二乔玉兰开花过程中花色变化的生理生化机制

以4年生二乔玉兰不同花期外层花瓣为试材,测定其在开花过程中花瓣色度值、花色苷、类黄酮、可溶性糖含量、细胞pH值以及相关酶活性的变化,以探讨二乔玉兰花色呈色机理。结果显示:(1)随着花期的推移,苯丙氨酸解胺酶(PAL)和查尔酮异构酶(CHI)活性逐渐减弱,细胞pH值逐渐变大,可溶性糖、花色苷、类黄酮含量不断降低,而花瓣明亮度增强,红色度以及彩色度减弱,且不同花期各参数值之间差异显著。(2)花瓣可溶性糖含量、PAL和CHI的活性与其花色素苷、类黄酮含量变化之间呈显著正相关关系,花瓣pH值的变化、明亮度L*值与花色素苷、类黄酮含量之间呈显著负相关,色相值a*与花色苷含量的变化呈显著正相关。研究表明,二乔玉兰花瓣花色苷和类黄酮含量的高低可以影响其花色的深浅,可溶性糖含量、PAL和CHI活性、细胞pH通过参与一定的生理代谢来调节花色素的形成,进而引起二乔玉兰花色色调的改变。     

不同种源黄连木秋季色素含量与叶色参数的关系

该研究以陕西汉中、河南林州、河北涉县和北京中国科学院植物研究所4个种源黄连木(Pistacia chinensis Bunge)的苗木为对象,用分光光度计和色差仪对其叶绿素、类胡萝卜素、花色素苷含量及叶色参数(L*、a*、b*)进行了测定分析,探讨不同种源苗木秋季叶色变化规律及差异,揭示黄连木叶色呈现与叶片色素含量之间的内在关联,为筛选适合城市绿化的优良黄连木种源提供依据。结果表明:(1)在秋季叶片转色期,随着时间的推移,4个种源黄连木叶片的叶绿素、类胡萝卜素和花色素苷含量的比例呈现不同的变化趋势,其中:河北种源的花色素苷含量较高,叶片呈现红色;陕西种源叶绿素含量较高,叶片呈现绿色的时间较长;河南、北京种源处于两者之间。(2)各个种源黄连木的叶色参数a*值(红/绿)均与花色素苷含量呈正相关关系,与叶绿素含量呈负相关关系,且相关系数均达到显著水平(P0.05),各个种源叶色参数L*值(光泽明亮度)也与叶绿素含量间表现出显著或极显著的正相关性。研究发现,河北种源黄连木秋季的叶色最红,陕西种源黄连木叶片呈现绿色的时间最长;色差仪的应用实现了叶色和各色素含量间量化的关系。     

Use of the atLEAF+ chlorophyll meter for a nondestructive estimate of chlorophyll content

At present, chlorophyll meters are widely used for a quick and nondestructive estimate of chlorophyll (Chl) contents in plant leaves. Chl meters allow to estimate the Chl content in relative units - the Chl index (CI). However, using such meters, one can face a problem of converting CI into absolute values of the pigment content and comparing data acquired with different devices and for different plant species. Many Chl meters (SPAD-502, CL-01, CCM-200) demonstrated a high degree of correlation between the CI and the absolute pigment content. A number of formulas have been deduced for different plant species to convert the CI into the absolute value of the photosynthetic pigment content. However, such data have not been yet acquired for the atLEAF+ Chl meter. The purpose of the present study was to assess the applicability of the atLEAF+ Chl meter for estimating the Chl content. A significant species-specific exponential relationships between the atLEAF value (corresponding to CI) and extractable Chl a, Chl b, Chl (a+b) for Calamus dioicus and Cleistanthus sp. were shown. The correlations between the atLEAF values and the content of Chl a, Chl b, and Chl (a+b) per unit of leaf area was stronger than that per unit of dry leaf mass. The atLEAF value- Chl b correlation was weaker than that of atLEAF value-Chl a and atLEAF value-Chl (a+b) correlations. The influence of light conditions (Chl a/b ratio) on the atLEAF value has been also shown. The obtained results indicated that the atLEAF+ Chl meter is a cheap and convenient tool for a quick nondestructive estimate of the Chl content, if properly calibrated, and can be used for this purpose along with other Chl meters.     

Temperature sensitivity of complementation at the Maroonlike eye color locus in Drosophila melanogaster

Summary In contrast to the wild-type eye color seen when Drosophila melanogaster heterozygous for mal ¹/mal ^F1 are cultured at 25 C, a mutant eye color is observed in heterozygotes cultured at 29–30 C throughout development. Furthermore, heterozygotes have wild-type eyes upon emergence provided development proceeds at 25 C during either of two critical periods: 1) The third quarter of the 3rd larval instar or 2) an imprecisely defined pupal period beginning less than 12 hours before the visual appearance of brown eye pigment and terminating about the time pigment appears in the wings.     

铁筷子花瓣中花青素苷成分及含量对其呈色的影响北大核心CSCD

该研究以7个品种铁筷子(Helleborus thibetanus Franch.)为试验材料,借助目视测色、RHSCC比色卡、色差仪进行花色表型的测定,采用高效液相色谱法-光电二极管阵列检测方法(HPLC-DAD)及高效液相色谱-电喷雾离子化-质谱联用技术(HPLC-ESI-MS)测定分析铁筷子花瓣中花青素苷成分及含量,以探究不同品种铁筷子的花色与花青素苷成分及含量之间的关系。结果显示:(1)紫色系品种花瓣的a*值最高b*值最低,黄色系品种花瓣的b*值最高a*值最低,不同品种的铁筷子花色越深L*值越低。(2)从5个有花青素苷积累的铁筷子品种中检测出11种花青素苷成分,分别为6种矢车菊素苷,4种飞燕草素苷,1种矮牵牛素苷;供试的铁筷子材料中红色系2个品种的花青素苷含量最高,紫色系品种次之;矢车菊素苷与飞燕草素苷为影响铁筷子花瓣呈色的主要色素物质。(3)不同种类的花青素和修饰基团的差异,导致铁筷子花瓣呈现不同的色彩,含有多种酰基化修饰的飞燕草素苷使铁筷子花色蓝移进而使花色加深。(4)相关分析表明,铁筷子花瓣的L*值与a*值呈显著负相关关系,与b*值呈显著的正相关关系;L*值与总花青素苷含量呈显著负相关关系,且随着花青素苷含量的累积a*值增加,花色红移。研究表明,花青素苷的成分及含量是导致铁筷子花瓣呈现不同颜色的主要原因,矢车菊素苷和飞燕草素苷的互作以及酰基化的修饰使铁筷子呈现不同程度的紫色,花青素苷的不同累积量影响了花瓣颜色的明暗变化,从而使铁筷子花瓣颜色丰富。     

The blue anthocyanin pigments from the blue flowers of Heliophila coronopifolia L. (Brassicaceae)

Six acylated delphinidin glycosides (pigments 1-6) and one acylated kaempferol glycoside (pigment 9) were isolated from the blue flowers of cape stock (Heliophila coronopifolia) in Brassicaceae along with two known acylated cyanidin glycosides (pigments 7 and 8). Pigments 1-8, based on 3-sambubioside-5-glucosides of delphinidin and cyanidin, were acylated with hydroxycinnamic acids at 3-glycosyl residues of anthocyanidins. Using spectroscopic and chemical methods, the structures of pigments 1, 2, 5, and 6 were determined to be: delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(acyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which acyl moieties were, respectively, cis-p-coumaric acid for pigment 1, trans-caffeic acid for pigment 2, trans-p-coumaric acid for pigment 5 (a main pigment) and trans-ferulic acid for pigment 6, respectively. Moreover, the structure of pigments 3 and 4 were elucidated, respectively, as a demalonyl pigment 5 and a demalonyl pigment 6. Two known anthocyanins (pigments 7 and 8) were identified to be cyanidin 3-(6-p-coumaroyl-sambubioside)-5-(6-malonyl-glucoside) for pigment 7 and cyanidin 3-(6-feruloyl-sambubioside)-5-(6-malonyl-glucoside) for pigment 8 as minor anthocyanin pigments. A flavonol pigment (pigment 9) was isolated from its flowers and determined to be kaempferol 3-O-[6-O-(trans-feruloyl)-β-glucopyranoside]-7-O-cellobioside-4′-O-glucopyranoside as the main flavonol pigment.On the visible absorption spectral curve of the fresh blue petals of this plant and its petal pressed juice in the pH 5.0 buffer solution, three characteristic absorption maxima were observed at 546, 583 and 635 nm. However, the absorption curve of pigment 5 (a main anthocyanin in its flower) exhibited only one maximum at 569 nm in the pH 5.0 buffer solution, and violet color. The color of pigment 5 was observed to be very unstable in the pH 5.0 solution and soon decayed. In the pH 5.0 solution, the violet color of pigment 5 was restored as pure blue color by addition of pigment 9 (a main flavonol in this flower) like its fresh flower, and its blue solution exhibited the same three maxima at 546, 583 and 635 nm. On the other hand, the violet color of pigment 5 in the pH 5.0 buffer solution was not restored as pure blue color by addition of deacyl pigment 9 or rutin (a typical flower copigment). It is particularly interesting that, a blue anthocyanin-flavonol complex was extracted from the blue flowers of this plant with H₂O or 5% HOAc solution as a dark blue powder. This complex exhibited the same absorption maxima at 546, 583 and 635 nm in the pH 5.0 buffer solution. Analysis of FAB mass measurement established that this blue anthocyanin-flavonol complex was composed of one molecule each of pigment 5 and pigment 9, exhibiting a molecular ion [M+1] ⁺ at 2102 m/z (C₉₃H₁₀₅O₅₅ calc. 2101.542). However, this blue complex is extremely unstable in acid solution. It really dissociates into pigment 5 and pigment 9.     

Carbon discrimination,water-use efficiency,nitrogen and phosphorus nutrition of the host / mistletoe pair Eucalyptus behriana F. Muell and Amyema miquelii (Lehm. ex Miq.) Tiegh. at permanently low plant water status in the field

Summary Under conditions where both plants had permanently low water status, the mistletoe, Amyema miquelii (Lehm. ex Miq.) Tiegh., had lower nitrogen contents in leaf tissue than its host, Eucalyptus behriana F. Muell. The parasite transpired less than its host which is consistent with the hypothesis that mistletoe transpiration acts as a nitrogen gathering mechanism. Nitrogen and phosphorus contents were generally low in both plants; they were positively correlated, and mistletoes reduced nutrient contents of infested hosts. The carbon discrimination ratio, ¹³C (a measure of water-use efficiency) of each plant was within the range reported for other mistletoes and their hosts. Although it did not differ significantly between host and parasite it indicated lower water-use efficiency in the mistletoe. For the nitrogen content of host leaves the gradient within the pair, (¹³C), is much lower compared to the correlation given by Ehleringer et al. (1985). It is concluded that at permanently low water status on nitrogen and phosphorus deficient soils a water-saving strategy accompanied with slow growth is more appropriate for both mistletoe and host.     

Calibration of the Minolta SPAD-502 leaf chlorophyll meter

Use of leaf meters to provide an instantaneous assessment of leaf chlorophyll has become common, but calibration of meter output into direct units of leaf chlorophyll concentration has been difficult and an understanding of the relationship between these two parameters has remained elusive. We examined the correlation of soybean (Glycine max) and maize (Zea mays L.) leaf chlorophyll concentration, as measured by organic extraction and spectrophotometric analysis, with output (M) of the Minolta SPAD-502 leaf chlorophyll meter. The relationship is non-linear and can be described by the equation chlorophyll (mol m^–2)=10(^M0.265), r ²=0.94. Use of such an exponential equation is theoretically justified and forces a more appropriate fit to a limited data set than polynomial equations. The exact relationship will vary from meter to meter, but will be similar and can be readily determined by empirical methods. The ability to rapidly determine leaf chlorophyll concentrations by use of the calibration method reported herein should be useful in studies on photosynthesis and crop physiology.Abbreviations Chl- chlorophyll - M- SPAD-502 meter value     

Inhibition of Pigment Biosynthesis in Cucumber Cotyledons by Isoxaflutole

Isoxaflutole [5-cyclopropyl-4-(2-methylsulphonyl-4-trifluromethylbenzoyl)isoxazole] is a new preemergence herbicide for broad-spectrum weed control in maize. The effect of isoxaflutole on chlorophyll (Chl) and carotenoid (Car) biosynthesis was investigated in cucumber (Cucumis sativus L.) cotyledons. Etiolated tissue was incubated with 5 mM isoxaflutole for 24 h and irradiated (60 mol m^-2 s^-1). The irradiation for 3 h did not reduce Chl a, Chl b, and Car contents, but after a 28-h irradiation the contents of Chl a and Car decreased by 35 and 15 %, respectively, and the content of Chl b increased by 24 %. Increasing the concentration of isoxaflutole beyond 5 mM resulted in reduction of Chl a (71 %), Chl b (20 %), and Car (31 %) contents. Similarly, increase in irradiance from 60 to 180 mol m^-2 s^-1 resulted in larger reduction of Chl and Car contents. Exogenously supplied 5-aminolevulinic acid did not reverse the isoxaflutole-inhibited Chl synthesis, whereas an exogenously supplied homogentisic acid lactone reversed the inhibition of pigment synthesis due to isoxaflutole.     

Dynamics of seston constituants in the Ariège and Garonne rivers (France)

Water contents of suspended matter, algal pigments, particulate organic carbon and particulate phosphorus were measured in the rivers Garonne (2 sites) and Ariège (1 site) throughout an annual cycle. The general trend of the parameters was similar at the three sites. Depending on the sites, the period of algal growth (chlorophyll a + phaeopigments > 25 µg l^–1), lasted from two to six weeks in August–September. The algal peaks reached 50 to 90 µg 1^–1 of total pigments. High contents of particulate organic carbon (> 2 mg 1^–1) occurred at the end of summer (coinciding with algal growth), and during the November and May floods. In summer 50–75 % of the suspended matter was organic, in spring this was 10 times less. The high linear correlation between particulate organic carbon and pigment contents (r = 0.87; P = 0.0001) suggested an algal origin of at least part of the particulate carbon. Algal carbon was minor in the annual fluxes of particulate carbon (25 to 39% depending on the sites), but relatively high in comparison with other rivers. The mean particulate phosphorus content calculated over the year was 24 µg l^–1 ; it varied from 15 µg l^–1 during the high water period to 28 µg 1^–1 during the low water period. Likewise the percentage of particulate phosphorus in the suspended matter varied from 0.17 to 0.40. A negative linear correlation existed between particulate phosphorus content and specific discharge (r = – 0.46; P = 0.0001).The very marked seasonal trend of the parameters and the interactions led us to differentiate two modes of the rivers' functioning: a hydrologic phase and a biological phase. The hydrologic phase (high water) was dominated by the processes of erosion and transfer over the whole catchment area and the flood plain, while the biological phase was characterized by a high primary production in the river bed.     

Growth and photosynthetic responses in Jatropha curcas L. seedlings of different provenances to watering regimes

Seedlings from four provenances of Jatropha curcas were subjected to 80, 50, and 30% of soil field capacity in potted experiments in order to study their responses to water availability. Our results showed that with the decline of soil water availability, plant growth, biomass accumulation, net photosynthetic rate, stomatal conductance (g_s), and transpiration rate (E) decreased, whereas leaf carbon isotope composition (δ¹³C), leaf pigment contents, and stomatal limitation value increased, while maximal quantum yield of PSII photochemistry was not affected. Our findings proved that stomatal limitation to photosynthesis dominated in J. curcas under low water availability. The increase of δ¹³C should be attributed to the decrease in g_s and E under the lowest water supply. J. curcas could adapt to low water availability by adjusting its plant size, stomata closure, reduction of E, increasing δ¹³C, and leaf pigment contents. Moreover, effects of provenance and the interaction with the watering regime were detected in growth and many physiological parameters. The provenance from xeric habitats showed stronger plasticity in the plant size than that from other provenances under drought. The variations may be used as criteria for variety/provenance selection and improvement of J. curcas performance.     

Isolation and characterization of ferritin from the hepatopancreas of the musselMytilus edulis

Summary The main iron-binding protein in the hepatopancreas of the musselMytilus edulis, which had been previously iron-loaded by exposure to carbonyl iron (spheres of elemental iron less than 5 m diameter), has been isolated to electrophoretic purity and identified as ferritin. This ferritin hasM _r, of 480000, pI of 4.7–5.0 and is composed of two subunits,M _r 18500 andM _r 24600. Under the electron microscope, it appears as electron-dense iron cores of average diameter 5 nm surrounded by a polypeptide shell to a final average overall diameter of 11 nm. The purified protein contains, on average, 200 iron atoms/molecule protein. On immunodiffusion,M. edulis hepatopancreas ferritin gives a partial cross-reaction with antiserum to horse spleen ferritin and lamprey (Geotria australis) liver ferritin but does not react with antiserum to chiton (Acanthopleura hirtosa) haemolymph ferritin.     

Accumulation and depuration of microcystin produced by the cyanobacterium <Emphasis Type="Italic">Microcystis</Emphasis> in a freshwater snail

Seasonal changes in microcystin concentrations in a resident snail (Sinotaia histrica) and an edible clam (Corbicula sandai) in Lake Biwa were surveyed. To clarify both the accumulation and depuration of microcystins, experimental studies with microcystin were also carried out on the snail. In the field investigation, microcystin was detected from the hepatopancreas and intestine of S. histrica (up to 3.2µgg^–1 dry weight and 19.5µgg^–1 dry weight, respectively); however, no microcystin was detected in the hepatopancreas of C. sandai. In the laboratory experiment, the microcystin-LR concentration in the hepatopancreas of S. histrica reached a value of 436µgg^–1 dry weight on day 10 of 15 days of uptake, and a high value persisted despite a depuration period of 15 days. The depuration rate constant of microcystin and its biological half-life were 0.0828 day^–1 and 8.4 days, respectively. These results indicate that S. histrica has a high ability to accumulate microcystin in its tissue. Because S. histrica is predated by fish and water fowl, it is likely to play an important role as a vector for microcystin in lakes with dense blooms of toxic cyanobacteria.     

Enhanced colchicine production in root cultures of Gloriosa superba by direct and indirect precursors of the biosynthetic pathway

Excised root cultures of Gloriosa superba reached 7.5 g dry wt l^–1 and accumulated 240±40 g colchicine g^–1 cell dry wt after 4 weeks growth. While all precursors (except trans-cinnamic acid) enhanced colchicine content of root cultures without adversely affecting root growth, treatment with p-coumaric acid + tyramine (each at 20 mg l^–1) increased colchicine content to 1.9 mg g^–1 cell dry wt.     

Predictive capability of a leaf optical meter for determining leaf pigment status during senescence

We conducted an experiment to assess the predictive capability of a leaf optical meter for determining leaf pigment status of Acer mono Maxim., A. ginnala Maxim., Quercus mongolica Fisch., and Cornus alba displaying a range of visually different leaf colors during senescence. Concentrations of chlorophyll (Chl) a, Chl b, and total Chl [i.e., Chl (a+b)] decreased while the concentration of carotenoids (Car) remained relatively static for all species as leaf development continued from maturity to senescence. C. alba exhibited the lowest average concentration of Chl (a+b), Chl a, and Car, but the highest relative anthocyanin concentration, while Q. mongolica exhibited the highest Chl (a+b), Chl b, and the lowest relative anthocyanin concentration. A. mono exhibited the highest Chl a and Car concentrations. The relationships between leaf pigments and the values measured by the optical meter generally followed an exponential function. The strongest relationships between leaf pigments and optical measurements were for A. mono, A. ginnala, and Q. mongolica (R ² ranged from 0.64 to 0.95), and the weakest relationships were for C. alba (R ² ranged from 0.13 to 0.67). Moreover, optical measurements were more strongly related to Chl a than to Chl b or Chl (a+b). Optical measurements were not related to Car or relative anthocyanin concentrations. We predicted that weak relationships between leaf pigments and optical measurements would occur under very low Chl concentrations or under very high anthocyanin concentrations; however, these factors could not explain the weak relationship between Chl and optical measurements observed in C. alba. Overall, our results indicated that an optical meter can accurately estimate leaf pigment concentrations during leaf senescence — a time when pigment concentrations are dynamically changing — but that the accuracy of the estimate varies across species. Future research should investigate how species-specific leaf traits may influence the accuracy of pigment estimates derived from optical meters.     

Transaminase reactions and glutamate dehydrogenase in gastropod hepatopancreas

Summary Hepatopancreas tissue from the terrestrial snailsOtala lactea, Helix aspersa andStrophocheilus oblongus and the aquatic snailsBiomphalaria glabrata, Viviparus viviparus andLymnaea stagnalis was investigated for the presence of the various transaminases and glutamate dehydrogenase (EC 1.4.1.2 L-glutamate: NAD⁺ oxidoreductase). The cytosolic transaminases showed a broad substrate specificity, transferring the -amino function of most amino acids to -ketoglutarate. The main transaminase activities present were those of asparate transaminase (EC 2.6.1.1 L-aspartate: 2-oxoglutarate aminotransferase) and alanine transaminase (EC 2.6.1.2 L-alanine: 2-oxoglutarate aminotransferase). These two transaminases were also present in the mitochondrial fraction and thus exist in gastropod hepatopancreas as isozymes.Low levels of glutamate dehydrogenase activity were detected in hepatopancreas mitochondria from terrestrial and aquatic snails. The activity appears to be that of a typical animal glutamate dehydrogenase, preferentially utilizing NAD⁺ as a cofactor and being activated by adenine nucleotides and inhibited by guanine nucleotides.Supported by grants from the USPHS (AI 05006 and DE-00118) and the NSF (GB-38138)     

Seasonal Variability in the Levels of Fe, Zn, Cu, Mn, and Cd in the Hepatopancreas of the Japanese Scallop Mizuhopecten yessoensis

The relationships between concentrations (g/g of tissue) and content (g/organ) of the metals Fe, Zn, Cu, Mn, and Cd with seasonal changes in the weight of the hepatopancreas in the Japanese scallop Mizuhopecten yessoensis are studied. It is shown that, during a year, the weight of the hepatopancreas in the mollusk shows significant (more than twofold) changes. A positive correlation is revealed between the seasonal changes in the concentrations of the physiologically important metals Fe, Zn, Cu, and Mn and the weight of this organ, although no general consistent pattern of seasonal variability in the metal concentrations is found. For toxic Cd, a negative correlation is found between its concentration and the weight of the hepatopancreas.     

Effects of nitrogen deposition on growth and phosphate efficiency of Schima superba of different provenances grown in phosphorus-barren soil

Aims

We determined whether nitrogen (N) deposition on phosphorus (P)-limited soil could increase Schima superba growth or alter root formation or P efficiency. The effects of N deposition on S. superba were also used to investigate the N/P requirements of plants of different provenances.

Methods

One-year-old S. superba seedlings from eight geographic areas were grown in P-limited soil and treated with N (0, 50, 100, and 200 -kg?N?ha^?1?year^?1; i.e., control, N50, N100, or N200, respectively). Seedling growth, root development, phosphorus acquisition efficiency (PAE), and phosphorus utilization efficiency (PUE) were measured.

Results

S. superba responded positively to N supplementation. Seedling growth and dry biomass were highest with N100 treatment and lowest with N200. Root biomass and acquisition of soil P were greatest with N100. Significant differences were observed among plants of different geographical provenances. PAE and PUE had a strong relationship with root growth in plants subjected to N100 treatment.

Conclusion

A threshold for N and P requirements related to different genetic conditions and soil nutrients may exist for S. superba. Root growth and PAE can be divided into three categories based on soil nitrate levels. Nutrients were found to control root morphology and to enhance aboveground differences.     

铝胁迫对木荷幼苗光合特性的影响及添加盐基阳离子和磷的调节作用

为探讨铝(Al)胁迫对木荷(Schima superba)幼苗光合特征的影响,采用营养液水培的方法,对铝(Al)胁迫下木荷幼苗的光合响应及盐基阳离子(BC)和磷(P)的调节作用进行了研究。结果表明,在低浓度Al(0.25 mmol L–1)处理下,木荷幼苗的光合色素(Chl a、Chl b、Car)含量、光合作用参数(P n、g s、WUE、C i/C a)以及光响应特征参数(P max、AQY、R d、LSP)均呈下降趋势,添加BC或同时添加BC和P均能缓解上述参数的降低。中、高浓度Al(0.75、1.50 mmol L–1)处理,除光合色素含量呈增加趋势外,光合作用参数、光响应特征参数均下降,且下降幅度随Al浓度的升高而增大,添加P比添加BC更能有效缓解Al胁迫对木荷幼苗的影响。这揭示了BC、P在缓解木荷Al胁迫的相对重要性。     

中亚热带几种典型森林土壤养分含量分析及综合评价

分析及综合评价不同森林植被对土壤养分因子的影响,对揭示森林植被与土壤养分的相互关系,全面衡量森林土壤养分水平具有重要的意义。以中亚热带杉木(Cunninghamia lanceolata)纯林、木荷(Schima superb)纯林、木荷+楠木(Phoebe ahenre)混交林、木荷+杉木混交林、青冈栎(Cyclobalanopsis glauca)天然次生林、毛竹(Phyllostachys edulis)林6种森林类型为研究对象,在分析不同森林类型土壤养分特征状况差异的基础上,采用结构方程模型确定土壤养分因子权重,对其土壤养分水平进行综合评价。结果表明:(1)6种森林类型0-60 cm土壤有机质、全氮、碱解氮和有效磷的含量分别为8.24-28.17 g/kg、0.67-1.31 g/kg、44.88-89.31 mg/kg和1.24-6.50mg/kg,其含量最高的都是青冈栎天然次生林,土壤有机质和碱解氮含量最低的是毛竹林,土壤全氮和有效磷的含量最低的分别为杉木纯林和木荷纯林,0-60 cm土壤全磷和速效钾的含量分别为0.15-0.21 g/kg和35.54-54.32mg/kg,其含量最高的都是木荷+楠木混交林,含量最低的分别为木荷纯林和毛竹林;(2)土壤有机质、全氮、全磷和有效磷的含量在6种森林类型中都一致表现出随土层加深而逐渐减小的规律,而碱解氮和速效钾含量在土壤垂直剖面的变化却因森林类型而异,没呈现出具体的变化规律;(3)栎类天然次生林的土壤养分等级综合评分值为3.47,评价等级属于中上水平,杉木纯林、木荷纯林、木荷+楠木混交林、木荷+杉木混交林的土壤养分等级综合评分值分别为2.45、2.76、2.83、2.68,评价等级均属于中下水平,而毛竹林的土壤养分等级综合评分值仅为1.95,评价等级属于土壤养分缺乏。