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COMPOSX'-ilOl* AuU JUi tfiuwiUiuu'iAM ur a uAiul.Au
i- uluS'ilul) AhuA. CP uui.li.iUj iuiuv
by
Clair Loonard Kucora
A liaeertation Submitted to the
Graduate faculty in Partial Pulfillnent of
tlia Hoqulrononta for the i oqreo of
DOCTor. 01-' PiilLOSOPiiY
Major Subject! Plant Ecology
Approvedi
t
* * • • •
n Charge of Major mork -* • :/
• « • •
I/O / /
Head of Major
loan of Graduate College
Iowa State College
I960
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UMI Number: DP12237
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QH 5 4 1 .5 . h* ii
tabu: of '..oht'biits
iiiTFODUcTIOH..*........................ •••.•••....•••.... 1
LiTh’RATUHK UiiVlbT:..............••••••••*.••...••............ 3
Forest Composition Within the Forest-Prairie
Border*.•••«•.•«••••*....».*...•••••••••••• 3
The Kffect of Climate and Soil on the Di atri-
bution and Composition of Forests*.....•••• 6
The Sffeot of Forest Vegotation on its Aerial
and Soil Environm ent........••••••*..••••.. 10
Find.................. 11
E v a p o r a t i o n . . . 12
T e m p e r a t u r e . 13
Frost dopth and snow accumulation.......* 14
Soil moisture.••••*•••••••••••••.••........... 16
Soil structure.••••*•••..........•*••••••.•••• 17
Organic matter and soil fe rtility .••••... 18
EXPFJdllflHTAU..... ................................... 21
Methods of P ro c e d u re .......................... 21
Location and description of field sites.. 21
Field m e t h o d s . . 31
Analysis of the vogetation..•••••••• 31
Determination of the olimatic
factors.. . • • 33
Investigation of winter conditions** 35
T.eathor bureau d ata......* .* .••••••• 35
Soil sampling for moisture detomi-
* nations and profile analysis..... 35
laboratory and greenhouse methods.••••... 40
Determination of soil moisture.... •• 40
Vdlting per cent determ ination...... 40
Physical analysis of undisturbed
profile samples*.**...•••».••»..* 41
Organic matter determinations of
the profile samples.••••.............. 41
T 9 £ 4 r O
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ill
Determination of soil reaction*••••• 42
Litter and duff m e a s u r e m e n t s 43
Results*•••••••••••••••«•••••••••••*•••••••••• 44
Composition of the vegetation************ 44
The forest stand,•••••••••••••*••••• 44
Rate of groTrth********************** 66
Herbaceous layers******************* 66
Litter and duff********************* 66
Climatic factors•••••••••••••••••••••••• • 69
Tenperaturo*••••••••••••••••••*.*••• 69
Vapor pressure deficit and wind
velocity* •••••••••••••«•••••••••• 73
Evaporation*•••••••••••••••••••••••* 78
Snow accumulation******************* 83
Edaphio factors***.•*.•••••.••••••••••••• 90
Soil moisturo*••*•••••••••••*••••••• 90
Porosity and volume weight********** 103
Organic mattor*.••*.•••••••••••••*•• 114
Soil reaction*********************** 116
DISCUSSION....................... 120
SUMMARY.......................................................... *. 138
ACKNOWLEDGEMKNTS......................................... *..... 146
LITEiiATURE CITED..............*...................................................*.......... 146
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imoLucnoH
Aocording to land office surreys of the mid-ninoteenth
oantury, native deciduous forests oocupied the major stream
courses and tributaries in oenbral Iowa* hecords of 1847 for
Story County* locatod in the geographic center of Aowa* re
veal that forests occupied 8 per cent of the area* For the
state as a whole* approximately 16 per cent of the land* or
about 5*360,000 aoros* was originally wooded*
Interest in the native forest areas has been gradually
increasing for soveral reasons including production of lumber
for looal uses* reoroational possibilities* wildlife cover*
soil conservation and flood control* Information arising from
the past ecological studies of the areas is basic to our
knowledge of forest development in a prairie region* and also
to the adoption of a sound policy of land use* Adequately
protected forest cover on rough lands aids in the stabilisation
of stream flow* ami the ourtailment of soil erosion and stream
silting*
The present Investigation attempts further study of
plant composition and environmental relationships of the
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2
existing forest cover* as compared to adjacent areas where the
forest oovor has boan depleted or removed as a result of
grasing, cultivation* and other disturbances* For tiiis purpose*
a number of suitable forest sitos wore selected along the fes
inodnos River in and near the Ledges State Park* Boone County*
I ova* These locations wore ideal for the study to bo under
taken because a variety of slopes* aspects and oovor conditions
were available within a limited area* thus facilitating the
investigation of the interactions of vogotation and environmental
factors in and among definite microhabitats* furthermore, the
proximity of orop and pasture land to undisturbed forest
ooRcmnities* under similar conditions of climate* topography*
and parent materials, made it possible for studies to be made
of edaphio and olimatio ohangos resulting from the removal or
depletion of the original forest cover*
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