HOW DOES IRRIGATION MANAGEMENT AND WEED CONTROL INFLUENCE ON EXOTIC PLANT ASSEMBLAGES?
-
Upload
vincent-cabrera -
Category
Documents
-
view
25 -
download
1
description
Transcript of HOW DOES IRRIGATION MANAGEMENT AND WEED CONTROL INFLUENCE ON EXOTIC PLANT ASSEMBLAGES?
HOW DOES IRRIGATION MANAGEMENT AND WEED CONTROL INFLUENCE ON
EXOTIC PLANT ASSEMBLAGES?
Alejandro Juárez, Xavier Solé & Josep Antoni ConesaDepartament d’Hortofructicultura, Botànica i Jardineria Escola Tècnica Superior d’Enginyeria
Agrària. Universitat de Lleida
INTRODUCTION
Catalan western plain:- Strongly contrasted temperatures- Low annual precipitation (380mm)- Summer water deficit
The landscape consists on semiarid plant communities in mosaic with rainfed crops
Implementation and extension of irrigated crops, as fruit tree orchards, have transformed traditional landscape in recent decades
These irrigated crops were established because of their larger productivity compared to traditional rainfed crops
INTRODUCTION
Irrigated fruit tree orchards favor the entry and maintenance of exotic weed species:
1. Water facilitates diaspore entry2. High disponibility of water and nutrients3. Elevated temperatures in summer4. Open structure of the orchards
Consequences:Affect negatively to the crop yield and may develop invasive behaviour in surrounding natural habitats
1 2 3 4
INTRODUCTION
Management of irrigated fruit tree orchards
Irrigation system
Flood irrigation
Weed control
Mecanically on inter-rows
Herbicide application under the trees
INTRODUCTION
Drip irrigation
Hypothesis:
Orchard management determines weed richness and diversity and could favor the presence of exotic flora
Objectives:
1.Find relationships between irrigation system and richness and diversity of native and exotic flora
2.Analyze differences in richness and diversity of native and exotic flora between inter-rows and under the tree lines
3.Assess whether there is a synergistic effect between these two factors on richness and diversity of native and exotic flora
INTRODUCTION
July-September 2009
75 fields with drip irrigation system
75 fields with flood irrigation system
MATERIALS & METHODS
3 X
Phytosociological surveys (Braun-Blanquet)
3 X
1m
10m
2m
5m
MATERIALS & METHODS
DATA ANALYSIS
Origin of species: Natives and exotics (Bolòs & Vigo, 1984-2001)
Richness
-Total
-By family
-Depending on: irrigation system Plot position in field
-By origin
Shannon-Weaver diversity(from cover data for the same groups as richness)
1
·ln
n
i ii
H p p
pi = Ri / R (Ri: relative cover of the i species; R: total cover of all species).
Two-way ANOVA to evaluate the effect of irrigation system , plot position and the interaction between these two factors on richness and diversity
MATERIALS & METHODS
Total: 179 species 40 families
Flood irrigated: 104 species 32 families
Drip irrigated: 157species 36 families
Inter-rows: 86 speciesUnder the tree: 92 species
Inter-rows: 133 speciesUnder the tree: 118 species
RESULTS & DISCUSSION
Flood irrigated orchards Inter-rows % Freq
Under tree %Freq
Trifolium repens 70,22 Sonchus oleraceus 60,70
Taraxacum officinale 64,89 Portulaca oleracea 53,40
Bromus catharticus 61,33 Trifolium repens 52,00
Setaria pumila 46,67 Echinochloa colona 39,07
Rumex obtusifolius 42,22 Euphorbia prostrata 36,57
Sorghum halepense 38,22 Setaria adhaerens 36,06
Cyperus rotundus 34,22 Digitaria sanguinalis 34,96
Echinochloa colona 32,89 Bromus catharticus 28,49
Paspalum distichum 28,00 Taraxacum officinale 24,63
Eleusine indica 27,56 Malva sylvestris 24,36
In bold: exotic species
Bromus catharticusSetaria pumila
Sorghum halepense
Eleusine indica
Cyperus rotundusPaspalum distichum Euphorbia prostrata
Setaria adhaerens
Echinochloa colona
RESULTS & DISCUSSION
In bold: exotic species
Drip irrigated orchards Inter-rows % Freq
Under tree %Freq
Sonchus oleraceus 45,54 Sonchus oleraceus 75,53
Aster squamatus 39,79 Setaria adhaerens 34,36
Taraxacum officinale 36,86 Convolvulus arvensis 27,61
Polygonum aviculare 32,34 Malva sylvestris 25,66
Crepis bursifolia 32,31 Amaranthus albus 21,21
Malva sylvestris 28,74 Chenopodium album 20,71
Conyza bonariensis 26,71 Aster squamatus 19,42
Plantago coronopus 26,35 Cynodon dactylon 15,59
Kochia scoparia 23,90 Heliotropium europaeum 14,75
Plantago lanceolata 20,98 Sonchus tenerrimus 14,72
Conyza bonariensis Cynodon dactylon
Amaranthus albus
Aster squamatus
Crepis bursifolia
Setaria adhaerens
RESULTS & DISCUSSION
Mean richness (number of species) in % Mean Shannon diversity index
FI: flood irrigationDI: drip irrigation
RESULTS & DISCUSSION
VariableDependent variable F P Direction effect
irrigation system
total30,763
<0,001 **
F>D
exotics 261,386
<0,001 **
F>D
natives40,763
<0,001 **
D>F
Position
total80,164
<0,001 **
IR>TL
exotics56,716
<0,001 **
IR>TL
natives84,545
<0,001 **
IR>TL
Irrigation x position
total 2,627 0,105exotics
15,419<0,001 **
IR>TL in D and F
natives17,590
<0,001 **
IR>TL in D and F
TWO WAY ANOVA FOR RICHNESS/PLOT
D: drip irrigationF: flood irrigationIR: inter-rowsTL: tree line
RESULTS & DISCUSSION
VariableDependent variable F P Direction effect
irrigation system
total 66,217
<0,001 **
F>D
exotics 261,46
<0,001 **
F>D
natives 11,182
<0,001 **
D>F
position
total 43,942
<0,001 **
IR>TL
exotics 30,448
<0,001 **
IR>TL
natives 12,299
<0,001 **
IR>TL
Irrigation x position
total 0,284 0,594exotics 18,73
0<0,001 **
IR>TL in D and F
natives8,296 0,004 *
IR>TL in D and F
D: drip irrigationF: flood irrigationIR: inter-rowsTL: tree line
TWO WAY ANOVA FOR SHANNON DIVERSITY INDEX
RESULTS & DISCUSSION
• Drip irrigated orchards have a larger total richness than flood irrigated orchads because they present different environments with contrasting conditions: irrigated under the tree and rainfed in the inter-rows
• Flood irrigated orchards have a higher Shannon diversity because cover of weeds is higher and more homogeneously distributed
• Flood irrigation favors both the presence and diversity of exotic flora to the detriment of native flora
• Exotic weeds presents in orchards are different depending on irrigation system
CONCLUSIONS
• Drip irrigation orchards shelter more native weeds because inter-rows maintain typical mediterranean stress conditions
• Below the tree rows in both irrigation systems, there are the lowest richness and diversity of species because the herbicide application ocurrs there
• There is a synergistic effect between irrigation system and weed management (plot position) over native and exotic weeds that favors exotic weeds in the inter-rows of flood irrigation and native weeds in the inter-rows of drip irrigation
CONCLUSIONS
IMPLICATIONS FOR MANAGEMENT
The choice of irrigation system becomes a crucial aspect in the design of a management system aimed to prevent the establishment of exotic flora in mediterranean areas
Thank you for your attention
Acknowledgements: Financial support provided by AGAUR PhD grants Generalitat de Catalunya