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PROGRESS REPORT: RUSTAND BRAMBLE BARRIER
Currently, the 200-yard-long bramble barrier is growing rapidly under an automatic watering and fertigation system
1 . This will help to protect the upper half of the levee along the bank of the Tanque Verde wash from water erosion. Hopefully, barrier plants will have another growing season to send their roots deep into the soil before major flooding of the wash occurs. The lower part of the levee should probably be protected by extending the bramble barrier another 200 yards. The criteria for plant species selection included ecological considerations, aesthetics (attractiveness) and availability. Trees were planted in groups of five of the same species for both ecological and aesthetical reasons. In nature, plants tend to group rather than grow singly for more efficient use of resources such as soil and water. Additionally, groups of deciduous and evergreen trees were alternated to improve winter appearance. Deep-rooted leguminous shrubs and trees were interspersed along the barrier to add stability to the levee and nitrogen to the soil. Most of the trees selected were 5 gallons in size because the available 15 gallon plants were much more expensive and severely root bound
2 . Second story plants were in one or five gallon pots before transplanting. See Appendix for a listing of the bramble barrier plants by species, etc.
Currently, first story vegetation is primarily tumbleweed which is rapidly being displaced by bermuda grass through the natural process of plant succession
3 . In turn, as the tree canopy develops, the bermuda grass will be replaced by more shade tolerant species. In the meantime, the low-growing vegetation is providing such benefits as erosion control, microclimate and soil improvement, and wildlife habitat enhancement. Several well-hidden nests of quail and dove along with one large rattlesnake and countless lizards and insects have been observed in the bramble barrier. Resident great horned owls and house cats are controlling the population of snakes, whereas pocket gophers seem to be outsmarting both owls and cats. The first story vegetation is forming a green band about 10 feet in width which is expected to widen ultimately to about 50 feet with the width expanding during wet years and shrinking during dry periods. We plan to plant desert-adapted flowering annuals along the outer edges of the green band for the sake of beautification, wildlife habitat improvement, and ecosystem and levee stability.
Although the bramble barrier is off to a good start some further work will be required during the next 18 months including:
• Periodic checking and adjusting the irrigation/fertigation system to meet the daily needs of the developing bramble barrier.
• Trimming of first story vegetation to allow growth and development of low-growing shrubs in the second story and to produce a beneficial layer of mulch.
• Planting of more first story species such as perennial grasses and flowering annuals.
• Monitoring of the vertical and lateral growth of the bramble barrier and its basal green band.
• Monitoring of the spatiotemporal plant succession occurring in the bramble barrier. 4
• Replacement of the water-tank trailer with a 500-gallon tank mounted on a short stand near the water pump.
• Staking and restaking of plants as the need arises and replacement of any plants succumbing to environmental stresses such as hungry pocket gophers.
There will be no charges for the foregoing seven items beyond the sum initially agreed upon.
Notes:
• Fertigation entails the addition of mineral fertilizer to the irrigation water to accomplish fertilization and irrigation simultaneously.
• Seedlings and cuttings which spend a long period of time in a container become environmentally stunted because roots are unable to extend without encountering the walls and bottom of the container. Consequently, roots become circular forming an entangled ball which delays and in some cases prevents growth after outplanting.
• An important principle in plant ecology is plant succession. This involves a change in plant species as a plant community develops over a period of time. Generally following a land disturbance, a plant community begins with short-growing annuals (often called weeds or pioneer species) which are succeeded in time by taller-growing perennial species. The early successional species improve the microenvironment enough to be displaced by the environmentally more demanding mid and late successional species. Tumbleweed is a good example of a pioneer species, which is currently paving the way for later successional species in the bramble barrier such as bermuda grass.
• Plant succession occurs, not only in time but also in space, or spatiotemporally. The fastest rate of succession will occur in the center of the green band with the slowest rates being along the outer edges which are more remote with respect to the line source of water provided by the irrigation tubing. During wet years, when rainfall is supplying a greater portion of the soil moisture, the difference in rates of succession will be somewhat less. As the green band expands to the maximum width, making the source of irrigation water even more remote, rate of succession along the edges will decrease correspondingly.
APPENDIX A: Bramble Barrier Plants
1. Firethorn (Pyracantha coccinea) SE 36. Aleppo Pine ( Pinus halepensis ) TE
2. Firethorn (Pyracantha coccinea) SE 37. Sickle Cassia ( Cassia phyllodenia ) SEL
3. Firethorn ( Pyracantha coccinea ) SE 38. Lysiloma ( Lysiloma microphylla ) SEL
4. AZ Cottonwood ( Populus fremontii ) TD 39. Sickle Cassia ( Cassia phyllodenia ) SEL
5. Oleander (red) ( Nerium oleander ) SE 40. Aleppo Pine ( Pinus halepensis ) TE
6. AZ Bird of Paradise ( Caesalpinia gilliesii ) SDL 41. Sickle Cassia ( Cassia phyllodenia ) SEL
7. Oleander (red) ( Nerium oleander ) SE 42. Lysiloma ( Lysiloma microphylla ) SEL
8. AZ Cottonwood ( Populus fremontii ) TD 43. Sickle Cassia ( Cassia phyllodenia ) SEL
9. Oleander (red) ( Nerium oleander ) SE
10. AZ Bird of Paradise ( Caesalpinia gilliesii ) SDL 44. NM Cottonwood ( Populus wrightii ) TD
11. Oleander (red) ( Nerium Oleander ) SE 45. TX Ranger ( Leucophyllum frutescens ) SE
12. AZ Cottonwood ( Populus fremontii ) TD 46. Willow Acacia ( Acacia saligna ) S/TEL
13. Oleander (red) ( Nerium Oleander ) SE 47. TX Ranger ( Leucophyllum frutescens ) SE
14. AZ Bird of Paradise ( Caesalpinia gilliesii ) SDL 48. NM Cottonwood ( Populus wrightii ) TD
15. Oleander (red) ( Nerium oleander ) SE 49. TX Ranger ( Leucophyllum frutescens ) SE
16. AZ Cottonwood ( Populus fremontii ) TD 50. Willow Acacia ( Acacia saligna ) S/TEL
17. Oleander (red) ( Nerium oleander ) SE 51. TX Ranger ( Leucophyllum frutescens )SE
18. AZ Bird of Paradise ( Caesalpinia gilliesii ) SDL 52. NM Cottonwood ( Populus wrightii ) TD
19. Oleander (red) ( Nerium oleander ) SE 53. Willow Acacia ( Acacia saligna ) S/TEL
20. AZ Cottonwood ( Populus fremontii ) TD 54. Willow Acacia ( Acacia saligna ) S/TEL
21. Oleander (red) ( Nerium oleander ) SE 55. NM Cottonwood ( Populus wrightii ) TD
22. AZ Bird of Paradise (Caesalpinia gilliesii ) SDL 56. TX Ranger ( Leucophyllum frutescens ) SE
23. Oleander (red) ( Nerium oleander ) SE 57. Willow Acacia ( Acacia saligna ) S/TEL
58. TX Ranger ( Leucophyllum frutescens ) SE
24. Aleppo Pine ( Pinus halepensis ) TE 59. NM Cottonwood ( Populus wrightii ) TD
25. Feathery Cassia ( Cassia artemisioides ) SEL 60. TX Ranger ( Leucophyllum frutescens ) SE
26. Lysiloma ( Lysiloma microphylla ) SEL 61. Velvet Mesquite ( Prosopis velutina ) S/TDL
27. Feathery Cassia ( Cassia artemisioides ) SEL 62. TX Ranger ( Leucophyllum frutescens ) SE
28. Aleppo Pine ( Pinus halepensis ) TE
29. Feathery Cassia ( Cassia artemisioides) SEL 63. Eucalyptus ( Eucalyptus microtheca ) TE
30. Lysiloma ( Lysiloma microphylla ) SEL 64. TX Ranger ( Leucophyllum frutescens ) SE
31. Feathery Cassia ( Cassia aremisioides ) SEL 65. Velvet Mesquite ( Prosopis velutina ) S/TDL
32. Aleppo Pine ( Pinus halepensis ) TE 66. TX Ranger ( Leucophyllum frutescens ) SE
33. Feathery Cassia ( Cassia aremisioides ) SEL 67. Eucalyptus ( Eucalyptus microtheca ) TE
34. Lysiloma ( Lysiloma microphylla ) SEL 68. TX Ranger ( Leucophyllum frutescens ) SE
35. Sickle Cassia ( Cassia phyllodenia ) SEL 69. Velvet Mesquite ( Prosopis velutina ) S/TDL
70. TX Ranger ( Leucophyllum frutescens ) SE
71. Eucalyptus ( Eucalyptus microtheca ) TE
72. TX Ranger ( Leucophyllum frutescens ) SE
73. Velvet Mesquite ( Prosopis velutina )S/TDL
74. TX Ranger ( Leucophyllum frutescens ) SE
75. Eucalyptus ( Eucalyptus microtheca ) TE
76. TX Ranger ( Leucophyllum frutescens ) SE
77. Velvet Mesquite ( Prosopis velutina )S/TDL
78. TX Ranger ( Leucophyllum frutescens) SE
79. Eucalyptus( Eucalyptus microtheca ) TE
80. TX Ranger( Leucophyllum frutescens ) SE
81. Blue Paloverde ( Cercidium floridum )S/TDL
82. TX Ranger ( Leucophyllum frutescens ) TE
83. Navajo Willow ( Salix matsudana ) TD
84. TX Ranger ( Leucophyllum frutescens ) SE
85. Blue Paloverde( Cercidium floridum )S/TEL
86. TX Ranger ( Leucophyllum frutescens ) SE
87. Navajo Willow ( Salix matsudana ) TD
88. TX Ranger ( Luecophyllum frutescens ) SE
89. Blue Paloverde ( Cercidium floridum )S/TEL
90. TX Ranger ( Leucophyllum frutescens ) SE
91. Navajo Willow( Salix matsudana ) TD
92. TX Ranger ( Leucophyllum frutescens ) SE
93. Blue Paloverde ( Cercidium floridum )S/TEL
94. TX Ranger( Leucophyllum frutescens ) SE
95. Navajo Willow( Salix matsudana ) TD
96. TX Ranger( Leucophyllum frutescens) SE
97. Blue Paloverde ( Cercidium floridum) S/TEL
98. TX Ranger ( Leucophyllum frutescens ) SE
99. Navajo Willow ( Salix matsudana ) TD
100. Desert Hackberry ( Celtis pallida) SD
101. Desert Hackberry ( Celtis pallida ) SD
102. Desert Hackberry ( Celtis pallida ) SD
103. Willow Acacia( Acacia salicina) TEL
104. Desert Hackberry ( Celtis pallida ) SD
105. Desert Hackberry ( Celtis pallida ) SD
106. Desert Hackberry ( Celtis pallida ) SD
107. Willow Acacia( Acacia salicina ) TEL
108. Desert Hackberry ( Celtis pallida ) SD
109. Desert Hackberry ( Celtis pallida ) SD
110. Desert Hackberry ( Celtis pallida ) SD
111. Willow Acacia ( Acacia salicina )TEL
112. Desert Hackberry ( Celtis pallida ) SD
113. Desert Hackberry ( Celtis pallida ) SD
114. Desert Hackberry ( Celtis pallida ) SD
115. Willow Acacia ( Acacia salicina )TEL
116. Desert Hackberry ( Celtis pallida ) SD
117. Desert Hackberry ( Celtis pallida ) SD
118. Desert Hackberry ( Celtis pallida ) SD
119. Willow Acacia ( Acacia salicina )TEL
120. Brewers Saltbush ( Atriplex lentiformis )SE
121. Blue Paloverde ( Circidium floridum )S/TEL
122. Brewer Saltbush ( Atriplex lentiformis )SE
123. Honey Mesquite ( Prosopis glandulosa )TDL
124. Brewer Saltbush( Atriplex lentiformis )SE
125. Blue Paloverde( Circidium floridum ) S/TEL
126. Brewer Saltbush ( Atriplex lentiformis )SE
127. Honey Mesquite( Prosopis glandulosa )TDL
128. Brewer Saltbush ( Atriplex lentiformis )SE
129. Blue Paloverde( Circidium floridum ) S/TEL
130. Brewer Saltbush ( Atriplex lentiformis )SE
131. Honey Mesquite ( Prosopis glandulosa )TDL
132. Velvet mesquite ( Prosopis velutina ) S/TEL
133. Blue Paloverde( Circidium floridum ) S/TEL
134. Velvet Mesquite ( Prosopis velutina ) S/TEL
135. Honey Mesquite ( Prosopis glandulosa )TDL
136. Velvet Mesquite ( Prosopis velutina ) S/TEL
137. Blue Paloverde( Circidium floridum ) S/TEL
138. Velvet Mesquite ( Prosopis velutina ) S/TL
139. Honey Mesquite ( prosopis glandulosa ) TDL
140. Velvet Mesquite ( Prosopis velutina) S/TDL
141. Velvet Mesquite ( Prosopis velutina ) S/TDL 152. Canyon Hackberry ( Celtis reticulata ) S/TD 151. Hybrid Mesquite ( Prosopis hybrid ) S/TDL
142. Chilean Mesquite ( Prosopis chilensis ) TDL 153. Hybrid Mesquite ( Prosopis hybrid ) S/TDL
143. Hybrid Mesquite ( Prosopis hybrid ) S/TDL 154. Chilean Mesquite ( Prosopis chilensis ) TDL
144. Canyon Hackberry ( Celtis reticulata ) S/TD 155. Velvet Mesquite ( Prosopis velutina ) S/TDL
145. Hybrid Mesquite ( Prosopis hybrid ) S/TDL 156. Canyon Hackberry ( Celtis reticulata ) S/TD
146. Chilean Mesquite ( Prosopis chilensis ) TDL 157. Velvet Mesquite ( Prosopis velutina ) S/TDL
147. Hybrid Mesquite ( Prosopis hybrid ) S/TDL 158. Chilean Mesquite ( Prosopsis chilensis ) TDL
148. Canyon Hackberry ( Celtis reticulata ) S/TD 159. Velvet Mesquite ( Prosopsis velutina ) S/TDL
149. Hybrid Mesquite ( Prosopis hybrid ) S/TDL 160. Canyon Hackberry ( Celtis reticulata ) S/TD
150. Chilean Mesquite ( Prosopis chilensis ) TDL 161. Velvet Mesquite ( Prosopis velutina ) S/TDL
Notes for Plant List :
• Plants are listed in the order in which they were out-planted to initiate the bramble barrier beginning with No. 1 at the southeast end and proceeding up to No. 161 at the northwest end.
• The eight tree groups in the listing are separated by a space before and after each group. In the order in which they appear in the bramble barrier these groups are (1) AZ Cottonwood, (2) Aleppo Pine, (3) NM Cottonwood, (4) Eucalyptus, (5) Navajo Willow, (6) Willow Acacia, (7) Honey Mesquite and (8) Chilean Mesquite.
• Plant type abbreviations are: T = Tree, S= Shrub, E = Evergreen, D = Deciduous, L = Legume and slash (/) = or.
APPENDIX B: Bramble Barrier Photos
Photos 1 & 2: Bramble barrier was initiated at the base of the levee near the south bank of the Tanque Verde Wash. Upper photo shows the location for the S.E. part of barrier, whereas lower photo is of the N.W. part. Note the snowmelt streaming down the wash in the lower photo (10 Mar 97).
Photos 3 & 4: The first step in barrier initiation was to grade a shallow furrow and ridge combination at the base of the levee to intercept runoff rainwater from the sloping side of the levee to, in turn, supplement well-water irrigation. A small garden tractor with grader blade attachment formed the interception terrace (11-12 Mar 97).
Photos 5 & 6: The second step in barrier initiation was to auger holes for out-planting of potted plants in the middle of the shallow furrow at the base of the levee. A four-foot deep hole was augered every 15 feet for the tree seedlings with 3 more equally-spaced holes being dug between the tree holes to receive shrub & half shrub seedlings (15-16 Mar 97).
Photos 7 & 8: The augered holes were backfilled with a 50-50 mix of topsoil and peatmoss to encourage rapid and deep root growth of the seedlings. A nearby source of good topsoil for the mix was located just east of the S.E. end of the bramble barrier (18-25 Mar 97).
Photos 9 & 10: After back-filling and out-planting the surplus augured soil was used to form a small circular levee to hold several gallons of water delivered by a garden hose connected to a small trailer tank. In this manner plants were hand watered one at a time for several weeks until an irrigation system was installed (18-25 Mar 97).
Photos 11 & 12: The source of water for the irrigation system was a well equipped with a submersible pump which had been idle for some time. Consequently it pumped rusty water, clogging the soaker hoses for much of the summer. The rust apparently came from the black steel well casing. The 3,500 gal/hr pump nearly filled the 1,000 tank trailer (perched on top of the levee) in 15 minutes which in turn gravity fed the irrigation tubing (15 Apr 97).
Photo 13: Plumbing of the irrigation system involved running 2-inch plastic tubing from the pump to the trailer tanks and a return flow 2-inch tubing from the trailer tanks to the 2-inch main irrigation tubing. Note the NM cottonwood in the foreground of the photo (15 Apr 97).
Photos 14 & 15: These photos show the main irrigation tubing snaking along the bramble barrier with the 5/8-inch soaker hose running just to the right. Photo 14 shows three of the NM cottonwoods and the power source for the submersible pump. In a northwesterly view, the staked tree seedling in the foreground of photo 15 is the last plant in the willow acacia group (15 Apr 97).
Photo 16: Plants have overcome the out-planting shock and are beginning to grow. Pictured are the AZ cottonwoods at the SE end of the bramble barrier. Red-flowering oleander and AZ bird of paradise are blooming (1 May 97).
Photos 17 & 18: Photo 17 pictures the NM cottonwood group located near the power poles and at the bend in the bramble barrier. Photo 18 was taken from the northwest end of the bramble barrier toward the clump of giant reed grass near the power poles. Note the response of tumbleweed to irrigation water appearing as two narrow green bands on each side of the graded furrow and ridge. Mesquite groups are in the foreground (1 May 97).
Photos 19 & 20: Cottonwoods grew rapidly during the 4-month period, May to September. AZ cottonwoods are pictured in photo 19 along with the developing first story green band. In photo 20 the NM cottonwood is large enough to hide the power pole and its unsightly boxes. For a reference point, note the giant reed grass just above the desert broom (1 Sep 97).
Photos 21 & 22: These photos were taken from the lower part of the bramble barrier in an easterly direction toward the reed grass clump and power poles. Photo 21 shows a mesquite group in the foreground with mostly tumbleweed in the first story which is now being displaced by perennial grasses. Photo 22 pictures part of the willow acacia group with the grayish second story plant being a brewer saltbush (1 Sep 97).
Photo 23: This photo taken from near the NM cottonwood group toward the southeast end of the bramble barrier shows a well delineated green band of bermuda grass which grades into tumbleweed along the outer edges. The band which is currently about 10 feet wide is expected to grow to about 50 feet within a few years. The edges of the green band is an excellent site for wild flowers (1 Sep 97).
Photos 24 & 25: The water from the submersible pump finally cleared of rust and sediment by September, thereby eliminating the plugging of the soaker hose. However, in order to get enough water to the plants while plugging was occurring, holes were drilled in the soaker hose almost daily during most of the summer. With the plugging problem eliminated, the next step was to automate the irrigation system. The filling time for the tanks was only 15 minutes, but the minimum on-time for the existing timer was 60 minutes or 4 times too long. This necessitated the replacement of the existing timer with a new timer having a 12-minute minimum which is the padlocked dark gray box in photo 25. Note, the plyboard wing that was attached to the existing mounting board to shield the new timer from the hot afternoon sun. The new timer has a skip day feature to reduce the rate of irrigation during rainy and cool weather periods and when the plants start drawing directly from the water table. This irrigation system can be easily expanded to include the lower half of the levee in case of future extension of the bramble barrier.
The Imprinting Foundation
1616 E. Lind Road
Tucson, Arizona 85719