Assessing the relative importance of sunshine, temperature, precipitation, and spring phenology in regulating leaf senescence timing of herbaceous species in China

Fruit type is a key reproductive trait associated with plant evolution and adaptation. However, large-scale geographical patterns in fruit type composition and the mechanisms driving these patterns remain to be established. Contemporary environment, plant functional traits and evolutionary age may all influence fruit type composition, while their relative importance remains unclear. Here, using data on fruit types, plant height and distributions of 28,222 (∼ 90.1%) angiosperm species in China, we analyzed the geographical patterns in the proportion of fleshy-fruited species for all angiosperms, trees, shrubs, and herbaceous species separately, and compared the relative effects of contemporary climate, ecosystem primary productivity, plant height, and evolutionary age on these patterns. We found that the proportion of fleshy-fruited species per grid cell for all species and different growth forms all showed significant latitudinal patterns, being the highest in southeastern China. Mean plant height per grid cell and actual evapotranspiration (AET) representing ecosystem primary productivity were the strongest drivers of geographical variations in the proportion of fleshy-fruited species, but their relative importance varied between growth forms. From herbaceous species to shrubs and trees, the relative effects of mean plant height decreased. Mean genus age had significant yet consistently weaker effects on proportion of fleshy-fruited species than mean plant height and AET, and environmental temperature and precipitation contributed to those of only trees and shrubs. These results suggest that biotic and environmental factors and evolutionary age of floras jointly shape the pattern in proportion of fleshy-fruited species, and improve our understanding of the mechanisms underlying geographical variations in fruit type composition. Our study also demonstrates the need of integrating multiple biotic and abiotic factors to fully understand the drivers of large-scale patterns of plant reproductive traits.

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A survey of proximal methods for monitoring leaf phenology in temperate deciduous forests

10.5194/bg-2020-389 ◽

2020 ◽

Author(s):

Kamel Soudani ◽

Nicolas Delpierre ◽

Daniel Berveiller ◽

Gabriel Hmimina ◽

Jean-Yves Pontailler ◽

...

Keyword(s):

Interannual Variability ◽

Leaf Senescence ◽

Vegetation Index ◽

Broad Band ◽

Flux Measurement ◽

Spring Phenology ◽

Area Index ◽

Tree Phenology ◽

Temperate Deciduous ◽

Energy Exchanges

Abstract. Tree phenology is a major driver of forest-atmosphere mass and energy exchanges. Yet tree phenology has historically not been recorded at flux measurement sites. Here, we used seasonal time-series of ground-based NDVI (Normalized Difference Vegetation Index), RGB camera GCC (Greenness Chromatic Coordinate), broad-band NDVI, LAI (Leaf Area Index), fAPAR (fraction of Absorbed Photosynthetic Active Radiation), CC (Canopy Closure), fRvis (fraction of Reflected Radiation) and GPP (Gross Primary Productivity) to predict six phenological markers detecting the start, middle and end of budburst and of leaf senescence in a temperate deciduous forest. We compared them to observations of budburst and leaf senescence achieved by field phenologists over a 13-year period. GCC, NDVI and CC captured very well the interannual variability of spring phenology (R2 > 0.80) and provided the best estimates of the observed budburst dates, with a mean absolute deviation (MAD) less than 4 days. For the CC and GCC methods, mid-amplitude (50 %) threshold dates during spring phenological transition agreed well with the observed phenological dates. For the NDVI-based method, on average, the mean observed date coincides with the date when NDVI reaches 25 % of its amplitude of annual variation. For the other methods, MAD ranges from 6 to 17 days. GPP provides the most biased estimates. During the leaf senescence stage, NDVI- and CC-derived dates correlated significantly with observed dates (R2 = 0.63 and 0.80 for NDVI and CC, respectively), with MAD less than 7 days. Our results show that proximal sensing methods can be used to derive robust phenological metrics. They can be used to retrieve long-term phenological series at flux measurement sites and help interpret the interannual variability and trends of mass and energy exchanges.

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A survey of proximal methods for monitoring leaf phenology in temperate deciduous forests

10.1101/2020.09.24.311191 ◽

2020 ◽

Author(s):

Kamel Soudani ◽

Nicolas Delpierre ◽

Daniel Berveiller ◽

Gabriel Hmimina ◽

Jean-Yves Pontailler ◽

...

Keyword(s):

Interannual Variability ◽

Leaf Senescence ◽

Flux Measurement ◽

List Type ◽

Spring Phenology ◽

Area Index ◽

Tree Phenology ◽

Temperate Deciduous ◽

Energy Exchanges ◽

Best Estimates

AbstractTree phenology is a major driver of forest-atmosphere mass and energy exchanges. Yet tree phenology has historically not been recorded at flux measurement sites. Here, we used seasonal time-series of ground-based NDVI (Normalized Difference Vegetation Index), RGB camera GCC (Greenness Chromatic Coordinate), broad-band NDVI, LAI (Leaf Area Index), fAPAR (fraction of Absorbed Photosynthetic Active Radiation), CC (Canopy Closure), fRvis (fraction of Reflected Radiation) and GPP (Gross Primary Productivity) to predict six phenological markers detecting the start, middle and end of budburst and of leaf senescence in a temperate deciduous forest. We compared them to observations of budburst and leaf senescence achieved by field phenologists over a 13-year period. GCC, NDVI and CC captured very well the interannual variability of spring phenology (R2 > 0.80) and provided the best estimates of the observed budburst dates, with a mean absolute deviation (MAD) less than 4 days. For the CC and GCC methods, mid-amplitude (50%) threshold dates during spring phenological transition agreed well with the observed phenological dates. For the NDVI-based method, on average, the mean observed date coincides with the date when NDVI reaches 25% of its amplitude of annual variation. For the other methods, MAD ranges from 6 to 17 days. GPP provides the most biased estimates. During the leaf senescence stage, NDVI- and CC-derived dates correlated significantly with observed dates (R2 =0.63 and 0.80 for NDVI and CC, respectively), with MAD less than 7 days. Our results show that proximal sensing methods can be used to derive robust phenological indexes. They can be used to retrieve long-term phenological series at flux measurement sites and help interpret the interannual variability and decadal trends of mass and energy exchanges.HighlightsWe used 8 indirect methods to predict the timing of phenological events.GCC, NDVI and CC captured very well the interannual variation of spring phenology.GCC, NDVI and CC provided the best estimates of observed budburst dates.NDVI and CC derived-dates correlated with observed leaf senescence dates.

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Effects of the Simulated Enhancement of Precipitation on the Phenology of Nitraria tangutorum under Extremely Dry and Wet Years

Plants ◽

10.3390/plants10071474 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1474

Author(s):

Fang Bao ◽

Zhiming Xin ◽

Jiazhu Li ◽

Minghu Liu ◽

Yanli Cao ◽

...

Keyword(s):

Leaf Senescence ◽

Plant Phenology ◽

Regulation Mechanism ◽

Arid Areas ◽

Leaf Fall ◽

Spring Phenology ◽

Leaf Unfolding ◽

Simulated Precipitation ◽

Leaf Budding ◽

End Times

Plant phenology is the most sensitive biological indicator that responds to climate change. Many climate models predict that extreme precipitation events will occur frequently in the arid areas of northwest China in the future, with an increase in the quantity and unpredictability of rain. Future changes in precipitation will inevitably have a profound impact on plant phenology in arid areas. A recent study has shown that after the simulated enhancement of precipitation, the end time of the leaf unfolding period of Nitraria tangutorum advanced, and the end time of leaf senescence was delayed. Under extreme climatic conditions, such as extremely dry or wet years, it is unclear whether the influence of the simulated enhancement of precipitation on the phenology of N. tangutorum remains stable. To solve this problem, this study systematically analyzed the effects of the simulated enhancement of precipitation on the start, end and duration of four phenological events of N. tangutorum, including leaf budding, leaf unfolding, leaf senescence and leaf fall under extremely dry and wet conditions. The aim of this study was to clarify the similarities and differences of the effects of the simulated enhancement of precipitation on the start, end and duration of each phenological period of N. tangutorum in an extremely dry and an extremely wet year to reveal the regulatory effect of extremely dry and excessive amounts of precipitation on the phenology of N. tangutorum. (1) After the simulated enhancement of precipitation, the start and end times of the spring phenology (leaf budding and leaf unfolding) of N. tangutorum advanced during an extremely dry and an extremely wet year, but the duration of phenology was shortened during an extremely wet year and prolonged during an extremely drought-stricken year. The amplitude of variation increased with the increase in simulated precipitation. (2) After the simulated enhancement of precipitation, the start and end times of the phenology (leaf senescence and leaf fall) of N. tangutorum during the autumn advanced in an extremely wet year but was delayed during an extremely dry year, and the duration of phenology was prolonged in both extremely dry and wet years. The amplitude of variation increased with the increase in simulated precipitation. (3) The regulation mechanism of extremely dry or wet years on the spring phenology of N. tangutorum lay in the different degree of influence on the start and end times of leaf budding and leaf unfolding. However, the regulation mechanism of extremely dry or wet years on the autumn phenology of N. tangutorum lay in different reasons. Water stress caused by excessive water forced N. tangutorum to start its leaf senescence early during an extremely wet year. In contrast, the alleviation of drought stress after watering during the senescence of N. tangutorum caused a delay in the autumn phenology during an extremely dry year.

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A survey of proximal methods for monitoring leaf phenology in temperate deciduous forests

Biogeosciences ◽

10.5194/bg-18-3391-2021 ◽

2021 ◽

Vol 18 (11) ◽

pp. 3391-3408

Author(s):

Kamel Soudani ◽

Nicolas Delpierre ◽

Daniel Berveiller ◽

Gabriel Hmimina ◽

Jean-Yves Pontailler ◽

...

Keyword(s):

Time Series ◽

Interannual Variability ◽

Leaf Senescence ◽

Vegetation Index ◽

Sigmoid Function ◽

Spring Phenology ◽

Area Index ◽

Tree Phenology ◽

Temperate Deciduous ◽

Energy Exchanges

Abstract. Tree phenology is a major driver of forest–atmosphere mass and energy exchanges. Yet, tree phenology has rarely been monitored in a consistent way throughout the life of a flux-tower site. Here, we used seasonal time series of ground-based NDVI (Normalized Difference Vegetation Index), RGB camera GCC (greenness chromatic coordinate), broadband NDVI, LAI (leaf area index), fAPAR (fraction of absorbed photosynthetic active radiation), CC (canopy closure), fRvis (fraction of reflected radiation) and GPP (gross primary productivity) to predict six phenological markers detecting the start, middle and end of budburst and of leaf senescence in a temperate deciduous forest using an asymmetric double sigmoid function (ADS) fitted to the time series. We compared them to observations of budburst and leaf senescence achieved by field phenologists over a 13-year period. GCC, NDVI and CC captured the interannual variability of spring phenology very well (R2>0.80) and provided the best estimates of the observed budburst dates, with a mean absolute deviation (MAD) of less than 4 d. For the CC and GCC methods, mid-amplitude (50 %) threshold dates during spring phenological transition agreed well with the observed phenological dates. For the NDVI-based method, on average, the mean observed date coincides with the date when NDVI reaches 25 % of its amplitude of annual variation. For the other methods, MAD ranges from 6 to 17 d. The ADS method used to derive the phenological markers provides the most biased estimates for the GPP and GCC. During the leaf senescence stage, NDVI- and CC-derived dates correlated significantly with observed dates (R2=0.63 and 0.80 for NDVI and CC, respectively), with an MAD of less than 7 d. Our results show that proximal-sensing methods can be used to derive robust phenological metrics. They can be used to retrieve long-term phenological series at eddy covariance (EC) flux measurement sites and help interpret the interannual variability and trends of mass and energy exchanges.

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Determining the relative importance of climatic drivers on spring phenology in grassland ecosystems of semi-arid areas

International Journal of Biometeorology ◽

10.1007/s00484-014-0839-z ◽

2014 ◽

Vol 59 (2) ◽

pp. 237-248 ◽

Cited By ~ 15

Author(s):

Likai Zhu ◽

Jijun Meng

Keyword(s):

Arid Areas ◽

Relative Importance ◽

Spring Phenology ◽

Grassland Ecosystems ◽

Climatic Drivers ◽

Semi Arid

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Developmental versus environmental control of early leaf phenology in juvenile Ohio buckeye (Aesculus glabra)

Canadian Journal of Botany ◽

10.1139/b03-121 ◽

2004 ◽

Vol 82 (1) ◽

pp. 31-36 ◽

Cited By ~ 11

Author(s):

Carol K Augspurger

Keyword(s):

Leaf Senescence ◽

Environmental Control ◽

Vertical Gradient ◽

Leaf Expansion ◽

Forest Understory ◽

Bud Break ◽

Spring Phenology ◽

Canopy Trees ◽

Leaf Drop ◽

Aesculus Glabra

The spring phenology of juveniles of many canopy tree species in deciduous forests predates that of adult conspecifics. To determine whether the earlier phenology of seedlings of Aesculus glabra Willd. (Ohio buckeye) in Illinois, U.S.A., is developmentally or environmentally controlled, seedlings of five maternal parents were grown either in the understory or above a barn roof, simulating environmental conditions experienced at canopy height. Relative to canopy seedlings, understory seedlings had significantly earlier bud break (mean = 6 d), leaf expansion (8 d), leaf senescence (23 d), and leaf drop (18 d). Bud break and leaf expansion of canopy seedlings equalled that of canopy trees of Ohio buckeye, but senescence and leaf drop of canopy seedlings predated canopy trees by 45 and 67 d, respectively. Overall, results show evidence for environmental control over the spring phenology of juveniles. Thermal sums in spring accumulated more rapidly in the forest understory where nighttime temperatures were warmer than above the barn roof. Thus, the environmental control of spring phenology appears to be a non-stage-specific temperature cue that accumulates at different rates along the forest's vertical gradient. In contrast, senescence and leaf drop, while somewhat responsive to the environment, displayed strong developmental constraint.Key words: bud break, developmental constraint, leaf drop, leaf expansion, leaf senescence, thermal sums.

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