Determine vegetation period
Calculate start and end date of vegetation periods based on daily average air temperature and the day of the year (DOY). The sum of day degrees within vegetation periods is calculated for convenience sake.
vegperiod( dates, Tavg, start.method, end.method, Tsum.out = FALSE, species = NULL, est.prev = 0 )
dates |
vector of calendar dates (objects of class |
Tavg |
vector of daily average air temperatures in degree Celsius.
Same length as |
start.method |
name of method to use for vegetation start.
One of "Menzel" (needs additional argument
|
end.method |
name of method to use for vegetation end. One of "vonWilpert", "LWF-BROOK90", "NuskeAlbert" and "StdMeteo" resp. "ETCCDI". Can be abbreviated (partial matching). For further discussion see Details. |
Tsum.out |
boolean. Return the sum of day degrees within vegetation period. |
species |
name of tree species [required if Must be one of "Larix decidua", "Picea abies (frueh)", "Picea abies (spaet)", "Picea abies (noerdl.)", "Picea omorika", "Pinus sylvestris", "Betula pubescens", "Quercus robur", "Quercus petraea", "Fagus sylvatica". |
est.prev |
number of years to estimate previous year's
chill days for the first year
[required if Menzel requires the number of chill days of previous November
and December. If |
A data.frame with year and DOY of start and end day of
vegetation period. If Tsum.out=TRUE, the data.frame contains an
additional column with the sum of day degrees within vegetation periods.
The method "Menzel" implements the algorithm described in Menzel (1997). The method is parameterized for 10 common tree species. It needs previous year's chill days. "ETCCDI" resp. "StdMeteo" is a simple threshold based procedure as defined by the Expert Team on Climate Change Detection and Indices (cf. ETCCDI 2009, Frich et al. 2002, Zhang et al. 2011) leading to quite early vegetation starts. This method is widely used in climate change studies. The method "Ribes uva-crispa" is based on leaf-out of gooseberry (Janssen 2009). It was developed by the Germany's National Meteorological Service (Deutscher Wetterdienst, DWD) and is more robust against early starts than common simple meteorological procedures.
The end method "vonWilpert" is based on von Wilpert (1990). It was originally developed for "Picea abies" in the Black Forest but is commonly used for all tree species throughout Germany. As usual, the rules regarding the soilmatrix are neglected in this implementation. "LWF-BROOK90" is -for the sake of convenience- a reimplementation of the LWF-BROOK90 VBA (version 3.4) variant of "vonWilpert" (Hammel and Kennel 2001). Their interpretation of von Wilpert (1990) and the somewhat lower precision of VBA was mimicked. "NuskeAlbert" provide a very simple method which is inspired by standard climatological procedures but employs a 7 day moving average and a 5 °C threshold (cf. Walther and Linderholm 2006). "ETCCDI" resp. "StdMeteo" is a simple threshold based procedure as defined by the Expert Team on Climate Change Detection and Indices (cf. ETCCDI 2009, Frich et al. 2002, Zhang et al. 2011) leading to quite late vegetation ends.
ETCCDI (2009) Climate Change Indices: Definitions of the 27 core indices. http://etccdi.pacificclimate.org/list_27_indices.shtml
Frich, P., Alexander, L., Della-Marta, P., Gleason, B., Haylock, M., Klein Tank, A. and Peterson, T. (2002) Observed coherent changes in climatic extremes during the second half of the twentieth century. Climate Research, 19, 193–212. doi: 10.3354/cr019193.
Hammel, K. and Kennel, M. (2001) Charakterisierung und Analyse der Wasserverfügbarkeit und des Wasserhaushalts von Waldstandorten in Bayern mit dem Simulationsmodell BROOK90. Forstliche Forschungsberichte München.
Janssen, W. (2009) Definition des Vegetationsanfanges. Internal Report, Deutscher Wetterdienst, Abteilung Agrarmeteorologie.
Menzel, A. (1997) Phänologie von Waldbäumen unter sich ändernden Klimabedingungen - Auswertung der Beobachtungen in den Internationalen Phänologischen Gärten und Möglichkeiten der Modellierung von Phänodaten. Forstliche Forschungsberichte München.
von Wilpert, K. (1990) Die Jahrringstruktur von Fichten in Abhängigkeit vom Bodenwasserhaushalt auf Pseudogley und Parabraunerde: Ein Methodenkonzept zur Erfassung standortsspezifischer Wasserstreßdispostion. Freiburger Bodenkundliche Abhandlungen.
Walther, A. and Linderholm, H. W. (2006) A comparison of growing season indices for the Greater Baltic Area. International Journal of Biometeorology, 51(2), 107–118. doi: 10.1007/s00484-006-0048-5.
Zhang, X., Alexander, L., Hegerl, G. C., Jones, P., Tank, A. K., Peterson, T. C., Trewin, B. and Zwiers, F. W. (2011) Indices for monitoring changes in extremes based on daily temperature and precipitation data. Wiley Interdisciplinary Reviews: Climate Change, 2(6), 851–870. doi: 10.1002/wcc.147.
data(goe)
vegperiod(dates=goe$date, Tavg=goe$t,
start.method="Menzel", end.method="vonWilpert",
species="Picea abies (frueh)", est.prev=5)
# take chill days from first year, which is then dropped
vegperiod(dates=goe$date, Tavg=goe$t, start="Menzel", end="vonWilpert",
species="Picea abies (frueh)", est.prev=0)
# add column with sum of day degrees in vegetation periods
vegperiod(dates=goe$date, Tavg=goe$t, Tsum.out=TRUE,
start="StdMeteo", end="StdMeteo")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.