally abundant resource (i.e., increase the capture of light resource in the high light patch and of water in the high water patch). As a result,biomass and number of ramets in the connected ramet pairs were greatly improved. Functional specialization of ramets, modified by clonal integration, may have contributed greatly to the growth increase of D. indica in the reciprocally patchy environment. 相似文献
20.
Root morphological and physiological plasticity of perennial grass species and the exploitation of spatial and temporal heterogeneous nutrient patches 总被引:10,自引:0,他引:10
Root morphological and physiological characteristics of four perennial grass species were investigated in response to spatial
and temporal heterogeneous nutrient patches. Two species from nutrient-rich habitats (i.e. Holcus lanatus and Lolium perenne)
and two species from nutrient-poor habitats (i.e. Festuca rubra and Anthoxanthum odoratum) were included in the study. Patches
were created by injecting equal amounts of nutrient solution into the soil either on one location (i.e. spatial heterogeneity)
or on several, alternating locations (i.e. temporal heterogeneity) within the pot. The consequences of changes in root morphology
and the implications for the exploitation of the nutrient patches by individual plants were quantified by the amount of 15N captured from the enriched patches. The effects of nutrient heterogeneity on the acquisition of nutrients by species were
determined by comparing the total nitrogen and phosphorus acquisition of the species in the two heterogeneous habitats with
the total nitrogen and phosphorus acquisition in a homogeneous treatment. In this homogeneous treatment the same amount of
nutrient solution was supplied homogeneously over the soil surface. The experiment lasted for 27 days and comprised one harvest.
In response to the spatial enrichment treatment, all species produced significantly more root biomass within the enriched
patch. The magnitude of the response was similar for species from nutrient-rich and nutrient-poor habitats. In contrast to
this response of root biomass, root morphology, including specific root length, branching frequency and mean lateral root
length was not affected by the treatments. In response to the temporal enrichment treatment, all species were able to increase
the nitrogen uptake rate per unit of root biomass. The species from nutrient-poor habitats had, on average, higher uptake
rates per unit root biomass than the species from nutrient-rich habitats, but the magnitude of the response did not differ
between the species. These results question the general validity of the assumptions that root foraging characteristics differ
among species from nutrient-rich and nutrient-poor habitats.
As a result of these root responses, all species captured an equal amount of 15N from the spatial and temporal enriched nutrient patches and all species acquired significantly more nitrogen in the heterogeneous
treatments than in homogeneous treatment. Hence, the ability to exploit local and temporal nutrient heterogeneity does not
appear to differ between species from nutrient-rich and nutrient-poor habitats, but is achieved by these species in different
ways. The ecological implications of these differences are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献