Issuu on Google+

 

Investigation  of  native  plants  in  Jogasaki  coast   for  semi-­‐extensive  green  roofs  in  Japan   Ayako  Nagase,  Chiba  University,  Graduate  School  of  Engineering,  Japan,  a-­‐nagase@faculty.chiba-­‐u.jp   Yurika  Tashiro,  Chiba  University,  Graduate  school  of  Horticulture,  Japan  

Abstract   Many   species   of   coastal   plants   are   endangered   because   of   urban   development,  however,  green  roofs  using  such  plants  could  help  conserve   local   plant   communities.   Coastal   plants   may   be   suitable   for   green   roofs   because   the   maritime   environment   is   similar   to   that   found   on   roofs,   such   as   very   free   draining   soils   and   strong   wind.   However,   there   have   been   few  studies  on  coastal  plants  for  green  roofs.  This  study  investigated  the   suitability  of  plants  found  on  the  Jogasaki  coast  for  green  roofs  in  Japan.   Aboveground  of  sixteen  plant  species  and  seeds  of  five  plant  species  were   collected  from  the  Jogasaki  coast  in  2011,  and  appropriate  propagation   methods   for   each   plant   were   investigated.   The   results   showed   that   two   species  Lysimachia  mauritima  and  Peucedanum  japonicum  showed  high   germination   rate   and   were   appropriate   for   direct   sowing,   whereas   division   and   cutting   were   appropriate   for   other   species,   especially   Chrisanthemum   pacificum,   Crepidiastrum   keiskeanum,   Sedum   oryzifolium  and  Tetragonia  tetragonioides.  Secondly,  the  performance  of   nine   plant   species   on   semi-­‐extensive   green   roofs   was   investigated.   The   Jogasaki  coastal  environment  was  recreated  on  volcanic  rocks  and  three   kinds   of   substrate,   commercial   green   roof   substrate,   crushed   roof   tiles   and   pumice.   It   was   shown   that   overall   plants   grew   fast   in   commercial   green  roof  substrate.    

Authors’  Biographies         Ayako  Nagase  is  an  assistant  professor  in  the  Graduate  school  of  Engineering  in   Chiba   University,   Japan.   Her   research   interest   is   plant   selection   for   green   roofs   and  biodiversity  in  urban  landscapes.        

 

World Green Roof Congress, 19-20 September 2012, Copenhagen Page 1


1.  Introduction   The  use  of  native  plants  on  green  roofs  has  recently  attracted  considerable  attention  (Bulter  et   al.,  2012).  Conservation  is  an  important  driving  force  behind  this  trend,  since  green  roofs  help   to  conserve  local  plant  communities.  For  example,  in  Wollishofen,  Zurich,  the  biological   diversity  of  species-­‐rich  wet  meadows  surrounding  a  water  filtration  plant  was  conserved  on   the  facility’s  roofs  after  much  of  the  habitat  disappeared  due  to  agricultural  development   (Brenneisen,  2006).  Coastal  plants,  which  are  endangered  by  urban  development,  may  be   suitable  for  green  roofs  because  the  maritime  environment  is  similar  to  that  found  on  roofs  in   terms  of  free-­‐draining  soil  and  strong  wind.  Moreover,  coastal  plants  have  the  advantage  of  less   competition  with  other  plants  on  green  roofs;  most  coastal  plants  are  difficult  to  establish  in   the  presence  of  naturally  emerging  inland  plants  (Yura,  2003).  Although  there  is  one  previous   study  on  the  use  of  coastal  plants  for  extensive  green  roofs  (MaIvor  and  Lundholm,  2011),  the   plants  were  selected  from  a  wide  range  of  coastal  areas  in  Atlantic  Canada  rather  than  from   native  plant  communities.     Currently,  the  definition  of  native  species  is  not  clear;  native  species  have  been  defined  as   ranging  from  a  building  site  to  a  country  (Bulter  et  al.,  2012).  Native  plants  found  on  many   green  roofs  often  originate  from  a  wide  area;  for  example,  some  plants  come  from  the   mountains  and  others  from  the  coast.  Another  concern  is  where  the  seeds  of  native  plant   species  come  from  and  where  they  are  propagated.  A  recent  study  showed  that  the   performance  of  some  native  Japanese  plants  differed  from  that  of  native  plants  from  Japan   (Abe  et  al.,  2004).  However,  most  commercial  Japanese  native  plant  seeds  are  produced   overseas  and  it  is  very  difficult  to  find  ones  produced  in  Japan.  Ideally,  plants  would  be   obtained  and  propagated  locally.  The  present  study  examined  whether  it  is  possible  to  recreate   a  local  herbaceous  plant  community  on  a  roof,  by  studying  the  natural  habitats  of  seacoast   plants,  and  their  propagation  and  performance  on  a  semi-­‐extensive  green  roof.      

2.  Methods     2.1  Investigation  of  seacoast  plants   The  Izu  peninsula  was  chosen  as  the  study  site  because  of  its  proximity  to  Tokyo  (200  km)  and     abundance  of  endemic  plant  species.  The  climate  is  relatively  mild,  with  a  mean  annual   temperature  of  15–17°C  and  annual  precipitation  of  2000  mm.  We  investigated  six  coastal   areas  of  the  peninsula:  Akazawa,    Jogasaki,  Kawana,  Kawazu,  Manazuru  and  Shiofuki  (Fig.  1).  A   vegetation  study  was  carried  out  in  seven  times,  on  August  11,  September  5,  October  4,   November  3,  and  December  4  in  2011,  and  on  February  27  and  April  29  in  2012.    

World Green Roof Congress, 19-20 September 2012, Copenhagen Page 2


Fig.  1  Location  of  the  study  site  on  the  Izu  peninsula  in  Japan.     2.2  Propagation     Ripe  seeds  of  five  species  were  collected  from  the  natural  vegetation  in  Jogasaki  between   August  and  December  2011.  The  plant  species  were  Crepidiastrum  keiskeanum,  Lysimachia   mauritiana,  Peucedanum  japonicum,  Hemerocallis  fulva  var.  littorea  and  Rosa  luciae.  The   collected  seeds  were  dried  at  room  temperature  (about  20°C)  for  one  week  and  then  kept  in  a   refrigerator  at  3°C.  Fifty  seeds  of  each  plant  species  were  placed  in  a  petri  dish  on  9-­‐cm  filter   paper  moistened  with  distilled  water.  On  December  28,  2011,  they  were  placed  in  an  incubator   at  20°C  (12  h  light,  12  h  dark).  There  were  three  replications  for  each  plant  species.  Germinated   seeds  were  counted  daily.       On  February  27,  2011  and  April  29,  2012,  sixteen  species  of  plants  were  collected  from  Jogasaki   and  Kawazu.  The  collected  species  and  number  of  plants  are  shown  in  Table  1.  Most  of  the   species  were  growing  roots  between  rocks  and  were  difficult  to  remove  with  the  roots  (Fig.  2).   Therefore,  only  the  aboveground  part  was  removed  for  most  species.  After  being  taken  from   their  natural  habitat,  the  plants  were  cut  to  an  appropriate  size  for  each  species  and  planted  in   9-­‐cm  pots  filled  with  soil  for  propagation.  The  potted  plants  were  kept  in  a  greenhouse  in   Matsudo,  Chiba  and  were  watered  daily.    

  Fig.  2  Jogasaki  seacoast.   World Green Roof Congress, 19-20 September 2012, Copenhagen Page 3


2.3  Substrate  and  plant  performance  on  the  green  roof   A  semi-­‐extensive  green  roof  was  installed  on  the  top  of  the  ninth  floor  of  a  building,  which  was   surrounded  by  a  parapet  1.2  m  in  height.  The  area  of  the  green  roof  was  3.0×7.3  m.  The  green   roof  was  framed  with  timbers,  and  consisted  of  a  root  protection  layer,  10  cm  of  pumice  for   drainage  and  20  cm  of  one  of  three  types  of  substrate:  commercial  green  roof  substrate   (Kusabanameijin),  pumice  with  10%  volume  of  peat  moss,  and  roof  tile  with  10%  volume  of   straw.  The  materials  were  obtained  from  Suikenkurieito  (Tokyo),  Hibia  Amenis  (Tokyo)  and   Nihoniringyohiryo  (Tokyo).  The  green  roof  was  divided  into  three  plots  by  type  of  substrate   (1.0×7.3  m).  On  May  25,  2012,  successfully  propagated  plants  were  randomly  planted  on  the   green  roof,  then  volcanic  rocks  (about  10  cm  in  diameter)  were  placed  as  mulch  to  create  a   similar  landscape  to  that  of  the  plant  community.  An  installed  drip  irrigation  system  was   programmed  for  automatic  watering  three  times  a  week.  Plant  height  was  measured  every  two   weeks.  Significance  of  differences  in  substrate  was  determined  using  one-­‐way  ANOVA  (Minitab   Release  14)  at  a  probability  level  of  P  <  0.05.  

  Fig.  3  Overview  of  experimental  site.  

 

3. Results  and  Discussion     3.1  Seacoast  plants  in  the  Izu  peninsula   The  plant  species  that  were  observed  in  the  studied  natural  habitats  are  shown  in  the   Appendix.  The  highest  number  of  plant  species,  thirty-­‐four,  was  observed  in  Jogasaki,  followed   in  order  by  twelve  in  Kawana,  nine  in  Akazawa,  six  in  Shiofuki,  five  in  Kawazu  and  four  in   Manazuru.  Yura  et  al.  (2008)  studied  the  vegetation  in  1308  seacoast  areas  in  Japan,  and  found   that  the  average  number  of  seacoast  plant  species  was  only  six;  the  decrease  in  seacoast  plants   is  a  serious  problem  in  Japan.  They  also  found  that  the  number  of  plants  was  related  to  the   seacoast  environment  such  as  the  presence  of  concrete  structures  (e.g.  embankment),  human   activity,  maintenance  such  as  weeding,  and  frequency  of  natural  disasters.  Their  findings  agree   with  the  results  of  our  study;  in  Jogasaki,  there  are  no  concrete  structures  near  the  sea  and  the   area  is  not  used  for  activities  such  as  swimming,  whereas  the  other  areas  have  embankments   and  most  places  are  used  for  swimming.       3.2  Propagation   Among  the  five  plant  species,  L.  mauritiana  and  P.  japonicum  showed  a  germination  rate  of   more  than  70%.  Therefore,  chilling  is  not  necessary  for  these  two  species,  which  readily   World Green Roof Congress, 19-20 September 2012, Copenhagen Page 4


germinated  with  the  appropriate  temperature  and  water.  However,  the  other  species  did  not   germinate  at  all,  showing  that  these  species  are  difficult  to  germinate  or  may  require  lengthy   chilling  to  break  dormancy.        

   

Fig.  4  Change  in  germination  rate  over  time.  

The  success  rate  for  the  cuttings  is  shown  in  Table  1.  It  was  possible  to  propagate  most  plants   from  cuttings.  Succulent-­‐type  plant  species  such  as  C.  keisukeanum,  S.  oryzifolium  and   T.  tetragonioides  showed  a  high  survival  rate.  Moreover,  Carex  spp.  C.  pacificum  and   L.  mauritiana  were  also  successful.  However,  some  species  such  as  C.  soldanella,  E.  jolkinii,   L.  japonicus,  L.  maculatum  and  R.  luciae  were  difficult  to  propagate.  E.  jolkinii  was  not   successful  probably  because  it  contains  latex,  although  the  cuttings  were  washed  before   propagation.  Woody  plants  such  as  R.  luciae  showed  a  low  percentage  of  late  survival  and  it   may  be  beneficial  to  use  root-­‐inducing  hormones.                       World Green Roof Congress, 19-20 September 2012, Copenhagen Page 5


Table  1  Success  rate  for  cuttings     1)

 

2)

Winter  collection  

 

Spring  collection  

Number  of   collected   plants  

Number  of   surviving   plants  

Survival   rate  

Number  of   collected   plants  

Number  of   surviving   plants  

Survival   rate  

Calystegia  soldanella  

3  

0  

0  

n/a  

n/a  

n/a  

Carex  meridian    

15  

7  

46.7    

20  

15  

75.0    

Carex  oshimensis  

25  

17  

68.0    

5  

3  

60.0    

Chrysanthemum   pacificum  

23  

18  

78.3    

21  

14  

66.7    

Crepidiastrum   keiskeanum  

16  

9  

56.3    

32  

25  

78.1    

Cytomium  fortunei  

18  

8  

44.4    

20  

4  

20.0    

Euonymus  japonicus   var.  litoralis  

15  

5  

33.3    

20  

4  

20.0    

Euphorbia  jolkinii  

42  

3  

7.1    

30  

3  

10.0    

Farfugium   japonicum  

12  

7  

58.3    

n/a  

n/a  

n/a  

Hemerocallis  fulva   var.  littorea  

13  

5  

38.5    

31  

15  

48.4    

Lathyrus  japonicus  

15  

0  

0  

n/a  

n/a  

n/a  

Lilium  maculatum  

n/a  

n/a  

n/a  

13  

0  

0  

Lysimachia   mauritiana  

18  

12  

66.7    

n/a  

n/a  

n/a  

uncountable  

all  

100  

n/a  

n/a  

n/a  

Tetragonia   tetragonioides  

3  

3  

100  

n/a  

n/a  

n/a  

Rosa  luciae  

24  

5  

20.8    

27  

3  

11.1    

Sedum  oryzifolium  

(%)  

(%)  

1) Winter  collection:  Plants  were  collected  on  February  27,  2012  and  surviving  plants  were  measured   on  April  23,  2012.     2) Spring  collection:  Plants  were  collected  on  April  29,  2012  and  surviving  plants  were  measured  on   May  9,  2012.    

3.3  Substrate  and  plant  performance  on  the  green  roof   The  results  for  plant  height  on  June  14,  2012  are  shown  in  Fig.  5  for  three  representative  plants   (Chrysanthemum  pacificum,  Hemerocallis  fulva  var.  littorea,  Rosa  luciae).  Currently,  all  plants   have  survived  and  are  growing  well  in  each  type  of  substrate.  However,  plants  in  the   commercial  green  roof  substrate  are  growing  faster  than  those  in  the  crushed  roof  tiles  and   pumice,  and  this  tendency  is  more  pronounced  in  herbaceous  perennials  than  in  woody  plants.   The  statistical  results  showed  that  the  difference  in  substrate  had  a  significant  effect  on  the   plant  height  of  C.  pacificum  and  H.  fulva  var.  littorea.  A  previous  study  showed  that  plants  with   World Green Roof Congress, 19-20 September 2012, Copenhagen Page 6


lush  growth  may  not  be  able  to  withstand  drought  (Nagase  and  Dunnett,  2011).  Further   observation  is  necessary  to  confirm  the  plant  performance  on  the  green  roof.    

  Fig.  5  Plant  height  on  June  14,  2012.   n  =  5.  Error  bars  represent  the  standard  error  of  mean  values.  P  =  probability.  n.s.  =  not   significant.  One-­‐way  ANOVA  was  used  to  compare  the  values  from  each  plant  species.   Substrate  type  had  a  significant  effect  on  plant  height  in  Chrysanthemum  pacificum  and   Hemerocallis  fulva  var.  littorea.      

4. Conclusion  

 

Green  roofs  may  be  ideal  places  for  conserving  coastal  plant  species.  Moreover,  the  process  of   studying  their  natural  habitat,  propagating  the  plants,  planting  them  on  the  roof  and  observing   their  performance  would  be  an  appropriate  environmental  education  for  understanding  local   plant  communities.  Green  roofs  also  have  potential  as  nurseries  for  growing  plants  and   returning  them  to  their  natural  seacoast  habitat,  where  endemic  plant  species  are  decreasing.   Longer-­‐term  study  is  necessary  to  confirm  the  plant  performance  in  different  types  of  substrate.      

References   1. Abe,  T.,  Nakano,  Y.,  Kuramoto,  N.,  2004.  Is  it  possible  to  consider  Chinese  origin  of   Indigofera     pseudotinctoria  as  Japanese  native  plants  ?  Journal  of  the  Japan  society  Revegetation     Technology  30  (1):  344-­‐347.  (in  Japanese)   2. Butler,  C.,  Butler,  Orians.  C.M.,  2012.  Native  plant  enthusiasm  reaches  new  heights:     Perceptions,  evidence,  and  the  future  of  green  roofs.  Urban  Forestry  and  Urban     greening  11:1-­‐10.     3. Brenneisen,2006.  Space  for  urban  wildlife:  Designing  green  roofs  as  habitats  in  Switzerland,     World Green Roof Congress, 19-20 September 2012, Copenhagen Page 7


4. 5. 6. 7.  

Urban  habitat  4  (1):  27-­‐33.     MacIvor,  J.S.,  Lundholm,  J.,  2011.  Performance  evaluation  of  native  plants  suited  to     extensive  green  roof  conditions  in  a  maritime  climate.  Ecological  Engineering.37,407-­‐   417.   Nagase  and  Dunnett,  2011.  The  relationship  between  percentage  of  organic  matter  in     substrate  and  plant  growth  in  extensive  green  roofs,  Landscape  and  Urban  Planning     103:230-­‐236.     Yura,H.  2003.    Survival  and  growth  of  Chrysanthemum  pacificum  Naki  seedlings  at  the     inland  site,  Natural  History  Research  7  (2):107-­‐114.   Yura,H.  2008.  Report  of  investigation  of  coastal  plants  with  citizens  2004-­‐2007.,  The  nature     conservation  society  of  Japan,  available  from  http://www.nacsj.or.jp/project/spc/  (in     Japanese)  

Acknowledgements   The   authors   would   like   to   thank   students   in   Laboratory   of   design   management,   Faculty   of   Engineering   in   Chiba   University   for   helping   set   up   the   experimental   site.   Funding   for   this   research  was  provided  by  the  new  technology  development  foundation.        

Appendix  

World Green Roof Congress, 19-20 September 2012, Copenhagen Page 8


Jogasaki  

Kawana  

Akazawa  

Shiofuki  

Kawazu  

Manazuru  

Ampelopsis  brevipedunculata  var.   hancei  

Angelica  keiskei  

B.  biloba  

A.  keiskei  

Calystegia   soldanella  

A.  brevipedunculata   var.  hancei  

Angelica  japonica  

A.   brevipedunculata   var.  hancei  

C.pacificum  

C.soldanella  

I.  repens  

B.  biloba  

Boehmeria  biloba  

C.  pacificum  

C.  falcantum  

C.  falcantum  

Lathyrus  japonicus  

C.  soldanella  

Carex  meridian  

C.   heterocarpa   var.   japonica  

C.  keiskeanum  

E.jolkinii  

M.  condensatus  

T.  tetragonioides  

Carex  oahuensis  var.  robusta  

C.  falcantum  

Ixeris  repens  

F.  japonicum  

Oenothera   laciniata  

 

Carex  oshimensis  

Dianthus  japonicus  

Lemmaphyllum   microphyllum  

P.  tobira  

 

 

Chrysanthemum  pacificum  

F.  japonicum  

M.  condensatus  

 

 

 

Ixeris  repens  

Piper  kadzura  

 

 

 

Crepidiastrum  keiskeanum  

Lilium  maculatum  

Polygonum  chinese  

 

 

 

Cyrtomium  falcantum  

M.  condensatus  

 

 

 

 

Cytomium  fortunei  

Raphanus   sativus   var.   hortensis   f.   raphanistroides  

 

 

 

 

Dioscorea  tokoro  

T.  tetragonioides  

 

 

 

 

Euonymus  japonicus  var.  litoralis  

 

 

 

 

 

Euphorbia  jolkinii  

 

 

 

 

 

Eurya  japonica  

 

 

 

 

 

 

 

 

 

 

Farfugium  japonicum  

 

 

 

 

 

Fimbristylis  pacifica  

 

 

 

 

 

Hedyotis  strigulosa  var.  parvifolia  

 

 

 

 

 

Hemerocallis  fulva  var.  littorea  

 

 

 

 

 

Juniperus  chinensis  

 

 

 

 

 

Lysimachia  mauritiana  

 

 

 

 

 

Miscanthus  condensatus  

 

 

 

 

 

Peucedanum  japonicum  

 

 

 

 

 

Pinus  thunbergii  

 

 

 

 

 

Pittosporum  tobira  

 

 

 

 

 

 

 

 

 

 

Rosa  luciae  

 

 

 

 

 

Rumex  acetosa  

 

 

 

 

 

Sagina  maxima  

 

 

 

 

 

Sedum  oryzifolium  

 

 

 

 

 

Setaria  viridis    var.  pachystachys  

 

 

 

 

 

Sphenomeris  biflora  

 

 

 

 

 

Tetragonia  tetragonioides  

 

 

 

 

 

Corydalis   japonica  

heterocarpa  

Elaeagnus   rotundifolia  

umbellata  

Rhaphiolepis   integerrima  

umbellata  

34  species  

var.  

var.  

var.  

12  species  

9  species  

6  species  

5  species  

World Green Roof Congress, 19-20 September 2012, Copenhagen Page 9

4  species  


 

World Green Roof Congress, 19-20 September 2012, Copenhagen Page 10


Investigation of native plants in Jogasaki coast for semi-extensive green roofs in Japan. WGRC 2012.