The Spatial Distribution of Mistletoe in a Southern Indian Tropical Forest at Multiple Scales

Abstract

Taxillus tomentosus is a mistletoe of significant management concern in southern India. This mistletoe affects the productivity of several nontimber forest products, most significantly Amla (Phyllanthus emblica and Phyllanthus indofischeri), whose fruits provide an important source of income for indigenous forest communities. Management interventions are required to secure the continued viability of Amla and thereby its role in livelihoods. To enhance the scientific basis for management, we characterized the distribution of T. tomentosus at three scales, examined potential mechanisms underlying this distribution, and compared both with those documented in other habitats. Mistletoes were aggregated at all three scales: on individual trees, within forest plots of 500 m 2 , and at scales of 3-4 km. Seed deposition patterns provide an initial distribution 'template' that largely determines patterns at tree and plot scales. This initial pattern is subsequently altered as variation in host suitability and mistletoe mortality from forest fires influence establishment success and postestablishment survival. Local prevalence of infection contributed most to infection spread, and areas of high infection prevalence are highlighted as appropriate foci for management intervention. Although novel underlying mechanisms and variation in the scale of aggregation have been identified, mistletoe distribution in a tropical forest appears to be shaped by similar forces as those documented previously in temperate systems.

Distribution, frequency and host patterns of European mistletoe (Viscum album subsp. album) in the major city of Lodz, Poland

“…The overall level of aggregation as indicated by the variance to mean ratio of mistletoe numbers per host fell within the midrange of values found in other published studies of host-mistletoe interactions (Overton 1994;Donohue 1995;Bannister & Strong 2001;Aukema & Martinez del Rio 2002;López de Buen et al 2002;Rist et al 2011). Mistletoes were aggregated at two scales: on individual trees and within plots.…”

“…The mean number of mistletoes per tree detected on all A. saccharinum hosts within a plot was used to represent the plot intensity of mistletoe infection, hereafter 'plot intensity', following Rist et al (2011). For each sample plot, we calculated mistletoe infection prevalence, the fraction of hosts infected, and infection intensity and host species composition.…”

“…were categorized as infected. Moreover, we used variance to mean ratios (hereafter denoted by /) of mistletoes per tree as a index of the degree of aggregation in our study population (Young & Young 1998; see also Rist et al 2011).…”

Host specificity and experimental assessment of the early establishment of the mistletoe Phoradendron crassifolium (Pohl ex DC.) Eichler (Santalaceae) in a fragment of Atlantic Forest in southeast Brazil

“…Unfortunately, as highlighted by Arruda et al (2012), most records in herbaria in Brazil do not include information about the host plant, constraining the understanding of host preference over the range of the mistletoe. Studies analyzing the factors influencing host preference at different scales are worthwhile (Rist et al 2011). Studies combining information from field and herbaria specimens may help bridge this gap.…”

Extent of infection by Viscum album L. and changes in its occurrence on ornamental woody species in the locality of Lednice (Czech Republic)

“…The European mistletoe (Viscum album L.) is a native hemiparasitic shrub, spread widely yet locally in many places of Europe and Asia (Hegi 1981, Luther and Becker 1987, Slavík 1997, Zuber 2004, Rist et al 2011, Kołodziejek et al 2013, Varga et. al 2014.…”