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We used long-term datasets (1984–1992) to contrast precipitation-use efficiency estimates between various disturbance kinds at a functional group and/or a species scale. Effects of varying amounts of precipitation and plant cover on PUE were also examined. Field studies were conducted at northeastern, arid Patagonia, Argentina (40°39′49″S, 62°53′6.4″W). Within each management kind, biomass was sampled in 0.5 × 0.5m permanent plots (n = 30) over 9 years after defoliation at 5 cm stubble at the end of each growing season, and it was separated into species. Biomass sampling allowed determination of annual net primary production. Thereafter, species were grouped into each of three functional groups. Precipitation-use efficiency (PUE) was calculated as the total dry matter produced per unit surface area on any given year divided by the total rainfall in that year. Plant cover on 20 out of those 30 plots was determined to study the relationship between plant cover and PUE. The contribution of cool-season perennial grasses to total PUE was higher (P <0.05) than that found for the other two functional groups in all management kinds and years. PUE was similar (P> 0.05) in wet than dry years, and it was greater (P <0.05) or similar (P> 0.05), but not lower, on the more than less competitive perennial grass species in all management kinds. The relationship between plant cover and PUE was positive, linear (P <0.0000) and management-kind dependent.
The cell size variations in woody plants in various environments are not well known, and the underlying mechanism has not been fully analyzed. 2. The current study focused on the intraspecific and interspecific size variations in palisade cells occurring in 76 woody species along an elevation gradient (1800–4500 m a.s.l.) on Gongga Montain (1400–7552 m a.s.l.) in southwest China, which included tropical and subtropical genera of broad-leaved forest flora including Salix hyperba as the species occurring on all elevations. We hypothesized that cell size is regulated by alterations in width-length scaling (L-D ratio) to mediate a surface-to-volume ratio (S/V) most suitable for the prevailing environmental conditions. 3. It was observed that cell size co-varied similarly with environmental conditions at the conspecifics, congenerics, and interspecifics levels investigated. Cell sizes decreased among conspecifics, or increase among congenerics and interspecifics via negative or positive scaling of width-length ratio at the cellular level. However, this dichotomously differing tendency may be ecologically constrained by both a cost-increasing and benefit-diminishing mechanism of cell dimension with increasing elevation at the species level, implying a ‘middle way’ strategy for species to stressed environments. 4. The implications of the results for regional floristic evolution are discussed.
Leaf carbon isotope composition (δ13C) of both vascular and non-vascular plants were investigated in order to assess their variability along an altitude gradient (414, 620, 850, 1086,1286 and 1462 m) from a subtropical monsoon forest located at Mt. Tianmu Reserve, eastern China. Leaf δ13C values of all plant species ranged from -34.4 to -26.6‰, with an average of -29.8‰. There is no significant difference in leaf δ13C between vascular plants and mosses, however, trees had significantly higher δ13C values than herbs. For pooled data, leaf δ13C was positively correlated with altitude. Leaf δ13C was significantly and negatively correlated with annual mean temperature and atmospheric pressure, while it was significantly and positively correlated with soil water content. Furthermore, there was no relationship between leaf δ13C and soil nitrogen content or soil phosphorus content. The altitudinal trend in leaf δ13C is the consequence of the interaction between temperature, atmospheric pressure and soil water content.
Fritillaria unibracteata is a classic perennial alpine herb. In this study, we examined it's responses to shading (SH) and nitrogen addition (NA), as well as its correlation with internal C-N balance to detect how it adjusted to the changes of habitat conditions. Randomized block experiment was carried out in the field in Chuanbeimu Research Station in Songpan County, Sichuan Province, China (32°09′54″N, 103°38′36″E, altitude 3300 m a.s.l.). Two growing seasons after NA and SH, Fritillaria unibracteata's total plant biomass decreased significantly, with the proportion of biomass allocated to aboveground significantly increased. In addition, in this study, under both SH and NA treatments, Fritillaria unibracteata increased its biomass allocation to above-ground, which consisted with optimal partitioning theory. Moreover, Fritillaria unibracteata's biomass allocation was significantly correlated with its internal C-N status, regardless of nitrogen and light condition. We conclude that Fritillaria unibracteata optimizes its biomass allocation between root and shoot by adjusting its internal C-N balance, which would not be changed by the specialized resource storage organ-bulb.
Larix chinensis, an endangered and endemic alpine tree, occurs on Mt. Taibai in the Qinling Mountains, China. The extreme sensitivity of this species to climate change makes predicting its future distribution important. Using high-resolution remote-sensing imagery, and the Maxent model, we analysed the current distribution and forecast future distribution of L. chinensis under two climate change scenarios, IPCC A2 and IPCC B2. The results showed that three dominant climatic factors influenced the geographic distribution of L. chinensis: mean annual temperature, mean temperature of the coldest quarter, and precipitation of wettest month. Currently, L. chinensis mainly concentrated at 3100 m and covers an area of 53.52 km2. The population on the southern slope covers approximately twice the area of that on the northern slope; the model simulations indicated that the area of suitable habitat would decrease continually under two climate change scenarios, A2 and B2; the decrease was more obvious in scenario A2, and the range in scenario A2 covers approximately twice the area of that in scenario B2. Under both scenarios, L. chinensis would first be extirpated at lower elevations, and the suitable habitat of this species would move to higher elevations in the Taibai Mountains.
Factors determining the distribution of highly endangered marsh dandelion species in Polish and Estonian coastal grasslands have been investigated. The aim of this study was twofold: (i) to determine which environmental variables are responsible for the vegetation patterns in coastal grasslands with marsh dandelion and (ii) to analyse the ecological spectra of the identified marsh dandelion species. Altogether 51 plots were sampled (in 2013 and 2014). They were used following statistical analysis: DCA, CCA, Spearman's rank correlation test, Kruskal-Wallis test and hierarchical divisive cluster analysis (TWINSPAN). In total, three marsh dandelion species were found in Polish and Estonian coastal grasslands. The only species found in Poland was Taraxacum balticum. In Estonia all three species occur: T. balticum, T. decolorans and T. suecicum. Taraxacum balticum has been found in the widest ranges of all soil properties included, usually on organic, saline, non-carbonate and acid to slightly acid substrate. Taraxacum suecicum and T. decolorans have been found only on mineral, non-saline and slightly alkaline to alkaline substrate. The ecological spectra determined for endangered marsh dandelion species can be used to improve the methods of their protection. Nomenclature: mosses - Ochyra et al. (2003); vascular plants - Mirek et al. (2002).
Decomposition rates and changes of carbon and nitrogen contents of Sphagnum litter in mire vegetation can help to explore the ecological effects of climate change and the role of environmental factors from a local to an ecosystem scale. The objective of the study was to determine the relationship between mentioned parameters in small and isolated Sphagnum dominated mires. Measurements had been conducted throughout a year by placing litterbags filled with Sphagnum biomass in three vegetation types (open peat bog, poor fen, alder carr) of a mire ecosystem in Hungary. Peat decomposition rates differed to a great extent; the slowest decomposition rate (39.1±9.52%) was in the alder carr, indicating that slower decomposition could be characteristic for this kind of vegetation type of mire. Between Sphagnum dominated microhabitats, open peat bog showed medium (65.57±4.05) while poor fen the fastest (68.61±5.5) rates in decomposition. The C/N ratio of the Sphagnum litter showed significant decrease (P <0.005) in all studied micro-environments. Slower N release was observed from litter of Alnus dominated association (31.3±6.9%) compared to Sphagnum dominated ones (56.5±8.3%). Our findings showed that the decomposition rates were more dependent on vegetation type than C/N ratio and this relationship was also revealed at a small spatial scale.
KEYWORDS: change in precipitation pattern, soil C:N:P ecological stoichiometry, increase in atmospheric N deposition, N resorption in leaves, the relative growth rate of plants
Changes in precipitation patterns and the deposition of atmospheric nitrogen (N) increase the possibility of altering soil carbon (C):N:phosphorus (P) stoichiometry through their effects on soil C and nutrient dynamics, especially in water- and N-limited ecosystems. We conducted separate 2-year watering and N addition experiments, and examined soil C:N:P stoichiometry, relative growth rate, and leaf N resorption traits of Glycyrrhiza uralensis Fisch in a desert steppe of northwestern China. Our objectives were to determine how soil C:N:P stoichiometry responded to climate change, and its indications for plant growth and N resorption. The results showed that additional water increased N loss and thus decreased N availability, resulting in high N resorption from senescing leaves of G. uralensis. N addition increased N availability, consequently reducing plant N dependence on leaf resorption. High relative growth rates occurred with intermediate N:P and C:N ratios, while high N resorption occurred with a low N:P ratio but a high C:N ratio. Our results indicate that soil C:N:P stoichiometry also could be a good indicator of N limitation for desert steppe species. Altered soil C:N:P stoichiometry affects the N strategy of plants, and will be expected to further influence the structure and function of the desert steppe community in the near future.
The informative power of species surrogacy with respect to ecological processes and anthropogenic influences has been rarely studied. Thus, five datasets on carabid beetles collected using pitfall traps were analysed in order to study the impact of changing the taxonomic resolution from species to genus level on their indicatory information: a dataset of eight study sites in differently managed habitats sampled in 2013, a dataset tracing successional changes from 2004 to 2013 in a naturally regenerated pine forest, a dataset of three sites on a heap of power plant ashes and a dataset of four sites on a colliery spoil heap, both sampled from 2004 to 2011, and a dataset of six sites along the roadside of a highway being renovated in 2009, sampled in 2008 and from 2010 to 2012. The datasets were analysed by studying correlations of species numbers with genus numbers and species based Shannon diversity with genus based Shannon diversity, testing compliance between species based and genera based similarity matrices, and comparing the information provided by ordination diagrams based on species information or genus information respectively. The results indicate that at least in our study a substantial amount of information provided by species data is still contained in the genus data, but information about fine graded differences between study sites gets lost. We conclude that, even if carabid genus information might be useful in some cases (e.g. preliminary biodiversity assessment), the limitation to higher taxonomic levels like the genus level has to be done with caution.
The paper describes chosen habitat conditions determining the occurrence and nesting of the Little Bittern Ixobrychus minutus and their effect on the nest type (breeding nest BN or mock nest MN). The Little Bittern is a monogamous bird whose male can build a couple of nests during the breeding season. The main questions posed in this work are: (1) what habitat is chosen for the nesting site, and (2) do habitat conditions influence the nest type? The study was carried out in a fishpond complex in the Lasy Janowskie Landscape Park (SE Poland) during the breeding seasons of 2010−2012. All 44 nests (23 BN and 21 MN) were built in a waterside belt of perennial Common Reed Phragmites australis. All nests were built at sites with water depth between 11 and 101 cm. The type of the nest did not depend on the date when it was built during the breeding season. There was a significant difference in the width of the nests between breeding and mock nests. Moreover, obtained results showed a significant influence of the reed belt height and reed stem diameter on the nest type. Further studies on the Little Bittern's nesting habitat, protection of suitable wetlands, and proper water management are important for the conservation of this vulnerable species.
We performed snow tracking of brown bear (Ursus arctos) in the area of the Eastern Carpathians affected by supplementary feeding during the winter periods from 2007 to 2013. On each snow track we recorded all food habits and collected all scats. From these data we calculated occurrence frequency of food habits on snow tracks, occurrence frequency, volumetric proportion and energy values of food items in scats. We revealed that: i) the most frequent food source on snow tracks was corn from supplementary feeding places for ungulates (FOST = 64%); ii) crops for ungulates was the most important food group found in scat samples of bears (EDEC = 61%, EDECST = 53%); iii) the analysis of the inter-seasonal (late autumn, winter and early spring) changes in winter bear diet based on scat analyses revealed decreasing importance of hard mast and fruit, and increasing importance of invertebrates, herbs and wood biomass and crops for ungulates from autumn to spring; iv) bears searched for food at lower elevations in comparison to the location of their beds which are situated at higher elevations. Winter bear activity and bear diet was affected by supplementary feeding for ungulates.
Invasive plants are one of the major treat to local communities and ecosystems in urban habitats. Aster lanceolatus Willd. is one of the most spreading invasive plant species in Serbia and to examine its impact on soil, flora and aboveground biomass in urban habitats we investigated the pH, electrical conductivity and concentration of trace elements (Zn, Cu, Ni, Mn) in four invaded and four uninvaded plots in urban habitats. We also studied floristic composition and floristic richness regarding these invasive plant populations. These parameters were assessed along transects arranged in the cross shape, running from the centre of the invaded area towards the peripheral uninvaded area. Trace elements were analysed using atomic absorption spectrophotometer. Statistical differences were analysed using ANOVA and post-hoc LSD-tests. The results showed an important decrease of the number of species and herbaceous cover under A. lanceolatus populations. There were no statistically significant differences between invaded and uninvaded patches when soil pH and electrical conductivity were considered. The concentration of Zn, Mn and Ni in the soil was higher in invaded areas. The content of Zn in aboveground biomass collected from invaded compare to uninvaded areas was higher. This study raises the possibility that invasive species changes soil characteristics and create conditions for their spreading.
Finding a mate of high quality is of key importance for reproducing birds, and thus positive assortative mating is commonly observed in avian populations. Although assortative mating by age, body size, condition or ornamental traits was reported for many bird taxa, there is a scarcity of empirical evidence for such mating patterns in wildfowl. We studied mating patterns in the Mute Swan Cygnus olor from the Central-European population. We analysed four body measurements (total wing length, forearm length, head length, foot web width) in 91 different breeding pairs. Contrary to our expectations, we found no evidence for assortative mating by any of the collected biometrical measurements and by overall structural size (PC1 from all measured skeletal traits). Further, Mute Swans mated randomly by the size of bill knob, which is considered a sexually selected ornament in this species. We suggest that in the species with long-term pair bonds and monogamous breeding system, such as the Mute Swan, the benefits from large size of mates may be less important for positive reproductive output than other individual traits, e.g., age or previous breeding experience.
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