Sampling Vegetation Attributes - Natural Resources Conservation ...

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IV. ATTRIBUTES ATTRIBUTES The following is a matrix of monitoring techniques and vegetation attributes that are described in this reference. The X indicates that this is the primary attribute that the technique collects. Some techniques have the capability of collecting other attributes; the • indicates the secondary attribute that can be collected or calculated. Method Frequency Cover Density Production Structure Composition Frequency X • Dry-weight- Rank • • X 3 Daubenmire • X • Line Intercept X • Step Point X • Point Intercept X • Density X • Double Weight <strong>Sampling</strong> X • Harvest X • Comparative Yield X • Cover Board X X Robel Pole • X A. Frequency 1. Description Frequency is one of the easiest and fastest methods available for monitoring vegetation. It describes the abundance and distribution of species and is useful to detect changes in a plant community over time. Frequency has been used to determine rangeland condition but only limited work has been done in most communities. This makes the interpretation difficult. The literature has discussed the relationship between density and frequency but this relationship is only consistent with randomly distributed plants (Greig-Smith 1983). 3 Species composition is calculated using production data. Frequency data should not be used to calculate species composition. 23
24 ATTRIBUTES Frequency is the number of times a species is present in a given number of sampling units. It is usually expressed as a percentage. 2. Advantages and Limitations a Frequency is highly influenced by the size and shape of the quadrats used. Quadrats or nested quadrats are the most common measurement used; however, point sampling and step point methods have also been used to estimate frequency. The size and shape of a quadrat needed to adequately determine frequency depends on the distribution, number, and size of the plant species. b To determine change, the frequency of a species must generally be at least 20% and no greater than 80%. Frequency comparisons must be made with quadrats of the same size and shape. While change can be detected with frequency, the extent to which the vegetation community has changed cannot be determined. c High repeatability is obtainable. d Frequency is highly sensitive to changes resulting from seedling establishment. Seedlings present one year may not be persistent the following year. This situation is problematic if data is collected only every few years. It is less of a problem if seedlings are recorded separately. e Frequency is also very sensitive to changes in pattern of distribution in the sampled area. f Rooted frequency data is less sensitive to fluctuations in climatic and biotic influences. g Interpretation of changes in frequency is difficult because of the inability to determine the vegetation attribute that changed. Frequency cannot tell which of three parameters has changed: canopy cover, density, or pattern of distribution. 3. Appropriate Use of Frequency for Rangeland Monitoring If the primary reason for collecting frequency data is to demonstrate that a change in vegetation has occurred, then on most sites the frequency method is capable of accomplishing the task with statistical evidence more rapidly and at less cost than any other method that is currently available (Hironaka 1985). Frequency should not be the only data collected if time and money are available. Additional information on ground cover, plant cover, and other vegetation and site data would contribute to a better understanding of the changes that have occurred (Hironaka 1985). West (1985) noted the following limitations: “Because of the greater risk of misjudging a downward than upward trend, frequency may provide the easiest early warning of undesirable changes in key or indicator species. However, because frequency data are so dependent on quadrat size and sensitive to non-random dispersion patterns that prevail on rangelands, managers are fooling themselves if they calculate percentage composition from frequency data and try to compare different sites at the same time or the same site over time in terms of total species
Page 1 and 2: SAMPLING VEGETATION ATTRIBUTES INTE
Page 3 and 4: TABLE OF CONTENTS SAMPLING VEGETATI
Page 5 and 6: TABLE OF CONTENTS TABLE OF CONTENTS
Page 7 and 8: I. PREFACE PREFACE The intent of th
Page 9 and 10: 2 INTRODUCTION values when individu
Page 11 and 12: 4 INTRODUCTION represent the “pul
Page 13 and 14: 6 INTRODUCTION G. Coordination Moni
Page 15 and 16: 8 STUDY DESIGN AND ANALYSIS A. Plan
Page 17 and 18: 10 STUDY DESIGN AND ANALYSIS Macrop
Page 19 and 20: 12 STUDY DESIGN AND ANALYSIS Becaus
Page 21 and 22: 14 STUDY DESIGN AND ANALYSIS d From
Page 23 and 24: 16 STUDY DESIGN AND ANALYSIS b Cove
Page 25 and 26: 18 STUDY DESIGN AND ANALYSIS sideoa
Page 27 and 28: 4 3.5 3 2.5 20 5 STUDY DESIGN AND A
Page 29: 22 STUDY DESIGN AND ANALYSIS C. Oth
Page 33 and 34: 26 ATTRIBUTES 2. Advantages and Lim
Page 35 and 36: 28 ATTRIBUTES b Standing crop and p
Page 37 and 38: 30 ATTRIBUTES
Page 39 and 40: 32 METHODS—Photographs c Angle ir
Page 41 and 42: METHODS—Photographs Hinge Rod sta
Page 43 and 44: METHODS—Photographs angle iron st
Page 45 and 46: 38 METHODS—Frequency • One tran
Page 47 and 48: 40 METHODS—Frequency transected,
Page 49 and 50: 42 METHODS—Frequency (3) Total fr
Page 51: Page of Frequency 44 Study Number D
Page 55 and 56: METHODS—Frequency The frame is ma
Page 57 and 58: 50 METHODS—Dry Weight Rank C. Dry
Page 59 and 60: 52 METHODS—Dry Weight Rank After
Page 62 and 63: D. Daubenmire Method METHODS—Daub
Page 64 and 65: METHODS—Daubenmire b Ten Cover Cl
Page 66: Page of Daubenmire Study Number Dat
Page 70 and 71: 50 cm Six Cover Class Frame 20 cm R
Page 72 and 73: METHODS—Line Intercept b Pilot St
Page 74 and 75: METHODS—Line Intercept Hanley, Th
Page 77 and 78: 70 METHODS—Step Point F. Step-Poi
Page 79 and 80: 72 METHODS—Step Point the boot an
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74 METHODS—Step Point measures AN
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78 METHODS—Point Intercept G. Poi
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80 METHODS—Point Intercept 8. Sam
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82 METHODS—Point Intercept b Tran
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METHODS—Point Intercept Examples
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86 METHODS—Cover Board H. Cover B
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88 METHODS—Cover Board g Study Do
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Page of Cover Board Method Profile
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94 METHODS—Density I. Density Met
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96 METHODS—Density (often very mu
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98 METHODS—Density able to make s
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Page of Density Study Number Date E
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• Herbage Yield Tables for Trees
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METHODS—Double Weight Sampling (4
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METHODS—Double Weight Sampling d
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Page of Production Study Number Dat
Page 119 and 120:
112 METHODS—Harvest K. Harvest Me
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114 METHODS—Harvest 7. Taking Pho
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116 METHODS—Comparative Yield L.
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118 METHODS—Comparative Yield (1)
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120 METHODS—Comparative Yield Tab
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M. Visual Obstruction Method - Robe
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METHODS—Visual Obstruction—Robe
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Sampling Interval Study Location 1
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130 METHODS—Other N. Other Method
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132 GLOSSARY browse: (1) the part o
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134 GLOSSARY grazable woodland: for
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136 GLOSSARY sample: a set of sampl
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138 GLOSSARY
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140 REFERENCES Crocker, R.L. and N.
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142 REFERENCES Hironaka, M. 1985. F
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144 REFERENCES Nie, Norman H., C. H
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146 REFERENCES Society for Range Ma
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148 REFERENCES Whitman, W.C. and E.
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Location 150 APPENDIX A Study Locat
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APPENDIX B APPENDIX B—STUDY AND P
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APPENDIX B 3. Label 3 A placard on
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APPENDIX C Photo Identification Lab
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160 APPENDIX C
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162 APPENDIX D The formula for usin
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Form Approved OMB No. 0704-0188 Pub
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