Halo-nitrophilous scrub species and their relationship to the atmospheric concentration of allergenic pollen: case study of the Mediterranean saltbush (Atriplex halimus L., Amaranthaceae)

Halo-nitrophilous scrubs are characterised by their floristic richness in species of the family Amaranthaceae (include Chenopodiaceae) and the Mediterranean saltbush (Atriplex halimus L.) is one of the most characteristic species in the Mediterranean region. Pollen from Amaranthaceae is the main cause of pollinosis at the end of summer and autumn. In this study, the floral phenology of the species Atriplex halimus L., was studied relating it to the atmospheric concentration of Amaranthaceae pollen with the aim to know if it can serve as an indicator of the maximum pollen concentrations. Observations of the male floral phenology of Atriplex halimus were performed over the course of three years in the central Iberian Peninsula (Spain) and the aerobiological pollen data of Amaranthaceae were obtained using a Hirst-type volumetric trap. The results demonstrated that the flowering period of Atriplex halimus closely coincided with the peak pollen levels. Besides, the prevailing movements of air masses in relation to the distribution and abundance of the halo-nitrophilous scrub during the flowering period of Atriplex halimus were studied using a back-trajectory analysis. The results showed that distinct predominant wind patterns led to differences in the quantity of pollen recorded during the pollen season and in the behaviour of the evolution of airborne pollen concentrations.     

Long distance pollen transport cause problems for determining the timing of birch pollen season in Fennoscandia by using phenological observations

The male flowering and leaf bud burst of birch take place almost simultaneously, suggesting that the observations of leaf bud burst could be used to determine the timing of birch pollen release. However, long‐distance transport of birch pollen before the onset of local flowering may complicate the utilization of phenological observations in pollen forecasting.

We compared the timing of leaf bud burst of silver birch with the timing of the stages of birch pollen season during an eight year period (1997–2004) at five sites in Finland. The stages of the birch pollen season were defined using four different thresholds: 1) the first date of the earliest three‐day period with airborne birch pollen counts exceeding 10 grains m^?3 air; and the dates when the accumulated pollen sum reaches 2) 5%; 3) 50% and 4) 95% of the annual total. Atmospheric modelling was used to determine the source areas for the observed long‐distance transported pollen, and the exploitability of phenological observations in pollen forecasting was evaluated.

Pair‐wise comparisons of means indicate that the timing of leaf bud burst fell closest to the date when the accumulated pollen sum reached 5% of the annual total, and did not differ significantly from it at any site (p<0.05; Student‐Newman‐Keuls test). It was found that the timing of leaf bud burst of silver birch overlaps with the first half of the main birch pollen season. However, phenological observations alone do not suffice to determine the timing of the main birch pollen season because of long‐distance transport of birch pollen.     

不同来源地同种植物种群间物候期比较研究

通过比较西双版纳植物园内雨树和甜菜豆不同大洲来源种群间的物候期,本研究探讨了两种植物种群间的物候分化现象及其与气候因子的关系。结果发现:(1)两种植物不同来源地种群间物候期相似,但是同步性不高,呈现明显的分化现象,且不同种群间萌叶起始期先后顺序差异显著;(2)不同种群间物候期同步系数与气候因子相关,尤其干季气候因子。因此可以认为:不同的生境气候因子是导致两种植物不同种群间出现物候变异的重要因子,并且这种关系可能会影响不同种群对气候变化的响应。     

Radiation-constrained boundaries cause nonuniform responses of the carbon uptake phenology to climatic warming in the Northern Hemisphere

Climatic warming has lengthened the photosynthetically active season in recent decades, thus affecting the functioning and biogeochemistry of ecosystems, the global carbon cycle and climate. Temperature response of carbon uptake phenology varies spatially and temporally, even within species, and daily total intensity of radiation may play a role. We empirically modelled the thresholds of temperature and radiation under which daily carbon uptake is constrained in the temperate and cold regions of the Northern Hemisphere, which include temperate forests, boreal forests, alpine and tundra biomes. The two-dimensionality of the temperature-radiation constraint was reduced to one single variable, θ, which represents the angle in a polar coordinate system for the temperature-radiation observations during the start and end of the growing season. We found that radiation will constrain the trend towards longer growing seasons with future warming but differently during the start and end of season and depending on the biome type and region. We revealed that radiation is a major factor limiting photosynthetic activity that constrains the phenology response to temperature during the end-of-season. In contrast, the start of the carbon uptake is overall highly sensitive to temperature but not constrained by radiation at the hemispheric scale. This study thus revealed that while at the end-of-season the phenology response to warming is constrained at the hemispheric scale, at the start-of-season the advance of spring onset may continue, even if it is at a slower pace.     

Flowering plant phenology and weather in Alberta,Canada

Plant phenology can be used for biomonitoring climate change. The flowering of certain temperate zone plant species occurs in response to accumulated heat. Networks of observers presently provide data on the timing of the growth of native and crop plants to Agro-meteorological Departments in Europe and the United States. In Alberta, a phenological survey which began in 1987 records flowering times for 15 native plants, with about 200 volunteers contributing observations annually. Six years of data have been summarized and correlated with temperature measurements. The Alberta phenological data can provide a key to sound decision-making in two ways: by providing proxy data on key variables to which vegetation responds, and by providing a model for transforming simple weather data into biologically meaningful zones.     

Utilization of aerobiological,phenological and phytogeographical data in allergology

Summary The practical aim of our research work was to point out the advantages of a deeper knowledge of botanical data in allergology. Aerobiological monitoring is not enough for an analysis of the formation and development of pollen rain. The following emphasizes the importance of interdisciplinary studies in the approach to the pollinosis problem: — A phytogeographical study in the area investigated has made it possible a) to ascertain the correlation between aerobiological and phytogeographical data and to understand the reasons of some of the discordances, b) to select an allergen panel for testing including pollens of species peculiar to that particular region; a more accurate appreciation of the distribution of different allergenic pollen source areas in the light of local meteorological conditions, will be an excellent guideline for the interpretation and prediction of symptoms in allergic patients. — A phenological checking of the flowering period on location for allergenic species in the area next to the sampling station has made it possible to assess the flowering interval and peak for each species and to attribute the responsibility for the pollen and symptom peaks to a particular species within the same family at a specific moment. The above data are the basis and sometimes the only support available for the interpretation of aerobiological data.     

The phenology of Guyanese timber species: a compilation of a century of observations

Flowering and fruiting of timber trees have been recorded in Guyana for over a century. Although the data are dispersed over a large number of non-consecutive years, from 1887 until 1989, they give a very good estimate of the probability of a species being in flower or fruit in a certain month. Flowering seems correlated with peak sunshine, while fruiting is related to maximum rainfall.     

Three‐dimensional change in temperature sensitivity of northern vegetation phenology

Understanding how the temperature sensitivity of phenology changes with three spatial dimensions (altitude, latitude, and longitude) is critical for the prediction of future phenological synchronization. Here we investigate the spatial pattern of temperature sensitivity of spring and autumn phenology with altitude, latitude, and longitude during 1982–2016 across mid‐ and high‐latitude Northern Hemisphere (north of 30°N). We find distinct spatial patterns of temperature sensitivity of spring phenology (hereafter “spring S_T”) among altitudinal, latitudinal, and longitudinal gradient. Spring S_T decreased with altitude mostly over eastern Europe, whereas the opposite occurs in eastern North America and the north China plain. Spring S_T decreased with latitude mainly in the boreal regions of North America, temperate Eurasia, and the arid/semi‐arid regions of Central Asia. This distribution may be related to the increased temperature variance, decreased precipitation, and radiation with latitude. Compared to spring S_T, the spatial pattern of temperature sensitivity of autumn phenology (hereafter “autumn S_T”) is more heterogeneous, only showing a clear spatial pattern of autumn S_T along the latitudinal gradient. Our results highlight the three‐dimensional view to understand the phenological response to climate change and provide new metrics for evaluating phenological models. Accordingly, establishing a dense, high‐quality three‐dimensional observation system of phenology data is necessary for enhancing our ability to both predict phenological changes under changing climatic conditions and to facilitate sustainable management of ecosystems.     

Climate controls on vegetation phenological patterns in northern mid- and high latitudes inferred from MODIS data

Recent studies using both field measurements and satellite-derived-vegetation indices have demonstrated that global warming is influencing vegetation growth and phenology. To accurately predict the future response of vegetation to climate variation, a thorough understanding of vegetation phenological cycles and their relationship to temperature and precipitation is required. In this paper, vegetation phenological transition dates identified using data from the moderate-resolution imaging spectroradiometer (MODIS) in 2001 are linked with MODIS land surface temperature (LST) data from the northern hemisphere between 35°N and 70°N. The results show well-defined patterns dependent on latitude, in which vegetation greenup gradually migrates northward starting in March, and dormancy spreads southward from late September. Among natural vegetation land-cover types, the growing-season length for forests is strongly correlated with variation in mean annual LST. For urban areas, the onset of greenup is 4–9 days earlier on average, and the onset of dormancy is about 2–16 days later, relative to adjacent natural vegetation. This difference (especially for urban vs. forests) is apparently related to urban heat island effects that result in both the average spring temperature and the mean annual temperature in urban areas being about 1–3°C higher relative to rural areas. The results also indicate that urban heat island effects on vegetation phenology are stronger in North America than in Europe and Asia. Finally, the onset of forest greenup at continental scales can be effectively described using a thermal time-chilling model, which can be used to infer the delay or advance of greenup onset in relation to climatic warming at global scale.     

高寒矮生嵩草草甸主要植物物候特征对养分和水分添加的响应

植物物候特征对环境条件的季节和年际变化具有较强的指示作用, 因此研究植物物候特征对环境条件变化的响应, 对理解植物和环境之间的相互作用关系、植物的适应机制和生存策略, 以及应对全球变化都具有重要的意义。该研究基于2009-2011年高寒矮生嵩草(Kobresia humilis)草甸养分水分控制实验的植物物候观测数据资料, 采用巢式方差分析、物候指数和聚类分析方法, 开展了高寒矮生嵩草草甸主要植物物候特征对养分和水分添加的响应研究。结果表明: (1)养分添加处理之间植物返青期和枯黄期均无显著差异, 但养分添加中氮磷处理对主要物种作用较明显, 使莎草科、禾本科、杂类草主要代表植物的返青期和枯黄期推迟。(2)增雪处理效应明显, 主要优势物种无论是何种养分添加, 在增雪处理后均表现出花期物候提前的趋势(p < 0.01), 同时增雪处理使杂类草植物返青期显著提前(p < 0.05)。增水处理对植物的作用效果并不一致, 其中垂穗披碱草(Elymus nutans)和双柱头藨草(Scirpus distigmaticus)的枯黄期显著推迟(p < 0.05), 而杂类草枯黄期提前。(3)养分添加后, 不同物种的物候特征表现出显著差异(p < 0.01), 例如雪白委陵菜(Potentilla nivea)枯黄期显著推迟(p < 0.05), 而双柱头藨草的枯黄期显著提前(p < 0.05), 但物种对养分添加响应的差异以植物类群为单位, 禾本科植物表现为返青期推迟, 而莎草科植物表现为返青期提前。(4)矮生嵩草草甸主要植物营养生长期与果后营养期持续天数之间呈负相关关系, 主要植物物候特征经聚类分析可以分为3个类群, 3个类群经氮磷钾、钾和氮钾三个养分添加处理后植物物候特征变化较大。研究表明, 高寒矮生嵩草草甸植物物候特征在物种水平响应和水分添加后的响应表现出较大差异, 而对养分添加的响应不显著。     

植物物候对气候变化的响应

植物物候的变化可以直观地反映某些气候变化,尤其是气候变暖.植物生长节律的变化引起植物与环境关系的改变.生态系统的物质循环（如水和碳的循环）等过程将随物候而改变.不同种类植物物候对气候变化的响应的差异,会使植物间和动植物间的竞争与依赖关系也发生深刻的变化.目前欧洲、美洲、亚洲等许多地区均有关于春季植物物候提前,秋季物候推迟,使植物的生长季延长,从而提示气候变暖的趋势.植物物候的模拟模型构成生态系统生产力模型的重要部分.     

西双版纳地区钝叶榕的物候变化规律

钝叶榕是西双版纳地区分布广泛的一种榕树(雌雄同株),具有较为特殊的传粉体系。近三年的野外物候观测数据显示,钝叶榕个体绝大多数每年结果1~2次,极少数一年结果3次,通常在雨季增加结果次数,出现树内异步的现象。钝叶榕结果树内同步,树间异步。钝叶榕雌花期和雄花期不能很好吻合,榕蜂系统在观测范围内处于不稳定状态,导致钝叶榕的雌花期和雄花期比其它种类的榕树长很多。结果表明：钝叶榕结果物候可能受相对湿度影响最大,但总体上其物候与温度、降雨量和相对湿度的相关关系未呈现明显的规律性。钝叶榕的物候变化应受其它气候因子作用或是各种生物因子和非生物因子共同作用的结果。物候和气候的现象十分复杂,进一步对钝叶榕物候的不同方面和各种气候因子进行相关性分析十分必要。     

民勤荒漠区16种植物物候持续日数及其积温变化

中国西北荒漠区植物物候随气温变暖表现为提前趋势。本文以甘肃民勤荒漠区16种植物34年的物候观测资料,采用一次趋势线方程研究了荒漠区植物在物候提前的过程中,物候日数变化和物候期积温变化。结果表明,随着气温升高,物候持续日数表现出一定的增长趋势。物候持续期积温增加显著,而且春、秋两季是积温变化较敏感的季节。积温的增减在很大程度上是由物候持续日数增加或减少引起的,其次才是由于气温增高引起的。表明,随着气温的增高或降低,植物的物候持续日数并不能无限制地缩短或延长。     

Delayed reproduction in Arabidopsis thaliana improves fitness in soil with suboptimal phosphorus availability

Low phosphorus availability (low P) often delays flowering and maturity in annual plants, while abiotic stress generally accelerates flowering and maturity. The utility of this response is unknown. We hypothesize that phenological delay in low P is beneficial by permitting more time for phosphorus acquisition and utilization. We grew seven genotypes of Arabidopsis thaliana with contrasting phenology in high and low P. Low P delayed bolting and maturity in all genotypes. Low P decreased root length, but not root-length duration (the integral of root length over time), because phenological delay allowed low-P plants to compensate for shorter root length. Root-length duration was correlated with phosphorus accumulation. Leaf phosphorus duration (the integral of leaf phosphorus over time) was correlated with reproductive biomass, indicating the utility of increased phosphorus utilization. Phenological delays accounted for up to 30% of biomass production when low-P plants were compared to models of plants with no delays. These results support the hypothesis that phenological delay in low P is adaptive and leads to increased phosphorus acquisition and utilization. Because low P conditions are prevalent, understanding the utility of this response could be useful in crop breeding and in predicting plant responses to global climate change.     

Phylogenetic conservatism and trait correlates of spring phenological responses to climate change in northeast China

Climate change has resulted in major changes in plant phenology across the globe that includes leaf‐out date and flowering time. The ability of species to respond to climate change, in part, depends on their response to climate as a phenological cue in general. Species that are not phenologically responsive may suffer in the face of continued climate change. Comparative studies of phenology have found phylogeny to be a reliable predictor of mean leaf‐out date and flowering time at both the local and global scales. This is less true for flowering time response (i.e., the correlation between phenological timing and climate factors), while no study to date has explored whether the response of leaf‐out date to climate factors exhibits phylogenetic signal. We used a 52‐year observational phenological dataset for 52 woody species from the Forest Botanical Garden of Heilongjiang Province, China, to test phylogenetic signal in leaf‐out date and flowering time, as well as, the response of these two phenological traits to both temperature and winter precipitation. Leaf‐out date and flowering time were significantly responsive to temperature for most species, advancing, on average, 3.11 and 2.87 day/°C, respectively. Both leaf‐out and flowering, and their responses to temperature exhibited significant phylogenetic signals. The response of leaf‐out date to precipitation exhibited no phylogenetic signal, while flowering time response to precipitation did. Native species tended to have a weaker flowering response to temperature than non‐native species. Earlier leaf‐out species tended to have a greater response to winter precipitation. This study is the first to assess phylogenetic signal of leaf‐out response to climate change, which suggests, that climate change has the potential to shape the plant communities, not only through flowering sensitivity, but also through leaf‐out sensitivity.     

Delayed autumn phenology in the Northern Hemisphere is related to change in both climate and spring phenology

The timing of the end of the vegetation growing season (EOS) plays a key role in terrestrial ecosystem carbon and nutrient cycles. Autumn phenology is, however, still poorly understood, and previous studies generally focused on few species or were very limited in scale. In this study, we applied four methods to extract EOS dates from NDVI records between 1982 and 2011 for the Northern Hemisphere, and determined the temporal correlations between EOS and environmental factors (i.e., temperature, precipitation and insolation), as well as the correlation between spring and autumn phenology, using partial correlation analyses. Overall, we observed a trend toward later EOS in ~70% of the pixels in Northern Hemisphere, with a mean rate of 0.18 ± 0.38 days yr^?1. Warming preseason temperature was positively associated with the rate of EOS in most of our study area, except for arid/semi‐arid regions, where the precipitation sum played a dominant positive role. Interestingly, increased preseason insolation sum might also lead to a later date of EOS. In addition to the climatic effects on EOS, we found an influence of spring vegetation green‐up dates on EOS, albeit biome dependent. Our study, therefore, suggests that both environmental factors and spring phenology should be included in the modeling of EOS to improve the predictions of autumn phenology as well as our understanding of the global carbon and nutrient balances.