Branch Wood Decomposition of Tree Species in a Deciduous Temperate Forest in Korea

Woody debris, which is supplied by branch litter, is an important component of forest ecosystems as it contains large quantities of organic matter and nutrients. We evaluated changes in branch wood dry weight and nutrient content of six common species (Fraxinus rhynchophylla, Pinus densiflora, Prunus sargentii, Quercus mongolica, Acer pseudosieboldianum, and Symplocos chinensis for. pilosa) in a deciduous temperate forest in Korea for 40 months. Branch wood disk samples 1.4–1.6 cm thick were cut, and mass loss was measured over time using the litterbag method. No significant differences in mass loss were recorded among the six tree species. Further, mass loss was negatively correlated with initial lignin concentration and positively correlated with both initial cellulose concentration and wood density for each species. Species with high wood cellulose content had high wood density while the lignin content in wood was relatively low. Accordingly, cellulose contributed to wood density, creating a relatively lower lignin content, and the decreased lignin concentration increased the wood decomposition rate

Effect of elevated atmospheric CO2 concentration on growth and leaf litter decomposition of Quercus acutissima and Fraxinus rhynchophylla.

The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition

Liming Alters the Soil Microbial Community and Extracellular Enzymatic Activities in Temperate Coniferous Forests

Soil acidification caused by anthropogenic activities adversely affects forest ecosystems by altering soil pH, which is an important factor in soil quality and function. Liming is one suggested way to solve this problem. This study was performed to evaluate the effects of liming in acidic forest soils by determining soil microbial biomass, microbial community structure, and extracellular enzyme activities associated with carbon, nitrogen, and phosphorus cycling. Lime treatment increased soil pH by up to 40%, significantly increased organic matter (OM) content at some sites, and altered the enzyme activity of the soil. With liming, the microbial biomass appeared to be affected by the chemical properties of the soil, such as pH, Ca2+, Mg2+, K+, and exchangeable aluminum (Ale) levels, although there were no significant differences at the site level. Enzymatic activity was found to be affected by pH, Ca2+, Mg2+, electrical conductivity (EC), and Ale; and acid phosphatase (AP) and phenol oxidase (POX) activity were significantly affected by lime treatment. AP activity decreased from 0.62 to 0.66, and POX activity increased from 1.75 to 3.00 in part of the sites. The bacterial community richness was influenced by pH as a direct effect of lime treatment. The fungal community richness was associated with changes in K+ that were not due to lime treatment. The bacterial community structure was affected by soil OM, total nitrogen (TN), pH, and Ca2+; and the fungal community structure was affected by pH, Mg2+, and K+. In conclusion, changes in soil environmental conditions by liming can affect soil microbial communities and functions through direct or indirect processes, further changing ecosystem processes

Pre-Plant Fumigation of Soils for Nematode Control Affects the Seedling Production and Morphological Properties of Pine and Larch Seedlings

Using a fumigation sterilizer (Dazomet) for nematode control, this study determined the effect of soil sterilization on the quantity and quality of the growth of Pinus densiflora Siebold & Zucc. and Larix kaempferi (Lamb.) Carrière seedlings in an open-field nursery at Jeongseon-gun, Kangwon-do, Republic of Korea. Most soil nematodes disappeared after fumigant sterilization. The organic matter content, cation exchange capacity, and Mg2+ content of the soil increased significantly, but the electrical conductivity (EC) decreased. The quantity of pine and larch seedlings was highly correlated with the soil nematode density. The soil properties changed due to soil fumigation, which affected the growth of both species. Pine seedling growth was affected by the soil chemical properties, such as available phosphorus (AP), Ca2+, Mg2+, and EC, and the growth of larch seedlings was affected by the EC and nematode density. The quality of the pine seedlings improved, whereas that of larch did not. This was a result of the difference in their tolerance to soil salinity. The seedling quality index (SQI) of the two species was related to the EC, but the pine seedlings were more affected by the EC, indicating that the control of soil nematodes by fumigant treatment significantly increased the quantity of seedlings produced and partly improved their quality. Soil management using a fumigant treatment was more efficient for producing pine seedlings than larch. Our results can be used to improve agricultural and forestry economics

Changes in CO₂ evolution from the decomposing leaf litter in the microcosms.

<p>Closed circles represent leaf litter obtained from the ambient air (380 ppm CO₂) chamber, and open circles represent leaf litter obtained from the elevated CO₂ (700 ppm) chamber. Bars show standard deviations (n = 4).</p

Changes in the remaining mass of the <i>Q</i>. <i>acutissima</i> (upper) and <i>F</i>. <i>rhynchophylla</i> (lower) leaf litter in the microcosms.

<p>Closed circles represent leaf litter obtained from the ambient air (380 ppm CO₂) chamber, and open circles represent that collected from the elevated CO₂ (700 ppm) chamber. Bars show standard deviations (n = 4).</p

Changes in the microbial biomass C and N of the decomposing leaf litter in the microcosms.

<p>Closed circles show leaf litter obtained from the ambient air (380 ppm CO₂) chamber, and open circles represent leaf litter obtained from the elevated CO₂ (700 ppm) chamber. Bars show standard deviations (n = 4).</p

Effect of Litter Quality on Needle Decomposition for Four Pine Species in Korea

Litter decomposition involves multiple complex processes, including interactions between the physicochemical characteristics of litter species and various environmental factors. We selected four representative pine species in South Korea (Pinus densiflora Siebold &amp; Zucc., Pinus thunbergii Parl., Pinus koraiensis Siebold &amp; Zucc., and Pinus rigida Miller) to investigate the decay rate and effects of the physicochemical properties on decomposition. Needle litters were incubated in microcosms at 23 &#176;C for 280 days and retrieved four times in about 70-day intervals. The mass loss showed significant differences among the species and was higher in the order of P. densiflora (30.5%), P. koraiensis (27.8%), P. rigida (26.5%), and P. thunbergii (23.6%). The needle litter decomposition showed a negative relationship with the initial surface area, volume, density, cellulose content, and lignin/nitrogen of the litter, and a positive relationship with the initial specific leaf area (SLA), surface-area-to-volume ratio (SA/V), and water- and ethanol-soluble substances. The decomposition rate was highly affected by the physical properties of litter when compared with the initial chemical litter quality, and it was strongly influenced by SLA and SA/V. Accordingly, the physical properties of pine needle litter, especially SLA and SA/V, may be the key factors, and they could be used as predictive indices for the decomposition rate of pine tree litters

Ordination biplot of NMDS based on the leaf litter decomposition rate of each species.

<p><b>Angles and lengths of the radiating arrows indicate the direction and strength of the relationships of the litter quality parameters.</b> Each vector's significance level was less than 0.05. Carbon (C), nitrogen (N), lignin (Lig), cellulose (Cel), soluble carbohydrate (SC), C/N (CN), lignin/N (LigN), respiration (RES), cQa (ambient CO₂ <i>Q</i>. <i>acutissima</i> group), eQa (elevated CO₂ <i>Q</i>. <i>acutissima</i> group), cFr (ambient CO₂ <i>F</i>. <i>rhynchophylla</i> group), and eFr (elevated CO₂ <i>F</i>. <i>rhynchophylla</i> group).</p

Summary of the MANOVA results for the effect of elevated CO₂ on <i>Q</i>. <i>acutissima</i> and <i>F</i>. <i>rhynchophylla</i>.

<p>Summary of the MANOVA results for the effect of elevated CO₂ on <i>Q</i>. <i>acutissima</i> and <i>F</i>. <i>rhynchophylla</i>.</p