Coniferous Soils Research Articles

Nitrification and denitrification as sources of gaseous nitrogen emission from different forest soils in Changbai Mountain

The contributions of nitrification and denitrification to N2O and N2 emissions from four forest soils on northern slop of Changbai Mountain were measured with acetylene inhibition methods. In incubation experiments, 0.06% and 3% C2H2 were used to inhibit nitrification and denitrification in these soils, respectively. Both nitrification and denitification existed in these soils except tundra soil, where only denitrification was found. The annually averaged rates of nitrification and denitrification in mountain dark brown forest soil were much higher than that in other three soils. In mountain brown coniferous soil, contributions of different processes to gaseous nitrogen emissions were Denitrification N2O>nitrification N2O>Denitrification N2. The same sequence exists in mountain soddy soil as that in the mountain brown coniferous soil. The sequence in mountain tundra soil was Denitrification N2O>Denitrification N2.

Electron microscopical observations and chemical analyses supporting Mn uptake in white rot degradedAlstoniaand pine wood stakes exposed in acid coniferous soil

Brownish-black spots and flecks several millimetres wide were frequently recognized on the surface and within nonpreservative-treated hardwood (Alstonia scholaris (R.Br.)) and softwood (Pinus sylvestris L.) test stakes placed in an acid forest soil. Energy-dispersive X-ray microanalysis in conjunction with transmission electron microscopy (TEM) and gross chemical analysis of wood using inductively coupled plasma spectrometry showed the flecks to be composed primarily of Mn, which was selectively removed from the surrounding soil. A similar uptake of Mn into wood stakes placed in presterilized acid soil was not noted, indicating the process resulted from biotic activity. Detailed TEM observations showed intrusion of Mn into the wood cell lumina and into areas of erosion, cavity formation, and decayed middle lamella in Alstonia and pine wood cells attacked by an unknown white rot decay fungus. Distinct zones of apparent delignification were also noted progressing across secondary cell walls and middle lamella regions of attacked cells, although it was unclear if the effect was caused by nonenzymatic attack by Mn, enzymatic attack by the fungus, or a combination of both. Mn is thought to play a major regulating role in both lignin depolymerization and mineralization in the presence of organic acids during white rot decay. Present observations also suggest that uptake of Mn into wood stakes during microbial degradation results from biotic activity and soil type and pH are of major significance.Key words: Mn, test stakes, electron microscopy, white rot decay, inductively coupled plasma spectrometry.

The environmental characteristics of forest land and the techniques of reforestation in fired land in Daxing’an mountains

Analysis of nature environmental condition and evaluation of selection and integration of techniques have been carried out in Daxing’an mountains from 1987. The character of soil generation in this area is influenced by the frigid, coniferous forest vegetation, weather, glacier and late soil formation process. Synthesis techniques for high yield plantation include high seedling quality, suitable site preparation and effective protection measures for young trees.

Organically bound halogens in coniferous forest soil -Distribution pattern and evidence of in situ production

We examined organically bound halogens in a coniferous soil profile and in Norway spruce litter enclosed in litter bags and subjected to degradation in field. Throughout the soil profile the total amount of organically bound halogens (TOX, μg Cl/g soil) was related to organic matter, i.e. amounts decreased with increasing depth. In contrast, the organic chlorine to organic carbon ratio (mg Cl org:g C org) increased with increasing depth, and a pronounced increase in this ratio was observed in the transition between the O-horizon and the A-horizon, strongly indicating that in situ production of organically bound halogens occur in soil. This conclusion was strengtened by the results of the litter bag study, which clearly showed that a net-production of organically bound halogens occurred during decomposition of the spruce needle litter. Furthermore, this part of the study showed that organically bound halogens are not a static factor of organic matter. On the contrary, the results strongly indicated that during decomposition of organic matter, organically bound halogens are subjected to both production, i.e. incorporation of inorganic halides into organic matter, and mineralisation, i.e. release of inorganic halides from organic matter. A method previously developed in our laboratory to determine TOX in soil was further evaluated; there were no indications that inorganic halides interfere with the determination.

Influence of forest age on nutrient availability and storage in coniferous soils of the Oregon Coast Range

A substantial fraction of the organic matter and plant essential nutrients in forest ecosystems are contained in the soil. The role of soils in nutrient storage and availability is an essential component of ecosystem function and stability. The top 10 cm of soil contains the highest concentration of nutrients. To determine the influence of forest age on nutrient storage and availability in riparian soils, we compared concentrations, storage, and extractability of plant nutrients in the litter layer and top 10 cm of mineral soil in old-, second-, and young-growth riparian forests. The analysis of variance for nutrient concentration, nutrient storage, or nutrients extracted in both the litter layer and top 10 cm of mineral soil showed no significant differences among sites or seasons for any nutrient; only differences among forest ages will be discussed. Concentrations of N, P, Mg, Mn, and Cu in forest litter did not differ by forest age, but concentrations of K, Ca, and B were significantly higher in old-growth forest litter than in the litter of second-or young-growth forests. In mineral soil, the concentrations of all nutrients were statistically equal for all forest ages. Old-growth forests stored significantly (P ≤ 0.05) greater amounts of all nutrients measured in the litter layer, and greater amounts of N, P, and K in the mineral soil, than were stored in second- or young-growth forests. Greater amounts of P, B, and Zn were extracted from old-growth forest litter than from either second- or young-growth forest litter, and greater amounts of P, K, Mn, B, and Zn were extracted from old-growth mineral soil than from second- or young-growth mineral soil. The amount of each nutrient stored in the litter layer of the different-aged forests correlated curvilinearly with the amount of C in the litter layer of these forests; r2 ranged from 0.60 to 0.83. Also, the amount of N, K, and Ca stored in the mineral soil correlated curvilinearly with the amount of C in the soil; r2 ranged from 0.50 to 0.76.

Apparent differences in binding site distributions and aluminum(III) complexation for three molecular weight fractions of a coniferous soil fulvic acid

A soil fulvic acid isolated from a northern coniferous forest (NCFA) was fractionated into three different molecular sizes ranging from less than 500 to 10 000 daltons by ultrafiltration and the fractions were studied by synchronous scan fluorescence spectroscopy (SSFS). The SSFS gives three distinct emission peaks (I, II and III) for these fractions of NCFA, which are attributed to different fluorophores. The lower-wavelength peaks (315 and 370 nm) are attributed to fluorophores that consist of a single aromatic ring with carboxyl and/or hydroxyl groups attached to it, whereas the longest-wavelength peak (470 nm) is associated with a fluorophore containing three or four condensed aromatic rings with substituted groups. The ratio of the intensity of peak III to II increases from the lower to higher molecular weight fraction which indicates a higher content of condensed aromatic rings in the high molecular weight fraction. This study also included aluminum(III) binding experiments with the different molecular weight fractions of NCFA. Results showed that the high molecular weight fraction has a stronger affinity for aluminum(III) than the low molecular weight fraction.

Earthworm communities of limed coniferous soils: Field observations and implications for forest management

A field experiment and two soil faunal surveys were carried out to determine the effect of liming on earthworm populations of European forests. In the UK, a mixed species assemblage of earthworms was introduced into a deep peat soil under a young stand of Picea sitchensis, following addition of lime. Dendrodrilus rubidus was the only introduced species to be recovered after nearly a year. Total earthworm numbers and biomass were 70% and 15% of those introduced; this included species which had not been inoculated. Earthworms were found only where the soil had been limed; most individuals were found where earthworms and lime had been applied. In a survey of long-established limed plots of Picea abies on an acid, brown earth soil in northern France, liming increased earthworm density (5 to 11 individuals m −2, compared with 6 m −2 in a nearby deciduous woodland, and 0 m −2 in unlimed P. abies plots). Similarly, in Northern Ireland, the addition of lime permitted a substantial community of earthworms to develop in deep peat soil under P. sitchensis (79 individuals m −2, compared with 5 m −2 in unlimed soils), including acid intolerant species rare in coniferous soils. Different species assemblages were found in the four different limed plots sampled. The trees growing on limed soil at this site showed greater height growth than the trees in the unlimed plots, and it is suggested that earthworms have a beneficial effect in limed coniferous soils by increasing nutrient turnover.

Early colonization of red alder and Douglas fir by ectomycorrhizal fungi and Frankia in soils from the Oregon coast range

The potential for mycorrhizal formation and Frankia nodulation were studied in soils from six sites in the Pacific Northwest. The sites included young and old alder stands, a 1-year-old conifer clear-cut, a young conifer plantation, and rotation-aged and old-growth conifer stands. A bioassay procedure was used with both red alder and Douglas fir seedlings as hosts. After 6 weeks growth, seedlings of both hosts were harvested every 3 weeks for 21 weeks and numbers of nodules and ectomycorrhizal types estimated. Nodules formed on red alder and ectomycorrhizae formed on both alder and Douglas fir in soil from all sites. Nodulation potential was highest in soil from the alder stands and the conifer plantation. Seven morphologically distinct ectomycorrhizal types were recovered on Douglas fir and five on alder. Only Thelephora terrestris, a broad-host-range mycobiont, formed mycorrhizae on both hosts. New ectomycorrhizal types formed on both hosts throughout the bioassay. Ectomycorrhizal colonization of alder was greatest in the alder and clear-cut soils. Low ectomycorrhizal colonization on alder was found in soils from sites where conifers were actively growing. Ectomycorrhizal colonization of Douglas fir was highest in the young alder and conifer plantation soils and was low in the rotation-aged conifer soil. The highest diversity of ectomycorrhizal types was found on alder in the conifer clear-cut soil and on Douglas fir in the rotation-aged conifer soil. Effects of host specificity, nodulation and mycorrhiza-forming potential and nodule-mycorrhiza interactions on seedling establishment are discussed in relation to seral stage dynamics and attributes of pioneer ectomycorrhizal fungal species.

Water repellency, mat formation, and leaf-stimulated growth of some ectomycorrhizal fungi

Ectomycorrhizal short roots, mycelia, rhizomorphs and mats from conifer soil were examined in relation to their hydrophobic properties. In some cases connected fruit bodies were included in the study. Mycorrhizal soils gathered from the forest and/or colonized in a laboratory rhizoscope were studied, as were mycelia in pure culture. Most forest-derived species were hydrophobic. The drought-resistant Cenococcum geophilum and the more ruderal and moisture-dependent Thelephora terrestris were both strongly hydrophilic. The hydrophobic mycelium seemed solely responsible for the water repellence properties, and adjacent soil and plant debris remained unaffected and hydrophilic. In hydrophobic fungi, mat formation was induced in the rhizoscope by hyphal contact with alder litter leaves. This stimulating effect was not found when the leaves were covered by water or when fresh, green alder leaves were used. Thelephora terrestris did not form such mats in vitro and spread sparsely in air pockets as well as in the adjacent water film. The possibility is discussed that many mycorrhizal fungi in the forest may partly control their soil environment via aeration created by their hydrophobia.

Biology and chemistry of conifer oils

AbstractConifers are widespread through the northern hemisphere and many of their essential oils and oleoresins have acquired high commercial significance. After a short review of conifer taxonomy and some cytological aspects of oil secretion and accumulation, general characteristics of conifer oils and resins are discussed in more detail.Since considerable differences can be found in literature concerning the composition of commercially important conifer oils, we have analysed some of them originating from several species of the genera Abies, Larix, Pseudotsuga, Tsuga, Picea and Pinus. The results were compared with those of self‐distilled oils from authentic botanical origin and discussed in regard to the systematic grouping of the individual conifer.In addition to investigations of the chemistry of selected conifer oils, the paper outlines the influence of the raw material, especially the relation of needles to twigs and the effect that this variable has on the composition of an individual oil.

A new perfusion system for the measurement and characterization of potential rates of soil nitrification

A new perfusion system for the rapid and simple measurement and characterization of potential rates of soil nitrification is presented. The system involved pumping a buffered NH 4 + solution, containing chlorate to block oxidation of NO 2 − to NO 3 t- sole product of nitrification), through a soil column. Perfusate was then passed through a cation exchange resin to remove remaining NH 4 + (preventing further nitrification), and through a sephadex gel to control the perfusion rate. Determinations of NO 2 − eluting from the column enabled rates of nitrification to be calculated. Soil samples were also perfused with C2H2 (1%) in the perfusing solution, as a partition of autotrophic and heterotrophic nitrification. In an agricultural soil adjusted to a range of pH values (then maintained at constant pH over 25 years), potential rates of nitrification (using unbuffered perfusate) decreased with increasing soil acidity, while at each pH almost all nitrification was blocked by C2H2. This suggested autotrophs dominate nitrification in agricultural soil, regardless of acidity. In an acid coniferous soil, however, 90% of potential nitrification was unaffected by C2H2, suggesting heterotrophic nitrification is of particular significance in acid forest soils.

Mycorrhizal Fungi Prevent Disease in Stressed Pine Seedlings

AbstractThe common rhizospheric fungus Cylindrocarpon destructans caused severe root damage leading to mortality in light‐starved, stunted seedlings of Pinus sylvestris. This effect was, however, almost fully prevented by the presence of mycorrhizal fungi; i.e. Laccaria laccata, Pisolithus tinctorius, or unidentified species present in small amounts of conifer soil. Protection took place even before visible mycorrhizae were found on the roots. This is the first time that protection ofstressed plants against non‐parasitic (non‐invasive) pathogens has been reported. The results indicate that root protection by mycorrhizal fungi may not only be effective inside the root but probably also extends out into the rhizoplane or rhizosphere.

Effect of clear-felling and slash removal on the acidity of Northern coniferous soils

Measurements of pH were carried out at two experimental sites in Sweden before and after clear-felling. At eleven sites, pH, cation-exchange capacity, base saturation and exchangeable hydrogen ions were compared in clear-felled areas where slash was left and removed, respectively. It is shown that pH increases significantly after clear-felling. The increase is larger than can be explained by the release of basic cations in connection with decomposition of slash and humus. The increase in pH is less in a clear-felled area when the slash is removed than when it is left. There is a decrease in exchangeable Ca 2+, Mg 2+ and Mn 2+ and an increase in H + and Al 3+. There is a decrease in base saturation of about 80%.

Demand, supply and application possibilities of domestic waste compost in agriculture and horticulture

Increasing quantities of fermented domestic waste compost resulted, in the present experiments, in a decrease in the production of Lactuca sativa (lettuce) in contrast to a yield increase for Apium graveolens (celery). The application of a calculated quantity of ion exchangers can modify the phytotoxic effect of the presence of heavy metals as well as the salt concentration of the domestic waste compost. The use of anion exchangers in the lettuce culture resulted in a considerable yield increase in comparison with the control. With regard to Chrysanthenum morifolium cv. ‘Angora’, Pelargonium zonale cv. ‘Flirt’ and Dieffenbachia perfecta, it was demonstrated that the use of a mixture of domestic waste compost and coniferous soil in a ratio of 1:3 is very useful for these ornamental plants, on the basis of comparison of results of vegetative development with the control substrate. Analysis of the vegetables cultivated with increasing quantities of domestic waste compost enriched sand-loam soil showed that the concentrations of Cu, Pb and Zn fairly quickly exceeded the normal average values. As far as pathogenesis is concerned, increasing quantities of domestic waste compost positively influenced the health index of Phaseolus vulgaris and Pisum sativum with regard to Rhizoctonia solani and Pythium ultimum.

SOIL FATTY ACIDS UNDER ALDER, CONIFER AND MIXED ALDER-CONIFER STANDS OF COASTAL OREGON

Total soil lipid contents among alder, conifer, and mixed alder-conifer stands near the Oregon coast did not differ significantly. The lipids contained a number of fatty acids ranging in carbon-chain length from 12 (lauric acid) to 24 (lignoceric acid). Concentration levels of several fatty acids differed significantly among stands: lignoceric acid was highest in conifer soil; palmitic acid, in alder soil; and lauric acid, in mixed alder-conifer soil.

Phytophthora megasperma . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Phytophthora megasperma . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a wide range of hosts (inculding sugarcane, lucerne, soyabean, crucifers (Brussels sprouts, cabbage, cauliflower, kale, rutabaga, turnip), beet, carrot, spinach, potato), also in soil and plant debris in pond water. Phytophthora megasperma var. megasperma has been recorded on Althaea rosea, Brassica oleracea, Castanea sativa, Matthiola incana, Narcissus sp. and conifer soil; Phytophthora megasperma var. sojae on Asparagus officinalis, Brassica oleracea, Cicer arietinum, Glycine max, Medicago saliva, Melilotus spp., Prunus amygdalus, P. persica, Saccharum officinarum, Senecio cruentus, Solanum tuberosum and pond and soil water (Tompkins et al. , 1936, Herb. IMI). DISEASES: Causing seed-piece rot of sugarcane and a shoot rot of lucerne, soyabean and vegetables particularly crucifers (Brussels sprouts, cabbage, cauliflower, kale, rutabaga, turnip) as well as beet, carrot, spinach, and potato ('pink rot'). Infected plants wilt and their foliage may be discoloured red or purple at the leaf margins. DISTRIBUTION: Australasia (Australia, New Zealand, Tasmania); Europe (England, France, Ireland, Italy); North America (Canada, U.S.A.); South America (Argentina). (CMI Map 157, ed 2.) TRANSMISSION: Soil-borne and favoured by wet conditions with temperatures around 15-24°C. Persistence in soil for over 1 yr. is possible due to delayed germination of oospores (31: 394).