Mesic Soil Research Articles

Biotic homogenization of herb layer composition between two contrasting beech forest communities on limestone over 50 years

AbstractQuestionsHow do vegetation changes in a limestone beech forest community on dry and nutrient‐poor slopes differ from changes in a community on moist and nutrient‐rich soils over the past 50 yr? Have temporal changes led to a further differentiation between communities?LocationAncient, beech‐dominated forest region on limestone in central Germany.MethodsWe compared vegetation relevés sampled between 1955 and 1960 and resurveyed between 2009 and 2012 on quasi‐permanent plots in the Carici‐Fagetum primuletosum (n = 26) on dry, nutrient‐poor and sun‐exposed slopes, and in the Hordelymo‐Fagetum allietosum (n = 25) on nutrient‐rich plateau sites with mesic soils in spring. We concentrated on changes in species richness, vegetation structure and vegetation composition, identified winner and loser species and calculated pair‐wise dissimilarity indices within and between communities to test for differentiation or homogenization over time.ResultsOur results show a more pronounced change in community composition in the Carici‐Fagetum primuletosum within 50 yr compared to the Hordelymo‐Fagetum allietosum. Despite no significant increase in total canopy cover, shade‐tolerant, mesophilous, nutrient‐demanding species expanded, whereas light‐demanding, drought‐tolerant, oligotrophic, often Red List species decreased. Changes in the Hordelymo‐Fagetum allietosum were more random. Overall, vegetation dynamics led to a homogenization between the two contrasting communities caused by a loss of specialized species from the Carici‐Fagetum community and a gain in generalist species in both communities.ConclusionThe drastic changes in the Carici‐Fagetum community indicate the higher susceptibility of marginal sites – that often have a high conservation value – to local environmental changes. In particular, N deposition and the abandonment of former (more traditional) forest management, such as coppice‐with‐standards and wood pasture, are responsible for this development. On the other hand, the increasing temperatures from climate change are not sufficient to secure the survival of the once frequent thermophilous species. Therefore, adequate forest management and conservation measures, such as the removal of competitive or exotic tree species or the re‐establishment of coppice‐with‐standards management, are necessary to counteract the on‐going biotic homogenization of beech forest communities and should focus on marginal sites.

Temperature Sensitivity of Soil Greenhouse Gas Production in Three High‐Arctic Plant Community Types at Cape Bounty, Nunavut

Enhanced precipitation and higher temperatures are expected in the Arctic as the result of future climatic warming. To understand future contributions of high‐arctic ecosystems to the climate system, we need to understand the feedbacks between climate and greenhouse gas production, and how they might vary between plant community types distributed along soil moisture gradients. We incubated intact soil cores in the laboratory to explore the temperature sensitivity of soil greenhouse gas (CO2, CH4, N2O) production across the three main plant community types of Cape Bounty, Nunavut: polar desert, mesic tundra and wet sedge. Two sets of cores (0‐10 cm mineral soil) were incubated in the laboratory at 4, 8, and 12°C for one month. We also measured plant community differences in soil thermal regimes for one year. Mean field temperatures were highest in the polar desert during the summer months, while temperatures in the mesic tundra were lowest during this time. In the winter, soil temperatures were lowest in the polar desert and highest in the wet sedge communities. Initial incubation results demonstrate Q10 values for CO2 production ranging from 2.18 in wet sedge to 8.67 in polar desert soils. We observed a Q10 of 4.03 for CH4 output in mesic tundra soils and a Q10 of 16.42 for N2O output in wet sedge soils. Our results suggest that use of single Q10 values to predict future greenhouse gas emissions from high‐arctic ecosystems would likely underestimate the contribution of these ecosystems to the global climate system in a warmer climate.

An individual-based forest model links canopy dynamics and shade tolerances along a soil moisture gradient.

Understanding how forested ecosystems respond to climatic changes is a challenging problem as forest self-organization occurs simultaneously across multiple scales. Here, we explore the hypothesis that soil water availability shapes above-ground competition and gap dynamics, and ultimately alters the dominance of shade tolerant and intolerant species along the moisture gradient. We adapt a spatially explicit individual-based model with simultaneous crown and root competitions. Simulations show that the transition from xeric to mesic soils is accompanied by an increase in shade-tolerant species similar to the patterns documented in the North American forests. This transition is accompanied by a change from water to sunlight competitions, and happens at three successive stages: (i) mostly water-limited parkland, (ii) simultaneously water- and sunlight-limited closed canopy forests featuring a very sparse understory, and (iii) mostly sunlight-limited forests with a populated understory. This pattern is caused by contrasting successional dynamics that favour either shade-tolerant or shade-intolerant species, depending on soil moisture and understory density. This work demonstrates that forest patterns along environmental gradients can emerge from spatial competition without physiological trade-offs between shade and growth tolerance. Mechanistic understanding of population processes involved in the forest–parkland–desert transition will improve our ability to explain species distributions and predict forest responses to climatic changes.

Seed morphology and post-seminal development in species of Comanthera (Eriocaulaceae)

<p><em>Comanthera brasiliana</em>, <em>C</em>. <em>magnifica</em> y <em>C</em>. <em>suberosa</em> (Eriocaulaceae) forman parte de la lista de especies amenazadas de extinción en Brasil, debido a su alto grado de endemismo y a la recolecta indiscriminada. Estas tres especies junto con <em>C</em>. <em>brunnea</em> y <em>C</em>. <em>linearis</em> constituyen el clado de <em>Comanthera</em><strong> </strong><em>magnifica</em>. Se estudió la germinación, la morfología de semillas y el desarrollo post-seminal de las cinco especies, buscando caracterizar morfológica y anatómicamente las semillas y estadios posteriores a la germinación, así como generar datos que ayuden en la conservación de estas especies. Se recolectaron semillas maduras en los “campos rupestres” de Minas Gerais, Brasil. Fueron puestas a germinar cuatro repeticiones de 15 semillas para cada especie en cajas de Petri con papel filtro humedecido con agua destilada, a 25 ºC y luz fluorescente. Para el estudio morfológico de las semillas fue usado microscopía electrónica de barrido. Para la anatomía del desarrollo post-seminal, cada estado del desarrollo fue incluido en historresina, cortado con un micrótomo rotativo y analizado con microscopía de luz. Forma y tamaño de las semillas, así como las estructuras de la cubierta seminal permiten diferenciar las especies; a partir de estos caracteres desarrollamos una clave de identificación.<strong> </strong>Las semillas germinan en altos porcentajes (> 90 %) y rápidamente (< 7 días). La germinación ocurre a través de la protrusión del eje embrionario. Aproximadamente cuatro días después de germinar aparece la primera hoja, seguida por la raíz adventicia; después de 10-15 días se desarrollan la segunda hoja y nuevas raíces adventicias. En condiciones naturales estas especies habitan en suelos derivados de cuarcita y poseen semillas diminutas (tipo polvo) que germinan y se desarrollan rápidamente, incluso más rápido que en otras Eriocaulaceae de suelos mésicos. Estos datos pueden ayudar en la obtención de plántulas de las especies estudiadas, contribuyendo en la conservación de las mismas.</p><p><strong> </strong></p>

Flood Tolerance in Common Buckthorn (Rhamnus cathartica)

ABSTRACT: Rhamnus cathartica is a Eurasian shrub that has invaded woodland habitats of eastern North America. While historically known from more mesic habitats, it is often found in wetland habitats in Illinois, Minnesota, and Wisconsin, USA. This study assessed R. cathartica's growth, architecture, and biomass allocation across multiple flooding treatments representing a soil moisture gradient spanning upland (mesic soil moisture) to wetland habitats (saturated within 30 cm of the soil surface, periodic flooding, and permanently flooded conditions) for two age classes of saplings of R. cathartica. Our results on plant growth patterns under these treatments show that young R. cathartica saplings were able to tolerate saturated soil conditions, while old saplings were able to tolerate periodic flooding. Allocation of biomass to above- versus below-ground tissues showed that both young and old saplings have similar biomass allocation patterns in relation to soil moisture treatments. Collectively, our result...

Topology of tree–mycorrhizal fungus interaction networks in xeric and mesic Douglas‐fir forests

Summary From the phytocentric perspective, a mycorrhizal network (MN) is formed when the roots of two or more plants are colonized by the same fungal genet. MNs can be modelled as interaction networks with plants as nodes and fungal genets as links. The potential effects of MNs on facilitation or competition between plants are increasingly recognized, but their network topologies remain largely unknown. This information is needed to understand the ecological significance of MN functional traits. The objectives of this study were to describe the interaction network topologies of MNs formed between two ectomycorrhizal fungal species, Rhizopogon vesiculosus and R. vinicolor, and interior Douglas‐fir trees at the forest stand scale, identify factors leading to this structure and to contrast MN structures between forest plots with xeric versus mesic soil moisture regimes. Tuberculate mycorrhizas were sampled in six 10 × 10 m plots with either xeric or mesic soil moisture regimes. Microsatellite DNA markers were used to identify tree and fungal genotypes isolated from mycorrhizas and for comparison with reference tree boles above‐ground. In all six plots, trees and fungal genets were highly interconnected. Size asymmetries between different tree cohorts led to non‐random MN topologies, while differences in size and connectivity between Rhizopogon species‐specific subnetwork components contributed towards MN nestedness. Large mature trees acted as network hubs with a significantly higher node degree compared to smaller trees. MNs representing trees linked by R. vinicolor genets were mostly nested within larger, more highly connected R. vesiculosus‐linked MNs. Attributes of network nodes showed that hub trees were more important to MN topology on xeric than mesic sites, but the emergent structures of MNs were similar in the two soil moisture regimes. Synthesis. This study suggests MNs formed between interior Douglas‐fir trees and R. vesiculosus and R. vinicolor genets are resilient to the random loss of participants, and to soil water stress, but may be susceptible to the loss of large trees or fungal genets. Our results regarding the topology of MNs contribute to the understanding of forest stand dynamics and the resilience of forests to stress or disturbance.

Differential effects of contrasting phenotypes of a foundation legume shrub drive plant–plant interactions in a Mediterranean mountain

AbstractQuestionsAre variable effects of different phenotypes of foundation plant species on subordinates across contrasting habitat conditions (with varying stress and disturbance levels) due to either varying environmental conditions or heritable differences in traits between phenotypes? To evaluate the contribution of environmental effects we quantified the effects of contrasting phenotypes of a foundation legume shrub on their subordinate species across exposure (drought stress) and grazing conditions.LocationA sub‐alpine xerophytic community of western Mount Lebanon, Lebanon.MethodsFor two phenotypes of the spiny cushion shrub Onobrychis cornuta, a facilitative phenotype that occurs in concave topographies (mesic soil) and a competitive phenotype that occurs in convex topographies (xeric soil), we quantified cushion traits, environmental conditions and subordinate plant species abundances (within and outside the cushions) for the two phenotypes in northern (low stress) and southern (high stress) exposures, and with and without grazing. Relative interaction index (RII) for subordinate species richness and abundance was calculated in the eight treatment combinations and a correspondence analysis (CA) was conducted on species composition.ResultsDrought stress exacerbated phenotypic effects in southern exposure, with loose phenotypes being more facilitative and tight phenotypes more competitive than in northern exposure. This was related to both changes in cushion traits of the two phenotypes and to an increase in the pool of subordinate species sensitive to cushion effects. In contrast, grazing increased cushion positive effects of both phenotypes through the occurrence of indirect facilitation, with loose phenotypes becoming more facilitative and tight phenotypes less competitive. This was due both to changes in cushion traits of the two phenotypes and to their shared spiny phenotype limiting grazing effects.ConclusionsBecause increasing stress from northern to southern exposure did not increase competitive effects of either phenotype, and because the cessation of grazing did not cancel out differences in facilitative effects between phenotypes, neither drought stress nor grazing disturbance appeared to be the main drivers of the observed phenotypic effects on subordinate species across habitats. We conclude that differences in phenotypic effects of this legume shrub are very likely due to heritable differences in traits between phenotypes.

Late Pennsylvanian aridification on the southwestern margin of Gondwana (Paganzo Basin, NW Argentina): A regional expression of a global climate perturbation

Paleosols of the Paganzo Group preserve a shift from the cool climate of the glaciated high-latitudes of Gondwana to a long-term aridification punctuated by shorter-term fluctuations in moisture regime in the late Carboniferous. A quantitative reconstruction of paleoclimate inferred from the major element chemistry of paleosol horizons and the stable isotope geochemistry of soil-formed minerals and organic matter indicates that the climate varied substantially during deglaciation along the southwestern margin of Gondwana in the Middle Pennsylvanian including two geologically abrupt shifts to notably drier conditions. This dynamic climate terminates in a dry subhumid moisture regime characterized by steppe/dry scrub floral provinces. Quantitative estimates of net primary production during the post-glacial interval inferred from paleosol major element geochemistry are consistent with a mesic soil temperature regime, in agreement with paleotemperatures inferred from pedogenic goethite δD and δ18O. Contemporaneous aridification is well expressed in paleotropical continental records with Middle to Late Pennsylvanian aridification coincident with an abrupt evolutionary change in many marine and terrestrial species. The synchrony of aridification between the high and low paleo-latitudes and concomitant major restructuring of some ecosystems suggests that a paleoclimate change of global nature occurred during the Moscovian and Kasimovian.

Bacterial community composition of divergent soil habitats in a polar desert

Edaphic factors such as pH, organic matter, and salinity are often the most significant drivers of diversity patterns in soil bacterial communities. Desert ecosystems in particular are model locations for examining such relationships as food web complexity is low and the soil environment is biogeochemically heterogeneous. Here, we present the findings from a 16S rRNA gene sequencing approach used to observe the differences in diversity and community composition among three divergent soil habitats of the McMurdo Dry Valleys, Antarctica. Results show that alpha diversity is significantly lowered in high pH soils, which contain higher proportions of the phyla Acidobacteria and Actinobacteria, while mesic soils with higher soil organic carbon (and ammonium) content contain high proportions of Nitrospira, a nitrite-oxidizing bacteria. Taxonomic community resolution also had a significant impact on our conclusions, as pH was the primary predictor of phylum-level diversity, while moisture was the most significant predictor of diversity at the genus level. Predictive power also increased with increasing taxonomic resolution, suggesting a potential increase in niche-based drivers of bacterial community composition at such levels.

Simulating long-term effects of abandonment on plant diversity in Mediterranean mountain farmland

In this paper, long-term impacts of meadow abandonment scenarios on plant diversity were forecasted for high nature value farmland in northern Portugal, and implications for conservation planning and agri-environmental management are addressed. Vegetation patches representative of forests, meadows and edges, on mesic and wet soils, were surveyed for vascular plant diversity. Species richness and composition were compared across vegetation types, and additive partitioning was used to quantify hierarchic components of species richness. The implications of total and partial meadow abandonment were simulated according to landscape outcomes predicted for each scenario, and confirmed with a Monte-Carlo resampling. Forests hosted the highest number of species, as well as of exclusive species. Nonetheless, from the total pool (213), 21.6% were exclusive to meadows. Vegetation types generally shared small proportions of their species pools. With total meadow abandonment, a drastic decrease in total species richness (41.1%) and in endemic species richness (loss of 20.8%) was forecasted. However, only 12.3% of all species were forecasted to disappear under scenarios of partial abandonment. Landscape-level plant diversity can, therefore, be maintained by promoting farmland mosaics, even if the loss of scattered meadows in favour of native forests could be acceptable. Agri-environmental schemes should thus prioritize the maintenance of landscape heterogeneity.

Using functional diversity as an indicator of restoration success of a cut-over bog

A trait-based approach was used to evaluate the restoration success of a moss layer transfer technique on the herbaceous community of a cut-over bog. In order to understand the herbaceous dynamics following restoration, the bog was monitored prior to restoration and biannually over ten subsequent years, in two initial drainage conditions (dry peat fields and wet ditches), and compared to seven undisturbed bogs. Herbaceous community found prior to and in the early stage after restoration were characterized by species associated to mesic soil conditions with a fen-like pH, ruderal or wetland species, species with mycorrhiza or exotic species. These species did not persist in the latter stage after restoration and were replaced by species that are carnivorous, are associated to variable water availability and show mostly sexual reproduction. The extent of changes in traits composition of the herbaceous community between the early and latter stages after restoration showed the importance of multiple-year monitoring to evaluate restoration projects. The trait composition found in the latter stage after restoration appeared to converge toward the reference ecosystem where the community was characterized by species with large seeds, associated to humid soil conditions and a forest or peatland habitat. Lower trait diversity was found in the latter stage after restoration than in the reference ecosystem, especially in peat fields. In addition, species and functional diversity pattern varied with the initial drainage conditions, decreasing in peat fields while remaining stable in ditches. This suggests that different initial topography for restoration might help increase species and functional diversity of a managed ecosystem. Finally, our results outline measures to improve the moss layer transfer technique: sowing herbaceous species with large seeds in the latter stage after restoration, applying the restoration technique as soon as exploitation has terminated or removing all vegetation (including seeds and rhizomes) from the site to be restored.

Vertical partitioning between sister species of Rhizopogon fungi on mesic and xeric sites in an interior Douglas‐fir forest

Understanding ectomycorrhizal fungal (EMF) community structure is limited by a lack of taxonomic resolution and autecological information. Rhizopogon vesiculosus and Rhizopogon vinicolor (Basidiomycota) are morphologically and genetically related species. They are dominant members of interior Douglas-fir (Pseudotsuga menziesii var. glauca) EMF communities, but mechanisms leading to their coexistence are unknown. We investigated the microsite associations and foraging strategy of individual R.vesiculosus and R.vinicolor genets. Mycelia spatial patterns, pervasiveness and root colonization patterns of fungal genets were compared between Rhizopogon species and between xeric and mesic soil moisture regimes. Rhizopogon spp. mycelia were systematically excavated from the soil and identified using microsatellite DNA markers. Rhizopogon vesiculosus mycelia occurred at greater depth, were more spatially pervasive, and colonized more tree roots than R.vinicolor mycelia. Both species were frequently encountered in organic layers and between the interface of organic and mineral horizons. They were particularly abundant within microsites associated with soil moisture retention. The occurrence of R.vesiculosus shifted in the presence of R.vinicolor towards mineral soil horizons, where R.vinicolor was mostly absent. This suggests that competition and foraging strategy may contribute towards the vertical partitioning observed between these species. Rhizopogon vesiculosus and R.vinicolor mycelia systems occurred at greater mean depths and were more pervasive in mesic plots compared with xeric plots. The spatial continuity and number of trees colonized by genets of each species did not significantly differ between soil moisture regimes.

Diversity and distribution of ammonia-oxidizing Archaea in the seasonally frozen soils in Northeastern China

The genetic diversity and distribution of ammonia-oxidizing Archaea (AOA) in nine seasonally frozen soils sampled around the city of Harbin, China, is analyzed based on archaeal amoA gene. Soil samples are divided into four groups by its properties: fertilized/unfertilized mesic (well-balanced supply of moisture) soils and fertilized/unfertilized hydric (abundant of moisture) soils. Clone libraries based on AOA amoA gene polymerase chain reaction products are constructed, and the phylogenetic analysis at 5% cutoff level shows that AOA members mainly belong to the soil/sediment lineage which includes four clusters, and very few archaeal amoA gene sequences fall into the marine lineage. The four groups of soils have different archaeal amoA gene assemblage, and the available nitrogen and organic carbon are significantly correlated with diversity indexes. The result shows that long-term artificial amendment such as fertilization and agriculture cultivation has an important impact on AOA community shift in terrestrial environment. Moisture may drive the shape of different AOA communities by changing the aerobic environment into anaerobic. Soil composition is another noticeable factor effect AOA community, which can help the shape of a special AOA community with only two species.

Why does land-use history facilitate non-native plant invasion? A field experiment with Celastrus orbiculatus in the southern Appalachians

Although historic land use is often impli- cated in non-native plant invasion of forests, little is known about how land-use legacies might actually facilitate invasion. We conducted a 2-year field seeding experiment in western North Carolina, USA, to compare germination and first-year seedling sur- vival of Celastrus orbiculatus Thunb. in stands that had been cultivated and abandoned a century earlier and were dominated by tulip poplar (Liriodendron tulipifera L.), and in paired stands that had never been cultivated and were dominated by oaks (Quercus spp.). Experiments were conducted at five sites with paired tulip poplar and oak stands by varying litter mass (none, low, or high) and litter type (tulip poplar or oak). We also performed reciprocal soil translocations using pots seeded with C. orbiculatus. Soil moisture and temper- ature were measured throughout the growing season. Germination and survival were highest in the tulip poplar stands. Germination was also higher in plots with low litter mass. Seedling survival was highest in plots with low litter mass or no litter. Soil moisture was higher in tulip poplar stands and under low-mass litter. Differences in germination and survival among the potted plants were minimal, suggesting that soil type and ambient site conditions were less important than litter conditions for C. orbiculatus establishment. Our results suggest that the low litter mass and mesic soil conditions that are characteristic of tulip poplar stands may confer higher invasibility and explain the higher abundance of C. orbiculatus in areas with successional overstory communities associated with historically cultivated forests.

Local versus regional processes: can soil characteristics overcome climate and fire regimes by modifying vegetation trajectories?

AbstractWe analysed charcoal and pollen from sediments obtained from two lakes in the northwestern mixed‐wood Canadian boreal forest in order to reconstruct fire‐return intervals and vegetation dynamics over the last 8000 years. Sites were selected with contrasting soil properties (mesic versus dry‐sandy soils), allowing an estimation of the potential influence of soils on long‐term vegetation and fire dynamics. The sites likely experienced fewer fires during the period extending from 8000 to 4000 cal. a BP than over the last 4000 years. At both sites, eastern white pine (Pinus strobus) populations were most extensive shortly after deglaciation, with vegetation later shifting towards mixed woodlands with less P. strobus and more extensive Picea and Pinus banksiana populations. This gradual vegetation shift was probably induced by the establishment of colder and moister conditions along with a fire‐regime change. In spite of the parallel long‐term vegetation trajectories, vegetation composition differed between the two sites in both the past and present. Whereas Picea was more abundant at the mesic site, the fire‐adapted P. banksiana populations were more extensive at the sandy‐soil site. These differences in vegetation composition indicate that, in addition to climate changes and fire occurrence, soil properties also influenced vegetation dynamics. A likely increase in fire frequency in the Canadian boreal forest during the 21st century might therefore favour the expansion of these two disturbance‐adapted trees with spatial heterogeneity in the populations due to varying soil types. Copyright © 2012 John Wiley & Sons, Ltd.

Soil formation in loess-derived soils along a subhumid to humid climate gradient, Northeastern Iran

In order to contribute to the understanding of carbonate enrichment and clay illuviation in loess-derived soils of subhumid to humid regions, the development of soils was studied along a climate gradient with xeric and udic soil moisture regimes (SMR) and thermic and mesic soil temperature regimes (STR), respectively, in the Golestan Province, Northeastern Iran. Six representative pedons along a climate gradient were investigated. Soils were classified mainly as Hapludalfs and Haploxeralfs. Stability of the geomorphic surface under forest vegetation associated with high leaching conditions has provided appropriate conditions for decalcification followed by clay migration through the profile and formation of argillic horizons in all the studied soils. Clay content of the Bt horizons, soil organic carbon concentration of the A horizons, and depth of the Bk horizons increased significantly with increasing precipitation and decreasing temperature. There was a considerable decrease in silt content with soil development. The main pedofeatures observed in the Bt horizons were clay coatings and decalcified zones. Nodules, coatings and hypocoatings were the main calcitic pedofeatures observed in the Bk horizons. Occurrence and preservation of clay coatings were more pronounced in the udic regions with illite and vermiculite as the dominant clay minerals. Type of clay minerals, shrink/swell properties, and precipitation rate are factors affecting the abundance and preservation of clay coatings. In the strongly developed horizons of the udic SMR, the occurrence of vermiculite clay minerals could reduce the shrink/swell potential and increase the amount of clay coatings. The presence of crystallitic b-fabrics and the high carbonate contents (CaCO3) in the lower horizons (Bk) were mainly related to decalcification processes under descending water flow in the overlying horizons.

High species richness in hemiboreal forests of the northern Russian Altai, southern Siberia

AbstractQuestionsWe discovered forests with very high local numbers of vascular plant species in southern Siberia. Are these the most species‐rich forests of the Eurasian boreal and temperate zones, and which factors cause such high species richness?LocationAltai Mountains in southern Siberia, Altai Republic, Russia.MethodsWe sampled vegetation and measured environmental variables across the Altai Mountains in plots of 100 m2 and established series of nested plots of the size from 1 to 1000 m2 at sites with the highest species richness. We compared the richest forests with other forests of the Altai and with literature records of species‐rich vegetation types from elsewhere.ResultsThe richest forests contained 45 vascular plant species per 1 m2, 82 per 10 m2, 114 per 100 m2 and 149 per 1000 m2. They are open hemiboreal forests dominated by Pinus sylvestris, with an admixture of Betula pendula, and sparse shrub and moss layers. About 95% of their vascular plant species are in the herb layer. All species are native. These forests occur in a forest‐steppe landscape of the northern Altai, where the mean January temperature is between –12.5 and –10 °C, mean July temperature is 16–18 °C, and total annual precipitation is 560–610 mm. Soils are deep and mesic, with a pH of 6.2–6.4.ConclusionsHemiboreal forests of the northern Russian Altai are probably the most species‐rich forests in boreal and temperate Eurasia. Such a high concentration of many species in small plots probably results from the incidental combination of several factors conducive to high species richness. These factors include the rich regional flora of the Altai Mountains, stability of the environment of this region since the Pleistocene, heterogeneity of the mountainous forest‐steppe landscape with a combination of forested areas on north‐facing slopes and steppes on south‐facing ones, an open canopy that ameliorates microclimate conditions but does not exclude light‐demanding species through strong shading, a macroclimate that is not too harsh, mesic soils with near‐neutral pH, and limited competition within the herb layer.

하성평탄지 토양인 청원통의 분류 및 생성

하성평탄지에 분포하는 토양으로 Inceptisols인 Fluvaqentic Epiaquepts로 분류되고 있는 청원통을 재분류하고, 그 생성을 구명하기 위하여 청원통 대표단면의 형태적 특성을 조사하고, Soil Taxonomy의 표준 분석방법인 Soil survey laboratory methods manual에 따라서 토양을 분석하여 Laboratory data sheets를 작성하였다. Ap층 (0~18 cm)은 암회갈색 (2.5Y 4/2)의 미사질양토이고, BA층 (18~30 cm)은 암회갈색 (2.5Y 4/2)의 미사질양토, Bt1층 (30~60 cm)은 암황갈색 (10YR 4/6)의 미사질양토, Bt2층 (60-91 cm)은 진갈색 (7.5YR 4/6)의 미사질식양토, BC층 (91~104 cm)은 갈색 (10YR 4/4)의 미사질양토, C층 (104~160 cm)은 잡색 (7.5YR 4/6, 7.5YR 5/2)의 미사질양토이다. 하성평탄지 충적층을 모재로 하는 토양으로 주로 논으로 이용되고 있다. udic 토양수분상과 mesic 토양온도상을 보유하며, 배수 약간양호하다. 청원통은 0~18 cm 깊이에서 ochric 감식표층을 보유하고, 30~91 cm 깊이에서 점토집적층인 argillic층을 보유하고 있다. 또한 argillic층의 상부경계에서 125 cm 아래 깊이인 155 cm 깊이에서의 염기포화도 (양이온 합)가 63.9%로 35% 이상이다. 따라서 청원통은 Inceptisols이 아니라 Alfisols로 분류되어야 한다. 청원통은 토양표면에서 50 cm 이내 깊이의 1개 이상의 층위에서 aquic 조건을 보유하고, 25~40 cm 깊이의 모든 층위에서 산화환원성인을 보유하고 있으나, argillic층의 상부 12.5 cm 깊이에서는 이러한 조건을 충족시키지 못하고 있으므로 Aqualfs가 아니라 Udalfs 아목으로 분류할 수 있다. natric층, glossic층, fragipan 등을 보유하지 않으며 Hapludalfs의 분류기준을 충족시키고 있다. 논토양으로 토양 표면에서 30 cm 깊이까지만 회색화 되어 있는 anthraquic 조건을 보유하고 있으므로 아군은 Anthraquic Hapludalfs의 분류할 수 있다. 토성속 제어부위에서의 토성속이 미사식양질이고, 토양온도상이 mesic 온도상이기 때문에 청원통은 Fine silty, mixed, nonacid, mesic family of Fluvaquentic Epiaquepts가 아니라 Fine silty, mixed, mesic family of Aeric Epiaqualfs로 분류되어야 한다. 청원통이 제4기 신층인 충적세 (Holocene)의 퇴적물에 의하여 형성된 하성충적층을 모재로 하고 있으면서도 점토집적층인 argillic층을 보유하는 토양으로 생성 발달한 것은 과거 어느 시기에 충적이 일어난 후 비교적 오랫동안 새로운 충적물이 별로 퇴적되지 않은 비교적 안정한 지형에 분포하고 있기 때문이라고 생각된다. 특히 벼 재배기간 동안 담수되어 있기 때문에 점토의 이동과 집적이 빠른 속도로 일어나 토양 발달이 빠른 속도로 진행되었을 뿐만 아니라 Ca, Mg, K, Na 등의 염기의 하향 이동도 계속적으로 일어나 argillic층 상부경계에서 125 cm 아래 깊이까지도 이들 염기성분이 집적되고 있을 것이다. 따라서 청원통이 Inceptisols이 아니라 Alfisols로 생성 발달한 것이라고 생각된다. This study was conducted to reclassify Cheongweon series based on the second edition of Soil Taxonomy and to discuss the formation of Cheongweon series distributed on broad continental alluvial plains. Morphological properties of typifying pedon of Cheongweon series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Cheongweon series has dark grayish brown (2.5Y 4/2) silt loam Ap horizon (0~18 cm), dark grayish brown (2.5Y 4/2) silt loam BA horizon (18~30 cm), dark yellowish brown (10YR 4/6) silty clay loam Bt1 horizon (30~60 cm), strong brown (7.5YR 4/6) silty clay loam Bt2 horizon (60~91 cm), brown (10YR 4/4) silt loam BC horizon (91~104 cm), and mottled (7.5YR 4/6, and 7.5YR 5/2) silt loam C horizon (104~160 cm). The typifying pedon has an argillic horizon from a depth of 30 to 91 cm and a base saturation (sum of cations) of 35% or more at 125 cm below the upper boundary of the argillic horizon. It can be classified as Alfisol, not as Incceptisol. It has udic soil moisture regime, and can be classified as Udalf. Also that meets the requirements of Hapluadalf. It has anthraquic condition, and keys out as Anthraquic Hapludalf. That has fine silty textural family, and has mesic soil temperature regime. Therefore Cheongweon series can be classified as fine silty, mixed, mesic family of Anthraquic Hapludalfs, not as fine silty, mixed, mesic family of Fluvaquentic Epiaquepts.

구릉지 토양인 아산통의 분류 및 생성

Soil Taxonomy 분류체계 변화에 대응하여 구릉지에 널리 분포하는 토양으로 Inceptisols인 Typic Dystrudepts로 분류되고 있는 아산통을 재분류하고, 그 생성을 구명하기 위하여 아산통 대표단면의 형태적 특성을 조사하고, Soil Taxonomy의 표준 분석방법인 Soil survey laboratory methods manual에 따라서 토양을 분석하여 Laboratory data sheets를 작성하였다. A층 (0~18 cm)은 암황갈색 (10YR 4/4)의 자갈이 있는 양토이고, BA층 (18~30 cm)은 진갈색 (7.5YR 5/6)의 자갈이 있는 양토, Bt1층 (30~52 cm)은 적색 (2.5YR 4/6)의 자갈이 있는 식양토, Bt2층 (52~98 cm)은 적색 (2.5YR 4/8)의 자갈이 있는 식양토, C층 (98~160 cm)은 적색 (2.5YR 4/8)의 자갈이 있는 양토이다. 구릉지 잔적층을 모재로 하는 토양으로 주로 임지로 이용되고 있다. udic 토양수분상과 mesic 토양온도상을 보유하며, 배수 양호하다. 아산통은 0~18 cm 깊이에 ochric 감식표층을 보유하고, 30~98 cm 깊이에서 점토집적층인 argillic층을 보유하고 있다. 또한 argillic층 상부경계에서 125 cm 아래 깊이인 155 cm 깊이에서의 염기포화도 (양이온 합)가 7.8%로 35% 미만이다. 따라서 아산통은 Inceptisols이 아니라 Ultisols로 분류되어야 한다. 아산통은 udic 토양수분상을 보유하고 있으므로 Udults로 분류할 수 있으며, Hapludults의 분류기준을 충족시키고 있다. Typic Hapludults의 분류기준을 충족시키고 있으며, 토성속 제어부위에서의 토성속이 식양질이고, 토양온도상이 mesic 온도상이기 때문에 아산통은 Fine Loamy, mesic family of Typic Dystrudepts가 아니라 Fine loamy, mesic family of Typic Hapludults로 재분류되어야 한다. 아산통은 경사가 비교적 완만하여 지형이 안정되어 있는 구릉지에 분포하고 있으므로 침식이 일어나는 것에 비하여 토양수의 하향이동에 따른 점토집적작용과 염기용탈작용이 우선되고 있다. 그 결과 점토집적층인 argillic층을 보유하는 토양으로 생성 발달되었다. 또한 Alfisols과 Ultisols을 구분하는 가장 기본적인 분류기준인 기준깊이에서의 염기포화도 (양이온 합)가 35% 미만으로서 Alfisols이 아니라 강산성 토양인 Ultisols로 발달하였다. This study was conducted to reclassify Asan series based on the second edition of Soil Taxonomy and to discuss the formation of Asan series distributed on the rolling to hilly areas. Morphological properties of typifying pedon of Asan series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Asan series has dark yellowish brown (10YR 4/4) gravelly loam Ap horizon (0-18 cm), strong brown (7.5YR 5/6) gravelly clay loam BA horizon (18-30 cm), red (2.5YR 4/6) gravelly clay loam Bt1 horizon (30-52 cm), red (2.5YR 4/8) gravelly clay loam Bt2 horizon (52-98 cm), and red (2.5YR 4/8) gravelly clay loam C horizon (98-160 cm). The typifying pedon has an argillic horizon from a depth of 30 to 98 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. It can be classified as Ultisol, not as Inceptisol. It has udic soil moisture regime, and can be classified as Udult. Also that meets the requirements of Typic Hapludults. It has 18-35% clay at the particle-size control section, and has mesic soil temperature regime. Therefore Asan series can be classified as fine loamy, mesic family of Typic Hapludults, not as fine loamy, mesic family of Typic Dystrudepts. Asan series occur on rolling to hilly areas in residual materials derived from granite gneiss, schist, and gneiss rocks. They are developed as Ultisols with clay mineral weathering, translocation of clays to accumulate in an argillic horizon, and leaching of base-forming cations from the profile for relatively long periods under humid and temperate climates in Korea.

Impacts of Fire and Invasive Species on Desert Soil Ecology

A review of literature shows that both fire and invasive species may cause changes in biological, chemical, and physical properties of desert soils . Although soil may recover from the impacts of fire during succession, these changes are permanent under persistent invasive species. The most severe effects of fire occur under high temperatures with high fuel buildup and soil moisture that conducts heat downward. Deserts typically have low fuel mass and low soil moisture, both conditions that would contribute to lower impacts of fire than in mesic soils. Soil is a good insulator , so soil microorganisms will survive a few centimeters deep even in hot surface fires. Immediately postfire there is often an increase in mineral nitrogen (N) and a decrease in soil carbon (C) and organic N, but these changes are often minimal in desert soils, except under fertile shrub islands that have higher fuel loads and fire temperature. Both hot and cold deserts have experienced slow recovery of native shrubs and increased growth of invasive grasses following fire. Invasive species may either increase or decrease soil N and C depending on fire temperature and site and species characteristics. Mineralization and fixation of N are often high enough after fire that subsequent productivity balances N losses. The elimination of islands of fertility coupled with postfire erosion may be a major impact after fire in grass-invaded shrub lands. In the long term, the interaction of fire and invasive species may result in more frequent fires that eliminate fertile islands and reduce the productivity of deserts. Managers may use fire as a tool to control desert invasives without the concern that N will be irrevocably lost, but this must be done judiciously to avoid eliminating shrubs and further increasing invasive species. La revisión de literatura demuestra que tanto el fuego como las especies invasoras pueden causar cambios en las propiedades biológicas, químicas y físicas de los suelos del desierto. Mientras que el suelo puede recuperarse del impacto del fuego durante la sucesión, las especies invasoras producen cambios permanentes. Los efectos más severos del fuego ocurren bajo temperaturas altas con una alta acumulación de combustible y con una humedad del suelo que conduce el calor hacia abajo. Los desiertos tienen típicamente una humedad y masa de combustible baja, ambas condiciones podrían contribuir a un menor impacto del fuego en suelos mésicos. El suelo es un buen aislador, así que los microorganismos del suelo pueden sobrevivir a pocos cm de profundidad incluso en fuegos superficiales calientes. A menudo, inmediatamente después del fuego hay un incremento en nitrógeno mineral (N) y una disminución en el carbón del suelo (C) y N orgánico, pero estos cambios son a menudo mínimos en los suelos del desierto, con excepción de debajo de los arbustos en las islas fértiles que tienen cargas de combustibles y temperaturas más altas. Tanto los desiertos calientes como los desiertos fríos han experimentado una recuperación muy lenta de arbustos nativos y un incremento en el crecimiento de gramíneas invasivas después de los fuegos. Las especies invasivas pueden incrementar o disminuir el N y el C del suelo dependiendo de la temperatura del fuego, así como las características de las especies y del sitio. La mineralización y la fijación del N son a menudo bastante altos después del fuego que la productividad subsecuente estabiliza las pérdidas de N. La eliminación de las islas de fertilidad unida con la erosión después del fuego puede ser un impacto importante después del fuego en pastizales invadidos por arbustivas. A largo plazo la interacción del fuego y las especies invasivas puede dar lugar a fuegos más frecuentes que eliminen las islas fértiles y reduzcan la productividad de los desiertos. Los manejadores del recurso pueden utilizar fuego como una herramienta para controlar las especies invasivas del desierto sin la preocupación que la pérdida del N sea para siempre, pero esto puede hacerse cautelosamente evitando la eliminación de los arbustos y fomentando un incremento en las especies invasoras.