Soil- Vegetation Relationships in Hawaiian Kipukas 1 
D. Mueller-Dombois and C. H. Lamoureux 2 
Kipuka, the Hawaiian word for "opening/’ has 
come into scientific usage as a term used to 
designate an older area on the slopes of vol- 
canic mountains that has been surrounded by 
more recent lava flows. Kipukas are common 
landscape features on the slopes of Mauna Loa 
and Kilauea volcanoes on the island of Hawaii, 
where they can be readily recognized as islands 
of denser vegetation in the vast, sparsely vege- 
tated areas. They range in size from a few 
square meters to hundreds of acres. 
Kipukas are of special interest for several 
reasons. As vegetation islands they provide seed- 
source centers for the invasion of vegetation on 
new volcanic material. As vegetation islands 
they represent somewhat simplified ecosystems, 
analogous to bogs or lakes, that are very suitable 
for studying internal ecological relationships. 
The isolation of small populations in kipukas 
provides unique opportunities for evolutionary 
studies. 
So far, very little ecological work has been 
done with Hawaiian kipukas. Need for such 
work has arisen in Hawaii Volcanoes National 
Park, where the Park Service is confronted with 
the task of interpreting certain kipuka features 
to the Park visitors. Kipuka Puaulu, popularly 
known as "Bird Park,” has been accessible to 
the public for some time and the nearby Kipuka 
Ki is soon to be opened. For this reason the 
present study was begun in these two kipukas. 
Rock described the flora of both kipukas in 
an undated manuscript (probably written around 
1910) and reported a few general ecological 
observations. He remarked upon the unique and 
complex composition of arborescent species from 
which he judged both kipukas to be "of great 
age.” However, as an approximation he cited 
the estimate of Professor T. Jaggar (geologist 
at the Hawaii Volcano Observatory at that 
1 The study was financed through U.S. Government 
Contract No. 14-10-0434-1504 to Dr. M. S. Doty, 
"Bioecological investigations of Hawaii Volcanoes 
National Park.” Manuscript received April 15, 1966. 
2 Department of Botany, University of Hawaii. 
time), which placed the kipuka’s origin within 
the Christian era (i.e., less than 2,000 years). 
Rock recorded 40 arborescent native species 
forming a complex forest type in Kipuka Pu- 
aulu. Only half this number of tree species 
were found in Kipuka Ki. He also noted the 
presence of two vegetation types in Kipuka 
Puaulu, a complex forest type containing many 
tree species and a Metrosideros - dominated type. 
He believed that soil differences were respon- 
sible for the presence of these two types of 
forest. A general description of the kipuka soils 
is given in the Soil Survey report for the Ter- 
ritory of Hawaii (Cline et ah, 1955), where 
the soils were classified as Latosolic Brown 
Forest soils derived from two layers of volcanic 
ash. 
The primary objectives of this present study 
were to determine the floras of both kipukas, to 
describe the vegetation types present in each, 
and to determine what soil-vegetation relation- 
ships exist in these places. 
DESCRIPTION OF AREA 
Both kipukas occur at an elevation of from 
1200 to 1300 m on the southeast slope of 
Mauna Loa approximately 3 km northwest of 
Kilauea crater (Fig. 1). The central elevation 
of Kipuka Ki is about 60 m higher than that 
of Kipuka Puaulu. Both are surrounded and 
separated by recent beds of rough aa lava. Their 
boundaries are about 800 m apart. Kipuka 
Puaulu is about 42 hectares and Kipuka Ki 
about 18 hectares in size. The climate is char- 
acterized by a rather uniform mean annual tern- 
perature of 16°C, which is 7°C cooler than that 
experienced at sea level. The mean variation be- 
tween the warmest month (August) and the 
coolest (February) is only 3.5 °C. Occasional 
freezing temperatures can be expected during 
February nights. Approximate annual rainfall is 
1500 mm, varying monthly from about 25 mm 
in June to 200 mm in January. According to 
Krajina’s (1963) zonal classification, the ki- 
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