Determine the vegetation period and regional trends in Germany Wolfgang Janssen [email protected]

German Weather Serviceagrometeorological department

Determine the vegetation period and regional trends in Germany

Wolfgang [email protected]

Phenology 2010, June



Background:

- different crops have different growth periods- some issues need a general definition of the vegetation period- impacts of climate change

how to define?

good reproduction in past years?

any trends?


How to define? many different approaches with different results use only temperature as meteorological input link to definition of the phenological year

vegetation starts in early springwith plant stages:

forsythia, flowering (25.3.)gooseberry, leaf unfolding (27.3.)

vegetation stops at beginning of winter with plant stages: oak, leaf fall beech, leaf fall (27.10.)



large variation of phenological observations in small areas

most probable values by interpolation

58 stations with meterological and phenelogical observations

many different relations where tested not the best but simplest relation with good results was taken

Tsum = start day(Tmean day temperature – Treference temperature)



60 different start dates30 different ref. temp.(1800 cases)

for each case date reachingopt. temp. sum at 58 stations in 18 years

for each case optimal temp. sum for 58stations in 18 years

observed phenologicaldates of 58 stations in18 years

difference between observedand calculated dates =>dispersion for each case

Tsum = start date(Tmean day temperature – Treference temperature)

a simple methode to find the optimal start date and reference temperature



day of the year (start date)

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

3

4,4-4,6 4,6-4,8 4,8-5 5-5,2 5,2-5,4 5,4-5,6 5,6-5,8 5,8-6 6-6,2 6,2-6,4 6,4-6,6 6,6-6,8 6,8-77-7,2 7,2-7,4 7,4-7,6 7,6-7,8 7,8-8 8-8,2 8,2-8,4 8,4-8,6 8,6-8,8 8,8-9 9-9,2 9,2-9,4

refe

renc

e te

mpe

ratu

re

start date = 49. day of year, reference temperature = 0 °C, sum = 164 °C

dispersion matrix for gooseberry (leaf unfolding)




a fixed start date or end of dormancy can‘t be correct ! start date must depend from weather situation made a test with the both coldest and warmest years

15 20 25 30 35 40 45 50 55 60-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

start date

refe

renc

e te

mpe

ratu

re7,2-7,47-7,26,8-76,6-6,86,4-6,66,2-6,46-6,25,8-65,6-5,85,4-5,65,2-5,45-5,24,8-54,6-4,84,4-4,6

15 20 25 30 35 40 45 50 55 60-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

start date

refe

renc

e te

mpe

ratu

re

4,7-4,94,5-4,74,3-4,54,1-4,33,9-4,13,7-3,93,5-3,73,3-3,53,1-3,32,9-3,12,7-2,92,5-2,72,3-2,52,1-2,31,9-2,1

warm years

cold years

same ref. temp. -2.5 °Cdifferent start days


determing for every year with a fixed reference temperature of -2.5 °Coptimal start date and optimum temperature sum (TScrop)


0

50

100

150

200

250

300

350

36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

start date

optim

al te

mpe

ratu

re s

um

startdaycrop eTS *01962.053465

fitted dependence

observed

correlation 0.87



startdaycrop eTS *01962.053465

Calculation cheme:• starting at 1.1.• for every following day• calculating TScrop

• calculate TSlimit

TS > TSlimit ?

as start date is earlier, a higher temperatur sum is required (small chilling)as start date is later, a lower temperatur sum is required (large chilling)

plant state reached

yes

no

itcropit TSTSTSTS limlim ,min

60

70

80

90

100

110

60 70 80 90 100 110

calculated

obse

rved

correlation of 0,90dispersion of 4.3 days

startday temprefTTMTS ..


calculated phenologicalplant state in 2009

in mean +0,8 days differencePhenology 2010, June

observed phenologicalplant state in 2009


160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 24025

27

28

30

31

33

34

36

37

39

40

5,5-5,7 5,7-5,9 5,9-6,1 6,1-6,3 6,3-6,5 6,5-6,7 6,7-6,9 6,9-7,1 7,1-7,3 7,3-7,5 7,5-7,77,7-7,9 7,9-8,1 8,1-8,3 8,3-8,5 8,5-8,7 8,7-8,9 8,9-9,1 9,1-9,3 9,3-9,5 9,5-9,7 9,7-9,9

day of the year (start date)

start date = 214. day of year, reference temperature = 30 °C, sum = -1383 °C

refe

renc

e te

mpe

ratu

re

dispersion matrix for beech (leaf fall, 300. day of year)



determing for every year with a fixed reference temperature of 30 °Coptimal start date and optimum temperature sum (TScrop)


startdateTScrop *25,134265

fitted dependence

observed

correlation 0.99

-2000

-1800

-1600

-1400

-1200

-1000

-800

-600

-400

-200

0

170 180 190 200 210 220 230 240 250 260 270 280

start date

optim

al te

mpe

ratu

re s

um



Calculation cheme:• starting at 180. day • for every following day• calculating TScrop

• calculate TSlimit

TS < TSlimit ?

with high temperatures end of vegetation is laterlatest possible end is 18.11. (322. day of year)

plant state reached

yes

no

),max( limlim itcropit TSTSTSTS

275

285

295

305

315

325

275 285 295 305 315 325calculated

obse

rved

correlation of 0,60dispersion of 5,1 days

startdateTScrop *25,134265 startday temprefTTMTS ..


in mean +0,4 days differencePhenology 2010, June

calculated phenologicalplant state in 2007

observed phenologicalplant state in 2007



Comparison between observed and calculated mean values for Germany

70

75

80

85

90

95

100

105

110

1961

1966

1971

1976

1981

1986

1991

1996

2001

2006

years

day

of th

e ye

ar

270

275

280

285

290

295

300

305

310

calculated begin observed begin calculatetd end observed end


time series for mean vegetation period in Germany


185

190

195

200

205

210

215

220

225

230

1961

1966

1971

1976

1981

1986

1991

1996

2001

2006

years

perio

d in

day

s

calculated period observed period running average

1980 1991period 1 period 28 days longer



calculated vegetationperiod 1961 - 1980

calculated vegetationperiod 1991 - 2009

trend


optimal parameter for other plant stages

phenological plant stage ref. temp. correlation dispersion

grasland, start of greening (19.3.) -2.5 0.89 4.5

dandelion, flowering (14.4.) -2.5 0.89 4.1

apple, flowering (28.4.) 1.0 0.90 3.7




begin greening of grasland

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

day of the yearre

fere

nce

tem

pera

ture

in °C

6-6,2 6,2-6,4 6,4-6,6 6,6-6,8 6,8-7 7-7,2 7,2-7,4 7,4-7,6 7,6-7,8 7,8-88-8,2 8,2-8,4 8,4-8,6 8,6-8,8 8,8-9 9-9,2 9,2-9,4 9,4-9,6 9,6-9,8 9,8-10



ref. Temp. = -2,5 °Cstartday

crop eTS *01962.060035

0

50

100

150

200

250

300

350

400

450

500

20 25 30 35 40 45 50 55 60 65

correlation 0,84

55

60

65

70

75

80

85

90

95

100

105

110

115

55 60 65 70 75 80 85 90 95 100 105 110 115

calculated

obse

rved

correlation 0,89mean dispersion 4,5 days



21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81

-10-9-8-7-6-5-4-3-2-1012345

start day

refe

renc

e te

mpe

ratu

re in

°C

4,8-5 5-5,2 5,2-5,4 5,4-5,6 5,6-5,8 5,8-6 6-6,2 6,2-6,4 6,4-6,6 6,6-6,86,8-7 7-7,2 7,2-7,4 7,4-7,6 7,6-7,8 7,8-8 8-8,2 8,2-8,4 8,4-8,6 8,6-8,88,8-9 9-9,2 9,2-9,4 9,4-9,6 9,6-9,8

flowering of dandelion



ref. Temp. = -2,5 °Cstartday

crop eTS *01.071515

0

100

200

300

400

500

600

700

20 25 30 35 40 45 50 55 60

correlation 0,81

70

80

90

100

110

120

130

70 80 90 100 110 120 130

calculated

obse

rved

correlation 0,89mean dispersion 4,1 days


20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100-5-4-3-2-1012345678910

3,8-4 4-4,2 4,2-4,4 4,4-4,6 4,6-4,8 4,8-5 5-5,2 5,2-5,4 5,4-5,6 5,6-5,8 5,8-6 6-6,26,2-6,4 6,4-6,6 6,6-6,8 6,8-7 7-7,2 7,2-7,4 7,4-7,6 7,6-7,8 7,8-8 8-8,2

apple, flowering


always 24.2. for start day, ref. temp. of 1 °C, temp. sum of 361 °C

correlation of 0,90 and 3,7 days deviation



Thank you for your attention!

Documents

Determine the vegetation period and regional trends in Germany Wolfgang Janssen [email protected]