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Moss crusts are the highest developmental stage of biological crusts in arid and semiarid ecosystems worldwide. Under natural conditions, elementary functional units of moss crusts are patches. However, to date, the quantitative features, distribution pattern, ecological effect and relationship with environmental factors of moss patches in desert ecosystems remain unclear. In this study, 3303 moss patches in 22 plots and relevant environmental variables were investigated and quantified in the Gurbantunggut Desert, China. Thirty-six patch classes were defined. Moss crusts accounted on average for 11.7% of the plot area, and the mean moss patch area was 23.4 cm2. Small patches dominated, indicating a serious fragmentation of moss crusts. Significant density-dependent effects between patch density and size, humped relationships between patch size and moss plant density, and soil water content under moss patches were observed. The overall distribution of moss crusts showed a tendency of moss patch size and moss plant density decreasing from the southeastern part of the desert to the northwestern part, while moss patch density showed the opposite trend. Pearson's correlation analysis and nonmetric multidimensional scaling analysis consistently demonstrated that the distributions of moss patches were dominantly influenced by non-moss crust coverage, sand particle size, latitude, mean annual precipitation (MAP) and mean annual temperature. Of these parameters, fine sand, high MAP and low latitude were beneficial to the development of moss crusts. Consequently, the factors influencing the distribution pattern of moss crusts are complex and contain the soil factor, current climatic conditions and natural and human disturbances.
Soil respiration plays a crucial role in global carbon cycling of terrestrial ecosystems. Changes in atmospheric CO2 and nitrogen (N) addition across the globe are likely to affect soil respiration. However, the effects of elevated CO2, and N addition on soil respiration are not fully understood especially in wetland ecosystems. To evaluate the effects of atmospheric CO2 and N availability on soil respiration, a paired, nested manipulative in situ experiment was performed, using CO2 fumigation within Open-Top Chambers as the primary factor, and N (as NH4NO3) as the secondary factor in a temperate wetland in northeastern China in 2010 and 2011. CO2 fumigation significantly enhanced soil respiration, according to repeated-measures ANOVA, and the stimulatory effect of CO2 fumigation on soil respiration was sustained during the whole experimental period regardless of N addition. However, the positive soil respiration effect of N addition alone weakened over time. Moreover, there was a significant interaction between CO2 fumigation and N addition. Soil temperature explained 50–66% of the variation in soil respiration. Moreover, soil respiration was positively correlated with the root N content and litter decomposition rate. The results suggested that elevated CO2 concentrations will accelerate soil respiration and ecosystem carbon cycling, thus, limiting soil carbon sequestration, especially when coupled with increasing N deposition.
Study of the radial growth response to climate factors at different tree ages is essential for predicting forest dynamics and formulating correct management policies. In this study, we analysed the growth responsiveness of Picea crassifolia to climate conditions, and evaluated its relationship to tree age at the individual tree scale, in the transitional zone between regions affected by the East Asian monsoon and winds blowing from the west (westerlies) in the Qilian Mountains. On three study sites, 150 cores were taken from 75 trees. Pearson correlation coefficients were calculated between the standardized tree-ring series of each core (and chronology) and climatic factors which were utilized to research the climate-growth relationships. Quadratic polynomial fitting was used to test the relationships between tree age, chronological parameters, and the radial growth response to climate. Radial growth was positively influenced by total precipitation for the previous July-September and the current May-July. Additionally, radial growth was negatively correlated with the total monthly precipitation for the current September, and the mean monthly temperature for the previous July. Trees younger than 80 years old showed a stronger response to accumulative precipitation in the previous July-September, those older than 160 years old showed a stronger response to precipitation at the end of current growing season, while those of 140–160 years old showed a weaker response to precipitation in the current May-July.
Liparis loeselii (L.) Rich. is an endangered orchid species which occurs in wetland habitats. For successful conservation of this orchid it is necessary to recognize its adaptive traits and special habitat requirements. Therefore, we examined morphological and anatomical traits in relation to the water level, cover of vascular plants and seed viability of L. loeselii in habitats with different water level fluctuations. Field studies of L. loeselii were carried out in nine localities and four habitat types: alkaline fen, calcareous fen with Cladium mariscus, transition mire and quaking bog. The fluctuations of seasonal water level were defined in the range from dry substrate to short time flooding (up to two weeks). Leaf length and width of 30 flowering specimens of L. loeselii as well as angle between the leaf blade and the axis of the inflorescence were measured at each locality. Seed viability and root anatomy were examined in the laboratory. The leaf angle was significantly affected (P < 0.05) by water level in the studied habitat. The leaf length to width ratio in each population of L. loeselii did not show significant differences between the years, but was characteristic for the habitat type. L. loeselii sensitivity to the long-term flooding in the habitat is associated with a lack of aerenchyma in its roots. During short-term flooding specimens of L. loeselii can survive due to a shallow root system and hyponastic leaf movements. As evidenced by seed viability, the most favourable growth conditions for L. loeselii are in the habitats with partially water saturated substrate with balanced water supply.
Post-industrial sites form a unique phenomenon in the landscape. They enable us to study the human-altered succession of communities. Regarding this, we studied an ant community in three types of habitats – reclamation and spontaneous succession in an ore basin together with unaltered surroundings in the Czech Republic. More than 30 years after being abandoned, the site with spontaneous succession was more species rich than the reclaimed one. Moreover, spontaneous succession created a habitat that was more similar regarding ant diversity to the unaltered surrounding environment than that after traditional reclamation. Ants dependent on tree vegetation were rather rare in both the reclaimed and spontaneous succession parts of the ore basin compared to the surrounding landscape. The relative abundance of socially parasitic ants increases in a gradient from the reclaimed basin, through the basin with spontaneous succession to the unaltered surroundings. Our study highlighted the fact that the formation of ant communities at post-industrial sites is clearly more complicated than for other arthropods, including related aculeate hymenopterans. The potential of both reclaimed and spontaneous succession basins for harbouring endangered species appeared to be lower for ants than for other taxa indicated by recent studies.
An increasing urbanization of habitats in which birds live influences their populations by modifying behaviour, dietary composition, causes of mortality and variables related to breeding. This study aimed to compare breeding periods and productivity among tawny owls, Strix aluco, inhabiting either an urban or an extra-urban area. Studies were conducted in parallel in two locations: central zone of Warsaw – the Polish capital – and the Rogów Forest – ca 70 km west of Warsaw. Number of fledglings and the beginning of the breeding period was assessed by direct observations and listening to calls of juveniles within tawny owl territories. Birds in the urban area were found to start breeding significantly earlier (from 5th February) than those in the extra-urban area (from 17th March). However, the two populations proved to be similarly productive, with 3.2 or 3.4 young per nest on average. The phenomenon of early breeding in city dwelling birds was confirmed in other tawny owl populations as well as other bird species. It can be potentially driven by factors such as higher temperature, artificial light and rich and stable food base.
We assessed the assemblages of birds inhabiting pine-dominated managed forest, aged between 1–5 years and above 140 years. Birds were counted on study plots representing eight different phases to the forest's development, with nesting, foraging and migratory guild categories recognised. Numbers of bird species and population densities, both increased markedly with stand age (respectively r = 0.988 and r = 0.936, P < 0.001). While numbers of ground-nesting bird species failed to correlate with stand age, successively older stands did support ever-greater proportions of species in the assemblage that nested in tree crowns (r = 0.976, P < 0.005) or tree holes (r = 0.833, P < 0.005). Raptors were most abundant in forest at the oldest stages of growth, and there was an age-gradient-related increase in the shares of both plant-eating species (r = 0.952, P < 0.005) and raptors (r = 0.764, P < 0.005). Resident birds were most numerous in the oldest forest. PCA for ten selected variables (relating to guild type) showed that the two principal components explained almost 98% of the variation among groups of bird guilds in relation to forest age. On the basis of their suitability for birds it was possible to distinguish three categories of stand by age group, of which the first encompasses the initial stage, the second a broad interval involving middle-aged stands of between 16 and 140 years, and the third forest more than 140 years old. The presence of the oldest stands of all can thus be seen to play a very important role in maintaining high-diversity populations of birds in managed forest.
Alpine accentors (Prunella collaris) and dunnocks (P. modularis) are closely related species of Prunellidae, which often breed in polygynandrous groups and have specific types of mating behaviour. The alpine accentor lives at high altitudes, in an extreme alpine environment; the dunnock is widely dispersed from lowland to tree line in the mountains. Both species are hosts of the related species of wing lice Philoptersus emiliae and Ph. modularis, respectively. Behavioural differences between these two host species may have resulted in different breeding and seasonal adaptations by their parasites. The main goal of this paper was to test this hypothesis. Sixty five alpine accentors Prunella collaris (Scopoli, 1769) and eighty four dunnocks Prunella modularis (Linnaeus, 1758) were examined for Ischnocera lice in the West Carpathians, Slovakia from 1988 to 2001, and from 2007 to 2010, respectively. Birds were found to be infested with two species of Ischnoceran lice: the parasite species are not competing as they each have their own host Philopterus emiliaeBalát, 1955/P. collaris and Philopterusmodularis (Denny, 1842) /P. modularis. Significant differences in abundance and prevalence existed between these two species of lice. High number of Ph. modularis nymphs in the comparison to Ph. emiliae nymphs reflects the different ecological, behavioural and phylogenetic trajectories of their host bird species. This work is the first to assess the louse breeding strategies on two closely related bird species in the high mountain environment.
This study evaluates and compares habitat preferences and spatial niche breadth and overlap between two sympatrically occurring species, the sand cat (Felis margarita) and Rüppell's fox (Vulpesrueppellii), in a desert landscape of central Iran. A field survey from 2014 to 2016 was conducted to collect occurrence points for the two species as well as to identify their structural characteristics of used habitats in the occurrences points. Jacobs' index as a measure of habitat preference, Shannon and Levins' indices as measures of niche breadth, MacArthur, Levins and Pianka's indices as measures of niche overlap were calculated and interpreted. The results of this study showed that the sand cats are specifically restricted to sand dune and sabulous habitat type, whereas Rüppell's foxes have wider ecological amplitude. Sand cats only prefers sand dunes while Rüppell's foxes were found to prefer foothills, badlands, and sand dunes. Rüppell's foxes therefore had a wider niche breadth compared to the sand cats. The asymmetric MacArthur and Levins indices yielded a higher value of niche overlap for the sand cats compared to Rüppell's foxes, while the symmetric Pianka's measure of niche overlap was relatively high for both species. Such habitat preference and niche segregation between the two species may be a result of their feeding habits or the physical protective structure of their habitats attributes.
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