INCIDENCIA DE INFESTACIÓN DE Arceuthobium globosum grandicaule (Hawksw. & Wiens) EN Pinus hartwegii Lindl.

Abstract

The level of 1nfection was obtamed far rnistletoe Arceuthobium globosum grondicaule (Loranthaceae) on indivíduals of different basal area of Pinus hartwegii (Pinaceae), in a 150 ')( 200 m2 plot, located in Zoquiapan National Park south of Papayo hill, Estado de Mexlco. 76.64% of P. hartwegii trees taller than 2 m were infected by A globosum, (N = 293), while only 1 8% of the individuals shorter than that height were damaged (N = 111 ). There is a direct relationship between the size of the pines and its level of lnfection: 1 5% of the trees with a basal area lower than 5.1 cm2 were infected, 26 to 72.4% of the pines with a basal area between 5.1 to 157.58 cm2 were attacked by mislletoe, where as 88% of P. hartwegli was infested. That pattern is explained because there 1s a high probability that the big trees 1ntercept the mist!etoe seeds. since these plants have a mechanical seed dispersa! mechanism as well as seed dispers1on by bird species Additionally, the tallest pines have had a longer exposition time to rnistletoe seed rain than the shorter trees, as this short trees are younger in the population than the tall pines.