Plantdivesity of Peatlands and related Organic Substances Humic and Fulvic acids
Juichi OMOTE* and Yutaka YAMAGIWA**
Abstract
Peatlands are regarded as a complex habitat type, that contain a full range of development:from ombrotrophic to geotrophic mires; dystrophic to eutrophic, calcareous fens to acidic bogs and so on.
They occupy a wide range of environmental conditions and dynamic systems which form part of the hydro- seral succession from open water to dryland sustaining a rich variety of plant species.
The principal abiotic factors which influence plant species and its distribution are those of the climatic factors and of the hydroedaphic factors. The organic substances are specially the key factors for the vegetation complexes in peatlands, and strongly affect many hydrogeochemical conditions ( e.g soil chemistry)
Therefore, an investigation on the plant species from various types of mires and its components have been discussed in this paper. The study described here investigated the differences in chemical characteristics between peat deposits with different habitats and plant species.
Keywords: Peatland, Vegetation complexes , Organic Substances, Humic and Fulvic acids, Plantdiversity
1.Introduction
Organic substances, so-called humus substances in dissolved or particulate forms, is found in all ecosystem types. Organic substance is produced by microbial degradation of dead organic matter (plant and animal remains) and is nutrient—rich.
It is a complex mixture of many different acids containing carboxyl and phenolate groups so that the mixture behaves functionally as a dibasic acid or. as a tribasic acid.(')
Humic substance is subdivided into three main fractions: humic acids, fulvic acids, and humin. Humic acids- the fraction of humic substances that is not soluble in water under acidic conditions (pH < 2) but is soluble at higher pH values. They can be extracted from soil by various reagents and which is insoluble in dilute acid. Humic acids are the major extractable component of soil humic substances.
They are dark brown to grey black in color.(Fig.l)
Humic substances (pigmented polymers)
Fiilvir arid Humic acid Humin
2 000 45%
48%
1 400
— increase in intensity of colour increase in degree of polymerization
increase in molecular weight —>300 000 ?
• increase in carbon content >62%
decrease in oxygen content >30%
-decrease in exchange acidity >500 decrease in degree of solubility
Chemical properties of humic substances. (Stevenson 1982)
*Kinki University, Technical College, Department of Total Systems Engineering & Urban Environment.
7-1Kasugaoka, Nabari-shi, Mie 518-0459, Japan E-Mail: omote@ktc. ac .jp
**Research Coodination Office, Managing Office of The Agriculture, Shizuoka Prefectural Government 9-6 Oute-machi,Aoi-ku,Shizuoka-shi,Shizuoka420-8601,Japan, E-Mail:yutakal [email protected]
Fig.1
Chemical nronerties of humic substances(1)
The hypothetical structure for humic acid, shown in figure 1, contains free and bound phenolic OH groups, quinone structures, nitrogen and oxygen as bridge units and COOH groups variously placed on aromatic rings.(Fig.2)
Fulvic acids- the fraction of humic substances that is soluble in water under all pH conditions. They remains in solution after
Fig.2
removal yellow
structun and ali
Exsample of a typical humic acid(2)
removal of humic acid by acidification. Fulvic acids are light yellow to yellow-brown in color. The hypothetical model structure of fulvic acid (Buffle's model) contains both aromatic and aliphatic structures, both extensively substituted with oxygen-containing functional groups. (Fig.3)(2)
r-..0 nu
Fig.3
Model structure of fulvic acid by Buffle(3)
Humin - the fraction of humic substances that is not soluble in water at any pH value and in alkali, humins are black in color.
In this paper has been studied:
1. Quantitative data on the variation of plant species, soil and organic matter in peatlands .
2. A relationships between plant species, organic components and Nutrients
3. Elementary composition of inorganic Elements
2. Site description
This paper investigated two peatlands. Minamidobu are covering an area of about 1 ha and Kitadobu moor are covering an area of about 7 ha.. Both are located on the northern foot of Mt. Daikura (altitude1,852 m) in the northeastern part of
Nagano prefecture in Central Japan, at 36°49'47.9"N, 138°29'57.9"E. for Minamidobu and 36°50'23.1"N, 138°30'22.9"E for Kitadobu.. Minamidobu moor lies at about 1,420 m altitude, and Kitadobu at about 1,500 m altitude.
Fig.4 Study areas
Minamidobu is made up of a sloping low moor with a high inclination, the water moves obliquely downwards. Kitadobu is a flat high moor. After Damman(1979) classification of peatlands. Minamidobu and Kitadobu are categorized by geogenous and topogeneous peatlands.(4) Minamidobu is characterized as a having low and intermediate moor types, whereas Kitadobu has intermediate and high moor types. These moors are surrounded with wide natural forest called Fagus crenata .
3.Materials and Methods
The vegetation have been investigated through the Braun - Blanquet phytosociological method. Carbon and Nitrogen for plant and soil samples were analysed by using the CHN Corder.
Na, K, Mg, Ca, Cl, and Mn were measured by X-ray fluores- cence spectrometric analysis. The analysis of the organic matter in peat sediment is shown in Figure 5.
3 gramm dried sediment samples( from upper layer of living and dead plants detritus. 0-20cm depth) were used for the extraction of the four humus fractions ( humic acid, fulvic acid, humin and Himatomelanic acid). The sample was washed with distilled water and sifted through a sieve (Advantec5C 150mm mesh). The samples that passed through the sieve were then mixed with 100% ethanol 30 ml solutions and left overnight.
The upper solutions ,which contain bitumen were dried at room
species between them.
Lysichiton camtschatcense,Menyanthes &Oil/a/a, Sphagnum cuspidatum, Sphagnum fitnbriatum and Sphagnum teres etc.can only be found in the area of Minamidobu moor, while Ibfieldia japonica, T7accinium oxycoccus, Sphagnum papillosum and Sphagnum magellanicum etc. grow in the area of Kitadobu moor.
Tab.1 Characteristic of plant species for
Minamidobu and Kitadobu Mooro)
Fig.5
Outline of method used to extract sued&
ml
organic matter fractions from sediments(5)
The remaining sample was dried at room temperature and mixed with 1N NaOH solutions 50 ml and left overnight.
The alkaline filtrate containing fulvic acid and humic acid fractions was siphoned. The residue from the alkaline filtrate on, the humin fraction, was washed with the distilled water and then dried at room temperature .The humic acid fraction was precipitated by adding 98% H2SO4 solution 3 ml into alkaline filtrate until pH < 1. The upper solution, which contains the fulvic acid fraction, was removed from the precipitated humic acid fraction. The precipitated humic acid was washed with distilled water and then dried at room temperature and was precipitated by adding 100% ethanol 30 ml, and left overnight.
Finally the humic and Himatomelanic acids were separated. (5).
4. Results and Discussions 4.1 Vegetation
All together 52 plant species and 9 moss species for Kitadobu moor and 65 plant species and 6 moss species for Minamidobu moor have been found in the study area.(6) Table 1 shows the characteristics of plant species for Minamidobu and Kitadobu Moors. There is a clear difference
Juncue effuses var. decimens Tofieldia japonica Fauna crisis walli Pleuffspermum camtschati MTh Epigaea aShtl.C6 Poligonatum macranthum Genii,an tritium var, japonic, Angelica genuflexa Carex stipata Ligularia fffeheri Callum kamtschaticum vaxacutifolium Vaccinium oxycoecus Artemisia montane Lycopts maaekianus Potamogeton names &hunch, aria palustris
Typha latifall Conioselium
Martheeium asiatieum Chamaenerion angustifolium Carex stipata Sphagnum papillosum
Ifyperieum pseudopetiolatum Sphagnum angustifonhm Sparganium glomeratum Sphagnum fallax Potamogeton distinctus Sphagnum flexuosum Equisetum lluviatile Sphagnum magellanicum
Gyskhitoneamtschateens6 Sphagnum tenellum Persicaria thunbergii
Menyhnthes trifoliath Ligularia stenocephala Lycopodium inundatum Lysimachia thysiflora Hydrangea seffata
Sphagnum cuspidatum Sphagnum fimbriatum Sphagnum tures
These peatland can be classified into five types:
1. Pond, 2. Low moor, 3. Intermediate moor type between low and high moors, 4. High moor type, 5. Moorrand, These moors are regard as a complex habitat type within fen and bogs. They occupy a wide range of environmental conditions and dynamics systems, which form part of the hydroseral succession from open water to dry land.
Therefore, they sustain a rich variety of plant species.
As result, 38 vegetation series, identified at the association level were recognized.(6)
4.2 Soil chemistry (Inorganic and Organic components)
Uptake of major plant nutrients is mediated by humic substances. One stimulative effect of humic substances on plant growth is enhanced uptake of major plant nutrients:
nitrogen, phosphorus, and potassium.
The organic matter is also important to calculations of fluxes of carbon and macronutrients such as nitrogen and phosphorus (Kortelainen2003). 7
Analysis of the peat soil includes the main macronutrients, especially the main nutrients C, N, P, K, Ca, Mg, Na, Cl, and Mn. The poor-rich gradient in peatlands is controlled mainly by the properties of the peat soils, namely pH and concentrations of C, N, P, K, Ca, and Mg.
According to the Table 2 we see a clear differences of nutrients compositions among pond, low, intermediate, high moor and moorrand peat soil types.
Tab.2 Relation between Peat Soil Types and Main Macro nutrients(8)
pH C(%) N(%) 13(%) K(%) Ca(%)
Pond 145 17.18 1.068 0.07 056 0.411
Low moor 186 27.52 1.82 0.07 0.30 028
Intermediate moor 115 3206 202 0.4'1 027 011 High moor 126 1843 1.62 0.06 0.41 056 Moorrand 171 3117 213 008 0245 0040
Mg(t) Na(%) CI (ppm)Mn(ppm) CAM
Pond 021 010 16715 18015 1625
Low moor 021 013 7969 1980 13.81
Intermediate moor 011 011 81.1 258.6 1608 High moor 011 008 2226 253.2 919 Moorrand 0181 a Bs 78085 9775 1658
This difference may be attributed to the influence of the rate of decomposition. The high organic matter observed in the high moor can be associated with the low demand of nutrients for plants. Low and Intermediate moor contains more carbon, nitrogen and phosphorus than high moor. An increase in the rate of decomposition raises the total carbon content. The nutrient accumulations of peatsoils for the intermediate moor is estimated to be about 0.41(wt %) for P and 2.02 (wt %) for N, which indicate high nutrients conditions, because this moor
— 74 –
type has a mixture of habitats between low and high moors.
On other hand, K, and Mg are most accumulated for pond.
C and N are most accumulated for moorrand. The availability of plant nutrients peatsoils decreases in this two moors, because the acidity in all five moor types is below pH 6; pH ranges from 5.26 for high moor- Sphagnum peat to 5.86 for low moor- Carex peat.
The ratio of one soil chemical to another, for C/N, is used to help interpret aspects of fertility. Peat C/N ratios differ between peat soil types and plant species. A high ratio of C/N (>30: N-deficient) can be interpreted as a low production and low ratio of C/N (< 20: N-rich) as a high production for plant growth.
Fig.6 Relation between Carbon and Nitrogen in Peat soilso)
C in peat soils is positively correlated with N (Fig.6).
We suggests that this high correlation between C and N, and low C/N ratios are important for vegetation patterns. This implies that plant species distributions are important sinks for nutrients, especially for N. Other chemical components are not well correlated with each other.
Peat is composed of an enormously complex mixture of organic compounds, derived mainly from plant remains. The degree of decomposition and accumulations of organic matter and its components in wetlands depends on climatic conditions, soil moisture and water table conditions etc.
Plant species can influence soil organic matter. The rates of decomposition processes of organic matter are again determined by the nature of the components of plant species.
This indicates a very close relationship between plant distribution and organic matter.
Therefore, the relationship between plant species and peatsoils have been investigated. The ratios and concentrations of peatsoils with various levels of humic and fulvic acids and humine and bitumen are compared with inorganic components in the peatsoils under each plant species in Figure 7.
Fig.7 Composition of organic-and inorganic components of Peat soil(8)
The percentage of the humus which occurs in the various humic fractions varies considerably from one peatsoil type to another.
The results of these studies show that there is a clear difference in peatsoils among low moor, intermediate, high moor, and moor rand.
The total mean values of the five groups of moor types decrease in the order humic acid, fulvic acid, humine and then bitumen. The rate of inorganic to organic matter ( humic acids, fulvic acids, humin and bitumen) is 3 to 7 in the pond, 2 to 3 in the low moor , 3 to 7 in the intermediate moor , 1 to 15 in the high moor, and 3 to7 in the moorrand. (Table3). High rate of organic substances to inorganic subsutances are due to samples from upper layer of living and dead plants detritus.
Dehmer(1995) found large amounts of humic and fulvic acids in a highly decomposed peat that had formed in an oxygen-rich environment.(9)
Figures 8 and 9 shows a relatioship between plant species and humic acids, and fulvic acids.
Osmundastrunwinnarnonzetan,Rhododendron japonicum, and
Tab.3
comaO
Composition of nents of Peat soils at
organic-and the
inorganic surface laver from different plant species (%)(8)
Moor type
Plant species
In- organic
Humic acid
Fulvic acid
Humine Bitumen
pond Polamogelon
distinct.
32.4 16 37.2 10.8 3.68
Aletntanthes trijOhaM
27.5 41.3 22 9.17 0.02
Mean value
30 28.7 29.6 10 1.9
Low moor Carex rhynchophisa 44.6 23.5 15 14.9 1.93
Phragmites australis 25.5 48.8 14.2 8.5 3
Caltha palustris var.
Nipponica 53 19.2 8.8 17.7 1.34
Mean value
41 30.5 12.7 13.7 2.1
Intermediate moor
Sanguisorbe tenuifoli
a var. Purpurea 48.7 13.9 20.2 16.2 1.02
Lysichiton canItschencense
39.6 16.3 28.1 13.2 2.94
liennetvcaills (Imo/nth
var. esculents 24.4 47.9 14.8 8.13 4.7
Sphagnum recurvum
var. Arnblyphyllum 36.5 15.7 46.4 1.48
Mean value
28.2 28.7 19.7 21 2.5
High moor Rhynchospora alba 19.1 37.7 35.6 6.37 1.28
Sphagnum papillosum 17.4 28.4 49.2 4.97
Racomitrium lanugi-
nosum 47.3 6.6 40 5.98
Mean value
6.4 34.1 23.5 31.9 4.1
Moorrand Aconitum japonicum
var. Montanum 27.8 41.2 20.8 9.28 0.93
Allium victorialis ssp.
Platyphyllum 25.9 40.4 22.8 8.64 2.25
Ver.trum stamineum 40.7 13.9 28.6 13.6 3.21
Mean value
(31.5) (31.8) (24.1) (10.5) (2.13)
Total mean value
27.4 30.8 21.3 17.4 2.5
Scirpus wichurae, which are low moor plant indicators , have high content of humic acids. Whereas a high content of fulvic acids is only for Sanguisorba officinal's.
Fig.8
A relationshi between lant species
and Humic acids(8)
This different contents of organic substances from different plant species within a mire complex may suggest that the rate of decomposition is related to hydrological conditions (dryness or wetness) and organic acids content through geochemical processes that operate during temporary drying.
The fulvic acids have the positive effect on plant nutrition. High contents of fulvic acids can be explained by the relatively small size molecules they can readily enter plant roots, stems, and leaves.
Fig.9
A relationship between plant species.and Fulvic acidsm
5. Conclusions
The study described here investigated the differences in chemical characteristics between peat deposits with different habitats and plant species.
1) There is a clear difference in soil organic matter ( humic and fulvic acids) among fen, transitional moor, high moor( Raised bog), and moorrand. We suggest that different organic matter compounds may be attributed to the strong influence of plant richness in wetland ecosystem.
2) Plant species can influence soil organic matter. The rates of decomposition processes of organic matter are again determined by the nature of the components of plants species.
This indicates a very close relationship between plant distribution and organic matter.
3) The ratio of one soil chemical to another, for C/N, is used to help interpret aspects of fertility. Peat C/N ratios differ between peat soil types and plant species. C in peat soils is positively correlated with N. We suggests that this high correlation between C and N, and low C/N ratios are important for vegetation patterns. This implies that plant species distributions are important sinks for nutrients, especially for N.
4) The total mean values of the five groups of moor types decrease in the order humic acid, fulvic acid, humine and then
I-7/1
bitumen. High rate of organic substances to inorganic substances are due to samples from upper layer of living and dead plants detritus.
6. Acknowledgements
Naturalist Mr. Atuo Ikeda and my friend Mr. Dip. Ing.Helmut Miiller helped us and we discussed very fruitfully technically about plant ecology , flora and the identification of moss
References
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(4)Damman, A.W.H.,(1979): Geographic patterns in Peatland
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Peatlands, v Finland, September 17-21,1979. International
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(6)Omote, J.,and Yamagiwa,Y.,(2004):Vegetation in
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