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Richardson AD, Hufkens K, Li X, Ault TR. Testing Hopkins' Bioclimatic Law with PhenoCam data. APPLICATIONS IN PLANT SCIENCES 2019; 7:e01228. [PMID: 30937220 PMCID: PMC6426166 DOI: 10.1002/aps3.1228] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/03/2018] [Indexed: 05/23/2023]
Abstract
PREMISE OF THE STUDY We investigated the spatial and temporal patterns of vegetation phenology with phenometrics derived from PhenoCam imagery. Specifically, we evaluated the Bioclimatic Law proposed by Hopkins, which relates phenological transitions to latitude, longitude, and elevation. METHODS "Green-up" and "green-down" dates-representing the start and end of the annual cycles of vegetation activity-were estimated from measures of canopy greenness calculated from digital repeat photography. We used data from 65 deciduous broadleaf (DB) forest sites, 18 evergreen needleleaf (EN) forest sites, and 21 grassland (GR) sites. RESULTS DB green-up dates were well correlated with mean annual temperature and varied along spatial gradients consistent with the Bioclimatic Law. Interannual variation in DB phenology was most strongly associated with temperature anomalies during a relatively narrow window of time. EN phenology was not well correlated with either climatic factors or spatial gradients, but similar to DB phenology, interannual variation was most closely associated with temperature anomalies. For GR sites, mean annual precipitation explained most of the spatial variation in the duration of vegetation activity, whereas both temperature and precipitation anomalies explained interannual variation in phenology. DISCUSSION PhenoCam data provide an objective and consistent means by which spatial and temporal patterns in vegetation phenology can be investigated.
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Affiliation(s)
- Andrew D. Richardson
- School of Informatics, Computing, and Cyber SystemsNorthern Arizona UniversityFlagstaffArizona86011USA
- Center for Ecosystem Science and SocietyNorthern Arizona UniversityFlagstaffArizona86011USA
| | - Koen Hufkens
- Department of Applied Ecology and Environmental BiologyGhent UniversityGhentBelgium
- INRAUMR ISPAVillenave d'OrnonFrance
| | - Xiaolu Li
- Department of Earth and Atmospheric SciencesCornell UniversityIthacaNew York14853USA
| | - Toby R. Ault
- Department of Earth and Atmospheric SciencesCornell UniversityIthacaNew York14853USA
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Zhang J, Gou X, Pederson N, Zhang F, Niu H, Zhao S, Wang F. Cambial phenology in Juniperus przewalskii along different altitudinal gradients in a cold and arid region. TREE PHYSIOLOGY 2018; 38:840-852. [PMID: 29401316 DOI: 10.1093/treephys/tpx160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 01/16/2018] [Indexed: 05/12/2023]
Abstract
Knowing more precisely the cambial phenology and wood formation dynamics of trees can lead to a better understanding on how trees react to short-term changes in environmental conditions. Such an understanding could also shed light on the physiological foundation of climate-growth interactions at a regional scale. Although it has been documented that temperature is an important factor determining the cambial phenology in cold and humid climates, there is less agreement on the driver(s) that trigger the onset and end of wood formation in cold and arid climates. Here, the phenological traits of cambial activity and xylem formation were analyzed biweekly along an altitudinal transect ranging from 3580 to 3980 m above sea level, a transect that covers the distribution of Qilian juniper (Juniperus przewalskii Kom.) along a slope of the Tibetan Plateau. Cambial phenology and the duration and rate of wood formation were assessed from anatomical observations during the growing season of the developing xylem obtained from microcores collected from the stem of 10 trees total in 2012 (five at two altitudes each) and 25 trees (five at five altitudes each) in 2013. We found that the onset of wood formation was significantly correlated with altitude in 2013, with onset beginning 8.2 days earlier with every 100 m decrease in elevation. The change in onset with elevation corresponds to a change of 14.1 days °C-1 when adjusted for the monitored altitudinal lapse rate of -0.58 °C per 100 m. The duration of wood formation lasted from mid-May to mid-August, with the length of the 2013 growing season decreasing from 97 to 65 days from low to high elevation. Although the end of growing season appeared minimally related to altitude during both growing seasons, differences in end of wood production and wood formation between the two growing seasons were significant. It appears that summer drought conditions constricted the end of growing season across all elevations along our transect in 2013. Sensitivity analysis found xylem growth was positively correlated with rate and duration of wood production, with the former explaining most variability in growth. Our findings provide new data on the timing and duration of wood formation and help quantify the potential impacts of global warming on tree growth and productivity in cold and arid regions.
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Affiliation(s)
- Junzhou Zhang
- Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
- Harvard Forest, Harvard University, 324 North Main Street, Petersham, MA 01366, USA
| | - Xiaohua Gou
- Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
| | - Neil Pederson
- Harvard Forest, Harvard University, 324 North Main Street, Petersham, MA 01366, USA
| | - Fen Zhang
- Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
| | - Haoge Niu
- Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
| | - Shoudong Zhao
- Harvard Forest, Harvard University, 324 North Main Street, Petersham, MA 01366, USA
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
| | - Fang Wang
- Key Laboratory of Western China's Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
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Arend M, Gessler A, Schaub M. The influence of the soil on spring and autumn phenology in European beech. TREE PHYSIOLOGY 2016; 36:78-85. [PMID: 26420791 DOI: 10.1093/treephys/tpv087] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 08/10/2015] [Indexed: 06/05/2023]
Abstract
Tree phenology is a key discipline in forest ecology linking seasonal fluctuations of photoperiod and temperature with the annual development of buds, leaves and flowers. Temperature and photoperiod are commonly considered as main determinants of tree phenology while little is known about interactions with soil chemical characteristics. Seedlings of 12 European beech (Fagus sylvatica L.) provenances were transplanted in 2011 to model ecosystems and grown for 4 years on acidic or calcareous forest soil. Spring bud burst and autumnal leaf senescence were assessed in the last 2 years, 2013 and 2014, which were characterized by contrasting annual temperatures with a very warm spring and autumn in 2014. In 2013, spring bud burst and autumnal leaf senescence were advanced on acidic soil with a greater effect on leaf senescence. Hence, the vegetation period 2013 was shorter on this soil type compared with that on calcareous soil. In 2014, a similar soil effect was observed for spring bud burst while autumnal leaf senescence and the length of the vegetation period were not affected, probably due to interferences with the overall extension of the vegetation period in this exceptionally warm year. A different soil responsiveness was observed among the provenances with early bursting or senescing provenances being more sensitive than late bursting or senescing provenances. The findings of this study highlight the soil as an ecologically relevant factor in tree phenology and might help explain existing uncertainties in current phenology models.
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Affiliation(s)
- Matthias Arend
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Marcus Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
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Jochner S, Menzel A. Urban phenological studies - Past, present, future. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2015; 203:250-261. [PMID: 25624020 DOI: 10.1016/j.envpol.2015.01.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 01/02/2015] [Accepted: 01/04/2015] [Indexed: 05/20/2023]
Abstract
Phenology is believed to be a suitable bio-indicator to track climate change. Based on the strong statistical association between phenology and temperature phenological observations provide an inexpensive means for the temporal and spatial analysis of the urban heat island. However, other environmental factors might also weaken this relationship. In addition, the investigation of urban phenology allows an estimation of future phenology from current information since cities with their amplified temperatures may serve as a proxy for future conditions. Nevertheless, the design of spatial compared to long-term studies might be influenced by different factors which should be taken into consideration when interpreting results from a specific study. In general, plants located in urban areas tend to flush and bloom earlier than in the countryside. What are the consequences of these urban-rural differences? This review will document existing findings on urban phenology and will highlight areas in which further research is needed.
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Affiliation(s)
- Susanne Jochner
- Department of Ecology and Ecosystem Management, Ecoclimatology, Technische Universität München, 85354 Freising, Germany; Institute for Advanced Study, Technische Universität München, 85748 Garching, Germany.
| | - Annette Menzel
- Department of Ecology and Ecosystem Management, Ecoclimatology, Technische Universität München, 85354 Freising, Germany; Institute for Advanced Study, Technische Universität München, 85748 Garching, Germany.
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Fu YH, Piao S, Vitasse Y, Zhao H, De Boeck HJ, Liu Q, Yang H, Weber U, Hänninen H, Janssens IA. Increased heat requirement for leaf flushing in temperate woody species over 1980-2012: effects of chilling, precipitation and insolation. GLOBAL CHANGE BIOLOGY 2015; 21:2687-2697. [PMID: 25580596 DOI: 10.1111/gcb.12863] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/30/2014] [Indexed: 05/21/2023]
Abstract
Recent studies have revealed large unexplained variation in heat requirement-based phenology models, resulting in large uncertainty when predicting ecosystem carbon and water balance responses to climate variability. Improving our understanding of the heat requirement for spring phenology is thus urgently needed. In this study, we estimated the species-specific heat requirement for leaf flushing of 13 temperate woody species using long-term phenological observations from Europe and North America. The species were defined as early and late flushing species according to the mean date of leaf flushing across all sites. Partial correlation analyses were applied to determine the temporal correlations between heat requirement and chilling accumulation, precipitation and insolation sum during dormancy. We found that the heat requirement for leaf flushing increased by almost 50% over the study period 1980-2012, with an average of 30 heat units per decade. This temporal increase in heat requirement was observed in all species, but was much larger for late than for early flushing species. Consistent with previous studies, we found that the heat requirement negatively correlates with chilling accumulation. Interestingly, after removing the variation induced by chilling accumulation, a predominantly positive partial correlation exists between heat requirement and precipitation sum, and a predominantly negative correlation between heat requirement and insolation sum. This suggests that besides the well-known effect of chilling, the heat requirement for leaf flushing is also influenced by precipitation and insolation sum during dormancy. However, we hypothesize that the observed precipitation and insolation effects might be artefacts attributable to the inappropriate use of air temperature in the heat requirement quantification. Rather than air temperature, meristem temperature is probably the prominent driver of the leaf flushing process, but these data are not available. Further experimental research is thus needed to verify whether insolation and precipitation sums directly affect the heat requirement for leaf flushing.
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Affiliation(s)
- Yongshuo H Fu
- College of Urban and Environmental Sciences, Peking University, Yiheyuan Road 5, 100871, Beijing, China
- Department of Biology, Centre of Excellence PLECO (Plant and Vegetation Ecology), University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
| | - Shilong Piao
- College of Urban and Environmental Sciences, Peking University, Yiheyuan Road 5, 100871, Beijing, China
- Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Center for Excellence in Tibetan Earth Science, Chinese Academy of Sciences, Beijing, 100085, China
| | - Yann Vitasse
- Institute of Geography, University of Neuchatel, Neuchatel, Switzerland
- Snow and Landscape Research, WSL Swiss Federal Institute for Forest, Neuchatel, Switzerland
- Group Mountain Ecosystems, WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
| | - Hongfang Zhao
- College of Urban and Environmental Sciences, Peking University, Yiheyuan Road 5, 100871, Beijing, China
| | - Hans J De Boeck
- Department of Biology, Centre of Excellence PLECO (Plant and Vegetation Ecology), University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
| | - Qiang Liu
- College of Urban and Environmental Sciences, Peking University, Yiheyuan Road 5, 100871, Beijing, China
| | - Hui Yang
- College of Urban and Environmental Sciences, Peking University, Yiheyuan Road 5, 100871, Beijing, China
| | - Ulrich Weber
- Max Planck Institute for Biogeochemistry, Hans Knöll Strasse 10, 07745, Jena, Germany
| | - Heikki Hänninen
- Department of Biosciences, University of Helsinki, Biocenter 3, FIN-00014, Helsinki, Finland
| | - Ivan A Janssens
- Department of Biology, Centre of Excellence PLECO (Plant and Vegetation Ecology), University of Antwerp, Universiteitsplein 1, B-2610, Wilrijk, Belgium
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