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E N VIRONMENTAL E FFECTS OF DE N S E LY PLA NTE D
WI LLOW AN D POPLAR I N A SILVOPASTORA L S YSTEM
A thesis presented in partial fulfilment of the requirements for the degree of
Doctor of Philosophy (PhD)
In Ag rofo restry
Institute of Natural Resources Massey University
Palmerston North, New Zealand
ZAKER HUSSAIN
2007
THIS THESIS IS DEDICATED TO MY PARENTS WHO ALWA YS PRA YED FOR MY SUCCESS TO
GAIN HIGHER QUALIFICA TION
Abstract
New Zea land , having large areas of h i l ly landscapes , is subject to the risk of soi l
eros ion , and summer and autumn d roug hts that l im it pasture g rowth , wh ich in
turn affects the l ivestock-based economy. The n itrogen and phosphorus input in
fert i l isers coup led with l ivestock excreta and so i l d istu rbance impose a ser ious
threat to downstream water qual ity . The p lant ing of trees is one opt ion used to
decrease soi l erosion , increase the quantity of forage and manage runoff.
To date , research has ma in ly focused on wide spaced poplar trees for feed
qua l ity and their effects on understorey pasture g rowth . However, there is
increasi ng i nterest in the use of densely p lanted wi l low and poplar for fodder
purpose. The effects of young « 5 yrs old) wi l low and poplar p lanted at c lose
spacing on runoff, soi l erosion , g rowth of understory pasture and n utrient losses
have never been stud ied in New Zealand .
Three field tr ia ls (two at Crop and Research Un it , Mog i n ie , Manawatu and one
at R iverside Farm , Masterton) were conducted between October 2004 and
November 2006 that i ncorporated comparative estab l ishment and g rowth of
densely p lanted wil low and poplar and their effects on soi l moisture, runoff,
sed iment load and nutrient losses from grazed and fert i l i sed farmland .
It was concluded that densely planted wi l low and poplar (3-4 yrs) reduced tota l
n itrogen (TN) and d issolved reactive phosphorus (DRP) by 47 % each and
sed iment load by 52 % . Young trees reduced su rface runoff and so i l moisture
more as they aged . However, due to their deciduous nature wi l low and poplar
were not effective i n reducing surface runoff i n winter and early spri ng . Sheep
p referred camping under trees , especial ly in late spring and summer, and th is
led to g reater deposit ion of d ung and u rine under trees than open pasture .
Sheep g raz ing , especial ly i n winter, s ign ificantly increased sed iment a nd
nutrient loads i n runoff water. The N and P fert i l iser appl ication i ncreased
nutrient load in runoff water wel l above the threshold level requ i red to in itiate
a lga l growth to create eutroph ication .
Densely p lanted wil low and pop lar s ign ificantly reduced u nderstorey pasture
g rowth by 23 % and 9 %, respectively, i n their second year at Mog in ie , ma in ly
due to shade, but coupled with soi l moisture deficit i n summer. The pasture
g rowth i n a wi l low browse block was 52 % of that in open pasture as a resu lt of
shade and d ifferences in pasture species composition . Sheep browsing reduced
wi l low leaf area s ign ificantly. Wi l low and poplar survival rates were simi lar (P >
0 . 05) after two years of estab l ishment ( 1 00 % vs 90 .5 % , respectively ) .
However, wi l low grew faster than poplar in height ( 1 .90 vs 1 . 35 m) , stem
d iameter (43 .5 vs 32 .6 mm), canopy d iameter (69 vs 34 cm) and number of
shoots (8 .7 vs 2 . 3) at the age of two years, respectively.
The research clearly demonstrated that densely p lanted young wi l low and
poplar trees can reduce runoff, sed iment load and n utrient losses from farm land
to freshwater, but shade and soi l moisture can l im it pasture g rowth under trees.
It is recommended that wi l low and poplar should be planted at wide spacing on
the whole farm to m in imise loss of pasture. Where b locks of trees a re
necessary , such as wi l low browse b locks, sheep browsing can be used as a
tool to red uce shade to improve pasture g rowth . Livestock access to r ipari an
strips shou ld be min imal to avoid l ivestock camping that can have deleterious
effects on water qual ity .
Key words : wi l low; poplar ; growth ; n utrients; pastu re ; runoff; so i l erosion ; so i l
moisture ; fert i l iser; water; sheep; brows ing ; camp ing .
11
Acknowledgements
The exploration of environmental effects of wi l low and poplar in a s i lvopastoral
system was not possib le without the physica l , financia l , technical and moral
support of many ind iv idua ls and some organ isat ions. These acknowledgements
a re intended to express gratitude and appreciat ion to a l l those who contributed
to the success of th is thesis . However, undoubted ly, God a lmighty stands first
and foremost for blessing me with the hea lth and mental capab i l ity to undertake
th is study.
S incere and heartfelt g ratitude to my chief supervisor Professor Peter Kemp for
h is support, gu idance and patience throughout my study. H is sympathetic
behaviour , generosity and g reat encouragement were instrumenta l to my
academic career at Massey. I also thank my co-supervisor Or Oavid Horne for
h is supervis ion and techn ical i nput i n my thes is . Or Horne made a sign ificant
contribution through corrections and fru itfu l crit icism of manuscripts of th is
thes is .
The physica l and techn ical support by Mr . Mark Osborne, sen ior techn ician , is
greatly appreciated . My thanks to Mr . Tom Oodd and Mr. Ross Wal lace for their
physical input i n sett ing up experiments and data col lection , Mr . Bob Toes for
constructing the t ipping buckets and help with laboratory analyses, l an Fu rkert ,
and Ms . Glenys Wal lace for their support i n laboratory works and analyses .
Thanks to I NR office support staff, especia l ly Oen ise Stewart, Oenise Bru nski l l
and Glenys G i l l igan for their friend ly behaviour and a lways avai lable support .
Specia l thanks to Mr. James Han ley, for h is techn ical support in i nstrumentation
of runoff measurements and nutrient ana lyses . I thank Or Alasda i r Noble , Or
Komang Jaya and Anne West for their contribution in statistical ana lyses of the
data . Thanks to Mr. Lance Currie for his support through good admin istration
and help for analyses of soi l samples. I appreciate Or James M i l l ner for h is
techn ica l advice and provis ion of instruments for the col lection of tree g rowth
data . Or Cory Matthew has been generous with h is advice whenever and where
ever approached . M ike Bretherton for developing the Excel Macro for
111
processing the t ipp ing bucket data logger fi les , used to measure surface runoff.
I appreciate Or Baisen Zhang , Or Ent in Oan ings ih , Or Tehseen Aslam and
Edmundo Viegas for their advice and company du ring thei r doctora l studies at
Massey. Thanks to M r. Bhoj Bahadu r Kshatri and Zulkefly Su la iman for he lp ing
me in data col lect ion and having usefu l d iscuss ions on my research . Thanks to
Gi r ija Page, B ijaya , D iwas and other postgraduate students for thei r company.
My g ratitude to the Doctoral Research Committee chairman and members for
g rant ing me the 'Massey doctoral scholarsh ip ' that laid the foundation for my
PhD . I a lso acknowledge the financia l support from Sustainable Farming Fund
Project, Helen E . Akers and John Hodgson pastoral science scholarsh ips .
Special thanks to AJK Forest Department for the g rant of study leave .
It is a g reat p leasure to acknowledge the friendsh ip , advice and k ind support by
Or M . A. Choudhary , Or Manzoor-u l Haque Awan and Mr. Zu lfiqar Haider B utt
that made it possible for me to jo in Massey Un ivers ity and ach ieve th is success.
I extend my gratitude to my friends i n Pakistan , i n particu lar , Mr. Tanveer
H ussa in Qureshi , Mr. Muhammad Shafiq , Mr. Muhammad Arif Quresh i , M r.
Abdu l Hamid , Mr . M ustafa Mugha l , M r. Muhammad Tayyab , Mr. Mushtaq
Quresh i , M r. Abdul Rauf Qureshi and Abdu l Rashid Jhang for their prayer and
appreciation that has been instrumental to me d ur ing my study at Massey.
I acknowledge the great support and friendship of Mr . Tah i r Mahmood and M rs .
Amsha Nah id from day one of my arr ival i n New Zea land . Their k i nd hospita l ity
and the i r role in looking after my fami ly were of g reat value to me and wi l l never
be forgotten . S im i larly , M r. and M rs . Babar Saeed , Mr . and Mrs . Muhammad
Nas im, M r. and Mrs . Tariq Choudhry , Mr. and M rs . Sarfraz, Mr. and Mrs .
Muhammad Ali and Mr and Mrs. Ahmer Khawaja deserve g reat appreciat ion for
their friendsh ip and support.
My humble and heartfelt acknowledgement goes to my beloved Father and
mother who prayed so much for my success . I can ' t be ind ifferent to my
brothers and sister for the i r love a nd appreciation to my success. F ina l ly , I
appreciate the patience and support of my wife Samina . My daughters Anum
and Aminah have been a source of p leasu re and rel ief du ring stress .
LV
Table of contents Page
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i i i
Table of contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
L ist of Tab les . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i
List of F igures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i i i
List of P lates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
List of Append ices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv i i
G lossary and abbreviat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi i i
CHAPTER 1 : Genera l i ntroduct ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
CHAPTER 2: Literature rev iew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
CHAPTER 3: Establ ishment of densely p lanted wi l low and poplar and their effect on
u nderstorey pasture growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
CHAPTER 4: Pasture g rowth i n a wi l low browse b lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 04
CHAPTER 5: Effects of densely p lanted wi l low and poplar on runoff, sed iment and nutrient
losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 45
CHAPTER 6: General d iscussion and concl usions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 6
v
Table 2 . 1
Table 3. 1
Table 3 .2
Table 4 . 1
Table 4 .2
Table 4 .3
Table 4 .4
Table 4 .5
Table 4 .6
Table 5 . 1
Table 5 .2
List of Tables
The d isti ngu ish ing features of the genus Popu/us and Sa/ix. -------------------------------------------------------------------- 1 5
The spr ing pasture species composit ion (%) from wil low pasture (WP) , poplar pasture (PP) and open pasture (OP) treatments at Mog in ie , Manawatu . ------------------ 8 1
Seasona l NHA rate (kg O M ha-1 day-1 ) i n wi l low pasture (WP) , poplar pasture (PP) and open pasture (OP) treatments at Mogin ie , Manawatu . ----------------------------- 83
Soi l Olsen P (\-lg g- 1 ) and pH in wi l low pasture (WP) and open pasture (OP) treatments at Riverside Farm near Masterton , Wai ra rapa. ------------------------------------- 1 1 4
Soi l bu lk density (g cm-3) in wi l low pastu re (WP) and open pastu re (OP) treatments at R iverside Farm near Masterton , Wa i ra rapa . --------------------------------------- ------ 1 1 5
Pasture species composit ion (%) i n early autumn 2005 in wi l low pastu re (WP) and open pasture (OP) treatments at Rivers ide Farm , near Masterton , Wairarapa. ------------------------------------------------------------------- 1 1 6
Pasture species composit ion (%) i n spring 2005 i n wi l low pasture (WP) and open pasture (OP) treatments at R ivers ide Farm near Masterton , Wai ra rapa. ------------------------------------------------------------------- 1 1 7
Seasonal N HA rate (kg OM ha-1 day-1 ) for 2004-05 i n wi l low pasture (WP) and open pasture (OP) treatments at R ivers ide Farm near Masterton , Wa i rarapa. ------------------------------------------------------------------- 1 1 8
Least square means comparison for volumetric soi l moisture content (%) between wi l low pasture (WP) and open pasture (OP) treatments at Riverside Farm nea r M a ste rto n, Wa i ra rapa . ------------------------------------- 1 23
Least square means for volumetric soi l moisture content (%) i n open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . ------------------------------ 1 59
Seasonal runoff (mm) comparison between open pasture (OP) and tree pasture (TP) treatments at M og i n ie, M a n awatu . ------------------------------------------------------- 1 62
VI
Table 5 . 3 Seasonal suspended sol id losses (kg ha-1 ) i n surface runoff (mm) from open pastu re (OP) and tree pasture (TP) treatments at Mog i n ie , Manawatu . ------------- 1 65
Table 5 .4 Least square means for suspended sol ids concentrat ions (mg L- 1 ) and losses (kg ha-1 ) in surface runoff (mm) i n open pastu re (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . ------------------- 1 66
Table 5 . 5 Tota l P concentrat ions (mg L-1 ) i n surface runoff (mm) in open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . ------------------------------------ 1 68
Table 5 .6 Seasonal comparison for tota l P and DRP losses (kg ha-1 ) in surface runoff (mm) in open pasture (OP) and tree pasture (TP) treatments at Mog i n ie , Manawatu . ------------------------------------------------------------------- 1 69
Table 5 .7 Least square means of total P and DRP concentrat ions (mg L-1 ) and losses (kg ha-1 ) i n surface runoff (mm) ) i n open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . ------------------- 1 70
Table 5 .8 Seasonal comparison of tota l n itrogen (TN) , ammon ium-N (NH/-N ) and n i trate-N (N03--N ) losses (kg ha-1 ) i n surface runoff (mm) i n open pasture (OP) and tree pasture (TP) treatments at Mog inie, Manawatu . ------------------------------------------------------- 1 77
Table 5 . 9 Least square means of concentrations (mg L-1 ) and losses (kg ha-1 ) of tota l n itrogen (TN) , tota l kje ldah l n itrogen (TKN) , ammonium-N (NH/-N ) and n itrateN (N03--N ) in surface runoff in open pasture (OP) and tree pasture (TP) treatments at Mog i n ie , M a nawatu . ------------------------------------------------------------------- 1 80
Table 5 . 1 0 Least squares means for suspended sol ids concentrat ions (mg L-1 ) and losses (kg ha-1 ) in surface runoff (mm) in open pasture (OP) and wi l low pasture (WP) treatments at Rivers ide Farm near Masterton, Wai rarapa. ---------------------------------------------------- 1 88
Table 5 . 1 1 Least squares means for total P and DRP concentrations (mg L- 1 ) and losses (kg ha-1 ) i n su rface runoff (mm) i n open pasture (OP) and wi l low pasture (WP) treatments at Riverside Farm near Masterton , Wai rarapa . --------------------------------------------------- - 1 90
Table 5 . 1 2 Least squares means for TN and N H/-N concentrations (mg L-1 ) and losses (kg ha-1 ) at R iverside Farm near Masterton , Wairarapa . ------------------------ 1 93
Vll
List of Figures
F igure 1 . 1 Outl i ne of the Thesis . ----------------------------------------------------- 7
F igure 2 . 1 P can be released from soi l and plant material to surface and subsurface runoff water or lost by e ro s ion . ----------------------------------------------------------------------- 35
F igure 3 . 1 The canop ies of four nuclei trees ( red circles) p lanted as a square grid ( 1 .2 x1 .2 m spacing) . The square with b lue l i nes ind icates the actual spacing at which trees were planted whi le the areas of red ci rcles i ns ide the square show the canopy. ------------------------- 71
F igure 3 .2 Tota l monthly ra infa l l (mm) and mean a i r and soi l temperature (QC) du ring the experimental period in Pa lmerston North , New Zealand . -------------------------------------- 76
F igure 3 .3 Data pattern shows the relationsh ip between the tree stem d iameter (mm) and tree height (m) of wi l low and poplar at Mog i n ie , Manawatu . ---------------------------- 78
F igure 3 .4 Data pattern shows l inear relationship between i n itia l tree stem diameter (mm) and fina l stem d iameter (mm) of wi l low and poplar at Mogin ie , Manawatu (n = 342 , P < 0 . 000 1 ) . -------------------------------------- 78
F ig u re 3 .5 Month wise mean da i ly NHA rate (kg OM ha-1 day-1 ) from wil l ow pasture (WP) , poplar pastu re (PP) and open pasture (OP) treatments at Mog in ie, Manawatu . Va lues for Ju ly and August were equa lly d istributed . Bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ------------------------------------ 82
F igure 3 .6 Volumetric soi l moisture content (%) from wi l low pasture (WP) , poplar pasture (PP) and open pasture (OP) treatments at 0- 1 50 mm depth at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 .05 . ---------------------- 84
F igure 3 .7 Volumetric soi l moisture content (%) from wi l low pastu re (WP) , poplar pasture (PP) and open pasture (OP) treatments at 0-300 mm depth at Mog i n ie , Manawatu . The l i ne bars show the SEM for each treatment. * denotes sign ificance at P < 0 .05 . ---------------------- 85
V 111
Fig ure 3 . 8
F igure 3 . 9
Fig u re 4 . 1
F igu re 4 .2
Volumetric soi l moisture content (%) from wil low pasture (WP) , poplar pasture ( PP) and open pasture (OP) treatments at 0-450 mm depth at Mogin ie , Manawatu . The l i ne bars show the SEM for each t reatme nt. -------------------------------------------------------------------- 86
Relationship between soi l moistu re at 0- 1 50 mm depth and NHA rate (Kg OM ha- 1 month- 1 ) from September-Apri l . Moisture data is the mean for each month from wi l low pasture (WP) , poplar pasture (PP) and open pasture (OP) treatments at Mog in ie , M a n awatu . ------------------------------------------------------------------- 87
Monthly ra infa l l (mm) for Massey's R iverside Farm , near Masterton , Wa irarapa . Data were obta ined from Wai rarapa Col lege Air Qua l ity Site (Coord NZMG 1 949 E2732767 N6024886) ----------------------------------- 1 1 5
Net herbage accumu lation (N HA) rate from November 2004 to October 2005 in wi l low pasture (WP) a nd open pasture (OP) treatments at Riverside Farm , near Masterton , Wairarapa. L ine bars show the SEM for each treatment. * denotes a significant d ifference between treatments at P < 0 . 05 . -------------------------------------------------------------------------- 1 1 8
Figu re 4 . 3 Cumu lative herbage accumu lation rate ( k g O M ha- 1
month-1 ) from November 2004 to Ju ly 2005 i n wi l low pasture (WP) treatment a t R iverside Farm near Masterton, Wa irarapa. Line bars show the SEM. -------------------------------------------------------------------------- 1 1 9
Figu re 4 .4 Leaf area d ifference (m2 tree- 1 ) between browsed ( 1 st year) and u nbrowsed (2nd year) wi l low copp ice trees i n wi l low pasture (WP) treatment at R iverside Farm near Masterton, Wai rarapa. Line bars show the SEM for each date. * denotes P < 0 .05 s ig n ifica nce. ----------------------------------------------------------------- 1 2 1
Figu re 4 .5 L inear relationsh ip between wi l low leaf a rea (m2
tree- 1 ) and u nderstorey net herbage accumu lation rate (kg OM ha- 1 day" 1 ) in wi l low pasture (WP) treatment from Decem ber to February at R iverside Farm nea r M a ste rto n , Wa i ra rapa . ------------------------------------- 1 2 1
F ig u re 4.6 Volumetric soi l moisture content (%) at 0- 1 50 mm depth at Massey's R iverside Fa rm near Masterton , Wai rarapa. L ine bars show the SEM for each date . * denotes sign ificance at P < 0 .05 . ------------------------------------ 1 23
IX
Figu re 4 .7 Vo lumetric soi l moisture content (%) at 0-300 mm depth i n wi l low pasture (WP) and open pasture (OP) treatments at R ivers ide Farm near Masterton , Wairarapa . L i ne bars show the SEM for each date . * denotes sign ificance at P < 0 .05 . -------------------------------------- 1 24
F igure 4 .8 Vo lumetric soi l moisture content (%) at 0-450 mm depth i n wi l low pasture (WP) and open pasture (OP) treatments at R iverside Farm near Masterton , Wai rarapa . Line bars show the SEM for each date . * denotes s ign ificance at P < 0 . 05 . ------------------------------------ 1 25
Fig ure 4 .9 Relationsh ip between mean monthly volumetric soi l moisture conten t (%) i n the 0- 1 50 mm depth and NHA rate (kg OM ha-1 month-1 ) from November 2004 to March 2005 in wi l low pasture (WP) and open pasture (OP) treatments at R ivers ide Farm near Masterton , Wairarapa. --------------------------------------------- 1 26
F igu re 5 . 1 Tota l monthly ra i nfa l l (mm) and mean a i r and soi l temperature (QC) during the experimental period in Palmerston North , New Zealand . -------------------------------------- 1 57
F igure 5 .2 Volumetric soi l moisture content (%) a t 0- 1 50 mm depth i n open pasture (OP) and tree pastu re (TP) treatments at Mog in ie , Manawatu . Line bars show the SEM for each treatment * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 58
F ig ure 5 .3 Volumetric soi l moisture content (%) a t 0-300 mm depth in open pasture (OP) and tree pastu re (TP) treatments at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 59
F igure 5 .4 Volumetric so i l moisture content (%) at 0-450 mm depth in open pasture (OP) and tree pasture (TP) treatments at Mog in ie , manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 60
F igu re 5 .5 Event-wise surface runoff (mm) in open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ig n ificance at P < 0 . 05 . ---------------------- 1 62
F igure 5 .6 Total suspended sol ids (TSS) concentrat ion (mg L-1 ) i n surface runoff in open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ig n ifica n ce at P < 0 .05 . -------------------------------------------------- 1 63
x
Figure 5 .7
F igure 5 .8
F igu re 5 .9
I norgan ic suspended sol ids ( ISS) concentrat ions (mg L-1 ) in surface runoff (mm) i n open pastu re (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 .05 . --------------------- 1 64
Organ ic suspended sol ids (OSS) concentrat ions (mg L-1 ) in surface runoff i n open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 . 05 . -------------------------------------- 1 64
Tota l suspended sol ids (TSS) losses (kg ha-1 ) in surface runoff (mm) i n open pasture (OP) and tree pasture (TP) treatments at Mogin ie, Manawatu . L ine bars show the SEM for each treatment. * denotes s ig n ifi ca n ce at P < 0 .05 . -------------------------------------------------- 1 66
F igu re 5 . 1 0 I norgan ic suspended sol ids ( ISS) losses (kg ha-1 ) in
F igure 5 . 1 1
F igure 5 . 1 2
F igure 5. 1 3
Figu re 5 . 1 4
F igure 5 . 1 5
surface runoff from OP and TP treatments at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 . 05 . -------------- 1 67
Organ ic suspended sol ids ( ISS) losses (kg ha-1 ) i n surface runoff (mm) i n open pasture (OP) a nd tree pastu re (TP) treatments at Mog i n ie , Manawatu . L ine bars show the SEM for each treatment. • denotes s ig n ifi ca nce at P < 0 .05 . -------------------------------------------------- 1 67
Total p hosphorus losses (kg ha-1 ) in surface runoff i n open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 7 1
DRP concentrations (mg L-1 ) i n surface runoff (mm) i n open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 72
Relationsh ip between total P and DRP concentrations (mg L- 1 ) i n surface runoff (mm) i n open pasture (OP) treatment a t Mog in ie , Manawatu . (n = 38) . ---------------------------------------------------------------------- 1 73
Relationsh ip between tota l P and DRP concentrations (mg L-1 ) i n surface runoff (mm) i n tree pasture (TP) treatment a t Mog in ie, Manawatu . ( n = 76) . ---------------------------------------------------------------------- 1 73
Xl
Figu re 5 . 1 6 DRP losses (kg ha-1 ) in surface runoff (mm) in open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment . * denotes sign ificance at P < 0 .05 . -------------- 1 75
F igure 5 . 1 7 TN concentrations (mg L-1 ) i n surface runoff (mm) i n open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu. L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0. 05 . -------------- 1 76
F igure 5 . 1 8 TN losses (kg ha-1 ) i n surface runoff (mm) in open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . --------------- 1 77
F igure 5 . 1 9 NH/-N concentrations (mg L-1 ) i n surface runoff (mm) i n open pasture (OP) a nd tree pastu re (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 78
F igure 5 .20 NH/-N losses (kg ha- 1 ) i n surface runoff (mm) in open pastu re (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 .05 . -------------- 1 80
F igure 5 . 2 1 N03--N concentrations (mg L- 1 ) in surface runoff (mm) in open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 8 1
F igu re 5.22 Total N03--N losses (kg ha-1 ) in surface runoff (mm) i n open pasture (OP) and tree pasture (TP) treatments at Mog in ie , Manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 . 05 . ------------------------------------------------------------------ 1 82
F igure 5 .23 DRP concentrat ions (mg L-1 ) i n soi l water samples taken from s uction cups in open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . L ine bars show the SEM for each treatment. ----------------------- 1 85
F igure 5 .24 Event-wise surface runoff (mm) in open pasture (OP) and tree pasture (WP) treatments at Riverside Farm , Masterton . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . ---------------------- 1 86
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Figure 5 .25
F igure 5 .26
F igure 5 .27
F igure 5 .28
F igure 5 .29
F igure 5 .30
F igure 5 . 3 1
F igure 5 .32
Tota l suspended sol ids (TSS) concentrations (mg L-1 ) in surface runoff in open pasture (OP) and wi l low pasture (WP) treatments at Rivers ide Farm, Masterton . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . --------------------- 1 87
Tota l suspended sol ids (TSS) losses (kg ha-1 ) i n surface runoff (mm) i n open pasture (OP) and tree pasture (WP) treatments at R iverside Farm, near Masterton , Wai rarapa . L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 . 05 . -------------- 1 88
Tota l P concentrations (mg L-1 ) i n surface runoff (mm) i n open pasture (OP) and wi l low pasture (WP) treatments at R ivers ide Farm , near Masterton , Waira rapa. Line bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . --------------------- 1 89
Total P losses (kg ha-1 ) i n surface runoff (mm) i n open pasture (OP) a nd wi l low pastu re (WP) treatments at R ivers ide Farm , near Masterton , Wairarapa. Line bars show the SEM for each treatment. -------------------------------------------------------------------- 1 90
DRP concentrat ions (mg L-1 ) i n surface runoff i n open pasture (OP) and tree pasture (WP) treatments at Riverside Farm , near Masterton , Wairarapa. L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . --------------------- 1 9 1
DRP losses (kg ha-1 ) i n surface runoff i n surface runoff (mm) in open pasture (OP) and tree pastu re (WP) treatments at R iverside Farm, near Masterton , Wairarapa . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 . 05 . --------------------- 1 9 1
TN concentrations (mg L-1 ) in surface runoff (mm) in open pasture (OP) and wi l l ow pasture (WP) treatments at R ivers ide Farm, near Masterton , Wairarapa . L i ne bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . --------------------- 1 92
TN losses (kg ha-1 ) i n surface runoff in open pasture (OP) and tree pasture (WP) treatments at Riverside Farm , near Masterton , Wai rarapa . Line bars show the SEM for each treatment . * denotes s ign ificance at P < 0 .05 . ------------------------------------------------------------------ 1 93
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Figu re 5 .33 NH/-N concentrations (mg L-1 ) i n surface runoff (mm) in open pastu re (OP) and tree pasture (WP) treatments at Riverside Farm, near Masterton , Wai rarapa . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0.05 . --------------------- 1 94
F igu re 5 . 34 NH/-N losses (kg ha-1 ) i n surface runoff (mm) in open pasture (OP) and tree pasture (WP) treatments at R iverside Farm, near Masterton , Wairarapa . Line bars show the SEM for each treatment . * denotes s ign ificance at P < 0 .05 . --------------------- 1 95
XIV
Plate 2 . 1
P late 2 .2
P late 2 . 3
P late 2 .4
P late 2 . 5
P late 2 .6
P late 3 . 1
Plate 3 .2
P late 3 .3
P late 3 .4
P late 3 .5
List of Plates
Tangoio wi l low g rowing at the Moginie block, Massey Un ivers ity , Palmerston North , New Zealand . ------------ 1 7
Kinyoyanagi w i l low growing at Massey Un iversity's Riverside farm , Near Masterton , New Zea land. -------------------- 1 8
Veronese poplar g rowing at the Mog in ie b lock, Massey Un ivers ity , Palmerston North , New Zea land . ------------ 1 9
Dudely poplar g rowing at Mog in ie b lock ,Massey Un ivers ity , Pa lmerston North , New Zealand . ----------------------- 20
Stabal is ing h i l ls lopes with poplar i n New Zealand . ---------------- 22
Wil low fodder b lock ready to be g razed du ring summer d rought period at Massey Un ivers ity's R iverside Farm near Masterton , New Zea land . -------------------- 24
(a) A view of the experimental s ite with wi l low and poplar stakes p lanted at Mogin ie , Manawatu . (b) Early sprouting and g rowth (December, 2004) of wi l low and pop lar at Mogin in ie , Manawatu . ------------------------- 72
(a) Wi l low shoots at the end of first year g rowth in wi l low pasture (WP) treatment at Mog in ie , Manawatu . (b) Poplar shoots at the end of fi rst year g rowth in poplar pastu re treatment (PP) at Mog in ie , M a nawatu . ------------------------------------------------------------------- 79
(a ) View of poplar defo l iation on May 29 , 2006 i n poplar pasture (PP) treatment at Mog in ie , Manawatu. (b) View of wi l low defo l iation on May 29, 2006 in wi l low pasture (WP) treatment at Mogin ie , Manawatu . ------------------------------------------------------------------- 80
(a ) Poplar leaf sprout ing as on 30th September 2006 in pop lar pasture (PP) treatment at Mogin ie , Manawatu . (b) Wi l low leaf sprouting as on 30th September 2006 in wi l low pasture (WP) treatment at Mogin ie , Manawatu . ------------------------------------------------------- 80
(a) I rrigation in wi l low pasture (WP) and poplar pasture (PP) treatments us ing sprink ler system d uring d rought in summer 2005 at Mog in ie , Manawatu . (b) Wi l low gal l saw fly (Pontania proxima) attack (redd ish b rown ga l ls ) on leaves du ring summer at Mog in ie , Manawatu . ---------------------------------------- 90
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Plate 4 . 1
Plate 5 . 1
Plate 5 .2
P late 5 .3
P late 5 .4
P late 5 .5
Wi l low ga l l sawfly attack on Kinuyanag i wil low (5. vim in a lis) leaves in wi l low pasture (WP) treatment at Riverside Farm near Masterton , Wairarapa. ------------------------ 1 20
(a) View of a tree pasture (TP) p lot showing p lot borders with wooden boards , down pipe and pit during setup for runoff measu rement at Mog i n ie , Manawatu . (b ) View of a t ipp ing bucket fixed i n a frame and mounted on a s lab i n the pit at Mog i n ie , Manawatu . ------------------------------------------------------------------- 1 53
(a) Trench excavated to discharge surp lus water from the ma in pit at R iverside Farm . Novaflow p ipe is ready to be la id i nto the trench . (b) Spouting la id i nto the trench at the bottom end of a tree pastu re (TP) plot at Mog in ie , Manawatu . --------------------------------------- 1 54
(a) Tree damage from summer sheep g razing . Broken and bent branches a re vis ib le i n a tree pasture (TP) plot. (b) Ma in tree stem broken from summer sheep grazing in a tree pasture (TP) p lot at M og i n ie, M a n awatu . ------------------------------------------------------- 1 83
(a) Day t ime sheep camping i n a tree pasture (TP) p lot in summer at Mog in ie , Manawatu . (b) Early winter sheep g razing i n a tree pasture (TP) plot at M og i n ie , M a n awatu . ------------------------------------------------------- 1 84
(a) A open pastu re (OP) plot after wi nter sheep g razing . Dung and ur ine spots a re not vis ib le at Mogin ie , Manawatu . (b) A tree pasture (TP) p lot after winter sheep g razing . Dung and urine spots are vis ib le at Mogin ie , Manawatu . ------------------------------------- 1 84
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List of Appendices
Appendix 3 . 1 Volumetric soi l moisture content (%) at 1 50-300 mm depth in wi l low pastu re (WP) , poplar pasture (PP) and open pasture (OP) treatments at Mog in ie Manawatu. L ine bars show the SEM for each treatment. * denotes sign ificance at P < 0 . 05 . --------------------------------------------------------------------- 233
Appendix 3 .2 Volumetric so i l moisture content (%) at 300-450 mm depth in wi l low pasture (WP) , poplar pasture (PP) and open pasture (OP) treatments at mog in ie L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 . 05 . ----------------- 233
Append ix 4 . 1 Volumetric so i l moisture content (%) at 1 50-300 mm depth in wi l low pasture (WP) , and open pasture (OP) treatments at R iverside Farm . L ine bars show the SEM for each treatment . * denotes s ign ificance at P < 0 . 05 . ---------------------------------- 234
Appendix 4 .2 Volumetric so i l moisture content (%) at 300-450 mm depth in wi l low pastu re (WP) , and open pastu re (OP) treatments at R iverside Farm . Line bars show the SEM for each treatment. *
denotes s ign ificance at P < 0 .05 . ---------------------------------- 234
Append ix 5 . 1 Volumetric soi l moisture content (%) at 1 50-300 mm depth in open pasture (OP) and tree pasture (TP) treatments at mog in ie , manawatu . L ine bars show the SEM for each treatment. * denotes s ign ificance at P < 0 .05 . --------------------------------------------- 235
Append ix 5 .2 Volumetric so i l moisture content (%) at 300-450 mm depth i n open pasture (OP) and tree pasture (TP) treatments at Mogin ie , Manawatu . Line bars show the SEM for each treatment. * denotes si g n ifi ca n ce at P < 0 . 05 . ----------------------------- ---------------- 235
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Glossary and Abbreviations
ANOVA: analysis of variance.
Blanket forestry: plantation of whole farm with a single species, i n New Zealand th is
usual ly refers to Pinus radiata. QC: centigrade.
cm-3: per cubic centimetre .
cm: centimetre .
Canopy: the part of a tree consist ing of branches and fo l iage.
OAP: diammonium phosphate .
OM: dry matter.
d.p: decimal point .
DOP: d issolved organic phosphorus.
DIP: d issolved inorganic phosphorus.
DRP: dissolved reactive phosphorus.
Densely planted: in this thesis it refers to pastureland planted with >6000 trees per
hectare.
dia: diameter.
g: gram.
GLM: general l i near mode l .
h : hour. ha: hectare.
ISS: i norgan ic suspended sol id .
Kg: kilogram.
L: l itre.
LSD: least significant diffe rence .
m: metre .
mg: mi l l igram.
mm: mi l l imetre.
N: nitrogen .
NHA: net herbage accumulation.
NH/-N: ammonical-nitrogen .
N03--N: n itrate-n itrogen.
OP: open pasture .
OSS: organic suspended sol id .
P: phosphorus.
PAR: photosynthet ical ly active rad iation .
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PP: poplar pasture . . . . pastureland planted with poplar trees
ReB: refers to experimental design as randomised complete block
SAS: statist ical analysis system.
SEM: standard error of mean.
SSP: s ing le superphosphate.
TKN: total kjeldahl n itrogen .
TN: total n itrogen.
TP: tree pasture . . . pastureland planted with trees.
TP: total phosphorus .
TSS: total suspended sol id .
WP: wi l low pasture . . . . pasture land planted with wi l low trees
yr: year. yrs: years . Zone 3: the centre of four nuclei trees planted at a square grid .
e: soi l moisture content. (j) : soi l volume at a given depth .
IJg: microgram .
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