Flowering Of Tree Species Research Articles

Consequences of Western Disturbance-Triggered Cooling on the Flowering of Tree Species in the Himalayan Terai Region

Consequences of Western Disturbance-Triggered Cooling on the Flowering of Tree Species in the Himalayan Terai Region

Responses of leaf unfolding and flowering to climate change in 12 tropical evergreen broadleaf tree species in Jianfengling, Hainan Island

Aims Our objective was to determine the impacts of climate change(mainly temperature and precipitation) on the phenology of tropical evergreen forests at the community and species level. Methods Two phenophases—the onset of leaf unfolding and the onset of first flowering—had been monitored in 12 evergreen broadleaf tree species in the tropical arboretum in Jianfengling, Hainan Island, since 2003. Observations were made on three mature and healthy individuals for each species once every two days in the same sunny direction in the afternoon by the same person. After the phenological data were collected, they transformed into the number of days from the first day of a calendar year(DOY, i.e. from 1th January). The outliers were excluded used the Grubbs principle. Meteorological data for the corresponding time period were derived from the National Climate Centre. Ultimately, the phenological and meteorological data were combined with the integrate regression method and used to identify the impacts of changing climate on the onset of leaf unfolding and the onset of first flowering in the 12 tree species and to determine their responses in the two phenophases to climate change. Important findings Both the onset of leaf unfolding and the onset of first flowering in the tree species were affected by climate change; the starting dates of the two phenophases in nearly all the tree species were closely related to changes in monthly temperature and precipitation. The onset of leaf unfolding was affected by the monthly mean temperature of the preceding winter and spring, and the impacts became more apparent with the time ap-proaching the occurrence of specific phenophases. Monthly precipitation in the preceding autumn had more effects on the onset of the first flowering than any other time period, in support of the hypothesis that the effect of precipitation on phenology had a hysteretic nature. Furthermore, the onset of leaf unfolding was more susceptible to climate change than the onset of first flowering in the native tree species, whereas the introduced tree species showed reversed responses. Generally, if the monthly mean temperature increases by 0.1 °C and the monthly precipitation increases by 10 mm in the month with the strongest effects, and given that the conditions of other 11 months preceding the occurrence of the specific phenophases remains unchanged, then most of the species would advance or delay the phenophases by about one to three days. Ultimately, the Integrate Regression method provides an effective and operational approach to understanding the dynamic and complex relationships between climate change and the phenology in tropical plants, as demonstrated by the high values of the coefficient of determination(R2 ≥ 0.943) for the integrate temperature and precipitation regression models for phenological predictions based on climatic factors. These models can well be used for predicting the trend of phenological changes in tropical evergreen broadleaf tree species in response to changing climate.

Airborne olive pollen in Vigo (Northwest Spain): a survey to forecast the onset and daily concentrations of the pollen season

Temperature is one of the main factors affecting the start of flowering in tree species that flower at the beginning of spring. Knowledge of the chilling and heat needs required by plants to overcome the period of dormancy enables us to determine the onset of pollination, which is of great importance to allergy sufferers. This study attempted to obtain behaviour models with a view to determining both the onset of the olive pollen season and daily pollen concentrations during the pollination period in Vigo. Monitoring was carried out using a Lanzoni VPPS 2000 pollen trap, from 1995 to 2002 inclusive. Olea pollen is mainly detected during the spring, principally in May. Given the geographical location, the very limited presence of this tree in the study area and the low Olea pollen concentrations detected in northern Spain as a whole, the values recorded here in the atmosphere of Vigo are particularly striking. A strong correlation was observed between total quantity olive pollen collected over the season and rainfall recorded during the second fortnight in February. According to the proposed model, an average of 680 Chilling Hours (CH) are necessary to overcome the chill period and break the state of bud dormancy, and 481 Growth Degree Days (GDD) °C are needed to induce flowering. Models for predicting daily mean pollen concentrations combine temperature and the previous days' pollen concentrations as predictor variables to provide a high level of prediction.

Airborne pollen records response to climatic conditions in arid areas of the Iberian Peninsula

This study analyses the responses of the different components of flora from a high-mountain area with a sub-desert climate to changeable meteorological conditions that may affect their normal development. Local airborne pollen levels are used as bio-indicators of the vegetation behavior. In order to determine the fluctuations in this status, a set of 6-year pollen data obtained using aerobiological methods was used. The results show that the tree species ( Cupressus sp., Olea europaea; Quercus sp. and Platanus hyspanica) react differently to situations of water stress and changeable temperatures than herbaceous species ( Urticaceae, Chenopodiaceae, Poaceae species and Artemisia sp.). The flowering of tree species seems to be affected more by conditions in the months prior to flowering, in particular for species flowering in winter-early spring. As important as the amount of rainfall is the distribution of rainfall throughout the year, since this ensures permanent water availability. Herbaceous species present the most immediate response to weather conditions and if rainfall occurs during their principal pollination period, this period lasts longer. Sometimes, under favorable conditions, non-seasonal flowering may occur.