Plant Phenological Changes

To generate realistic projections of species’ responses to climate change, we need to understand the factors that limit their ability to respond. Although climatic niche conservatism, the maintenance of a species’s climatic niche over time, is a critical assumption in niche-based species distribution models, little is known about how universal it is and how it operates. In particular, few studies have tested the role of climatic niche conservatism via phenological changes in explaining the reported wide variance in the extent of range shifts among species. Using historical records of the phenology and spatial distribution of British plants under a warming climate, we revealed that: (i) perennial species, as well as those with weaker or lagged phenological responses to temperature, experienced a greater increase in temperature during flowering (i.e. failed to maintain climatic niche via phenological changes); (ii) species that failed to maintain climatic niche via phenological changes showed greater northward range shifts; and (iii) there was a complementary relationship between the levels of climatic niche conservatism via phenological changes and range shifts. These results indicate that even species with high climatic niche conservatism might not show range shifts as instead they track warming temperatures during flowering by advancing their phenology.

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Classification of agricultural fields using time series of dual polarimetry TerraSAR-X images

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-2-w3-191-2014 ◽

2014 ◽

Vol XL-2/W3 ◽

pp. 191-196 ◽

Cited By ~ 2

Author(s):

S. Mirzaee ◽

M. Motagh ◽

H. Arefi ◽

M. Nooryazdan

Keyword(s):

Environmental Changes ◽

Support Vector ◽

Svm Classifier ◽

Sensing Applications ◽

Imaging Characteristics ◽

Training Samples ◽

Study Results ◽

Phenological Changes ◽

Multi Temporal

Due to its special imaging characteristics, Synthetic Aperture Radar (SAR) has become an important source of information for a variety of remote sensing applications dealing with environmental changes. SAR images contain information about both phase and intensity in different polarization modes, making them sensitive to geometrical structure and physical properties of the targets such as dielectric and plant water content. In this study we investigate multi temporal changes occurring to different crop types due to phenological changes using high-resolution TerraSAR-X imagers. The dataset includes 17 dual-polarimetry TSX data acquired from June 2012 to August 2013 in Lorestan province, Iran. Several features are extracted from polarized data and classified using support vector machine (SVM) classifier. Training samples and different features employed in classification are also assessed in the study. Results show a satisfactory accuracy for classification which is about 0.91 in kappa coefficient.

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Phenological Changes of Climate Warming Induced Local and Introduced Woody Plant Species

Vilnius University Proceedings ◽

10.15388/klimatokaita.2020.35 ◽

2020 ◽

Vol 10 ◽

pp. 43

Author(s):

Asta Malakauskienė

Keyword(s):

Plant Species ◽

Climate Warming ◽

Woody Plant ◽

Woody Plant Species ◽

Phenological Changes

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The influence of vegetation water dynamics on the ASCAT backscatter-incidence angle relationship in the Amazon

10.5194/hess-2021-406 ◽

2021 ◽

Author(s):

Ashwini Petchiappan ◽

Susan C. Steele-Dunne ◽

Mariette Vreugdenhil ◽

Sebastian Hahn ◽

Wolfgang Wagner ◽

...

Keyword(s):

Seasonal Cycle ◽

Incidence Angle ◽

Water Dynamics ◽

Plant Water ◽

Vegetation Monitoring ◽

Equivalent Water Thickness ◽

Moisture Availability ◽

Phenological Changes ◽

Data Record ◽

Vegetation Water

Abstract. Microwave observations are sensitive to plant water content and could therefore provide essential information on biomass and plant water status in ecological and agricultural applications. The combined data record of the C-band scatterometers on ERS 1/2, the Metop series and the planned Metop Second Generation satellites will span over 40 years, which would provide a long-term perspective on the role of vegetation in the climate system. Recent research has indicated that the unique viewing geometry of ASCAT could be exploited to observe vegetation water dynamics. The incidence angle dependence of backscatter can be described with a second order polynomial, the slope and curvature of which are related to vegetation. In a study limited to grasslands, seasonal cycles, spatial patterns and interannual variability in the slope and curvature were found to vary among grassland types and were attributed to differences in moisture availability, growing season length and phenological changes. To exploit ASCAT slope and curvature for global vegetation monitoring, their dynamics over a wider range of vegetation types needs to be quantified and explained in terms of vegetation water dynamics. Here, we compare ASCAT data with meteorological data and GRACE Equivalent Water Thickness (EWT) to explain the dynamics of ASCAT backscatter, slope and curvature in terms of moisture availability and demand. We consider differences in the seasonal cycle, diurnal differences, and the response to the 2010 and 2015 droughts across ecoregions in the Amazon basin and surroundings. Results show that spatial and temporal patterns in backscatter reflect moisture availability indicated by GRACE EWT. Slope and curvature dynamics vary considerably among the ecoregions. The evergreen forests, often used as a calibration target, exhibit very stable behaviour even under drought conditions. The limited seasonal variation follows changes in the radiation cycle, and may indicate phenological changes such as litterfall. In contrast, the diversity of land cover types within the Cerrado region results in considerable heterogeneity in terms of the seasonal cycle and the influence of drought on both slope and curvature. Seasonal flooding in forest and savanna areas also produced a distinctive signature in terms of the backscatter as a function of incidence angle. This improved understanding of the incidence angle behaviour of backscatter increases our ability to interpret and make optimal use of the ASCAT data record and VOD products for vegetation monitoring.

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Sex and age dependent migration phenology of the Pied Flycatcher in a stopover site in the Carpathian Basin

Ornis Hungarica ◽

10.1515/orhu-2015-0010 ◽

2015 ◽

Vol 23 (2) ◽

pp. 10-19 ◽

Cited By ~ 6

Author(s):

Andrea Harnos ◽

Zsolt Lang ◽

Péter Fehérvári ◽

Tibor Csörgő

Keyword(s):

Wing Length ◽

Carpathian Basin ◽

Stopover Site ◽

The Past ◽

Age Related ◽

Phenological Changes ◽

Comprehensive Picture ◽

Migration Phenology ◽

And Gender ◽

Gender Groups

Abstract Very little is known about Pied Flycatchers crossing the Carpathian Basin. We give a comprehensive picture about its migration based on the data collected during the past 26 years (1989–2014) at a stopover site in Hungary: (1) sex and age related phenological changes over the years, (2) sex, age and size dependent migration patterns during and (3) between migration periods, (4) sex and age composition in spring and in autumn and their change over years. The timing of spring migration shifted to earlier dates in the case of males, while that of females did not change implying an increasing rate of protandry. In autumn the timing did not change, but juveniles leave the area earlier than adults. The average wing length increased during the past decades in spring in the case of both sexes. In autumn, wing length did not change significantly during the years, but it increased during the seasons in all age and gender groups. The proportion of males is about 60% in spring and among juveniles in autumn, and it is around 39% in the adult group in autumn. The male ratio diminishes during spring, but it does not change during the autumn season. The average wing of adults is shorter in spring than in autumn. Based on this fact and the different sex ratios in the two seasons we may hypothesize that Pied Flycatchers are loop migrants on this area, and even the sexes of the same population take different routes.

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Spring and autumn phenology in sub-mesothermal beech stands from the southwestern extremity of the Carpathians

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha48211897 ◽

2020 ◽

Vol 48 (2) ◽

pp. 1057-1069

Author(s):

Radu POPESCU ◽

Neculae ȘOFLETEA

Keyword(s):

Climate Change ◽

Climate Data ◽

Phenological Data ◽

The Carpathians ◽

The North ◽

Research Areas ◽

Forest Sites ◽

Phenological Changes ◽

Southwestern Area ◽

The Impact

The research carried out was aimed to assessing the phenological behavior of beech (Fagus sylvatica L.) in the southwestern area of the Carpathians, in submesothermal forest sites, differentiated from the majority mesothermal ones of this species. The data obtained may be used for predicting the phenological changes of the species, especially in the Carpathian area, under the future influence of expected climate change. Assessments for spring and autumn phenology (buds burst -BB and foliation, flowering and leaves senescence) were carried out on a transect with a difference in altitude of 1000 meters, in phenological research areas located at 200 m, 700 m and 1200 m. At each altitude level, 100 trees of I and II Kraft classes were phenologically characterized: 50 trees on the south-facing slope (sunny exposure) and 50 on the north-facing slope (shade exposure).The phenological data were interpreted in relation to climate data recorded in each area by a HOBO U23 Pro v2 sensor. The site conditions of submesothermal climate in the low altitude area led to DOY (day of the year) values below 100. The phenological differentiation of populations is evident in relation with the altitude, while at the same altitudinal level the influence of the exposure was much lower. The gradiental values by altitude sectors highlighted the nonlinearity of the development of foliation phenophase, the value being lower in the first 500 m, where the beech is under the impact of the submesothermal climate. It has been proven both the dependence of the foliation onset depending on the cumulation of temperatures in relation to the DOY moment and also on the values recorded throughout the vegetative rest. The altitudinal gradiental values resulting for flowering in the first and second altitudinal half of transect also differentiate the stands, but are lower than that resulting for BB. The leaves senescence has a delay of 1.8 up to 2.4 days per 100 meters altitude, and the length of the vegetation season is reduced more sharply in the upper half of the analyzed altitudinal transect. The sub-mesothermal climate could be involved in condensation of spring phenophases in the stands of the lower half of the researched area. Our data may be used for predicting the phenological changes, especially in the Carpathian area, under the expected climate change.

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