Patterns of functional clonal traits and clonal growth modes in contrasting grasslands in the central Apennines,Italy

Abstract. Aim: Patterns of plant functional traits related to clonality (clonal growth modes; CGM) in plant communities were studied and hypotheses on the importance of the selected traits in plant communities supported by soils differing in moisture and nutrient status were tested. Material and Methods: Selected plant functional traits, such as the position of the mother‐daughter plants connections, length of spacers, frequency of multiplication, persistency of ramets connections, presence of storage organs and bud protection were studied in two contrasting plant communities (xeric and mesic abandoned pastures) typical of central Apennines, Italy. Results and Discussion: Clonality was shown to be of great importance in both mesic and xeric grasslands. The major differences between the two communities were due to the dominant CGMs: turf graminoids (having effective protection of growth meristems in dense tussocks) dominated xeric grasslands, while rhizomatous graminoids (typical of competitive resource‐rich environments) dominated mesic grasslands. Below‐ground CGOs (clonal growth organs), shorter spacers, higher multiplication potential, permanent ramet connection, large bud bank and increased importance of bud protection were found to be of importance in water stressed xeric grassland. Contrary to our expectations, the mesic (less stressed) grasslands have the higher number of clonal plants possessing storage organs.     

Growth of tree seedlings in a tropical dry forest in relation to soil moisture and leaf traits

"AimsThe growth of plant species in tropical dry forest (TDF) is expected to be largely governed by the availability of soil moisture. In this study we attempt to identify mechanisms by which seedlings of dry tropical trees cope with water stress by adjusting their leaf characteristics to water availability and micro environments, and address following questions: How are leaf traits and relative growth rate (RGR) of the dominant seedling species of TDF affected by seasonal changes in soil moisture content (SMC)? What is the relationship of functional traits with each other? Can leaf traits singly or in combination predict the growth rate of seedling species of TDF? The study was conducted in situ on four sites (viz., Hathinala, Gaighat, Harnakachar and Ranitali, listed in order of decreasing SMC) within the tropical dry deciduous forest in northern India. Methods Five leaf traits viz., specific leaf area (SLA), leaf dry matter content (LDMC), concentrations of leaf nitrogen (leaf N), phosphorus (leaf P) and chlorophyll (Chl) and two physiological processes, viz., stomatal conductance (Gs net) and photosynthetic rate (A net), and RGR, of four dominant tree seedling species of a TDF (viz., Buchanania lanzan, Diospyros melanoxylon, Shorea robusta and Terminalia tomentosa) on four sites were analysed for species, site and season effects over a 2-year period. Step-wise multiple regression was performed to predict RGR from mean values of SMC, leaf traits and physiological processes. Principal component analysis (PCA) was performed to observe the extent of intra- vs. inter-specific variability in the leaf traits and physiological rates.Important findings All the traits and physiological rates were interrelated and showed significant positive relationship with RGR except for the correlation of LDMC with RGR which was not significant. Further, relationships of SMC with all leaf traits, physiological rates and RGR were significant, except for that between SMC and SLA for B. lanzan and D. melanoxylon. The slope of seedling trait:SMC relationship, a measure of phenotypic plasticity in response to soil moisture gradient, varied among species. Among the four species, T. tomentosa was the most plastic and S. robusta the least. In conclusion, leaf traits and physiological processes were strongly related to soil water availability on the one hand and seedling growth on the other. Gs net is the most important variable which accounted for the greatest amount of variability (62%) in RGR, emphasizing the role of stomatal conductance in shaping growth patterns across spatial and temporal gradients of soil water availability. Gs net and SMC together explained 64% variability in RGR, indicating that other traits/factors, not studied by us are also important in modulating the growth of tropical tree seedlings.     

Interspecific variation in sapling mortality in relation to growth and soil moisture

To examine the causes of landscape variation in forest community composition, we have quantified sapling mortality as a function of growth and soil moisture for seven dominant species in transition oak-northern hardwood forests of the northeastern USA. We located saplings in sites that encompassed a wide range of variation in soil moisture and light availability. In mesic conditions, the probability of mortality decays rapidly with increasing growth among shade tolerant species and more gradually among shade intolerant species: the rank order of survivorship at low growth rates is Tsuga canadensis > Fagus grandifolia > Acer saccharum > Fraxinus americana > Acer rubrum > Quercus rubra > Pinus strobus . The relationship between probability of mortality and growth does not vary with soil moisture among species insensitive to drought: Tsuga canadensis , Quercus rubra, and Pinus strobus . However, probability of mortality increases substantially with decreasing soil water availability for the other four species. Acer saccharum and Fagus grandifolia have high mortality rates under xeric conditions even when their growth is not suppressed. Acer rubrum and Fraxinus americana exhibited a steady but more gradual increase in the probability of mortality with decreasing soil moisture. Among the five deciduous hardwood species we examined there is a weak inverse relationship between the ability to survive growth suppression, a measure of shade tolerance, and the ability to survive in xeric conditions, a measure of drought tolerance. Tsuga canadensis , however, is tolerant of growth suppression and exhibits high survivorship in xeric conditions, while Pinus strobus is intolerant of growth suppression but insensitive to soil moisture. Species differences in water-dependent mortality are consistent with the species distributions across landscape gradients of soil water availability.     

Dynamic floristic changes of Swedish beech forest in relation to soil acidity and stand management

This study reports dynamic changes in the beech forest vegetation during one decade, using 95 permanent observation areas representing a wide variety of soils and management regimes. Current soil acidification, including decreasing pH and base cation pools, increasing solubility of toxic elements and increasing deposition of N, as well as recent changes in the beech forest management have created good conditions for the study. Most species of vascular plants increased their frequencies during the 1980's. However, there were several notable exceptions, in particularGalium odoratum, Viola riviniana/reichenbachiana, Polygonatum multiflorum, andMercurialis perennis. These species, demanding a comparatively low soil acidity for survival, are distinctly disfavoured by the long-term soil changes in the forests, which seem to have approached or exceeded their limits of existence in many sites. With most other species, differences in management regimes between the beginning and the end of the observation period were more important to the frequency changes. Sensitive to heavy thinning of the stands were, e.g.Oxalis acetosella, Lamium galeobdolon andMelica uniflora, favoured by thinning wereStellaria nemorum, Carex pilulifera, Milium effusum and an appreciable number of more ephemeral species normally occurring in clear-cut areas or otherwise open land, e.g.,Rubus idaeus, Galeopsis tetrahit, Athyrium filix-femina, Juncus effusus, Agrostic capillaris, Veronica officinalis, Urtica dioica, andMoehringia trinervia. Saplings of woody plants usually also became more frequent during the 1980's.     

Fine-root vitality in a Norway spruce stand subjected to various nutrient supplies

The vitality of fine roots in a Norway spruce stand subjected to application of ammonium sulphate (NS), wood ash (A) and nitrogen-free fertilizer (V) respectively, was investigated using i) vitality classification of fine roots based on morphological characteristics and ii) the triphenyl tetrazolium chloride (TTC) method of estimating dehydrogenase activity.Although the NS-treated areas showed a 30% increase in above-ground production in response to the NS-application, the vitality of the fine-root system in the humus layer appeared to be in a state of deterioration, as indicated by a decrease in fine-root biomass, an increased amount of dead fine (0–1 mm) and small (1–2 mm) roots, a decreased specific root length (SRL = fine root length/fine root dry weight) and an increased dehydrogenase activity. The impact of the the A and V treatments was reflected in a decrease in fine-root biomass and an increase in SRL. The results make it clear that in order to study the vitality of forest trees, both fine-root studies and studies of above-ground tree parts are necessary.     

鄱阳湖典型湿地土壤微生物活性对季节性水位变化的响应

为探究湿地土壤微生物对季节性水位变化的响应关系,以鄱阳湖湿地土壤为研究对象,在2014年3、6、10及2015年1月4个季节采集了3个不同高程样带的土壤样品,对土壤微生物基础呼吸、生物量及胞外酶等活性进行了测定。研究结果表明:(1)季节性水位变化不仅显著改变了土壤有机碳、溶解性有机碳、有效磷等含量,也使得微生物量碳和4种水解酶β-葡萄糖苷酶、β-木糖苷酶、N-乙酰氨基葡萄糖苷酶、磷酸酶活性表现出夏冬季较高、秋季最低的动态变化,而2种氧化酶酚氧化酶和过氧化氢酶的表现正好相反。(2)水位高程和地上植被类型同样对土壤微生物产生了显著影响,表现为南荻样带有较高营养元素含量和微生物活性。(3)一些土壤理化指标(含水量、铵态氮、有机碳、有效磷等)与微生物活性(微生物量、基础呼吸、酶活)显著相关;季节水位变化对微生物活性的影响大于高程差异。研究结果表明水位波动对湿地土壤微生物活性产生了重要影响,鄱阳湖水文节律的改变将影响到湿地土壤的正常生态功能。     

Vertebrate-rich Plattenkalk of Pietraroia (Lower Cretaceous,Southern Apennines,Italy): a new model

The Lower Cretaceous Pietraroia Plattenkalk is a fossiliferous, fine-grained cherty limestone from the Matese Mountains – Southern Apennines, Italy. The deposits are well known for the exceptional state of vertebrate fossil preservation. First considered as shallow lagoonal deposits or as intra-platform basin-fill, the Pietraroia Plattenkalk sequences are here interpreted as abandon deposits of a submarine channel (Pietraroia Channel) documenting a major transgressive event. Transgression was associated with the development of suboxic to anoxic conditions at the seafloor which favoured the preservation of fossils, as well as the deposition of coprolith-rich and bituminous layers. A peculiar paleogeographic and paleotopographic setting, which was strongly controlled by local tectonic, experienced the contiguity of wide emerged areas with a relatively deep-water channelised area where fossiliferous Plattenkalk sequences were deposited.     

Fine-root growth, fine root mortality, and leaf morphological change of Populus alba in response to fluctuating water tables

Water table fluctuation in arid land regions may alter tree fine-root growth and mortality, thereby affecting leaf growth. To reveal the effects of water table fluctuation on fine-root growth and mortality and their relation to leaf growth, we exposed P. alba L. cuttings to various fluctuating water table depths. 1-year-old rooted cuttings were grown individually in pots containing sandy soil in a greenhouse in three water table depth treatments for 45 days: constant depth at 45 cm from the soil surface, fluctuating depths between 45 and 30 cm, and fluctuating depths between 45 and 15 cm. Fine-root biomass and mortality, biomass partitioning among plant parts, and whole-tree growth responses were determined in cuttings harvested every 15 days. Fluctuation of water tables increased the mortality of fine roots at the layers near the soil surface. Fine-root mortality increased during the shallower water table depth period. At the whole-root system level, although fine-root mortality increased when the water table was shallower, fine-root biomass was similar among the treatments, suggesting that P. alba cuttings would sustains its standing fine-root biomass under fluctuating water table depth conditions. Our structural equation modeling showed the fine-root proportion affects leaf morphological changes, suggesting that there would be a parallel relationship of morphological changes between roots and leaves with fluctuating water tables.     

Soil organic matter,nutrient distribution,fungal and microbial biomass and enzyme activities in a forest beech stand on the Apennines of southern Italy

The aim of this study was to analyse the amount and qualitative characteristics of organic matter (OM) in the litter horizon (considering leaf litter at different decomposition stages) and underlying soil to a 30-cm depth in a beech stand on the Apennines in southern Italy. Distribution of major nutrients as well as fungal and microbial biomass were also evaluated, in addition to beech leaf nutrient content monitor from full expansion to abscission in order to estimate annual nutrient input to soil from litterfall and nutrient retranslocation before abscission. OM was significantly higher in leaf litter. C/N ratio and the Na, Mn, Fe levels also decreased along the decomposition continuum, whereas N and S contents slowly decreased with soil depth. Generally, leaf nutrient content was also significantly lower in dead leaves, indicating efficient retranslocation to persistent organs. Fungal biomass was the highest in leaf layers, with no significant changes between spring and autumn samplings. Enzyme activities did not differ significantly along the decomposition continuum but marked decreases were found in the upper soil layer; these remained relatively constant, with the exception of laccase, at deeper soil depths. No seasonal effect on enzyme activities and OM content was found.     

Distribution and population dynamics of Collembola in relation to soil moisture

The significance of variations in soil moisture for the distribution and abundance of the four collembolan species Tomocerus minor, Orchesella cincta. Lepidocyrtus lignorum and Entomnbrya nivalis has been studied in a pine forest. During a relatively dry summer, the distribution and abundance of these species were examined on two sites with an initially different soil water content and depth of the titter/humus layer. The distribution of the species investigated could be described with the negative binomial distribution. During the sampling period. Lloyd's "index of patchiness", / for T. minor and E. nivalis was subject to changes. For T. minor this was probably related to soil water content.
The densities of T. minor and O. cincta were higher in the wet site than in the drier site. At the beginning and at the end of the sampling period the drought tolerant E. nivalis reached equal densities in both sites. The density fluctuations of the four species appeared to be totally different during the sampling period: the drought sensitive species T. minor decreased strongly, L. lignorum remained constant and the drought tolerant species O. cincta and E. nivalis increased strongly. These latter two species were able to survive the dry periods and to attain high densities by reproduction. The results agree with laboratory data on distribution and survival in relation to humidity.     

Occurrence of black wolves in the Northern Apennines,Italy

The occurrence of black-coated individuals in wolfCanis lupus Linnaeus, 1758 populations is not surprising itself, but their presence in populations recovering from a severe numerical decline has been considered a possible sign of crossbreeding with the domestic dog. In the northern Apennines (Italy), black wolves occur at a non-negligible frequency. In a 3300 km² area, 22% of wolves observed and 23% of all dead wolves found were represented by animals with a completely black coat. One ‘black’ wolf belonging to the studied population was analysed by a set of microsatellite loci, and no trace of hybridization was found in its ancestry. This result induced us to consider the occurrence of a black phenotype in this area possibly derived from a natural combination of wolf alleles in coat colour determining genes, and not necessarily as the result of crossbreeding with the domestic form.     

Organic phosphorus in soil water under a European beech (Fagus sylvatica L.) stand in northeastern Bavaria, Germany: seasonal variability and changes with soil depth

Organically bound phosphorus (P) is a mobile form of phosphorus in many soils and thus its dynamics relevant for the leaching and cycling of this element. Despite its importance, little is known about the chemical composition of dissolved organic P. We studied the concentrations, fluxes, and chemical composition of organic P in forest floor leachates and soil solutions in a Rendzic Leptosol under a 90-year-old European beech (Fagus sylvatica L.) forest over a 27-month period (1997–1999). The chemical composition of organic P was analysed using XAD-8 fractionation and ³¹P-nuclear magnetic resonance (NMR) spectroscopy. Organic P was the dominant P form in forest floor leachates as well as in porewaters of the mineral soil. The largest concentrations of organic P were observed during summer and peaked (330–400 g dissolved organic P l^–1) after rain storms following short dry periods, concurrently with the concentrations of organic carbon (OC). Because of high rainfall, fluxes of organic P (and C) were greatest in autumn although concentrations of organic C and P were lower than in summer. In forest floor leachates, the hydrophilic fraction of dissolved organic matter contained 83 ± 13% of the bulk organic P. In soil solutions from 90 cm depth, organic P was almost exclusively in the hydrophilic fraction. Because of the low retention of the hydrophilic fraction of dissolved organic matter in the mineral soils, concentrations of organic P in soil water remained almost constant with depth. Consequently, organic P contributed > 95% of the total P leached into deeper subsoils. The overall retention of organic P in the weakly developed mineral soils was little and so the average annual fluxes of organic P in subsoils at 90 cm depth (38 mg m^–2) comprised 67% of those from the forest floors (57 mg m^–2) during the study period. Hence, organic P proved to be mobile in the studied soil. ³¹P-NMR spectroscopy confirmed the dominance of organic P species in soil water. Signals due to inorganic P occurred only in spectra of samples collected in winter and spring months. Spectra of samples from summer and autumn revealed traces of condensed phosphates. Due to low P contents, identification of organic P species in samples from winter and spring was not always possible. In summer and autumn, monoester and diester phosphates were the dominant organic species and varied little in their relative distributions. The distribution of organic species changed little from forest floor leachates to the subsoil solutions indicating that the composition of P-containing compounds was not influenced by sorptive interactions or biological transformation.     

Growth of crop roots in relation to soil moisture extraction

Growth of the roots of sugar beet, potato and barley in the field was observed through glass panels and related to changes in soil moisture measured by a neutron probe during 1969–71. The depth of observed root growth was generally related to, but 10–15 cm deeper than, the maximum depth of soil-moisture extraction. On average of three years, sugar beet, potato and barley used water from the top 23, 33 and 45 cm soil respectively by the beginning of June, and from the top 70, 68 and > 100 cm soil by the end of June. Maximum soil drying in each horizon gave an in situ measure of available water capacity, and showed that sugar beet and barley eventually extracted similar amounts of water from each horizon, but potatoes extracted less, especially from below 60 cm. Between 30 and 100 cm deep, the in situ available water capacity (per 10 cm soil) progressively decreased from 16 to 10, 15 to 5 and 16 to 8 mm under sugar beet, potato and barley respectively. The calculated soil-moisture deficit (potential evapotranspiration minus rainfall) and measured soil moisture deficit were not related early in the growing period before the crops established much leaf cover.     

Detecting complex relations among vegetation,soil and geomorphology. An in-depth method applied to a case study in the Apennines (Italy)

Physical environment is the ruling factor of vegetation patterns in mountain areas, where vegetation mosaics are determined by a complex interplay among topography, geomorphology and soil. A deep analysis of such interplay is pivotal in order to build vegetation anamnesis and make sound projections. Instead, even recent cartographic models are still linked to standard statistical methods which are not on top of an efficient uncovering of knotty associations among these kinds of data. To this aim, in this study we propose a novel approach for: (a) assessing the associations among vegetation, soil, topography and geomorphology; (b) measuring the frequency and strength of these associations; (c) define in a rigorous way land units based on vegetation–soil–geomorphology associations; (d) advance hypotheses on the causes and prospects of the existing spatial pattern. In order to test the strength of the proposed methodology we applied it to a case study in the above-tree-line glacial cirque of Mount Prado (Northern Apennines, N Italy). In this area, the vegetation mosaic is still strongly conditioned by physical features but in a lower measure with respect to the higher alpine sites. We have been able to detect and weight 168 kinds of associations among vegetation, soil and geomorphological types, 1092 kinds of associations among vegetation and topographic variables and 12 land units with inner dominance of a particular association. The analysis of associations between vegetation types, soils, topography and landforms produced considerable insights into the ecology of the occurring plant communities. This proposed analytic methodology can be extended to other regions (e.g. mountain and alpine areas) and can also be considered a tool for interpreting present landscape heterogeneity also in a historical perspective.     

New biostratigraphical constraints for the Norian/Rhaetian boundary: data from Lagonegro Basin,Southern Apennines,Italy

Giordano, N., Rigo, M., Ciarapica G. & Bertinelli A. 2010: New biostratigraphical constraints for the Norian/Rhaetian boundary: data from Lagonegro Basin, Southern Apennines, Italy. Lethaia. 10.1111/j.1502‐3931.2010.00218.x. Four stratigraphic sections belonging to Lagonegro succession (Southern Apennines) at Mt S. Enoc, Pignola‐Abriola, Sasso di Castalda and Mt Volturino have been studied in detail under to provide a new micro‐palaeontological data set based on conodonts and radiolarians for the characterization of the Norian/Rhaetian interval. The studied sections represent the different settings of the Lagonegro Basin (from proximal to distal facies) and permit a detailed, integrated, biostratigraphy of the Calcari con Selce (cherty limestones) and Scisti Silicei formations (bedded cherts with radiolarians) to be drawn up. The upper portion of the Calcari con Selce Formation, exhibits intermediate characteristics between the Calcari con Selce and Scisti Silicei Formation, in particular the progressive decrease in carbonate content against an increase in shales and cherts. Within the four sections studied, the Norian/Rhaetian interval has been documented both with conodonts and radiolarians. Because of the continuity and the absence of condensed facies, it has been possible to recognize the morphocline between species Misikella hernsteini and Misikella posthernsteini, here represented by all the transitional forms characterized by common features between the two species, gathered in three evolutionary steps. Moreover, the morphocline between M. hernsteini and M. posthernsteini has been involved in the definition of the Norian/Rhaetian Boundary, recognizing thus the FAD of M. posthernsteini, one of the possible biomarkers proposed for the boundary. The rich, well‐preserved, radiolarian associations of Pignola‐Abriola, Sasso di Castalda and Mt Volturino permit the correlation of Tethyan and American conodont successions, highlighting the importance of the mostly coincident occurrences of M. posthernsteini and Epigondolella mosheri morphotype A, which correspond to the base of Proparvicingula moniliformis A. Z. and the disappearance of bivalve Monotis. These coincident bioevents are used here to define the base of the Rhaetian stage. □Biostratigraphy, conodonts, Lagonegro Basin, Late Triassic, Norian/Rhaetian boundary, radiolarians.     

A study of the role of root morphological traits in growth of barley in zinc-deficient soil

p. 2777,     

A study of the role of root morphological traits in growth of barley in zinc-deficient soil

Zinc (Zn) deficiency reduces crop yields globally. This study investigated the importance of root morphological traits, especially root hairs, in plant growth and Zn uptake. Wild-type barley (Hordeum vulgare) Pallas and its root-hairless mutant brb were grown in soil and solution culture at different levels of Zn supply for 16 d. Root morphological traits (root length, diameter, and surface area) were measured using the WinRHIZOPro Image Analysis system. In soil culture, Pallas had greater shoot dry matter, shoot Zn concentration, shoot Zn content, and Zn uptake per cm(2) root surface area than brb, primarily under zinc deficiency. Both Pallas and brb developed longer roots under Zn deficiency. Development of root hairs was not affected by plant Zn status. In solution culture, there were no significant genotypic differences in any of the parameters measured, indicating that mutation in brb does not affect growth and Zn uptake. However, both Pallas and brb developed longer and thinner roots, and root hair growth was less than in soil culture, and was not affected by plant Zn status. The better growth and greater Zn uptake of Pallas compared with brb in Zn-deficient soil can be attributed primarily to greater root surface area due to root hairs in Pallas rather than other root morphological differences.