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1.
Byung Bae Park Ruth D. Yanai Timothy J. Fahey Scott W. Bailey Thomas G. Siccama James B. Shanley Natalie L. Cleavitt 《Ecosystems》2008,11(2):325-341
Losses of soil base cations due to acid rain have been implicated in declines of red spruce and sugar maple in the northeastern
USA. We studied fine root and aboveground biomass and production in five northern hardwood and three conifer stands differing
in soil Ca status at Sleepers River, VT; Hubbard Brook, NH; and Cone Pond, NH. Neither aboveground biomass and production
nor belowground biomass were related to soil Ca or Ca:Al ratios across this gradient. Hardwood stands had 37% higher aboveground
biomass (P = 0.03) and 44% higher leaf litter production (P < 0.01) than the conifer stands, on average. Fine root biomass (<2 mm in diameter) in the upper 35 cm of the soil, including
the forest floor, was very similar in hardwoods and conifers (5.92 and 5.93 Mg ha−1). The turnover coefficient (TC) of fine roots smaller than 1 mm ranged from 0.62 to 1.86 y−1 and increased significantly with soil exchangeable Ca (P = 0.03). As a result, calculated fine root production was clearly higher in sites with higher soil Ca (P = 0.02). Fine root production (biomass times turnover) ranged from 1.2 to 3.7 Mg ha−1 y−1 for hardwood stands and from 0.9 to 2.3 Mg ha−1 y−1 for conifer stands. The relationship we observed between soil Ca availability and root production suggests that cation depletion
might lead to reduced carbon allocation to roots in these ecosystems. 相似文献
2.
Ola Palm W. Lionel Weerakoon M. Ananda P. de Silva Thomas Rosswall 《Plant and Soil》1988,108(2):201-209
Sesbania sesban was evaluated as green manure crop for lowland rice in the Dry Zone of Sri Lanka. The legume was grown during a fallow period
before lowland rice (Oryza sativa) and ploughed under just before transplanting. Weight loss and nitrogen content in litterbags containing leaves, stems and
roots of the legume were monitored. Comparisons were made between rice yields from 20 m2 plots after green manuring in combination with different nitrogen fertilizer levels (0, 2.4, 4.8 and 7.2 gm−2) and nitrogen fertilizer (9.6 gm−2) alone. Above-ground biomass ofS. sesban was 440 gm−2 (dry wt) when ploughed under after 84 days growth. N-content in leaves, stems and roots was 3.76%, 0.41% and 0.73%, respectively.
This gave a N-input fromS. sesban of 9.2 gm−2 (8.3 g from above-ground parts and 0.9 g from roots). The corresponding K and P inputs were 7.3 and 0.6 gm−2 respectively. The nitrogen rich leaves, which contained 88% of the nitrogen in the above-ground parts, decomposed and released
its nitrogen much more rapidly than the stems and roots. After only four days the leaves had released 5.3 g Nm−2 and after 14 days they had released 6.4 g Nm−2. The highest rice yield (505 gm−2) was obtained usingS. sesban and 4.8 gm−2 of N-fertilizer. The yields with only N-fertilizer or onlyS. sesban were 442 gm−2 and 396 gm−2, respectively. Due to the rapid decomposition of the nitrogen rich leaves,S. sesban did not behave as a slow release fertilizer. Thus, it is not necessary to apply nitrogen fertilizers as a basal dose. 相似文献
3.
Although fine roots might account for 50% of the annual net primary productivity in moist tropical forests, there are relatively
few studies of fine-root dynamics in this biome. We examined fine-root distributions, mass, growth and tissue N and C concentrations
for six tree species established in 16-year-old plantations in the Caribbean lowlands of Costa Rica in a randomized-block
design (n = 4). The study included five native species (Hyeronima alchorneoides, Pentaclethra macroloba, Virola koschnyi, Vochysia ferruginea and Vochysia guatemalensis) and one exotic (Pinus patula). Under all species >60% of the total fine-root mass to 1 m deep was located in the uppermost 15 cm of the soil. Fine-root
live biomass and necromass (i.e., the mass of dead fine-roots) varied significantly among species but only within the uppermost
15 cm, with biomass values ranging from 182 g m−2 in Pinus to 433 g m−2 in Hyeronima plots, and necromass ranging from 48 g m−2 in Pinus to 183 g m−2 in Virola plots. Root growth, measured using ingrowth cores, differed significantly among species, ranging from 304 g m−2 year−1 in Pinus to 1,308 g m−2 year−1 in Hyeronima. These growth rates were one to five times those reported for moist temperate areas. Turnover rates of fine-root biomass
ranged from 1.6 to 3.0 year−1 in Virola and Hyeronima plots, respectively. Fine-root biomass was significantly and positively correlated with fine-root growth (r = 0.79, P < 0.0001), but did not correlate with fine-root turnover (r = 0.10, P = 0.20), suggesting that fine-root accumulation is a function of growth rate rather than mortality. Fine-root longevity was
not correlated (r = 0.20, P = 0.34) and growth was negatively correlated with root N concentration across species (r = −0.78, P < 0.0001), contrary to reported trends for leaves, perhaps because N was relatively abundant at this site. 相似文献
4.
Seasonal dynamics of fine root biomass, root length density, specific root length, and soil resource availability in a Larix gmelinii plantation 总被引:1,自引:0,他引:1
Cheng Yunhuan Han Youzhi Wang Qingcheng Wang Zhengquan 《Frontiers of Biology in China》2006,1(3):310-317
Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive
to many global change factors. Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics
and the tremendous research efforts in the past, our understanding of it remains limited. This is because the dynamics processes
associated with soil resources availability are still poorly understood. Soil moisture, temperature, and available nitrogen
are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch
and at the ecosystem level. In temperate forest ecosystems, seasonal changes of soil resource availability will alter the
pattern of carbon allocation to belowground. Therefore, fine root biomass, root length density (RLD) and specific root length
(SRL) vary during the growing season. Studying seasonal changes of fine root biomass, RLD, and SRL associated with soil resource
availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover. The objective
of this study was to understand whether seasonal variations of fine root biomass, RLD and SRL were associated with soil resource
availability, such as moisture, temperature, and nitrogen, and to understand how these soil components impact fine root dynamics
in Larix gmelinii plantation. We used a soil coring method to obtain fine root samples (⩽2 mm in diameter) every month from May to October
in 2002 from a 17-year-old L. gmelinii plantation in Maoershan Experiment Station, Northeast Forestry University, China. Seventy-two soil cores (inside diameter
60 mm; depth intervals: 0–10 cm, 10–20 cm, 20–30 cm) were sampled randomly from three replicates 25 m × 30 m plots to estimate
fine root biomass (live and dead), and calculate RLD and SRL. Soil moisture, temperature, and nitrogen (ammonia and nitrates)
at three depth intervals were also analyzed in these plots. Results showed that the average standing fine root biomass (live
and dead) was 189.1 g·m−2·a−1, 50% (95.4 g·m−2·a−1) in the surface soil layer (0–10 cm), 33% (61.5 g·m−2·a−1), 17% (32.2 g·m−2·a−1) in the middle (10–20 cm) and deep layer (20–30cm), respectively. Live and dead fine root biomass was the highest from May
to July and in September, but lower in August and October. The live fine root biomass decreased and dead biomass increased
during the growing season. Mean RLD (7,411.56 m·m−3·a−1) and SRL (10.83 m·g−1·a−1) in the surface layer were higher than RLD (1 474.68 m·m−3·a−1) and SRL (8.56 m·g−1·a−1) in the deep soil layer. RLD and SRL in May were the highest (10 621.45 m·m−3 and 14.83m·g−1) compared with those in the other months, and RLD was the lowest in September (2 198.20 m·m−3) and SRL in October (3.77 m·g−1). Seasonal dynamics of fine root biomass, RLD, and SRL showed a close relationship with changes in soil moisture, temperature,
and nitrogen availability. To a lesser extent, the temperature could be determined by regression analysis. Fine roots in the
upper soil layer have a function of absorbing moisture and nutrients, while the main function of deeper soil may be moisture
uptake rather than nutrient acquisition. Therefore, carbon allocation to roots in the upper soil layer and deeper soil layer
was different. Multiple regression analysis showed that variation in soil resource availability could explain 71–73% of the
seasonal variation of RLD and SRL and 58% of the variation in fine root biomass. These results suggested a greater metabolic
activity of fine roots living in soil with higher resource availability, which resulted in an increased allocation of carbohydrate
to these roots, but a lower allocation of carbohydrate to those in soil with lower resource availability.
__________
Translated from Acta Phytoecologica Sinica, 2005, 29(3): 403–410 [译自: 植物生态学报, 2005, 29(3): 403–410] 相似文献
5.
CO2 and N-fertilization effects on fine-root length, production, and mortality: a 4-year ponderosa pine study 总被引:1,自引:0,他引:1
We conducted a 4-year study of juvenile Pinus ponderosa fine root (≤2 mm) responses to atmospheric CO2 and N-fertilization. Seedlings were grown in open-top chambers at three CO2 levels (ambient, ambient+175 μmol/mol, ambient+350 μmol/mol) and three N-fertilization levels (0, 10, 20 g m−2 year−1). Length and width of individual roots were measured from minirhizotron video images bimonthly over 4 years starting when the seedlings were 1.5 years old. Neither CO2 nor N-fertilization treatments affected the seasonal patterns of root production or mortality. Yearly values of fine-root length standing crop (m m−2), production (m m−2 year−1), and mortality (m m−2 year−1) were consistently higher in elevated CO2 treatments throughout the study, except for mortality in the first year; however, the only statistically significant CO2 effects were in the fine-root length standing crop (m m−2) in the second and third years, and production and mortality (m m−2 year−1) in the third year. Higher mortality (m m−2 year−1) in elevated CO2 was due to greater standing crop rather than shorter life span, as fine roots lived longer in elevated CO2. No significant N effects were noted for annual cumulative production, cumulative mortality, or mean standing crop. N availability did not significantly affect responses of fine-root standing crop, production, or mortality to elevated CO2. Multi-year studies at all life stages of trees are important to characterize belowground responses to factors such as atmospheric CO2 and N-fertilization. This study showed the potential for juvenile ponderosa pine to increase fine-root C pools and C fluxes through root mortality in response to elevated CO2. 相似文献
6.
Root Growth and Recovery in Temperate Broad-Leaved Forest Stands Differing in Tree Species Diversity
In contrast to studies on aboveground processes, the effect of species diversity on belowground productivity and fine-root
regrowth after disturbance is still poorly studied in forests. In 12 old-growth broad-leaved forest stands, we tested the
hypotheses that (i) the productivity and recovery rate (regrowth per standing biomass) of the fine-root system (root diameter < 2 mm)
increase with increasing tree species diversity, and that (ii) the seasonality of fine-root biomass and necromass is more
pronounced in pure than in tree species-rich stands as a consequence of non-synchronous root biomass peaks of the different
species. We investigated stands with 1, 3, and 5 dominant tree species growing under similar soil and climate conditions for
changes in fine-root biomass and necromass during a 12-month period and estimated fine-root productivity with two independent
approaches (ingrowth cores, sequential coring). According to the analysis of 360 ingrowth cores, fine-root growth into the
root-free soil increased with tree species diversity from 72 g m−2 y−1 in the monospecific plots to 166 g m−2 y−1 in the 5-species plots, indicating an enhanced recovery rate of the root system after soil disturbance with increasing species
diversity (0.26, 0.34, and 0.51 y−1 in 1-, 3-, and 5-species plots, respectively). Fine-root productivity as approximated by the sequential coring data also
indicated a roughly threefold increase from the monospecific to the 5-species stand. We found no indication of a more pronounced
seasonality of fine-root mass in species-poor as compared to species-rich stands. We conclude that species identification
on the fine root level, as conducted here, may open new perspectives on tree species effects on root system dynamics. Our
study produced first evidence in support of the hypothesis that the fine-root systems of more diverse forest stands are more
productive and recover more rapidly after soil disturbance than that of species-poor forests. 相似文献
7.
Fine root vertical distribution and temporal dynamics in mature stands of two enset (Enset ventricosum Welw Cheesman) clones 总被引:2,自引:0,他引:2
Quantification of the role of fine roots in the biological cycle of nutrients necessitates understanding root distribution,
estimating root biomass, turnover rate and nutrient concentrations, and the dynamics of these parameters in perennial systems.
Temporal dynamics, vertical distribution, annual production and turnover, and nitrogen use of fine roots (≤2 mm in diameter)
were studied in mature (5-year-old) stands of two enset (Ensete ventricosum) clones using the in-growth bag technique. Live fine root mass generally decreased with increasing depth across all seasons
except the dry period. Except for the dry period, more than 70% of the fine root mass was in the above 0-20 cm depth, and
the fine root mass in the upper 0–10 cm depth was significantly higher than in the lowest depth (20–30 cm). Live fine root
mass showed a seasonal peak at the end of the major rainy season but fell to its lowest value during the dry or short rainy
season. The difference between the peak and low periods were significant (p ≤ 0.05). Fine root nitrogen (N) use showed significant seasonal variation where the mean monthly fine root N use was highest
during the major rainy season. There were significant effects on N use due to depths and in-growth periods, but not due to
clones. Enset fine root production and turnover ranged from 2,339 to 2,451 kg ha−1 year−1 and from 1.55 to 1.80 year−1, respectively. Root N return, calculated from fine root turnover, was estimated at 64–65 kg ha−1 year−1. Fine root production, vertical distribution and temporal dynamics may be related to moisture variations and nutrient (N)
fluxes among seasons and along the soil depth. The study showed that fine root production and turnover can contribute considerably
to the carbon and nitrogen economy of mature enset plots. 相似文献
8.
Patterns of net nitrogen mineralization and nitrification in 0–7.5 cm deep mineral soils of different stages (seral ages 1,
6 and 20 years) of a post-fire coastal fynbos succession were assayed using laboratory andin situ incubations. No evidence of increasing allelopathic inhibition of nitrification with successional development was found as
NO3−N was the predominant product at all seral stages and the NO3−N∶NH4−N ratio remained constant. Rather the results of field incubations of soils beneathProtea repens stands of different successional ages showed that increased mineralization and nitrification appeared to be associated with
increased soil total N content rather than with successional age. Further, the incubation of soilsin situ during the dry summer months showed that NO3−N production appears to be closely related to temperature and soil moisture content, both of which are variables that vary
throughout succession due to the changing structure of the vegetation. 相似文献
9.
Fine Root Production across a Primary Successional Ecosystem Chronosequence at Mt. Shasta,California 总被引:1,自引:0,他引:1
Estimating changes in belowground biomass and production is essential for understanding fundamental patterns and processes
during ecosystem development. We examined patterns of fine root production, aboveground litterfall, and forest floor accumulation
during forest primary succession at the Mt. Shasta Mudflows ecosystem chronosequence. Fine root production was measured using
the root ingrowth cores method over 1 year, and aboveground litterfall was collected over 2 years. Fine root production increased
significantly with ecosystem age, but only the youngest ecosystem was significantly different from all of the older ecosystems.
Root production was 44.5 ± 13.3, 168.3 ± 20.6, 190.5 ± 33.8, and 236.3 ± 65.4 g m−2 y−1 in the 77, 255, 616, and >850-year-old ecosystems, respectively. Generally, aboveground litterfall and forest floor accumulation
did not follow the same pattern as root production. The relative contribution of fine root production to total fine detrital
production increased significantly with ecosystem age, from 14 to 49%, but only the youngest ecosystem was significantly different
from all of the older ecosystems. Fine root production was significantly correlated with some measures of soil fertility but
was not correlated with leaf or total litterfall, or forest floor accumulation. It was best predicted by soil N concentration
alone, but this relationship may not be causal, as soil N concentration was also correlated with ecosystem age. For the oldest
ecosystem, fine root production was also measured using the sequential intact cores/compartment-flow model method, and the
difference between the two estimates was not significant. Our study suggests that the relative contribution of fine roots
to fine detrital production, and hence to soil organic matter accumulation, may increase during forest primary succession. 相似文献
10.
Karibu Fukuzawa Hideaki Shibata Kentaro Takagi Fuyuki Satoh Takayoshi Koike Kaichiro Sasa 《Ecological Research》2007,22(3):485-495
We measured the vertical distribution and seasonal patterns of fine-root production and mortality using minirhizotrons in
a cool–temperate forest in northern Japan mainly dominated by Mongolian oak (Quercus crispula) and covered with a dense understory of dwarf bamboo (Sasa senanensis). We also investigated the vertical distribution of the fine-root biomass using soil coring. We also measured environmental
factors such as air and soil temperature, soil moisture and leaf area indices (LAI) of trees and the understory Sasa canopy for comparison with the fine-root dynamics. Fine-root biomass to a depth of 60 cm in September 2003 totaled 774 g m−2, of which 71% was accounted for by Sasa and 60% was concentrated in the surface soil layer (0–15 cm), indicating that understory Sasa was an important component of the fine-root biomass in this ecosystem. Fine-root production increased in late summer (August)
when soil temperatures were high, suggesting that temperature partially controls the seasonality of fine-root production.
In addition, monthly fine-root production was significantly related to Sasa LAI (P<0.001), suggesting that fine-root production was also affected by the specific phenology of Sasa. Fine-root mortality was relatively constant throughout the year. Fine-root production, mortality, and turnover rates were
highest in the surface soil (0–15 cm) and decreased with increasing soil depth. Turnover rates of production and mortality
in the surface soil were 1.7 year−1 and 1.1 year−1, respectively. 相似文献
11.
K. Lõhmus M. Truu J. Truu I. Ostonen E. Kaar A. Vares V. Uri S. Alama A. Kanal 《Plant and Soil》2006,283(1-2):1-10
Grey alder (Alnus incana) and black alder (Alnus glutinosa) stands on forest land, abandoned agricultural, and reclaimed oil-shale mining areas were investigated with the aim of analysing
the functional diversity and activity of microbial communities in the soil–root interface and in the bulk soil in relation
to fine-root parameters, alder species, and soil type. Biolog Ecoplates were used to determine community-level physiological
profiles (CLPP) of culturable bacteria in soil–root interface and bulk soil samples. CLPP were summarized as AWCD (average
well color development, OD 48 h−1) and by Shannon diversity index, which varied between 4.3 and 4.6 for soil–root interface. The soil–root interface/bulk soil
ratio of AWCD was estimated. Substrate-induced respiration (SIR) and basal respiration (BAS) of bulk soil samples were measured
and metabolic quotient (Q = BAS/SIR) was calculated. SIR and Q varied from 0.24 to 2.89 mg C g−1 and from 0.12 to 0.51, respectively. Short-root morphological studies were carried out by WinRHIZOTM Pro 2003b; mean specific root area (SRA) varied for grey alder and black alder from 69 to 103 and from 54 to 155 m2 kg−1, respectively. The greatest differences between AWCD values of culturable bacterial communities in soil–root interface and
bulk soil were found for the young alder stands on oil-shale mining spoil and on abandoned agricultural land. Soil–root interface/bulk
soil AWCD ratio, ratio for Shannon diversity indices, and SRA were positively correlated. Foliar assimilation efficiency (FOE)
was negatively correlated with soil–root interface/bulk soil AWCD ratio. The impact of soil and alder species on short-root
morphology was significant; short-root tip volume and mass were greater for black alder than grey alder. For the investigated
microbiological characteristics, no alder-species-related differences were revealed. 相似文献
12.
Jeffrey M. Klopatek 《Plant and Soil》2007,294(1-2):157-167
Litterfall and fine root production were measured for three years as part of a carbon balance study of three forest stands
in the Pacific Northwest of the United States. A young second-growth Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stand, a second-growth Douglas-fir with red alder (Alnus rubra Bong.) stand, and an old-growth (∼550 years) Douglas-fir stand were monitored for inputs of carbon and nitrogen into the
soil from litterfall and fine root production, as well as changes in soil C and N. Fine root production and soil nutrient
changes were measured through the use of soil ingrowth bags containing homogenized soil from the respective stands. Litterfall
biomass was greatest in the Douglas-fir-alder stand (527 g m−2 yr−1) that annually returned nearly three times the amount of N as the other stands. Mean residence time for forest floor material
was also shortest at this site averaging 4.6 years and 5.5 years for C an N, respectively. Fine root production in the upper
20 cm ranged from 584 g m−2 in the N rich Douglas-fir-alder stand to 836 g m−2 in the old-growth stand. Fine root production (down to one meter) was always greater than litterfall with a below:above ratio
ranging from 3.73 for the young Douglas-fir stand to 1.62 for the Douglas-fir-alder stand. The below:above N ratios for all
three stands closely approximate those for biomass. Soil changes in both C and N differed by site, but the soil C changes
in the old-growth stand mirrored those obtained in an ongoing CO2 flux study. Results from the soil ingrowth bags strongly suggest that this method provides a simple, but sufficient device
for measuring potential fine root biomass production as well as soil chemical changes. 相似文献
13.
A survey of the distribution and density of mounds of the harvester termite,Drepanotermes tamminensis (Hill), was carried out in the Durokoppin Nature Reserve, Western Australia in 1990. Vegetation and, to a lesser extent,
soil type, appear to be important factors in determining density and distribution of termite mounds within the Reserve. A
more detailed study of mounds in Wandoo (Eucalyptus capillosa) woodland and Casuarina (Allocasuarina campestris) shrubland indicated that the total number and size of mounds were significantly higher in the woodland than in the shrubland.
The total wet weight biomass ofD. tamminensis was calculated as 3.74 gm−2 (37.4 kg ha−1) in the woodland and 1.69 gm−2 (16.9 kg ha−1) in the shrubland. Thus, of the two favored habitats, Wandoo woodland appears to be more optimal for this termite species
than the Casuarina shrubland. 相似文献
14.
Biomass, morphology and nutrient contents of fine roots in four Norway spruce stands 总被引:2,自引:0,他引:2
Fine root systems may respond to soil chemical conditions, but contrasting results have been obtained from field studies in
non-manipulated forests with distinct soil chemical properties. We investigated biomass, necromass, live/dead ratios, morphology
and nutrient concentrations of fine roots (<2 mm) in four mature Norway spruce (Picea abies [L.] Karst.) stands of south-east Germany, encompassing variations in soil chemical properties and climate. All stands
were established on acidic soils (pH (CaCl2) range 2.8–3.8 in the humus layer), two of the four stands had molar ratios in soil solution below 1 and one of the four
stands had received a liming treatment 22 years before the study. Soil cores down to 40 cm mineral soil depth were taken in
autumn and separated into four fractions: humus layer, 0–10 cm, 10–20 cm and 20–40 cm. We found no indications of negative
effects of N availability on fine root properties despite large variations in inorganic N seepage fluxes (4–34 kg N ha−1 yr−1), suggesting that the variation in N deposition between 17 and 26 kg N ha−1 yr−1 does not affect the fine root system of Norway spruce. Fine root biomass was largest in the humus layer and increased with
the amount of organic matter stored in the humus layer, indicating that the vertical pattern of fine roots is largely affected
by the thickness of this horizon. Only two stands showed significant differences in fine root biomass of the mineral soil
which can be explained by differences in soil chemical conditions. The stand with the lowest total biomass had the lowest
Ca/Al ratio of 0.1 in seepage, however, Al, Ca, Mg and K concentrations of fine roots were not different among the stands.
The Ca/Al ratio in seepage might be a less reliable stress parameter because another stand also had Ca/Al ratios in seepage
far below the critical value of 1.0 without any signs of fine root damages. Large differences in the live/dead ratio were
positively correlated with the Mn concentration of live fine roots from the mineral soil. This relationship was attributed
to faster decay of dead fine roots because Mn is known as an essential element of lignin degrading enzymes. It is questionable
if the live/dead ratio can be used as a vitality parameter of fine roots since both longevity of fine roots and decay of root
litter may affect this parameter. Morphological properties were different in the humus layer of one stand that was limed in
1983, indicating that a single lime dose of 3–4 Mg ha−1 has a long-lasting effect on fine root architecture of Norway spruce. Almost no differences were found in morphological properties
in the mineral soil among the stands, but vertical patterns were apparently different. Two stands with high base saturation
in the subsoil showed a vertical decrease in specific root length and specific root tip density whereas the other two stands
showed an opposite pattern or no effect. Our results suggest that proliferation of fine roots increased with decreasing base
saturation in the subsoil of Norway spruce stands. 相似文献
15.
Zhi-Shan Zhang Xin-Rong Li Li-Chao Liu Rong-Liang Jia Jing-Guang Zhang Tao Wang 《Journal of plant research》2009,122(1):109-119
A field experiment was conducted to investigate root distribution, biomass, and seasonal dynamics in a revegetated stand of
Caragana korshinskii Kom. in the Tengger Desert. We used soil profile trenches, soil core sampling, and minirhizotron measurements to measure
root dynamics. Results showed that the roots of C. korshinskii were distributed vertically in the uppermost portion of the soil profile, especially the coarse roots, which were concentrated
in the upper 0.4 m. The horizontal distribution of the root length and weight of C. korshinskii coarse roots was concentrated within 0.6 and 0.4 m of the trunk, respectively. The lateral distribution of fine roots was
more uniform than coarse roots. Total-root and fine-root biomasses were 662.4 ± 45.8 and 361.1 ± 10.3 g m−2, accounting for about two-thirds and one-third of the total plant biomass, respectively. Fine-root turnover is closely affected
by soil water, and both of these parameters showed synchronously seasonal trends during the growing season in 2004 and 2005.
The interaction between fine-root turnover and soil water resulted in the fine-root length densities and soil water content
in the 0- to 1.0-m soil layer having similar trends, but the soil water peaks occurred before those of the fine-root length
densities. 相似文献
16.
Jianwei Shi Zhengquan Wang Shuiqiang Yu Xiankui Quan Yue Sun Shuxia Jia Li Mei 《Frontiers of Biology in China》2008,3(4):496-506
Fine root turnover is a major pathway for carbon and nutrient cycling in forest ecosystems. However, to estimate fine root
turnover, it is important to first understand the fine root dynamic processes associated with soil resource availability and
climate factors. The objectives of this study were: (1) to examine patterns of fine root production and mortality in different
seasons and soil depths in the Larix gmelinii and Fraxinus mandshurica plantations, (2) to analyze the correlation of fine root production and mortality with environmental factors such as air
temperature, precipitation, soil temperature and available nitrogen, and (3) to estimate fine root turnover. We installed
36 Minirhizotron tubes in six mono-specific plots of each species in September 2003 in the Mao’ershan Experimental Forest
Station. Minirhizotron sampling was conducted every two weeks from April 2004 to April 2005. We calculated the average fine
root length, annual fine root length production and mortality using image data of Minirhizotrons, and estimated fine root
turnover using three approaches. Results show that the average growth rate and mortality rate in L. melinii were markedly smaller than in F. mandshurica, and were highest in the surface soil and lowest at the bottom among all the four soil layers. The annual fine root production
and mortality in F. mandshurica were significantly higher than in L. gmelinii. The fine root production in spring and summer accounted for 41.7% and 39.7% of the total annual production in F. mandshurica and 24.0% and 51.2% in L. gmelinii. The majority of fine root mortality occurred in spring and summer for F. mandshurica and in summer and autumn for L. gmelinii. The turnover rate was 3.1 a−1 for L. gmelinii and 2.7 a−1 for F. mandshurica. Multiple regression analysis indicates that climate and soil resource factors together could explain 80% of the variations
of the fine root seasonal growth and 95% of the seasonal mortality. In conclusion, fine root production and mortality in L. gmelinii and F. mandshurica have different patterns in different seasons and at different soil depths. Air temperature, precipitation, soil temperature
and soil available nitrogen integratively control the dynamics of fine root production, mortality and turnover in both species.
Transtlated from Journal of Plant Ecology, 2007, 31(2): 333–342 [译自: 植物生态学报] 相似文献
17.
The estimation of practical radial oxygen loss (ROL) of wetland plant roots was attempted in this study. We have devised a
new method to measure ROL of wetland plant roots. The whole root system was bathed in an anoxic nutrient solution. Oxygen
released from the root was removed immediately by introducing oxygen-free nitrogen gas (O2 < 4 nmol L−1) to mimic natural habitats where released oxygen is consumed rapidly due to chemical and biological oxidation processes.
Oxygen removed from the root-bathing chamber was simultaneously detected colorimetrically by use of the highly oxygen-sensitive
anthraquinone radical anion (AQ·−) in a cell outside the root-bathing chamber, which decolorized by a rapid reaction with oxygen. An emergent macrophyte Typha latifolia L. was incubated, and its ROL was measured by both the new method and one of the conventional methods, the closed chamber/electrode
method, by which the ROL of Typha latifolia L. had not yet been measured. The new method succeeded in detecting the ROL, whereas the conventional method was not able
to detect oxygen, due to the level being below the detection limit of the oxygen electrode. The oxygen supply via the seedlings
of Typha latifolia L. was ca. 10 times higher compared with control measurements without plant. Light illumination significantly enhanced the
ROL of Typha latifolia L. (0.33 nmol O2 g−1 root dry weight s−1 under light and 0.18 nmol O2 g−1 root dry weight s−1 in the dark). Theses values fall between those previously reported by the closed chamber/titanium citrate method and the
open chamber/electrode method. 相似文献
18.
The effects of liquid and solid fertilizers on fine-root development were studied in a 130-year-old Scots pine (Pinus sylvestris L.) stand. Ingrowth cores,viz. initially root-free mesh bags with sieved mineral soil taken outside the plots and driven to a depth of 30 cm from the soil
surface, were subsequently resampled and the amount of fine roots was estimated.
The total accretion of both fine-root length and dry weight was comparatively high in the liquid fertilization plot. The most
substantial net accretion, however, during the 1984 period was in the control plot. The results of the study is that the ramification
pattern of the fine roots was strongly influenced by fertilization. The average number of root tips per unit length was 9.9
cm−1 in the control plot cm−1, compared with both the solid (A and B) and liquid fertilization plots (2.3, 3.2 and 3.3 cm−1, respectively) due to a greater occurrence of mycorrhizal aggregates (‘ball mycorrhiza’). The effects of fertilization on
the mineral nutrient concentrations in the fine roots were limited—the strongest effects were in the liquid-fertilized area.
The observed increase in the concentration of most mineral nutrients in the latter experimental area, however, may be due
to a change in the growth pattern of the fine roots rather than an effect of the fertilizers themselves. 相似文献
19.
Eva Remke Emiel Brouwer Annemieke Kooijman Irmgard Blindow Jan G. M. Roelofs 《Ecosystems》2009,12(7):1173-1188
The impact of atmospheric N-deposition on succession from open sand to dry, lichen-rich, short grassland, and tall grass vegetation
dominated by Carex arenaria was surveyed in 19 coastal dune sites along the Baltic Sea. Coastal dunes with acid or slightly calcareous sand reacted differently
to atmospheric wet deposition of 5–8 kg N ha−1 y−1. Accelerated acidification, as well as increased growth of Carex and accumulation of organic matter, was observed only at acid sites with pHNaCl of the parent material below 6.0. At sites with slightly calcareous parent material, increased N-deposition had no effect.
A trigger for grass encroachment seems to be high acidification in early successional stages to below pHNaCl 4.0. Metals like Al or Fe become freely available and may hamper intolerant species. At acid sites, N-mineralization increases
with elevated N-deposition, which may further stimulate Carex arenaria. Due to high growth plasticity, efficient resource allocation and tolerance of high metal concentrations, C. arenaria is a superior competitor under these conditions and can start to dominate the dune system. Carex-dominated vegetation is species-poor. Even at the moderate N-loads in this study, foliose lichens, forbs and grasses were
reduced in short grass vegetation at acid sites. Species indicating these first effects of atmospheric deposition on dry,
lichen-rich, short grasslands are identified and recommendations for restoration of grass-encroached sites given. 相似文献
20.
Diurnal variation in ion content of the solution bathing roots of two plants growing together in sand culture was analysed
for three pairs of grass-legume species (Lolium multiflorum andTrifolium pratense; Zea mays andGlycine hispida; Avena sativa andVicia sativa) and their monospecific controls. Biomass and nitrogen content of plants were determined.
Ion concentration (NO
3
−
, NO
2
−
, NH
4
+
, and K+) and pH of root solutions were measured for Lolium-Trifolium plant pairs and controls at 6 hours intervals over 36 h, starting
at 8 am within a circadian cycle. Root solutions were regularly depleted in NO
3
−
by the grasses (Lolium-Lolium control) throughout the cycle. For associations involving the legume (Lolium-Trifolium and
Trifolium-Trifolium), NO
3
−
depletion was followed by NO
3
−
enrichment at night, from late afternoon to early morning; the enrichment was more marked for the Lolium-Trifolium association.
Solutions which did not contain NO
2
−
ions, were enriched by trace amounts of NH
4
+
ions, largely depleted in K+ and alkalanized for all associations throughout the cycle.
Repeating the experiment with the three pairs of species at the vegetative phase of development confirmed the previous results:
NO
3
−
enrichment during the night for associations with legumes. When the experiment was repeated with older plants which had almost
completed their flowering stage, depletion only was observed and no NO
3
−
enrichment.
These data suggest that NO
3
−
enrichment results from N excretion from active nodulated roots of the legume, accounting for the increase in both biomass
and nitrogen content of the companion grass in grass-legume association. The quantitative importance and periodicity of nitrogen
excretion as well as the origin of nitrate enrichment are discussed. 相似文献