The influence of altitude and urbanisation on trends and mean dates in phenology (1980–2009)

Long-term studies on urban phenology using network data are commonly limited by the small number of observation sites within city centres. Moreover, cities are often located on major rivers and consequently at lower altitudes than their rural surroundings. For these reasons, it is important (1) to go beyond a plain urban–rural comparison by taking the degree of urbanisation into account, and (2) to evaluate urbanisation and altitudinal effects simultaneously. Temporal phenological trends (1980–2009) for nine phenological spring events centred on the German cities of Frankfurt, Cologne and Munich were analysed. Trends of phenological onset dates were negative (i.e. earlier onset in phenology) for 96% of the 808 time series and significantly negative for 56% of the total number. Mean trends for the nine phenological events ranged between −0.23 days year⁻¹ for beech and −0.50 days year⁻¹ for hazel. The dependence of these trends and of mean dates on altitude and on the degree of urbanisation was explored. For mean dates, we demonstrated an earlier phenological onset at lower altitude and with a higher degree of urbanisation: altitude effects were highly significant and ranged between 1.34 days (100 m)⁻¹ (beech) and 4.27 days (100 m)⁻¹ (hazel). Coefficients for the log-transformed urban index were statistically significant for five events and varied greatly between events (coefficients from −1.74 for spruce to −5.08 for hazel). For trends in phenology, altitude was only significant for Norway maple, and no urban effects were significant. Hence, trends in phenology did not change significantly with higher altitudes or urbanised areas.     

Temporal and spatial distribution of atmospheric Poaceae pollen in Catalonia (NE Spain) in 1996–2001

A preliminary study to compare Poaceae pollen data and to determine possible differences in pollen productivity and/or seasonality was performed at six locations in Catalonia (Spain): Barcelona, Bellaterra, Girona, Lleida, Manresa and Tarragona over a 6-year period (1996–2001). In the study area, Poaceae pollen grains are an important cause of respiratory allergies. Being present in the atmosphere all year round, the grass pollen concentrations are especially significant between May and August. The absolute peak occurs in June, except in Lleida where the peak comes earlier, possibly due to the early flowering of particular steppe species. Even if there are differences between different years, Girona and Lleida (inland locations) usually present the highest annual grass pollen index with, on average, 2177 pollen grains per year. Barcelona and Tarragona (the coastal sites) show the lowest levels, with around 1140 grass pollen grains per year. The respective local climates are very different, and pollen grains may originate in different grass species. A decreasing trend in the Poaceae annual pollen index was found over the period of the present study.     

Spatial–temporal patterns of flowering asynchrony and pollinator fidelity in hybridizing species of Narcissus

Speciation requires the evolution of reproductive barriers to achieve isolation between species. In this paper, we examine the role of two major pre-zygotic barriers in reducing the chance of F₁ hybrid formation between two pairs of Narcissus species. Field experiments were performed over 5?years in eight natural populations to determine whether flowering phenology and pollinator fidelity could act as reproductive isolation barriers in Narcissus. Our results show that reproductive isolation due to flowering phenology is highly variable and asymmetric. In some populations, pollinator fidelity was so strong that the quantification of reproductive isolation was complete and a strong negative correlation was found between the strength of this barrier and the abundance of hybrids. Nevertheless, the degree of pollinator fidelity was quite variable among populations indicating that reproductive isolation varies geographically but very consistent across years indicating that plant-pollinator interactions are well established. In fact, the finding that hybrid formation between these species occurs only in sites where pollinator fidelity is incomplete suggests that hybrid formation also varies geographically and that divergent evolutionary outcomes may occur in different sympatric populations of Narcissus.     

The spatial and temporal patterns of falciparum and vivax malaria in Perú: 1994–2006

Background

Malaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable. Increasing the understanding of the transmission dynamics of falciparum and vivax malaria and their relationship could suggest improvements for malaria control efforts. Here the weekly number of malaria cases due to Plasmodium falciparum (1994–2006) and Plasmodium vivax (1999–2006) in Perú at different spatial scales in conjunction with associated demographic, geographic and climatological data are analysed.

Methods

Malaria periodicity patterns were analysed through wavelet spectral analysis, studied patterns of persistence as a function of community size and assessed spatial heterogeneity via the Lorenz curve and the summary Gini index.

Results

Wavelet time series analyses identified annual cycles in the incidence of both malaria species as the dominant pattern. However, significant spatial heterogeneity was observed across jungle, mountain and coastal regions with slightly higher levels of spatial heterogeneity for P. vivax than P. falciparum. While the incidence of P. falciparum has been declining in recent years across geographic regions, P. vivax incidence has remained relatively steady in jungle and mountain regions with a slight decline in coastal regions. Factors that may be contributing to this decline are discussed. The time series of both malaria species were significantly synchronized in coastal (ρ = 0.9, P < 0.0001) and jungle regions (ρ = 0.76, P < 0.0001) but not in mountain regions. Community size was significantly associated with malaria persistence due to both species in jungle regions, but not in coastal and mountain regions.

Conclusion

Overall, findings highlight the importance of highly refined spatial and temporal data on malaria incidence together with demographic and geographic information in improving the understanding of malaria persistence patterns associated with multiple malaria species in human populations, impact of interventions, detection of heterogeneity and generation of hypotheses.     

Flowering phenology and airborne pollen grains of chosen tree taxa in Rzeszów (SE Poland)

The aim of the study was to compare the courseof flowering and the occurrence of Alnus,Corylus and Betula pollen grains inthe air in 1999–2001. In 2000 and 2001 birchesflowered in a typical way – the floweringperiod was short and intense and that periodhad the highest concentration of pollen. Bothyears had no rainfall then and the temperaturewas high, which caused intense flowering ofbirches over a large area. In 1999 and 2000most of the Alnus and Coryluspollen was recorded at the end or after theirflowering period. At that time the weather wasunstable (as is usual in February and March).Pollen must have been transported fromelsewhere. Wind analysis showed that the mainsources of Corylus pollen must have beenin the south, and of Alnus in the southand west. In the southern margin of Poland thevegetative period begins later due to a colderclimate.     

Lowland river reference condition: spatial and temporal patterns of the zoobenthos community in the Volga headwaters (2006–2010)

The Volga, the largest river in Europe, has experienced multiple stressors from human activities. Recently we showed that its upper course (about 500 km, from its source to Tver) still has large sections with low impact and a natural type-specific potamal flora and fauna. Our present research in the East European lowlands aim to define reference conditions for mid-sized to large lowland rivers in order to build a basis for future management and conservation. Three monitoring sites were selected based on the results from intensive sampling in 2005. In subsequent field campaigns between 2006 and 2010 regular surveys were carried out each year in summer and additional ones in spring. A taxon-rich macroinvertebrate fauna, including several rare potamal relict species, was recorded and the data was used to provide an overview of annual and interannual variation in community indices and metrics. The conditions described for the headwaters of the Volga River system can be used as a reference state for medium-sized and large lowland rivers in regions where reference sites of these types are lacking.     

Shrub (Prosopis velutina) encroachment in a semidesert grassland: spatial–temporal changes in soil organic carbon and nitrogen pools

Recent trends of increasing woody vegetation in arid and semiarid ecosystems may contribute substantially to the North American C sink. There is considerable uncertainty, however, in the extent to which woody encroachment alters dryland soil organic carbon (SOC) and total nitrogen (TN) pools. To date, studies assessing SOC and TN response to woody plant proliferation have not explicitly assessed the variability caused by shrub age or size and subcanopy spatial gradients. These factors were quantified via spatially intensive soil sampling around Prosopis velutina shrubs in a semidesert grassland, using shrub size as a proxy for age. We found that bulk density increased with distance from the bole (P < 0.005) and decreased with increasing shrub size (P= 0.056), while both SOC and TN increased with shrub size and decreased with distance from the bole (P < 0.001 for both). Significant (and predictable) spatial variation in bulk density suggests that use of generic values would generate unreliable estimates of SOC and TN mass, and subcanopy SOC pools could be overestimated by nearly 30% if intercanopy bulk density values were applied to subcanopy sites. Predictive models based on field-documented spatial patterns were used to generate integrated estimates of under-shrub SOC and TN pools, and these were compared with results obtained by typical area-weighting protocols based on point samples obtained next to the bole or at a specified distance from the bole. Values obtained using traditional area-weighting approaches generally overestimated SOC pools relative to those obtained using the spatially integrated approach, the discrepancy increasing with increasing shrub size and proximity of the point sample to the bole. These discrepancies were observed at the individual plant scale and for landscapes populated by various shrub size classes. Results suggest that sampling aimed at quantifying shrub encroachment impacts on SOC and TN pools will require area-weighting algorithms that simultaneously account for shrub size (age) and subcanopy spatial patterns.     

Airborne pollen characteristics and the influence of temperature and precipitation in Raleigh,North Carolina,USA (1999–2012)

The incidence of allergic diseases has been increasing in recent decades, in part due to increased exposure to aeroallergens, particularly pollen. Allergic diseases have a major burden on the health care system, with annual costs in the USA alone exceeding $30 billion. There is evidence that the production of aeroallergens, including pollen, is increasing in response to environmental and climatic change, which has important implications for the treatment of allergy sufferers. In this study, pollen data from a Rotorod sampler in Raleigh, North Carolina, was used to characterize and examine trends in the atmospheric pollen seasons for trees, grasses, and weeds over the period 1999–2012. The influence of mean monthly antecedent and concurrent temperature and precipitation on the timing, duration, and severity of the pollen seasons was assessed using Pearson’s product-moment correlation coefficients and multiple linear regression models. An increasing trend was noted in seasonal tree pollen concentrations, while seasonal and peak weed pollen concentrations declined over time. The atmospheric pollen seasons for grasses and weeds trended toward earlier start dates and longer durations, while the tree pollen season trended toward an earlier end date. Peak daily tree pollen concentrations were strongly associated with antecedent temperature and precipitation, while peak daily grass pollen concentrations were strongly associated with concurrent precipitation. The strongest relationships between climate and weed pollen were associated with the timing and duration of the pollen season, with drier antecedent and warmer concurrent conditions tied to longer weed pollen seasons.     

Increasing frost risk associated with advanced citrus flowering dates in Kerman and Shiraz,Iran: 1960–2010

Flowering dates and the timing of late season frost are both driven by local ambient temperatures. However, under climatic warming observed over the past century, it remains uncertain how such impacts affect frost risk associated with plant phenophase shifts. Any increase in frost frequency or severity has the potential to damage flowers and their resultant yields and, in more extreme cases, the survival of the plant. An accurate assessment of the relationship between the timing of last frost events and phenological shifts associated with warmer climate is thus imperative. We investigate spring advances in citrus flowering dates (orange, tangerine, sweet lemon, sour lemon and sour orange) for Kerman and Shiraz, Iran from 1960 to 2010. These cities have experienced increases in both T _max and T _min, advances in peak flowering dates and changes in last frost dates over the study period. Based on daily instrumental climate records, the last frost dates for each year are compared with the peak flowering dates. For both cities, the rate of last frost advance lags behind the phenological advance, thus increasing frost risk. Increased frost risk will likely have considerable direct impacts on crop yields and on the associated capacity to adapt, given future climatic uncertainty.     

Temporal–spatial variation and source analysis of carbon and nitrogen in a tidal wetland of Luoyuan Bay

Carbon and nitrogen are important elements in biogeochemical studies of tidal wetlands. Three wetland zones in Luoyuan Bay in the Fujian province were chosen for this study; the Spartina alterniflora flat zone with Spartina alterniflora growing, the silt zone with no Spartina alterniflora growing and the Spartina alterniflora-silt flat zone – a transition zone between the two. The spatial and seasonal variations of total organic carbon (TOC), total nitrogen (TN), stable isotopes of organic material (δ¹³C, δ¹⁵N), C/N ratio, average particle size and sediment composition in surface and vertical sediments of different ecological zones were analyzed. Carbon and nitrogen accumulation and particle size effects in the different ecological zones were discussed and the indicators of δ¹³C and C/N ratios were also compared. TOC, TN, δ¹³C contents, C/N ratios, and average particle size varied within the ranges of 0.611–1.133%, 0.053–0.090%, ?22.60 to ?18.92‰, 12.3–15.7, and 6.4–8.7 μm, respectively. Sediments were mainly silt-sized. Besides δ¹⁵N values, the other parameters, such as TOC, TN, δ¹³C contents, C/N ratios, and average particle size showed an obvious zonal distribution in surface sediments. The distribution of TOC and TN contents reflected the distribution of Spartina alterniflora within the bay. The profile and seasonal variations of these parameters in different ecological zones indicated that variations in the Spartina alterniflora flat and transition zones were complex because of the effect of Spartina alterniflora. Vertical and seasonal variations were sampled in the silt flat area. The profile and seasonal variations of TOC, TN and δ¹³C were similar in the transition zone and the Spartina alterniflora flat zone. Seasonal concentrations of TOC, TN and δ¹³C decreased from autumn > spring > winter > summer. The seasonal variation of carbon and nitrogen in the sediments may be influenced by temperature, particle size, plankton and benthos. The particle size effect was significant in the surface sediments and profile sediments of the transition zone. However, other factors had a greater effect on the distributions of TOC and TN in the Spartina alterniflora flat and silt flat zones. C/N ratios in sediments of the Spartina alterniflora flat, transition zone and silt flat were close to or > 12, indicating that the organic material source was dominated by terrestrial inputs. However, δ¹³C values decreased from the Spartina alterniflora flat zone > transition zone > silt flat zone indicating that the organic material source was predominantly from marine inputs. Thus the indications from C/N ratios and δ¹³C were different. There was no clear relationship between C/N ratios and δ¹³C values and a better relationship between δ¹³C values and TOC concentrations suggested that δ¹³C values provided a better indication of the organic source. Limited amounts of organic material came from Spartina alterniflora. This study has provided basic data for researching biogeochemical processes of biogenic elements in tidal wetlands and vegetation restoration, and has also provided a reference for assessing and protecting the environment and ecological systems in wetlands.     

Airborne pollen of Ambrosia in Burgundy (France) 1996–1997

Pollen counts in Burgundy were monitored by means of four Hirst volumetric traps. Their analysis revealed a sharp rise of Ambrosia from 1996 to 1997. The minimum amount of ragweed pollen likely to provoke allergies (13 grains m–3) was reached or exceeded several days every year, but without leading to clinical symptoms. The circadian variation of Ambrosia pollen showed two peaks: the first one in the morning was suggested to coincide with local pollination, although the second one, in the afternoon, seemed to result from a long range transport which was confirmed by the study of wind roses.     

Philopatry, nest choice, and aggregation temporal–spatial change in the digger wasp Cerceris arenaria (Hymenoptera: Crabronidae)

Studying temporal and spatial changes of aggregations of digger wasps through nesting seasons is interesting because of its link to social evolution via a semi-social pathway, but information about this topic is scarce. An aggregation of Cerceris arenaria Latreille was studied during 1997–1999 and for a short period in 2001. The colony grew in area and number of nests through the first three seasons, but the aggregation reduced in 2001, and this decrease was confirmed by a count of nests made in 2003 and 2005. The positions of the nest entrances remained almost constant over the years, at least in high-nest-density areas, because of the repeated use of the same burrows from which they emerged. This fact permits the population to exploit for many years a restricted area and could act as a nest-density-regulation method for fossorial species that rarely dig new nests, preventing an excessive nest density. The newly emerged females did not dig new nests, showed a high philopatry in the choice of their first nest, and preferred to look for other nests to occupy close to the ones recently abandoned (mainly for an undergone usurpation by a conspecific female). Philopatry, along with lack of new nest digging and position-dependent nest choice, is probably an important factor maintaining spatial stability of the aggregation through the years and could represent a first step in the evolution of a higher sociality in apoid burrowing Hymenoptera.     

Short term spatial — temporal distribution patterns of zooplankton in Admiralty Bay (Antarctica)

The present work analyses the abundance and species composition of mesozooplankton in relation to different patterns of wind speed and tides in Admiralty Bay. The plankton was sampled on 12, 13 and 15 March 1989 with a 385 m mesh size conical-cylindrical net by R.V. Barão de Teffé. In Martel Inlet, the zooplankton standing stock reached 25,223 individuals 100 m^–3 during the high tide. Under north-west winds, the abundance of the dominant species Ctenocalanus citer and Fritillaria borealis followed the tidal cycle. Weak south-west winds promoted the input of plankton even during low tide. Throughout the Bay, the highest densities of plankton (446–2,899 individuals 100 m^–3) were observed in surface waters flowing towards the Bransfield Strait. Surface waters flowing through the Bay and the inlets showed different species composition to surface waters flowing towards the Bransfield Strait.     

Comparative study of airborne pollen counts located in different areas of the city of Córdoba (south-western Spain)

Airborne pollen counts are mainly determined using a volumetric suction sampler based on the impact principle, that is, a Hirst-type spore trap. As a consequence of their volumetric nature, samplers detect pollen from a wide area, and therefore, a single sampler is frequently used to acquire information on airborne pollen counts for the whole city. The main goal of the present study was to compare airborne pollen counts at two sites located at opposite ends (south-west vs. north-east) of the southern Spanish city of Córdoba, to assess the advantages and disadvantages of using more than one sampler in the city. Also, a comparative study was carried out using two samplers at the same site, in order to confirm the efficiency of the samplers. Results revealed that data from one volumetric sampler—located within a city of medium size with uniform topography and vegetation conditions—are sufficient to establish monitoring of the main airborne pollen types, the pollen seasons involved and the timing of peak counts. For clinical studies, however, data on pollen counts in specific areas of the city may be of value, since pollen intensity may vary from one district to another, mainly in the case of ornamental plants with a local distribution inside the city. Comparison of data obtained by the two samplers running at the same site indicated that potential inter-site differences could not be attributed to differences in sampler efficiency.     

The spatial–temporal pattern changes of the red crowned crane (Grus japonensis) population in Zhalong NNR and the related driving forces

Understanding spatio-temporal distribution patterns of a species is essential to successful species and habitat conservation. The fluctuations of the red crowned crane population were studied after collecting the data about breeding red-crown cranes from Zhalong National Natural Reserve (Zhalong NNR) since 1981; and their spatial distribution patterns were also quantified in variant time periods with the method nearest neighbor analysis (NNA); the main factors leading to the dynamics of the bird population were analyzed. The results showed the red-crown crane population had fluctuated dramatically from 1981 to 2005. The number dropped rapidly to the minimum of the bird population to endanger the existence of the population by the year of 2005. And the spatial distribution pattern changed from uniform distribution to aggregated distribution during 1996–2005. These changes reflected that the distributions of habitats had undergone a process of fragmentation, and the area of the suitable habitats suffered such a continuous loss that there were insufficient habitats to sustain the bird population any more. And consequently, the decline of the bird population occurred. The wildfire and the anthropogenic activities were the driving forces which accounted for the degradation of the habitats and hereafter the fluctuations of the red-crown population.     

Pollen–pistil relationships and pollen size-number trade-off in species of the tribe Lycieae (Solanaceae)

Pollen volume may be involved in different associations with other floral traits. Particularly, the literature indicates that pollen volume can be implicated in a functional relationship with pistil length, and that it may be affected by a trade-off with pollen number because of the subdivision of limited resources. To assess these associations, pollen volume was subjected to correlation analyses with pollen number and pistil length in 20 Argentinean and Chilean taxa of the monophyletic tribe Lycieae. Depending on the mechanisms operating on pollen size and number, the variability of these traits may be different. Therefore, their coefficients of variation were compared. Pistil length and pollen volume showed a strong positive correlation. In contrast, pollen grain size and number were significantly correlated at neither inter- nor intraspecific levels. Results suggest that pollen size and pistil length may co-evolve. The central role of this interaction is discussed. The lack of a correlated variation in pollen size and number may be related to the similar constraints experienced by the species and/or because constraints are operating at the plant level and not at the species level. Lower variance in pollen size compared with pollen number denotes that pollen size may be the main trait subjected to natural selection. Electronic Publication     

The spatial–temporal pattern changes of the red crowned crane (Grus japonensis) population in Zhalong NNR and the related driving forces

Understanding spatio-temporal distribution patterns of a species is essential to successful species and habitat conservation. The fluctuations of the red crowned crane population were studied after collecting the data about breeding red-crown cranes from Zhalong National Natural Reserve (Zhalong NNR) since 1981; and their spatial distribution patterns were also quantified in variant time periods with the method nearest neighbor analysis (NNA); the main factors leading to the dynamics of the bird population were analyzed. The results showed the red-crown crane population had fluctuated dramatically from 1981 to 2005. The number dropped rapidly to the minimum of the bird population to endanger the existence of the population by the year of 2005. And the spatial distribution pattern changed from uniform distribution to aggregated distribution during 1996–2005. These changes reflected that the distributions of habitats had undergone a process of fragmentation, and the area of the suitable habitats suffered such a continuous loss that there were insufficient habitats to sustain the bird population any more. And consequently, the decline of the bird population occurred. The wildfire and the anthropogenic activities were the driving forces which accounted for the degradation of the habitats and hereafter the fluctuations of the red-crown population.     

Annual pollen spectrum variations in the air of Bratislava (Slovakia): years 2002–2009

Pollen grains in the atmosphere of Bratislava were quantitatively and qualitatively analysed during an 8-year period (2002–2009) using a Burkard volumetric pollen trap. The mean annual total pollen grain count recorded during this period was 36,608, belonging to 34 higher plant taxa (22 trees and/or shrubs and 12 herbaceous species). The maximum annual total pollen grain count (50,563) was recorded in 2003 and the minimum (14,172) in 2009. The taxa contributing the highest concentration of pollen grains were Betula, Urticaceae, Cupressaceae-Taxaceae, Populus, Pinus, Poaceae and Ambrosia. During the study period, there was a remarkable increase in the number of pollen grains from February to April, with the highest daily mean pollen counts recorded in April. Total pollen concentration began to decrease markedly in May, but there was a second increase between July and August, followed by a decrease in September. The timing and length of the pollen seasons varied. Betula and Poaceae showed a rather constant 2-year fluctuating rhythm. The relationships between airborne pollen concentration and meteorological variables were assessed. Based on these results, the first pollen calendar in Slovakia has been constructed for the area of Bratislava, which provides a great deal of useful and important information.