The diversity of woodland vegetation in Central Albania along an altitudinal gradient of 1300 m

Abstract

The woodland vegetation of Central Albania is studied and discussed along an altitudinal gradient in the Dajti National Park (DNP). The plant species combinations recorded in 168 plots were classified and subjected to indirect gradient analysis using environmental variables of geology, soil, topography, disturbance and grazing impact. The transect over more than 1300 m reflects the biogeographically intermediate paramediterranean vegetation zonation and the relatively humid Mediterranean “hygric series” at its eastern margins. It reveals the total range of woodland types known to occur in Central Albania, thus stressing the representativity of the area regarding biodiversity and biogeography, and its importance for nature conservation. Along the elevation gradient, we found three plant communities of the mesomediterranean Quercetalia ilicis, five of the supramediterranean Quercetalia pubescentis and five of the montane or oromediterranean Fagetalia sylvaticae.     

Trait evolution in an individual-based model of herbaceous vegetation

Many theoretical studies of evolution are based upon the concepts of the evolutionary stable strategy and optimal life-history solutions. An individual based model of vegetation is used to simulate life-history evolution under two different sets of environmental conditions. At one level the results suggest that optimal life-history solutions do appear to evolve. At the end of the simulations the vegetation that evolved in a fertile and uncut environment was taller, thinner and germinated later than that which developed in a less fertile and cut habitat. However, between simulation variation was observed to be high, particularly for the parameter regulating the timing of reproduction, and it showed no indication of reaching fixation. When this trait was prevented from mutating, the variances of other traits were seen to increase. Although at the population level between simulation variation was high, some traits achieved a degree of stability within simulations, suggesting that multiple adaptive peaks may be being approached. However, there was little evidence of trait fixation occurring within the most abundant genotype. It is considered that frequency dependent selection/Red Queen dynamics may be acting to prevent the most abundant genotype from reaching fixation. It is argued that if such processes prevent optimal genetic solutions from being achieved then the search for evolutionary stable strategies within the evolution of life-histories may be over simplistic.     

The woodland vegetation of Inchcailloch,Loch Lomond

Summary

A systematic sample of 416 stands of vegetation was subjected to Indicator Species Analysis which classified the stands into sixteen Groups. For practical reasons these were amalgamated into ten Interpreted Groups which are described in terms of species representation and cover. The distribution of stands in the various Groups is described and is related where possible to environmental factors.     

Root biomass distribution and soil properties of an open woodland on a duplex soil

Data on the distribution of root biomass are critical to understanding the ecophysiology of vegetation communities. This is particularly true when models are applied to describe ecohydrology and vegetation function. However, there is a paucity of such information across continental Australia. We quantified vertical and horizontal root biomass distribution in a woodland dominated by Angophora bakeri and Eucalyptus sclerophylla on the Cumberland Plains near Richmond, New South Wales. The site was characterised by a duplex (texture contrast) soil with the A horizon (to 70 cm) consisting of loamy sand and the B horizon (to > 10 m) consisting of sandy clay. The topsoil had a smaller bulk density, a smaller water holding capacity but a larger organic component and a larger hydraulic conductivity in comparison to the subsoil. Root biomass was sampled to 1.5 m depth and declined through the soil profile. Whilst total biomass in the B horizon was relatively small, its contribution to the function of the trees was highly significant. Coarse roots accounted for approximately 82% of the root mass recovered. Lateral distribution of fine roots was generally even but coarse roots were more likely to occur closer to tree stems. Variation in tree diameter explained 75% of the variation in total below-ground biomass. The trench method suggested the belowground biomass was 6.03?±?1.21 kg m^?2 but this method created bias towards sampling close to tree stems. We found that approximately 68% of root material was within a 2 m radius of tree stems and this made up 54% of the total number of samples but in reality, only approximately 5 to 10% of the site is within a 2 m radius of tree stems. Based on these proportions, our recalculated belowground biomass was 2.93?±?0.59 kg m^?2. These measurements provide valuable data for modeling of ecosystem water use and productivity.     

The response of sap flow to pulses of rain in a temperate Australian woodland

In water-limited systems, pulses of rainfall can trigger a cascade of plant physiological responses. However, the timing and size of the physiological response can vary depending on plant and environmental characteristics, such as rooting depth, plant size, rainfall amount, or antecedent soil moisture. We investigated the influence of pulses of rainfall on the response of sap flow of two dominant evergreen tree species, Eucalyptus crebra (a broadleaf) and Callitris glaucophylla (a needle leaved tree), in a remnant open woodland in eastern Australia. Sap flow data were collected using heat-pulse sensors installed in six trees of each species over a 2 year period which encompassed the tail-end of a widespread drought. Our objectives were to estimate the magnitude that a rainfall pulse had to exceed to increase tree water use (i.e., define the threshold response), and to determine how tree and environmental factors influenced the increase in tree water use following a rainfall pulse. We used data filtering techniques to isolate rainfall pulses, and analysed the resulting data with multivariate statistical analysis. We found that rainfall pulses less than 20 mm did not significantly increase tree water use (P > 0.05). Using partial regression analysis to hold all other variables constant, we determined that the size of the rain event (P < 0.05, R ² = 0.59), antecedent soil moisture (P < 0.05, R ² = 0.29), and tree size (DBH, cm, P < 0.05, R ² = 0.15), all significantly affected the response to rainfall. Our results suggest that the conceptual Threshold-Delay model describing physiological responses to rainfall pulses could be modified to include these factors. We further conclude that modelling of stand water use over an annual cycle could be improved by incorporating the T-D behaviour of tree transpiration. Responsible Editor: Stephen S.O. Burgess     

Biomass dynamics of herbaceous vegetation in Zambezi riverine woodlands

Seasonal changes in biomass, productivity and large mammal utilization of annual grasslands on Zambezi alluvium in Mana Pools National Park, Zimbabwe, were recorded over four years and compared with perennial grasslands. Annual grasses grew only in the wet season, but forb productivity peaked at the start of the dry season. Large mammals and termites ate dead annual grasses in the dry season. Production was usually greater in perennial grasslands, than in annual ones, and perennial grasses often grew throughout the year. Large mammal utilization of grasslands varied between 53 and 99% of annual production.

Résumé

L'on rapporte les changements saisonniers de biomasse, productivité et utilisation par les grands mammifères des herbages annuels dans les plaines alluviales du Zambèze au Parc National de Mana Pools, Zimbabwe, pendant 4 ans et on les compare avec ceux des herbages pérennes. Les herbes annuelles ne croissent que pendant la saison des pluies mais la productivité du fourrage était au maximum en début de pérennes que dans les annuels et les herbes pérennes poussaient souvent tout au long de I'année. L'utilisation par les grands mammifères variait de 53 à 99% de la production annuelle.     

A functional classification of herbaceous hedgerow vegetation for setting restoration objectives

Hedgerows are valuable habitats for biodiversity in farmed landscapes. The herbaceous vegetation at the hedge base is an important component of this habitat but its condition in Britain has deteriorated due to a combination of nutrient and pesticide contamination, and inappropriate management or neglect. The condition of herbaceous hedgerow vegetation is included in policy targets for biodiversity conservation, so a strategy is required for its restoration. This vegetation can be highly variable, so a classification of the main types is required to set realistic objectives. Vegetation classifications based on species’ functional characteristics can have more general application that those based on species identity. Using existing datasets from a countrywide survey, a functional classification of herbaceous vegetation from hedgerows in Britain was developed. Cluster analysis of vegetation plots, based on attributes of the species present, produced thirteen vegetation types in six broad groups. These were differentiated by the association of the component species with woodland, grassland or arable habitats and by gradients of soil nutrient status and pH, light availability, disturbance and grazing tolerance. By using species’ ecological characteristics as a basis for the classification, the condition of vegetation can be established and the prevailing environment predicted. From this information, a realistic strategy for restoration can then be determined.     

Site quality and vegetation biomass in the tropical Sal mixed deciduous forest of Central India

Landscape and Ecological Engineering - Tropical Sal forests are gaining wide recognitions due to its multifarious significance. An estimation of vegetational structure and biomass would be helpful...     

Responses of small vertebrates to linear clearings in a South Australian woodland

This work assesses whether the width and “permanence” of linear clearings affects the distribution and movement patterns of small, terrestrial vertebrates in a native South Australian woodland. We examined the influence of narrow (1.5 and 4.2 m), non-permanent seismic exploration tracks; and wide (6–7 and 12–15 m), permanent fire tracks. There were 1,007 captures of 14 species (four amphibians, six reptiles, four mammals) from 18,000 trap days/nights across 15 sites. Total species richness was highest adjacent to 6–7 m wide permanent tracks (8.3) and lowest in areas without clearings (5.3). There was heterogeneity of captures between track types (p < 0.008), species (p < 0.001), and species by track type (p < 0.001). Antechinus flavipes was most abundant adjacent to both types of permanent tracks, probably as a result of increased habitat complexity at these sites. Twenty-four percent of movements by recaptured A. flavipes involved track crossings. Animals crossed all track types; nevertheless, individuals were more likely to be recaptured on the same side of a track. Individuals were less likely to cross permanent tracks (p = 0.025 for 6–7 m and p = 0.008 for 12 to 15-m-wide tracks), with females being particularly inhibited. Although 11 % of 56 recaptured Rattus spp. had crossed a track, no individuals crossed the 12 to 15-m permanent tracks. In the habitat type studied here, narrow seismic lines may have a slightly positive effect on some ground-dwelling vertebrates, and do not appear to substantially inhibit movement. However, there is a need to carefully manage permanent tracks, which could isolate faunal populations.     

Methanotrophic communities in Australian woodland soils of varying salinity

Despite their large areas and potential importance as methane sinks, the role of methane-oxidizing bacteria (MOB) in native woodland soils is poorly understood. These environments are increasingly being altered by anthropogenic disturbances, which potentially alter ecosystem service provision. Dryland salinity is one such disturbance and is becoming increasingly prevalent in Australian soils. We used microarrays and analysis of soil physicochemical variables to investigate the methane-oxidizing communities of several Australian natural woodland soils affected to varying degrees by dryland salinity. Soils varied in terms of salinity, gravitational water content, NO(3)-N, SO(4)-S and Mg, all of which explained to a significant degree MOB community composition. Analysis of the relative abundance and diversity of the MOB communities also revealed significant differences between soils of different salinities. Type II and type Ib methanotrophs dominated the soils and differences in methanotroph communities existed between salinity groups. The low salinity soils possessed less diverse MOB communities, including most conspicuously, the low numbers or absence of type II Methylocystis phylotypes. The differences in MOB communities suggest niche separation of MOB across varying salinities, as has been observed in the closely related ammonia-oxidizing bacteria, and that anthropogenic disturbance, such as dryland salinity, has the potential to alter MOB community and therefore the methane uptake rates in soils in which disturbance occurs.     

The effects of dissolved macro-nutrients on the herbaceous vegetation around dune pools

In Dutch coastal dunes the relation was studied between the composition of the vegetation on the banks of pools and the nutrients supplied by the groundwater. Areas infiltrated with eutrophic river water were compared with non-affected areas. The floristic composition was interpreted according to classification systems of ruderal, nitrophilous tall hemicryptophytes and the conservation parameters richness and rarity. Of the three main macro-nutrients (orthophosphate, nitrate and potassium), the orthophosphate load shows the highest correlation with the vegetation variables. It is suggested that a reduction of orthophosphate during pre-purification of the infiltration water would reduce the dominance of the ruderals to the extent that the original dune slack species could return locally.Nomenclature of species follows Arnolds & Van der Meijden (1975).We thank G. J. de Bruyn, W. H. van Dobben, W. T. de Groot, W. J. ter Keurs, F. van der Meulen, W. H. van der Molen, M. A. W. Noordervliet, and I. S. Zonneveld for their comments on the study; J. Braak, J. Brakkee and R. van Nood for their assistance with the chemical analyses; A. R. Kaal for the translation, and G. P. G. Hock for the drawing of the figures.     

Clumped and isolated trees influence soil nutrient levels in an Australian temperate box woodland

Isolated paddock trees are a common feature of agri-pastoral landscapes in south-eastern Australia. We assessed the impact of trees on soil nutrients by examining (1) changes in soil nutrients under clumped and isolated (living and dead) trees at four microsites corresponding with increasing distance from the trunk (trunk, mid-canopy, drip line, open), and (2) changes with depth under trees growing in clearly-defined clumps. We detected significantly greater concentrations of organic C, and total N and S under trees growing in clumps compared with either isolated living or dead trees. Levels of soluble Ca²⁺, K⁺ and Mg²⁺, pH, electrical conductivity (EC) and available P declined with increasing distance from the trees, but there were no significant trends for organic C, or total N and S. The concentration of most nutrients declined with depth, particularly at microsites close to the trunk, while pH increased with depth. We believe that differences in chemistry were largely driven by greater inputs of organic matter under the trees. This study reinforces the view that trees, whether scattered or in clumps, are important for soil nutrient conservation in agri-pastoral landscapes.     

Effects of scale-dependent factors on herbaceous vegetation patterns in a wetland,northern Japan

Herbaceous vegetation was examined in an Otanoshike wetland in northern Japan to clarify the relationships between vegetation patterns and environmental factors with different scales. Alders (Alnus japonica) have recently invaded and might modify the herbaceous vegetation. In total, 150 50×50cm plots were established on the transitional areas between alder thickets and grassy marshland. Cover was measured for the vascular plant taxa, and canopy area, number of stumps, number of mounds, water depth, elevation difference, litter thickness, soil organic matter, and soil pH were measured in each plot. TWINSPAN cluster analysis classified four vegetation groups: (i), grasslands represented by Phragmites australis, Trientalis europaea, Lythrum salicaria, and Hosta rectifolia; (ii), Calamagrostis langsdorfii, and Polygonum thunbergii grasslands with Spiraea salicifolia; (iii), reed swamp dominated by Phragmites australis, and (iv), marshland dominated by Carex lyngbyei. Canonical correspondence analysis indicated that water depth primarily divided vegetation groups 1–2 and 3–4. Alder established in drier sites mostly by re-sprouting, and the canopy affected light and soil conditions on the ground surface. The second axis of canonical correspondence analysis was related to the canopy area and soil pH, and explained the vegetation differentiation between groups 1 and 2, and groups 3 and 4. In conclusion therefore, scale-dependent or hierarchical variables affected the vegetation patterns in different ways, that is, the herbaceous vegetation was first differentiated by water depth that was corresponding to alder establishment on a large scale, and subsequent light and soil conditions were second determinants on a small scale.     

The number and size of seeds in common versus restricted woodland herbaceous species in central Iowa, USA

Few plants have widespread distributions and occur wherever there is suitable habitat. Most species are absent from seemingly suitable sites because of limited colonizing ability. At a landscape scale colonization is limited by lack of seeds or suitable microsites, and this limit is likely to be exacerbated by current human alteration of the landscape. To test the hypothesis that species with restricted distributions have a more limited capacity for dispersal compared to common species, I compared seed number in a group of seven common woodland herbaceous species compared to seven species in the same genus or family with more restricted distributions. Restricted species had nearly an order of magnitude fewer seeds compared to closely related common species. They also produced over an order of magnitude larger seeds. These results support dispersal limitation. The ability to detect these differences was reduced when taxonomic information was not included. The data suggest that these species can not maximize both seed size and seed number. The results are interpreted in light of the human disturbance history that has had an overriding influence on the Iowa landscape and has likely favored species with an output advantage of abundant seeds over species with far many fewer seeds.     

Environmental determinants of woody and herbaceous riparian vegetation patterns in a semi-arid mediterranean basin

What environmental variables determine riparian vegetation patterns? Are there differences between woody and herbaceous species? To answer these questions, we first explored the composition and richness patterns of both riparian woody and herbaceous species in a semi-arid mediterranean basin. Then, we assessed the environmental factors (climate, geology, topography, hydrogeomorphology and land use) that best explain these patterns. We used the following methodological approaches: clustering analyses, distance-based linear models, generalised linear models and hierarchical partitioning procedures. Valley shape, drought duration, river habitat heterogeneity, water conductivity and agricultural land use were the most important variables explaining variation in species composition for both groups. Woody riparian richness was mainly influenced by flow conditions and valley shape, whereas herbaceous one was more dependent on substrate features. Thus, although some differences in the importance of individual variables were observed, we found a notable congruence in the composition and species richness of both groups and also in the main types of variables explaining these patterns (hydrogeomorphology and land use, especially agriculture). Our results show that both communities could be treated in a holistic way, since they respond similarly to the strong natural and anthropogenic environmental gradients present in mediterranean basins.