Teucrio chamaedrys-Festucetum rupicolae,eine neue Assoziation aus dem Gebiet des Mährischen Karstes

A new associationTeucrio chamaedrys-Festucetum rupicolae, the origin and development of which are due to specific soil relations on lapiés as well as to the character of human activity (deforestation, grazing) in the localities or in their close vicinity, was described from the lapiés slopes in the Moravian Karst. The species composition of the phytocoenoses of the association and of the two newly described subassociations (-sedetosum,-typicum) is shown in the phytocoenological table. Due attention is given to the synmorphology, synecology, synchorology, and syngenesis of these units.     

The halophilous vegetation of the Orumieh lake salt marshes,NW. Iran

The halophilous vegetation of the Orumieh lake salt marshes has been studied, using the Braun-Blanquet method. Vegetation types have been defined by physiognomic-floristic system. The following six main groups of communities are recognized: (1) Semi-woody shrub and perennial halophytic communities (Class Halocnemetea strobilacei) including 6 associations and 5 subassociations, (2) Annual halophytic communities (Class Thero-Salicornietea) including 5 associations and 1 subassociation, (3) Salt marsh brushwood communities (Class Tamaricetea) including 4 associations, (4) Rush and herbaceous perennial halophytic communities (Class Juncetea maritimi) including 7 associations and 1 subassociation, (5) Rush and herbaceous perennial halotolerant communities (Class Agrostietea stoloniferae) including 5 associations, (6) Hydrophilous halotolerant communities (Class Phragmitetea) including 3 associations and 2 subassociations. The soil of these communities has been analysed and their habitats are described and discussed.     

Forest communities of the northern whitefish range, rocky mountains, Montana, U.S.A.

The montane and subalpine forests of a mountain range in northwestern Montana were investigated using phytosociological and numerical methods. Twelve associations and two subassociations were identified, of which eight are described here for the first time. The forest vegetation of valleys and lower slopes is strongly affected by repeated fire and is placed in the new orderCalamagrostio-Pseudotsugetalia glaucae, which includes temperate, low elevation forests in inland regions of northwestern North America. These forests bear only weak resemblance to forests traditionally assigned to the classVaccinio-Piceetea, and occupy the habitats filled by broad-leaved forests elsewhere at temperate latitudes. Montane and subalpine forest vegetation is moister and has longer snow duration and a shorter growing season. Upper montane vegetation more closely resembles that of other temperate montane forests of the classVaccinio-Piceetea.     

The vegetation of the Puna Belt at laguna de Pozuelos Biosphere Reserve in northwest Argentina

The presence of species and their cover values together with soil and topographic characteristics were recorded at 40 sites along an altitudinal gradient of the Puna Belt at Pozuelos, in the High Andes in northwest Argentina. Classification and ordination of plant assemblages showed that soil and topography were the best predictors of the variation in species distribution. The different plant assemblages which occur along the topographic gradient follow the geographic variation in rainfall in this Andean region. Perennial bushes and grasses colonize the plains and slopes with fine textured soils which retain their water content. In contrast, deciduous bushes and cactuses grow on steep, rocky, dry slopes. Open woods also occur on east-facing steep, rocky slopes which are sheltered from winds.     

The impact of ski slopes management on Krvavec ski resort (Slovenia) on hydrological functions of soils

The study was performed on the ski resort Krvavec, which is one of the most frequented ski resorts in Slovenia. The ski slopes serve as pastures for cattle during summer time and range from 1500 to 2000 m a.s.l., which is at or above the upper timberline. To offer a longer ski season and to profit snow better (either natural or artificial one) the slopes have been levelled and consequently the soil profile has been changed. Such altered soil profile characteristics strongly impact hydrological functions of soils. To study these impacts, five plots (20 × 20 m) have been chosen on the slopes with a different history: pasture without any amelioration work, a patch of forest in the ski resort without any ameliorations, and three plots with different intensity of amelioration. Dynamics of soil water content on each plot has been determined by measuring soil water content in-situ with portable TDR system during several days after long lasting heavy rains. Statistically significant differences were shown in soil water content between the plots after the rain, although some differences between plots have disappeared in the following days.     

Leaf silicon content in banana (Musa spp.) reveals the weathering stage of volcanic ash soils in Guadeloupe

Several plant species accumulate silicon, which is taken up by roots in soil solution. The Si concentration in soil solution can be governed by silicate dissolution and formation, and thus soil constitution. Here, we study the Si leaf content of mature banana plants (Musa acuminata cv Grande Naine) cropped on soils derived from andesitic ash in Guadeloupe through standard foliar analysis. The soils strongly differ in weathering stage and total Si content. The most desilicated soils (Andosol–Nitisol–Ferralsol) occur in the wettest areas, on the Eastern slopes (Es) of the volcano exposed to rain bearing winds. Least weathered soils (Andosol–Cambisol) occur on Western slopes (Ws). The average leaf Si concentration ranges from 2.7 to 3.9 g kg^?1 for bananas cropped in Es soils, and from 7.7 to 9.6 g kg^?1 in Ws soils. The leaf Si concentrations are lowest for the Es gibbsite-rich Andosols and Ferralsols. The leaf Si concentration is positively correlated with soil CaCl₂-extractable Si content, soil Si content and total reserve in weatherable minerals. The silicon content of banana leaves thus reveals the weathering stage of volcanic ash soils in Guadeloupe.     

Mycocoenologic study of the macrofungi on the forest of Jbel elbir (Aïn Draham,Jendouba, Tunisia)

Macrofungi have important functions in forest ecosystems. It is essential to have information about these species to ensure proper management of such ecosystems. Due to the importance of forestry in Tunisia and the lack of information on fungal communities, this study was conducted in North Western of Tunisia. The objective was to enumerate macrofungal diversity in relation to various environmental factors. In total, 158 fruiting bodies were collected and 60 species were identified. Among them, 39 species are mycorrhizal. A fruiting body is the first visible appearance of the spore‐bearing surface until its disintegration. More fruiting bodies were found on the eastern slopes than on the western slopes. This reflects the distribution of tree species and soil type. Almost all fungal species were collected from soils of moderate acidity (pH 4–pH 5), 5 species from soils with low acidity (pH 5–pH 6.8), and only 3 species from soils with high acidity (pH < 4). The majority of fruiting bodies occurred in soils with a percentage of organic matter ranging from 1 to 5 and a phosphorus content ranging from 15.1 to 20 ppm.     

Plant community patterns in old embanked grasslands and the survival of halophytic flora

The presence of a halophytic and sub-halophytic flora in grasslands reclaimed from the sea several centuries ago on the west Atlantic coast in France appears very unusual and the reasons for its survival are still uncertain. Our objective is to document its distribution pattern and to investigate whether its persistence is related to abiotic conditions and/or management practices. Vegetation surveys were carried out in seven different sites with 26 relevés on grazed sites (15 on slopes and 10 on flats) and 11 on mown sites (six on slopes and five on flats).This flora shows some important similarity with the vegetation of recent polders and can be classified into groups of species differing by their degree of salt tolerance but also their response to management mode. It was found that halophytes are only present on very saline soils, in a situation where the level of competition with more competitive species is reduced. The sub-halophytes also required low competition on lower soil salinity. In old polders, these two groups only occurred on grazed slopes and declined or even disappeared in the absence of grazing. In exclosures, the community became strongly dominated by competitive species and the soil salinity decreased on the slopes. The maintenance of sub-halophytes in old polders seems to be mainly conditioned by competition limitation whereas halophytes showed also a strong dependency to soil salt level, two requirements, which are met on continuously grazed slopes. Grazing maintains inter-specific competition at a low level while trampling increases soil compaction. Soil compaction modifies water and salt circulation, which could explain the high level of soil conductivity observed on grazed slopes.     

Modeling water content of a vineyard soil in the Douro Region,Portugal

The soil moisture of a vineyard soil under two different plantation systems, bench terrace and straight down the slope (German system), was measured weekly from 1991 to 1997 in the Demarcated Region of Douro – the Port wine producing region in Portugal. The soils of the region are extremely stony, located on steep slopes along narrow valleys. These conditions complicate the study of soil water relations with deterministic functions. We fitted a large data set to stochastic models, with the objectives of (a) determining which stochastic model best forecasts soil moisture in various planting systems, (b) based on chosen models, objectively evaluate variation of soil moisture in each planting system, and (c) finding an objective factor on which to base management decisions. Soil moisture variation was best represented by a time frequency model (Fourier series). Soil under straight down the slope plantation had significantly higher water reserves for most of the year than bench terrace plantation but the difference was not high enough to drive a significant shift on production and fundamentally affect the choice of which system to choose for new plantations. The model-generated data suggested a superficial and subsuperficial downflow of water from upper slopes in the straight plantation relative to bench terraces. However, the model failed to shed additional information on the mechanisms related to soil water balance. Data generated by the time frequency model might prove useful for other management decisions such as schedule and intensity of topping and pesticide application.     

Topographic and climatic controls on soil respiration in six temperate mixed-hardwood forest slopes, Korea

To better understand the effects of local topography and climate on soil respiration, we conducted field measurements and soil incubation experiments to investigate various factors influencing spatial and temporal variations in soil respiration for six mixed‐hardwood forest slopes in the midst of the Korean Peninsula. Soil respiration and soil water content (SWC) were significantly greater (P=0.09 and 0.003, respectively) on north‐facing slopes compared to south‐facing slopes, while soil temperature was not significantly different between slopes (P>0.5). At all sites, soil temperature was the primary factor driving temporal variations in soil respiration (r²=0.84–0.96) followed by SWC, which accounted for 30% of soil respiration spatial and temporal variability. Results from both field measurements and incubation experiments indicate that variations in soil respiration due to aspect can be explained by a convex‐shaped function relating SWC to normalized soil respiration rates. Annual soil respiration estimates (1070–1246 g C m^?2 yr^?1) were not closely related to mean annual air temperatures among sites from different climate regimes. When soils from each site were incubated at similar temperatures in a laboratory, respiration rates for mineral soils from wetter and cooler sites were significantly higher than those for the drier and warmer sites (n=4, P<0.01). Our results indicate that the application of standard temperature‐based Q₁₀ models to estimate soil respiration rates for larger geographic areas covering different aspects or climatic regimes are not adequate unless other factors, such as SWC and total soil nitrogen, are considered in addition to soil temperature.     

The association of tree species,landform, soils and erosion on Narrabeen sandstone west of Putty,New South Wales

An exploratory study was made of the tree species, landform, soils and erosional sequence along altitudinal transects from interfluve to stream channel in a valley incised into Narrabeen Group sandstones and shales to the west of Putty, NSW. Four groups of soils with similar edaphic features were identified. These ranged from duplex soils on the apparently old and stable valley rim, through eroded earths on zones of depletion and sandy regoliths with thick surface horizons on zones of accumulation, to mature duplex soils with thick surface horizons on the colluvial toeslopes. Four communities of tree species were found associated with the four groups of soils. A Eucalyptus punctata –E. piperita open-forest was found on the stable valley rim and a related Eucalyptus punctata –E. piperita – E. oblonga open-forest to low woodland was found on zones of depletion. An Angophora costata open-forest was found associated with the sandy regoliths on zones of accumulation and a Eucalyptus viminalis – E. tereticornis open-forest to tall open-forest occurred on thick soils of the colluvial waning slopes. It was found that the landform fitted a hypothetical nine unit land surface model. The soil types and plant communities were found to reflect the dominant contemporary pedogenetic and geomorphic processes which are also used to define the units of this model. Erosion was evident in the catchment, and the sequence of alluvial soils on the valley floor was found to be consistent with previous suggestions of widespread slope instability during the Quaternary period. Speculation is offered about the effects of management of the valley, especially in terms of land surface instability.     

Effect of landscape position on the acidification of loess‐derived soils under Pinus radiata

Abstract Interactions between landscape position and the acidifying effect of trees planted into loess‐derived grassland soils were studied in the Ventana region of Argentina. Forests of Pinus radiata planted at the end of 1940, were selected in two different positions from the landscape, plains and slopes. Samples of the soil surface mineral horizon were taken from landscape positions at four distances from the trees and compared with grassland soils. The values of the main soil chemical properties changed significantly with distance from trees, with a decrease in pH, base saturation, exchangeable Ca²⁺, Mg²⁺ and K⁺, and increase in Na⁺, Al³⁺ and particularly H⁺ closer to the trees. This pattern confirms the prominent role of vegetation in bringing about changes in soil properties. Regression models showed high levels of explanation (r² > 0.85) indicating that a high percentage of the spatial variability of soil chemical properties is systematic and predictable with distance from the trees. The pH in KCl proved an excellent tool for predicting the cationic composition of soils. Organic carbon and total nitrogen were significantly higher in the plains positions than in the slopes under the trees, whereas there was no difference under grassland. The slopes of the regression lines indicated that acidification is more intense in soils on the plains. Vegetation was the main factor influencing acidification of the studied soils. The landscape position regulates the bio‐hydrological factor and thus the speed of acidification process.     

The ecology of granite outcrops at Wilson's Promontory,Victoria

Rock outcrops on spurs and summits on Wilson's Promontory tend to be more prevalent on hot dry slopes than cool moist ones. In this comparatively moist climate, the rock outcrop vegetation can be grouped into high altitude, low altitude and coastal types. The surrounding rock-heath is characterized below 400–500 m by Kunzea ambigua and above this altitude by Callistemon pallidus. Moss aprons of Campylopus bicolor on rock faces are often held in place by roots of surrounding shrubs on slopes up to 20°. Bryophyte and lichen communities vary with altitude, and annuals and geophytes are common. Fire may result in retrogression if forests and shrub zones are destroyed and humic top soil burnt or eroded away. Fossil root-grooves occur in granite on the summit of Mt Latrobe and are the legacy of a cloud forest of Nothofagus cunninghamii. The rock-heath species are more drought resistant than the‘climax’tree species and may develop very low water potentials. The rate of succession may be correlated with the highly variable rate of decay of each individual block of granite. The soils of the early successional stages are veneers of humic sands enriched with hill-wash, whilst the soils of the forest stages vary from duplex podzols to gradational podzolic soils of much greater moisture storage. Woody plant establishment is mostly initiated along rock joints: the rock surfaces and boulders so by-passed are colonized by more mesic species. Many zonations appear to be static since advances are cancelled by retreats. The rate of succession on bare granite is controlled by local climate, altitude, slope, fire and macro-and micro-jointing patterns. In general, the early stages bear strong similarities over a relatively wide range of climate. The so-called climaxes which have developed represent a continuum in response to the complex environments found on Wilson's Promontory.     

The desert vegetation of El Pinacate,Sonora, Mexico

The Pinacate region is part of the Gran Desierto, one of the driest deserts in North America. The presence-absence of perennial plant species, together with soil and landform characteristics, were registered in 110 sampling sites within this region. A classification and ordination of plant communities showed soil and landform units to be good predictors of plant variation. Plant distribution and species richness were also strongly related to altitude and rockiness. A Generalised Linear Model was used to fit the response curves of individual species.The environmental factors related with plant distribution are indicators of the water regime within a given site. Plant communities repeat along topographic gradients the large-scale biogeographic variation of the Sonoran Desert. Microphyllous shrubs colonise the drier bajada slopes, while more diverse communities, dominated by cacti and drought-deciduous trees, grow on the wetter pediments and in pockets within rocky soils.     

Post-fire diversity patterns in two subassociations of Californian coastal sage scrub

Abstract. Coastal sage scrub exhibits floristically dissimilar subassociations on opposing aspects in the Santa Monica Mountains of southern California. Southward-facing (Venturan I) and northward-facing (Ventaran II) subassociations were sampled at two scales (1 m² and 625 m²) each spring for five years following a fire. Mature (10- and 28 yr-old) sites of these subassociation types were also sampled in the study area. The subshrub and herbaceous components that were most prevalent on northerly slopes following the first post-burn year contributed the most cover for all ages examined. Aspect-related differences in species richness were most apparent at the smaller sampling scale where they were equal the first post-burn year and varied inversely thereafter. At this scale, richness values were two times higher on older north-facing sites, largely due to the herbaceous component. South-facing sites displayed progressive decreases in equitability through time. This pattern reflects gradual reduction in overall species richness combined with progressive site domination by fewer species, as manifested by increasing dominance concentration values. By contrast equitability on north-facing sites fluctuated little through time, though dominance concentration tended to decrease. Higher richness, equitability, and overall cover with time after burning on north-facing sites is associated with the relatively mesic habitats upon which this subassociation develops. Post-burn patterns of species richness and stratal differentiation on south-facing slopes are consistent with those reported for other mediterranean-type shrublands, i.e. peak richness was attained the first two years following a fire with subsequent decrease to a constant level.     

典型岩溶区域主要土壤类型分布特征与表层土壤保有量估算

在我国西南岩溶区域,土壤受地质和地形条件的影响程度较深,表现出强烈的非均一性;且在不同地质地形条件下,缺乏具体的量化参照系数,致使对土壤元素库容等方面的估算存在较大偏差。据此,本研究基于对贵阳市乌当区实地考察结果,归纳确立土壤在不同地质与地形下的分布特征,修正了现有的土壤图。利用地形图提取区域的坡度信息,再与土壤图和地质图进行叠加,乘以相应类型条件下土壤的经验系数,估算区域主要土壤类型表层(≤1m)土壤的保有量。结果表明,乌当区境内坡度>35°的碳酸盐岩地区无黄壤分布;石灰土的覆盖率和土壤剖面深度随坡度的增加,呈下降趋势,但连续性石灰岩分布区的石灰土变异程度较大;该区表层土壤(≤1m)保有量约为65656万t,主要集中分布在0°～15°碳酸盐岩分布区,且黄壤占50%以上。     

Soil requirements of central Australian sandridge plants in relation to the duneswale soil catena

The soil requirements of seven central Australian sandridge plant species were examined by comparing the soils associated with individuals of each species in their typical sandridge habitats and in anomalous habitats such as dry watercourses, grader banks on road verges, disturbed ground near boreholes, and sand-filled rock crevices. The species studied were Zygochloa paradoxa, Chamaesyce wheeleri, Calotis erinacea, Helichrysum ambiguum, Dampiera cinerea, Triodia basedowii and Monachather paradoxa. The first two of these are characteristic of open dunecrests, the next three of crests and upper dune slopes, and the last two of lower slopes and swales. The first five species grow in a range of anomalous habitats with nutrient status comparable to swales and lowerslopes, but only if the soils are loosened or have enhanced moisture status. The deep wellsorted sands of dry watercourses form the only anomalous habitat for Zygochloa paradoxa and Chamaesyce wheeleri. Calotis erinacea, Helichrysum ambiguum and Dampiera cinerea also grow on poorly sorted graderbank and borehole soils in the swales, but not on unmodified swale soils. The only anomalous habitats in which the last two have been found are very similar to their typical sandridge habitats and so reveal little of soil requirements.     

Soil nutrients distribution and moisture dynamics on upper catena in a semi-arid nature reserve

The distribution of soil nutrients and soil moisture dynamics on slopes of catenary landscape, were recorded in a semi-arid nature reserve located in the Eastern Transvaal, South Africa. Soil nutrients were accumulating in the slopes of the catena whereas the crests were highly leached. Open grassland bands segregating between the two soil types and their associated plant species, did not show clear stratification of nutrient deposition amongst ground levels down to 1.5 m below the surface. There was however, a tendency of soils with high nutrient contents to correlate with areas of high woody vegetation density. Patterns of soil moisture levels during two annual rainfall periods showed some segregation between soil depths, although the trends indicated that the duration of saturation and dry out of soils levels differed more between rainy seasons than between soil levels during a particular season.     

Crown development in tropical rain forest trees in gaps and understorey

Emergence and establishment of Tsuga sieboldii seedlings were monitored for six years in an old-growth mixed forest in Japan, to clarify the reason why adult T. sieboldii trees are distributed only on convex slopes. T. sieboldii seedlings germinated on exposed soils without broad-leaved litter cover on both convex and concave slopes, but they died out from concave slope during the first two years after germination. Along a gradient from convex to concave slope, litter cover became higher and surface soil erosion became severer, and T. sieboldii seedlings died at the plots with severe surface soil erosion. Other environmental variables, such as relative illuminance, vegetation cover of seedling layer and soil water potential were not significantly different between convex and concave slopes. We concluded that the restricted seedling establishment of T. sieboldii to convex slope is determined by stability of surface soils and broad-leaved litter cover.