Spatial heterogeneity of a parasitic plant drives the seed‐dispersal pattern of a zoochorous plant community in a generalist dispersal system

Abstract

Summary Biota plays a central role as sources of spatial heterogeneity, having great potential to define ecological processes and patterns in the landscape. Mistletoes are fleshy‐fruited parasitic plants that dwell in forest canopies showing a strong aggregated spatial distribution. Parasitized trees potentially concentrate frugivore activity on their canopy, where birds find food, places to perch and protection against predators. Thus, seed‐deposition patterns generated from the canopy are expected to reflect the heterogeneity associated with the parasite. This becomes especially important in generalist dispersal systems; however, so far, we do not know the implications of mistletoe spatial heterogeneity on the seed‐dispersal pattern of other plants with which they simultaneously fruit. In a Mediterranean pineland, we analyse the impact of Viscum album subsp. austriacum on the seed‐deposition pattern of a zoochorous plant community, taking into consideration the spatial and temporal variability of environmental factors influencing the frugivore's habitat use, such as fruit availability and forest tree density. For four consecutive years, we studied 55 pairs of trees parasitized and unparasitized by mistletoe, analysing zoochorous fruit availability, frugivore visits and the zoochorous seed rain in selected trees. As expected, frugivorous birds responded to mistletoe heterogeneity by visiting parasitized trees preferentially to unparasitized ones, generating a differential deposition of mistletoe seeds on tree branches while dispersing seeds of co‐fruiting species under the host canopy. Availability of understory fruits remained similar in patches of parasitized and unparasitized trees, but showed strong temporal fluctuations reflected in the seed rain. On the other hand, mistletoe proved more copious in patches of parasitized trees and their fruit crops varied little between years, making mistletoes reliable food resources likely to lead to consistency in fruit‐deposition patterns. In conclusion, mistletoes, by patchily growing on the canopy layer and concentrating zoochorous seeds underneath, can shape the spatial seed‐deposition pattern of fleshy‐fruited plants in the forest. Moreover, as seeds constantly reach the same deposition sites over long periods, the soil beneath the host canopy could become hotspots for community regeneration. In degraded areas, such mistletoe effects might be critical, possibly promoting recolonization and vegetation recovery through the frugivore's activity.

Do the arthropod communities on a parasitic plant and its hosts differ?

“…In Spain, a total of 617 species or subspecies are catalogued as threatened, of which only 116 are arthropods (IUCN, 2016), undoubtedly mainly due to a lack of information. This work clearly exemplifi es the mismatch between considering mistletoe as a pest that needs to be controlled vs. a keystone species providing new opportunities for novel species (Mellado & Zamora, 2015;Mellado et al, 2016).…”

Distribution patterns of plant communities and their associations with environmental soil factors on the eastern shore of Lake Taihu, China

“…Amorim and Batalha (2007) reported that P was the main factor that defined plant communities in Brazil, and nutrients in general played a major role in the classification of plant groups. A-P in the soil can be absorbed by the plant component; many other studies have noted the role of A-P in the distribution pattern of plant communities (Hammersmark et al 2009;Mellado and Zamora 2015;Onur and Suha 2016).…”

“…In addition to soil factors, the distribution of plant communities might be related to the specific geographical location providing unique habitats (Wassen, Peeters, and Venterink 2002;Dwirek, Kauffman, and Baham 2006;Mellado and Zamora 2015;Oliveira, Torezan, and Cunha 2015;Zellweger et al 2015;Whitworth et al 2016). The plant communities in the study area were divided into seven types, which had substantial differences in their growth requirements.…”

“…Benning and Seastedt (1995) emphasized how vegetation patterns affected the soil moisture, nutrients, and other processes detailed. The relationship between vegetation and soil environmental factors has been widely discussed (Juan, Carlos, and Donaldo 2011;Mellado and Zamora 2015;Liu et al 2016;Lucie, Jana, and Zuzana 2016). Soil environmental factors have important effects on plant growth and reproduction.…”

Characteristics and drivers of plant virus community spatial patterns in US west coast grasslands

“…The strong signal of co‐transmission in pathogen spatial patterns highlights vector control as a coinfection management strategy. While the effects of co‐transmission are analogous to effects of co‐dispersal observed for free‐living organisms (Mellado and Zamora , Wright et al ), pathogen‐specific factors can shape pathogen community spatial patterns as well. Importantly, pathogen spatial patterns are intrinsically linked with other living organisms – their hosts.…”