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Soil and root characteristics were contrasted between a "declining" and a "healthy" sugar maple (Acer saccharum Marsh.) stand in Vermont, USA. The declining stand had lower basal area increment and more crown dieback than the healthy stand. Soil pH and base cation content were lower and soil water content was higher at the site of the declining stand than at the site of the healthy stand, whereas soil temperature did not differ significantly between the sites. In live fine roots, concentrations of K and Ca were marginally (P < 0.07) lower in the declining than in the healthy stand, whereas concentrations of N, P, Mg, and Al were not significantly different (P = 0.13 to 0.87) between stands. Starch and soluble sugar concentrations of fine and coarse roots did not differ significantly between stands, indicating that crown dieback did not affect carbohydrate supply to the roots in the declining stand. Throughout the growing season, the standing live and dead root biomass were significantly higher in the declining stand than in the healthy stand, indicating that more carbon was allocated to roots and that root turnover was higher in the declining stand than in the healthy stand. 相似文献
3.
A closely spaced (1 x 1 m) cottonwood (Populus deltoides Bartr.) plantation was established to evaluate the effects of nutrient availability on fine root dynamics. Slow-release fertilizer (17:6:12 N,P,K plus micronutrients) was applied to 225-m(2) plots at 0, 50, 100 and 200 kg N ha(-1), and plots were monitored for two growing seasons. Fine root production, mortality, live root standing crop and life span were analyzed based on monthly minirhizotron observations. Fine root biomass was measured in soil cores. Fine root dynamics were controlled more by temporal, depth and root diameter factors than by fertilization. Cumulative fine root production and mortality showed strong seasonal patterns; production was greatest in the middle of the growing season and mortality was greatest after the growing season. Small diameter roots at shallow soil depths cycled more rapidly than larger or deeper roots. The strongest treatment effects were found in the most rapidly cycling roots. The standing crop of live roots increased with fertilizer treatment according to both minirhizotron and soil coring methods. However, production and mortality had unique treatment response patterns. Although cumulative mortality decreased in response to increased fertilization, cumulative production was intermediate at 0 kg N ha(-1), lowest with 50 kg N ha (-1), and highest with 200 kg N ha(-1). Aboveground growth responded positively to fertilization up to an application rate of 50 kg N ha(-1), but no further increases in growth were observed despite a threefold increase in application rate. Median fine root life span varied from 307 to over 700 days and increased with depth, diameter and nutrient availability. 相似文献
4.
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
5.
Patterns of fine root biomass, production, and distribution were estimated for pure stands and mixtures of three-year-old loblolly pine (Pinus taeda L.) with red maple (Acer rubrum L.) or black locust (Robinia pseudoacacia L.) on the Virginia Piedmont to determine the role of fine roots in interference between pine and hardwood tree species. Estimates were based on amounts of live and dead fine roots separated from monthly core samples during the third growing season after planting. Live and dead fine root biomass and production varied by species, but mixtures of loblolly pine and black locust generally had greater fine root biomass and fine root production than pure stands or loblolly pine-red maple mixtures. Hardwood species had greater live fine root biomass per tree in mixtures with pine compared to pure stands. Greater live fine root biomass in pine-locust stands may be attributed to differential utilization of the soil volume by fine roots of these species. For all stands, approximately 50% of live five root biomass was located in the upper 10 cm of soil. 相似文献
6.
Soil N mineralization is affected by microbial biomass and respiration, which are limited by available C and N. To examine
the relationship between C and N for soil microbial dynamics and N dynamics, we conducted long-term laboratory incubation
(150 days) after C and N amendment and measured changes in C and N mineralization, microbial biomass C, and dissolved C and
N throughout the incubation period. The study soil was volcanic immature soil from the southern part of Japan, which contains
lower C and N compared with other Japanese forest soils. Despite this, the area is covered by well-developed natural and plantation
forests. Carbon amendment resulted in an increase in both microbial biomass and respiration, and net N mineralization decreased,
probably due to increasing microbial immobilization. In contrast, N amendment resulted in a decrease in microbial respiration
and an increase in net N mineralization, possibly due to decreased immobilization by microbes. Amendment of both C and N simultaneously
did not affect microbial biomass and respiration, although net N mineralization was slightly increased. The results suggested
that inhibitory effect on microbial respiration by N amendment should be reduced if carbon availability is higher. Thus, soil
available C may limit microbial biomass and respiration in this volcanic immature soil. Even in immature soil where C and
N substrate is low, soil C, such as plant root exudates and materials from above- and belowground dead organisms, might help
to maintain microbial activity and N mineralization in this study site. 相似文献
7.
Kyotaro Noguchi Tadashi Sakata Takeo Mizoguchi Masamichi Takahashi 《Journal of Forest Research》2005,10(6):435-441
Fine roots are a key component of forested ecosystems, but available information is still limited. This study examined the
production and mortality of fine roots less than 1 mm in diameter in a Japanese cedar (Cryptomeria japonica D. Don) plantation located on the Kanto Plain in central Japan. We used a minirhizotron technique in combination with soil
coring, and collected data for 1 year (May 2002–May 2003). Fine root production and mortality were determined from changes
in the lengths of individual fine roots on minirhizotron tubes. Both fine root production and mortality rates were greater
in the upper soil than in lower soil levels. Both rates were seasonal, with higher values in summer than in winter; this trend
was more pronounced in upper soil levels. These results suggest that environmental conditions, such as temperature or soil
properties, affect the production and mortality rates of fine roots. Fine root production and mortality occurred simultaneously,
and their rates were similar, which may have led to unclear seasonal changes in fine root standing crop estimates. Soil coring
indicated that the fine root biomass of this stand was about 120 g m−2, of which 40% was from Japanese cedar. The estimated rates of dry matter production and mortality of total fine roots, including
understory plants, were both approximately 300 g m−2 year−1. 相似文献
8.
Xiaozhen Pu Chunying Yin Qunying Xiao Mingfeng Qiao Qing Liu 《Agroforestry Systems》2017,91(5):955-966
Root is an important plant organ and has high heterogeneity. Global warming could change root and affect belowground ecological processes. There is little information on how fine roots branch orders responds to global change. This study examined the growth, morphological and physiological responses of fine roots of a subalpine coniferous species to warming. We investigated biomass, average diameter, specific root length (SRL), triphenyltetrazolium chloride (TTC) reducing capacity, carbon (C), total non-structural carbon (TNC) and fractions of the primal five branch order roots of Abies faxoniana in April, August, October and December. The decrease in total fine roots biomass after a growing season was significantly greater under warming treatment compared to control, suggesting that warming could accelerate the carbon input from root to soil, but the increment depended on tree species. Warming did not affect average diameter and SRL. Responses of biomass, TTC reducing capacity, C, TNC and fractions to warming significantly differed with root order and month. Significant warming effects were only observed in C and starch concentration of the first order and also TNC and soluble sugar concentration of the first three orders. The results indicated that the lower order roots (the first three orders) were more sensitive to warming, probably because they had more frequent, intense interactions with soil and low defense capability. Thus, global warming may dramatically alter root functions such as nutrients and water uptake as well as the cycle of C and nutrients at the whole subalpine coniferous forest ecosystem. 相似文献
9.
Rui-Li WANG Rui-Mei CHENG Wen-Fa XIAO Xiao-Hui FENG Ze-Bin LIU Xiao-Rong WANG Zhi-Bo WANG 《中国林学(英文版)》2013,15(1):13-23
Environmental heterogeneity is a constant presence in the natural world that significantly affects plant behavior at a variety of levels of complexity. In order to estimate the spatial pattern of fine root biomass in the Three Gorges Reservoir Area, the spatial heterogeneity of fine root biomass in the upper layer of soils (0-10 cm) in three Masson pine (Pinus massoniana) stands in the Three Gorges Reservoir Area, China, was studied in 30 m × 30 m plots with geostatistical analysis. The results indicate that 1) both the live and dead fine root biomass of stand 2 were less than those of other stands, 2) the spatial variation of fine roots in the three stands was caused together by structural and random factors with moderate spatial dependence and 3) the magnitude of spatial heterogeneity of live fine roots ranked as: stand 3 > stand 1 > stand 2, while that of dead fine roots was similar in the three stands. These findings suggested that the range of spatial autocorrelation for fine root biomass varied considerably in the Three Gorges Reservoir Area, while soil properties, such as soil bulk density, organic matter and total nitrogen, may exhibit great effect on the spatial distribution of fine roots. Finally, we express our hope to be able to carry out further research on the quantitative relationship between the spatial heterogeneous patterns of plant and soil properties. 相似文献
10.
Mingfeng Qiao Ziliang Zhang Yuejiao Li Juan Xiao Bisong Yue 《Scandinavian Journal of Forest Research》2016,31(4):347-354
Climate warming may change soil nutrient supply and affect the biogeochemical processes, especially the nitrogen (N) cycle in forest ecosystems. However, little is still known about how root N uptake responds to climate warming, and whether forests will experience more intense N limitation under warming. We studied the N absorption and mycorrhizal infection rate in the roots of seedlings of a subalpine coniferous species, Picea asperata Mast., under experimental warming, four years after the seedlings were transplanted in the experimental plots. We found that warming had a significant positive effect on root N absorption, with increases of 151.1%, 99.6%, and 71.9% in May, July, and October of 2011, respectively, when compared to the control treatment. In addition, warming increased the N element content and reduced the C:N ratio of the roots over the warming period. Warming also increased mycorrhizal infections by 30.5%, 12.3%, and 108.1% in May, July, and October of 2011, respectively, when compared to the control treatment. Increases in the N absorption and mycorrhizal infection rates in roots may be an important adjustment to meet plant N demand in the subalpine coniferous forest under warming. 相似文献
11.
Hongying Chen Yufeng Dong Tan Xu Yanping Wang Huatian Wang Baoli Duan 《New Forests》2017,48(5):587-607
Fine roots play an important role in above- and belowground carbon (C) allocation in forest ecosystems. However, few studies have focused on the seasonal dynamics of fine roots with different branching orders. The objective of this study is to provide insight to the seasonal heterogeneity in roots of different orders within root hierarchies of poplar trees under different soil conditions. Three plots were established in high (plantation A) and low (plantation B) soil nutrient conditions. Fine roots were sampled in each of four seasons throughout one year. All sampled roots were classified into one to five groups depending on their branching order, and the dry biomass of living roots and the concentrations of C, nitrogen (N) and total non-structural carbohydrate (TNC) were examined. Low order (first- to second-order) roots demonstrated more significant seasonal dynamics than high order roots, and the biomass of first-order fine roots was positively influenced by soil temperature and moisture while the biomass of second-order fine roots was negatively affected by soil nutrient conditions. The different responses of fine roots to environmental fluctuations implied a high division of root function, even within low order roots. The C and N chemistry of poplar fine roots also differed significantly with branching order; element concentrations were lower in low order roots. Principal component analysis indicated that root order explained 98.2% of the variation in fine root chemistry. Moreover, the first-order roots in plantation A had greater C but less TNC concentrations than those in plantation B, suggesting that C allocation in low order roots may be more responsive to soil nutrient conditions. The allocation of C and N also exhibited significant seasonal dynamics (p < 0.05); the TNC concentration was highest in winter, whereas C:N ratios were significantly lower in the summer and fall in each order of fine roots (p < 0.05). All these results suggest that branching order may be related to root growth and photoassimilate allocation, which should receive greater attention in future studies on C and N fluxes in forest ecosystems. 相似文献
12.
By influencing belowground processes, streamside vegetation affects soil processes important to surface water quality. We
conducted this study to compare root distributions and dynamics, and total soil respiration among six sites comprising an
agricultural buffer system: poplar (Populus × euroamericana‘ Eugenei), switchgrass, cool-season pasture grasses, corn (Zea
mays L.), and soybean (Glycine max (L.) Merr.). The dynamics of fine (0--2 mm) and small roots (2--5 mm) were assessed by
sequentially collecting 35 cm deep, 5.4 cm diameter cores from April through November. Coarse roots were described by excavating
1 × 1 × 2 m pits and collecting all roots in 20 cm depth increments. Root distributions within the soil profile were determined
by counting roots that intersected the walls of the excavated pits. Soil respiration was measured monthly from July to October
using the soda-lime technique. Over the sampling period, live fine-root biomass in the top 35 cm of soil averaged over 6 Mg
ha-1 for the cool-season grass, poplar, and switchgrass sites while root biomass in the crop fields was < 2.3 Mg ha-1 at its maximum. Roots of trees, cool-season grasses, and switchgrass extended to more than 1.5 m in depth, with switchgrass
roots being more widely distributed in deeper horizons. Root density was significantly greater under switchgrass and cool-season
grasses than under corn or soybean. Soil respiration rates, which ranged from 1.4--7.2 g C m-2 day-1, were up to twice as high under the poplar, switchgrass and cool-season grasses as in the cropped fields. Abundant fine roots,
deep rooting depths, and high soil respiration rates in the multispecies riparian buffer zones suggest that these buffer systems
added more organic matter to the soil profile, and therefore provided better conditions for nutrient sequestration within
the riparian buffers.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
An investigation was conducted to quantify fine roots and roots nodules over the four seasons in forestry and agroforestry alder (Alnus rubra) stands in North Wales. Soil samples collected in each season were excavated at three sampling points (0.30 m, 0.57 m and 1.00 m distance from the base of each tree) from nine trees of the agroforestry and forestry plots. Result showed that the density of live fine root had significant differences in between seasons and treatments (P ＜ 0.001). The mean weight density of live fine root over the four seasons in agroforestry and forestry was 0.27±0.01 kg·m-3 and 0.54±0.03 kg·m-3, respectively. Weight density of dead root in each system remained constant throughout the year. The mean weight density of dead root was also significantly different (P ＜ 0.01) between forestry and agroforestry systems. Weight density of live and dead root nodule was both constant throughout the year and between the different sampling distances. The mean weight densities of live and dead root nodule over the four seasons were 0.09±0.03 kg·m-3 and 0.05±0.03 kg·m-3 in agroforestry and 0.08±0.02 kg·m-3 and 0.03±0.01 kg·m-3 in the forestry plots, respectively. 相似文献
14.
Warren JM Iversen CM Garten CT Norby RJ Childs J Brice D Evans RM Gu L Thornton P Weston DJ 《Tree physiology》2012,32(6):799-813
The dynamics of rapid changes in carbon (C) partitioning within forest ecosystems are not well understood, which limits improvement of mechanistic models of C cycling. Our objective was to inform model processes by describing relationships between C partitioning and accessible environmental or physiological measurements, with a special emphasis on short-term C flux through a forest ecosystem. We exposed eight 7-year-old loblolly pine (Pinus taeda L.) trees to air enriched with (13)CO(2) and then implemented adjacent light shade (LS) and heavy shade (HS) treatments in order to manipulate C uptake and flux. The impacts of shading on photosynthesis, plant water potential, sap flow, basal area growth, root growth and soil CO(2) efflux rate (CER) were assessed for each tree over a 3-week period. The progression of the (13)C label was concurrently tracked from the atmosphere through foliage, phloem, roots and surface soil CO(2) efflux. The HS treatment significantly reduced C uptake, sap flow, stem growth and fine root standing crop, and resulted in greater residual soil water content to 1 m depth. Soil CER was strongly correlated with sap flow on the previous day, but not the current day, with no apparent treatment effect on the relationship. Although there were apparent reductions in new C flux belowground, the HS treatment did not noticeably reduce the magnitude of belowground autotrophic and heterotrophic respiration based on surface soil CER, which was overwhelmingly driven by soil temperature and moisture. The (13)C label was immediately detected in foliage on label day (half-life = 0.5 day), progressed through phloem by Day 2 (half-life = 4.7 days), roots by Days 2-4, and subsequently was evident as respiratory release from soil which peaked between Days 3 and 6. The δ(13)C of soil CO(2) efflux was strongly correlated with phloem δ(13)C on the previous day, or 2 days earlier. While the (13)C label was readily tracked through the ecosystem, the fate of root C through respiratory, mycorrhizal or exudative release pathways was not assessed. These data detail the timing and relative magnitude of C flux through various components of a young pine stand in relation to environmental conditions. 相似文献
15.
水曲柳落叶松混交林中细根空间分布 总被引：4，自引：0，他引：4
采用根钻取样方法对年生水曲柳落叶松混交林中细根空间分布状况进行了研究。结果表明,水曲柳落叶松地下生物量的空间分配差异显著。在林分水平上,水曲柳的根生物量密度高于落叶松(分别为4442.3和2234.9g/m3)。两树种在相邻区域中分配的细根生物量较高,表明种间根系竞争较弱。落叶松行间的水曲柳细根生物量密度和根长密度均高于水曲柳行间的落叶松细根,表明水曲柳地下部分具有较强能力。根系的空间分布有利于混交林中水曲柳的生长。图1表4参19。 相似文献
16.
A rain shelter experiment was conducted in a 90‐year‐old Norway spruce stand, in the Kysucké Beskydy Mts (Slovakia). Three rain shelters were constructed in the stand to prevent the rainfall from reaching the soil and to reduce water availability in the rhizosphere. Fine root biomass and necromass were repeatedly measured throughout a growing season by soil coring. We established the quantities of fine root biomass (live) and necromass (dead) at soil depths of 0–5, 5–15, 15–25 and 25–35 cm. Significant differences in soil moisture contents between control and drought plots were found in the top 15 cm of soil after 20 weeks of rainfall manipulation (lasting from early June to late October). Our observations show that even relatively light drought decreased total fine root biomass from 272.0 to 242.8 g m?2 and increased the amount of necromass from 79.2 to 101.2 g m?2 in the top 35 cm of soil. Very fine roots (VFR), that is, those with diameter up to 1 mm, were more affected than total fine roots defined as 0–2 mm. The effect of reduced water availability was depth‐specific; as a result, we observed a modification of vertical distribution of fine roots. More roots in drought treatment were produced in the wetter soil horizons at 25–35 cm depth than at the surface. We conclude that fine and VFR systems of Norway spruce have the capacity to re‐allocate resources to roots at different depths in response to environmental signals, resulting in changes in necromass to biomass ratio. 相似文献
17.
Changes in fine root production and longevity in relation to water and nutrient availability in a Norway spruce stand in northern Sweden 总被引：2，自引：0，他引：2
Majdi H 《Tree physiology》2001,21(14):1057-1061
Effects of irrigation and liquid fertilization on fine root (< 1 mm) production and longevity, and fine root (< 0.5-2 mm) biomass were studied in a Norway spruce (Picea abies (L.) Karst.) stand in northern Sweden. Fine root length production and longevity were measured by the minirhizotron technique at 0-10 cm depth in the following treatments: irrigation (I), liquid fertilization (IL) and control (C). Standing root biomass and root length density (RLD) were studied in the litter-fermented humus (LFH) layer and at depths of 0-10, 10-20 and 20-30 cm using soil cores in solid fertilized (F) and C plots. Minirhizotrons were installed in October 1994 and measurements recorded monthly from July to September 1995 and during the growing season in 1996. Soil cores were sampled in 1996. Fine root production increased significantly in IL plots compared with C plots, but the I treatment did not increase root production. Root mortality increased significantly in IL plots compared with C plots. Fine root longevity in IL plots was significantly lower compared with C and I plots. No significant difference was found between longevity of fine roots in I and C plots. Compared with C, F treatment increased fine root biomass in the LFH and mineral soil layers, and increased the amount of fine roots in mineral soil layers relative to the LFH layer. Furthermore, F increased RLD and the number of mycorrhizal root tips significantly. 相似文献
18.
Biomass, carbon and nitrogen dynamics of multi-species riparian buffers within an agricultural watershed in Iowa, USA 总被引：2，自引：0，他引：2
This study was conducted to determine biomass dynamics, carbon sequestration and plant nitrogen immobilization in multispecies riparian buffers, cool-season grass buffers and adjacent crop fields in central Iowa. The seven-year-old multispecies buffers were composed of poplar (Populus×euroamericana Eugenei) and switchgrass (Panicum virgatum L.). The cool-season grass buffers were dominated by non-native forage grasses (Bromus inermis Leysser., Phleum pratense L. and Poa pratensis L). Crop fields were under an annual corn-soybean rotation. Aboveground non-woody live and dead biomass were determined by direct harvests throughout two growing seasons. The dynamics of fine (0–2 mm) and small roots (2–5 mm) were assessed by sequentially collecting 35 cm deep, 5.4 cm diameter cores (125 cm deep cores in the second year) from April through November. Biomass of poplar trees was estimated using allometric equations developed by destructive sampling of trees. Poplar had the greatest aboveground live biomass, N and C pools, while switchgrass had the highest mean aboveground dead biomass, C and N pools. Over the two-year sampling period, live fine root biomass and root C and N in the riparian buffers were significantly greater than in crop fields. Growing-season mean biomass, C and N pools were greater in the multispecies buffer than in either of the crop fields or cool-season grass buffers. Rates of C accumulation in plant and litter biomass in the planted poplar and switchgrass stands averaged 2960 and 820 kg C ha–1 y–1, respectively. Nitrogen immobilization rates in the poplar stands and switchgrass sites averaged 37 and 16 kg N ha–1 y–1, respectively. Planted riparian buffers containing native perennial species therefore have the potential to sequester C from the atmosphere, and to immobilize N in biomass, therefore slowing or preventing N losses to the atmosphere and to ground and surface waters.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
19.
Foliage, fine-root, woody-tissue and stand respiration in Pinus radiata in relation to nitrogen status 总被引：1，自引：0，他引：1
We measured respiration of 20-year-old Pinus radiata D. Don trees growing in control (C), irrigated (I), and irrigated + fertilized (IL) stands in the Biology of Forest Growth experimental plantation near Canberra, Australia. Respiration was measured on fully expanded foliage, live branches, boles, and fine and coarse roots to determine the relationship between CO(2) efflux, tissue temperature, and biomass or nitrogen (N) content of individual tissues. Efflux of CO(2) from foliage (dark respiration at night) and fine roots was linearly related to biomass and N content, but N was a better predictor of CO(2) efflux than biomass. Respiration (assumed to be maintenance) per unit N at 15 degrees C and a CO(2) concentration of 400 micro mol mol(-1) was 1.71 micro mol s(-1) mol(-1) N for foliage and 11.2 micro mol s(-1) mol(-1) N for fine roots. Efflux of CO(2) from stems, coarse roots and branches was linearly related to sapwood volume (stems) or total volume (branches + coarse roots) and growth, with rates for maintenance respiration at 15 degrees C ranging from 18 to 104 micro mol m(-3) s(-1). Among woody components, branches in the upper canopy and small diameter coarse roots had the highest respiration rates. Stem maintenance respiration per unit sapwood volume did not differ among treatments. Annual C flux was estimated by summing (1) dry matter production and respiration of aboveground components, (2) annual soil CO(2) efflux minus aboveground litterfall, and (3) the annual increment in coarse root biomass. Annual C flux was 24.4, 25.3 and 34.4 Mg ha(-1) year(-1) for the C, I and IL treatments, respectively. Total belowground C allocation, estimated as the sum of (2) and (3) above, was equal to the sum of root respiration and estimated root production in the IL treatment, whereas in the nutrient-limited C and I treatments, total belowground C allocation was greater than the sum of root respiration and estimated root production, suggesting higher fine root turnover or increased allocation to mycorrhizae and root exudation. Carbon use efficiency, the ratio of net primary production to assimilation, was similar among treatments for aboveground tissues (0.43-0.50). Therefore, the proportion of assimilation used for construction and maintenance respiration on an annual basis was also similar among treatments. 相似文献
20.
【目的】随着森林的发育过程,林木个体的生长和生物量分配,以及林分水平的结构和功能均发生了明显的变化。然而,细根生物量与林分年龄的联系,目前仍然了解有限。本研究以黑龙江省帽儿山地区兴安落叶松人工林为研究对象,比较了同一林分在19年和32年生时林分水平(单位面积)和单株水平细根生物量的垂直分布和季节动态,分析了影响细根生物量变化的林分与土壤因子,旨在明确林分年龄对细根生物量的影响和潜在的机制。【方法】在生长季内的5月、7月和9月,采用土钻法获取土壤0~30 cm深度细根并测定生物量,同时测定林分特征和土壤养分和水分含量。【结果】随林龄增加,落叶松人工林单位面积细根生物量显著下降,而单株细根生物量变化不显著;与19年生林分相比,32年生林分土壤表层(0~10 cm)细根生物量占总细根生物量的比例明显下降,土壤亚表层(10~20 cm)和底层(20~30 cm)细根生物量所占比例增加,呈现出细根向深层土壤增生的趋势。土壤表层(0~10cm)单位面积细根生物量随林分年龄的变化趋势与林分密度和胸高断面积、土壤铵态氮浓度变化有关,但是单株细根生物量受林分和土壤因子的影响均不显著。【结论】林分发育过程中,落叶松细根生物量降低,细根的资源吸收策略发生了明显的改变。 相似文献