Terrestrial forest management plan for Palmyra Atoll

Abstract

Cover:Images showing native species of the terrestrial forest at Palmyra Atoll (on the left from top to bottom: red-footed boobies, an undescribed gecko, and a coconut crab). The forests shown are examples of Pisonia grandis forest on Lost Islet (above) and an example of coconut palm monoculture on Kaula Islet (below) at Palmyra Atoll.

Proximity to encroaching coconut palm limits native forest water use and persistence on a Pacific atoll

“…grandis trees on Palmyra Atoll was detected in , and between 2002 and 2005 there was a loss of approximately 34% of P . grandis trees (Hathaway et al ., ). Handler et al .…”

“…grandis and coconut palm on Palmyra Atoll, and perhaps other atolls throughout the Pacific, is likely a major contributor to the overall reduced health of Pisonia forests. The health of Pisonia forests is central to atoll management (Hathaway et al ., ); manually removing coconut palm will be energy‐intensive and costly, so determining whether Pisonia forests perform better physiologically in the absence of coconut palm was central to our investigation. We hypothesized that P .…”

“…While Pisonia forests occur throughout the Indo-Pacific region (Airy Shaw, 1952;Mueller-Dombois and Fosberg, 1998), we focus on Palmyra Atoll which, because of its protected status as a National Wildlife Refuge of the United States, represents some of the most intact remaining Pisonia forests in the world (Hathaway et al, 2011). Pisonia forests on Palmyra Atoll receive large inputs of nutrient subsidies in the form of guano deposited from nesting seabirds, but subsidies are disrupted when suitable nesting trees are supplanted by coconut palm (Young et al, 2010).…”

“…On the one hand, defoliation and perhaps even mortality of Pisonia forests may be punctuated by specific environmental conditions (Greenslade, 2008). Widespread defoliation of P. grandis trees on Palmyra Atoll was detected in 2001, and between 2002 and 2005 there was a loss of approximately 34% of P. grandis trees (Hathaway et al, 2011). Handler et al (2007) noted that the green scale insect Pulvinaria urbicola Cockerell was particularly abundant on trees of poor health, and revealed a mutualistic relationship between introduced bigheaded ants (Pheidole megacephala Fabricius) and the scale insect.…”

“…After investigating several nutrient and biotic influences on P. grandis forest dynamics on Palmyra (Young et al, 2010;Young et al, 2011;Young et al, 2013), we suggest that competition for water resources between P. grandis and coconut palm on Palmyra Atoll, and perhaps other atolls throughout the Pacific, is likely a major contributor to the overall reduced health of Pisonia forests. The health of Pisonia forests is central to atoll management (Hathaway et al, 2011); manually removing coconut palm will be energy-intensive and costly, so determining whether Pisonia forests perform better physiologically in the absence of coconut palm was central to our investigation. We hypothesized that P. grandis trees would have lower rates of water use and growth in forest stands in which coconut palms were intermixed.…”