Why are so many rare plants found at Pohakuloa Training Area? In December 1989, Lani Stemmermann addressed this question in a short essay she wrote in an effort to elicit support for her lawsuit against the Army. We reprint portions below:
The southwest portion of PTA where construction is occurring is an area where there is an annual rainfall of 15 inches. This area is vegetated by a mosaic of native forest communities. Most areas of similar rainfall in the Hawaiian Islands tend to be vegetated by shrub vegetation and usually are disrupted by the invasion of alien species of plants and animals.
Of particular interest at PTA is the mosaic of montane dry forest communities present. Patches of relatively ancient lava (more than 4,000 years old) are juxtaposed with far more recent flows. A closed canopy naio forest grows on the older lava flows and a montane `ohi`a dry forest occurs on the more recent lava flows. The naio-dominated community survives under the very dry conditions at PTA and is not found elsewhere in Hawai`i. It is unique to the PTA area, being an extreme phase of the mamane-naio forest which occurs under relatively more mesic conditions on the slopes of Mauna Kea. The very old lavas upon which this community is situated are a rare volcanic feature on these upper slopes of the geologically active Mauna Loa. The montane `ohi`a dry forest is virtually weed free and though similar sorts of forest can be found elsewhere, such as at Hawai`i Volcanoes National Park, the PTA forest of this type is more intact than anywhere else.
Areas where native plant communities occur in a mosaic on juxtaposed ancient and recent substrates are of great scientific interest. Recently, the National Science Foundation funded a joint Stanford University-University of Hawai`i proposal to study Hawaiian ecosystem development. Such studies depend upon the described mosaic where nearby communities occur under similar climatic conditions, and differ only in their species composition and substrate age.
Also of particular interest at PTA is that these communities are viable — that is, the dominant species are reproducing and these communities are consequently capable of self-maintenance. Most ecologists believe that viable communities are much more ecologically valuable than endangered species per se. Rare species are sometimes found in completely disrupted ecosystems and may never survive without man’s intervention. In contrast, communities which can maintain themselves form the matrix which supports the rarer elements in addition to other ecosystem components upon which they depend (such as pollinators, for instance).
Tropical dry forest communities are the most endangered of all tropical forest types. Hawaiian dry forests are particularly so. Few of them exhibit active reproduction, and fewer exist in a mosaic where various substrate ages ensure that communities at all stages of successional development co-exist so that the system dynamics can be preserved.
In addition to the two communities directly impacted by the MPRC under construction, there are four other communities unique to PTA. The Dodonaea-Dubautia-Bidens scrub and Euphorbia forest at Kipuka Kalawamauna harbor the highest concentrations of officially listed endangered plant species in Hawai`i. The Eragrostis grassland and Chenopodium scrubland along the Saddle Road are also unique to the Pohakuloa area — found nowhere else in the world.
The number of unique vegetation units found at PTA, the juxtaposition of these communities, the intact nature and viability of these communities are all attributes that make the PTA area particularly suitable as consideration as a Natural Area Reserve. Instead a major training area is being constructed in the absence of an EIS.
Volume 7, Number 7 January 1997
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