Vegetation of Hawaiian lava flows

Author:

MacCaughey, Vaughn

Title:

Vegetation of Hawaiian lava flows

Periodical:

Botanical Gazette

Year:

1917

Volume:

64

Pages:

386-420

Subject:

Lava flows Soil development Vegetation surveys

Summary:

From the standpoint of area occupied by lava flows, cinder fields, and other waste lands that are a result of volcanic activity, the Hawaiian islands may be divided into two groups -- the lesser islands (Niihau, Kauai, Oahu, Molokai, Lanai, and Kahoolawe) and the greater islands (Maui and Hawaii). Due to a long period of erosion that has occurred on the lesser islands, the lava flows on these islands have been almost all turned into soil. While traceable flows still exist on some of the lesser islands, these are relatively insignificant as compared with the great stretches of lava fields that are found on the islands of Maui and Hawaii. The area above the timber line on Mauna Loa, alone, (on the island of Hawaii), occupies a greater area of lava wasteland as compared to what exists on the entire islands of Oahu, Kauai, and Molokai. Thus, a discussion of the vegetation of the Hawaiian lava flows refers mostly to the islands of Maui and Hawaii, the largest and youngest end of the archipelago. This paper deals largely with the ecological conditions under which the lava flow vegetation exists and is a result of many expeditions, made by the writer, who ascended all of the high mountains of the group and explored arid regions. It is a survey of the more important types of vegetation that exist on the lava fields of the Hawaiian Archipelago and their ecological relations. Since these have largely been neglected in the literature of Hawaiian botany, this paper is concerned with the ecology of the xerophytic regions where the lava flows are relatively barren. However, it requires a distinct readjustment of perspective to realize that many tropical regions possess large areas of extreme dryness and that under humid climate the flows rapidly disintegrate into rich volcanic soil and supports a luxuriant rain forest. As a result, there is a widespread association of ideas that are connected with tropical with humid conditions that are no doubt due to the many semipopular accounts of the "tropical jungle" and to the types of vegetation that is usually exhibited in the northern conservatories. The Hawaiian Archipelago, situated just within the tropics in the center of the North Pacific Ocean, illustrates this condition. Therefore, particular reference is made to the spermatophytes as the taxonomic knowledge of the native land algae, lichens, bryophytes, and pteridophytes is still somewhat in a fragmentary and unsettled condition.

Label:

Botany

URL:

http://www.jstor.org/stable/2468834

Date:

1917

Collection:

Periodicals