Introduction

Pisonia grandis is a species of lowland tropical tree that grows in wet habitats, generally on coraline substrates, in the Indo-Pacific region. It is becoming rare due to clearing for agriculture and development. Palmyra's Pisonia forest covers a large portion of the atoll. In some areas of Palmyra, this tree reaches 100 feet or more, and its broad leaves and dense canopy form a shady forest that supports little or no understory. If an understory exists it is generally reduced to small patches of laua'e fern (Phymatosorus scolopendria), bird's nest fern (Asplenium nidus)., and Laportea ruderalis . These species show up in areas with more open forest canopy.

Other natives species such as beach heliotrope (Tournefortia argentea) and naupaka (Scaevola sericea) generally occur on the margins of the Pisonia forest. Introduced coconut palms (Cocos nucifera) and a few other introductions, such as false kamani (Terminalia catappa), compete with Pisonia for space. In many areas coconut palms inhibit Pisonia from growing. Pisonia grandis is a great tree for seabirds to nest in, especially noddies, red-footed boobies, and frigatebirds. In Palmyra, Pisonia forests support nearly all tree nesting bird species. In turn, the guano produced by these seabirds may be vital for the maintanence of these forests. The seabirds also help with Pisonia propogation through the dispersal of the sticky Pisonia seeds. It is an interesting relationship that has allowed for the unique distribution of Pisonia grandis throughout the Indo-Pacific.

In addition to the encroachment by coconut palms, we noticed a significant infestation of scales and mealy bugs on Pisonia leaves and other vegetation types. We noticed that entire stands of Pisonia had defoliated as the trees dropped their leaves in most likely in response to this infestation. Because Palmyra is protected by The Nature Conservancy and US Fish and Wildlife Service, we have a great opportunity to explore the Pisonia forest's health and experiment with ways to protect it. Our ant-eradication 'link' discusses one such experiment that we set up to try to determine the effects of introduced insects on Pisonia.