Soil-Vegetation Relationships in Kipukas — Mueller-Dqmbois and Lamoureux 
287 
air photo taken October 1954.) 
pukas occur in the lower Metrosideros zone, 
whose climate is described as humid marine 
tropical (or subtropical) with common clouding. 
The kipukas are somewhat more sheltered from 
the windward rains than much of this zone, and 
Rock (1913) described them as being occupied 
by dry-mixed forest. 
Both kipukas are situated on moderate south 
slopes and have an irregularly undulating topog- 
raphy with a few short, steep slopes, several 
level areas, a few larger somewhat inclined 
areas, and scattered small pocket-like depres- 
sions. 
Two distinct vegetation formations were 
found in Kipuka Puaulu: a closed to semi-open 
forest type (Fig. 1, type 1), and a savannah 
type with a dense grass cover and scattered trees 
of Metrosideros and Acacia koa (Fig. 1, type 2). 
Kipuka Ki is dominated by a moderately 
stocked forest vegetation type, which in places 
is also semi-open (Fig. 1, type 1), but it lacks 
the very dense or closed forest stand segments 
found in Kipuka Puaulu: a closed to semi-open 
also in Kipuka Ki, representing there, however, 
mainly a transition zone in which occasional 
lava rocks protrude to the surface (Fig. 1, 
type 2). Characteristically, no rocks are found 
near the surface in either kipuka with the ex- 
ception of the transitory savannah in Kipuka Kb 
Within the forest formation of both kipukas 
several smaller plant communities can be recog- 
nized. One of the more obvious associations, 
common to both kipukas, is characterized by a 
ground cover of Microlepia setosa , a lush fern 
up to 1 m tall. The tree layer is dominated by 
Acacia koa and Sap Indus saponaria . This plant 
association occurs on level to moderately sloping 
ground. 
METHODS 
For the purpose of comparing the soils of the 
two kipukas, soil pits were dug in each kipuka 
in the Microlepia community near a tall Acacia 
koa tree in a level place. A level place near a 
tall koa tree was also chosen for a soil pit in the 
savannah for making a comparison between the 
soils of the forest and the savannah formation 
within Kipuka Puaulu (Fig. 1). The reason for 
choosing a level place was that the soils there 
were presumably not influenced by lateral seep- 
age. 
