Effect of distance to edge and edge interaction on seedling regeneration and biotic damage in tropical rainforest fragments: A long‐term experiment

Abstract

1. In forest fragments, edge effects can influence forest regeneration, but little is known about how edge effects influence seedling performance and the interaction between seedlings and their natural enemies over time.2. In central Amazonia, we recorded survival and growth (in height and leaf number) and damage by insect herbivores and leaf-fungal pathogens of Chrysophyllum pomiferum (Sapotaceae) seedlings that were exposed to different numbers of edges and to different distances from the forest edge. Grown seedlings were transplanted into one-square-metre plots within 1-ha blocks located in the centre (no edge), the edge (one edge), and the corner (two edges), and at different distances from the edge towards the interior (i.e., 20, 40, 60, 80, and 100 m) of two rectangular fragments (10-and 100-ha in size). Plots were visited once every 2 months for 1 year (1992)(1993) and thereafter every 2 years for almost 8 years (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001).3. Overall, results showed that seedling survival, height, leaf number, and biotic damage varied over time with the presence of nearby edges and with the distance from the edge. Survival was lower in fragment edges and corners than in centres. Increase in height was similar for all positions within the 100-ha fragment, whereas in the 10-ha fragment seedling height had a greater increase at the edge and corner than in the centre. Furthermore, survival increased with distance from the edge as did leaf number, whereas height showed a lower increase closer to the edge than farther away. 4. Regarding biotic damage, for both fragments herbivory was greater at the centres and decreased with edge proximity over time, whereas leaf-fungal damage was greater at the corners than in the edges and increased significantly over time.Biotic damage was correlated with seedling size. Small seedlings were more susceptible to fungal attack, whereas larger seedlings were so to herbivores. 5.Synthesis. This study demonstrated that despite stochastic environmental factors seedling survival, growth, and biotic damage by herbivores and fungal pathogens varied with the level of edge exposure and proximity, which may threaten forest regeneration in the long term. K E Y W O R D Sbiotic interactions, forest regeneration, fungal pathogens, habitat fragmentation, herbivory, long-term studies, seedling growth, seedling survival | 2205Journal of Ecology BENÍTEZ-MALVIDO ET AL.

Native and Invasive Woody Species Differentially Respond to Forest Edges and Forest Successional Age

“…The relatively low germination but high survivorship of native species in combination with traits such as shade tolerance and slow growth enable these species to persist in the resource-limited understory of interior eastern USA forests. A similar response of a native tree was observed in a tropical forest in Amazonia where seedling survival and leaf number increased with distance from edge for native Chrysophyllum pomiferum (Sapotaceae) seedlings over a 9.5-year period [63]. Yet, the traits enabling the success of native species in resource-limited interior forest habitats may put them at a disadvantage to phenotypically plastic invaders that are more effective at acquiring and allocating resources when availability increases due to large-scale forest fragmentation [64].…”

Climate severity and land‐cover transformation determine plant community attributes in Colombian dry forests

“…For example, higher wind exposure and lower forest area are important drivers of mortality rates in Amazonian forest patches (Laurance & Curran, 2008), and of lower species richness in the Chaco forests of Argentina (Cagnolo, Cabido & Valladares, 2006). Land-cover change may also affect biotic interactions such as herbivory (Benítez-Malvido, Lázaro & Ferraz, 2018;Herrerías-Diego et al, 2008), or seed dispersal (Jacquemyn, Butaye & Hermy, 2001), especially of large-seeded plants, which are more dispersal limited (Cramer, Mesquita & Williamson, 2007;Rodríguez-Cabal, Aizen & Novaro, 2007).…”

Impact of habitat loss on the diversity and structure of ecological networks between oxyurid nematodes and spur-thighed tortoises (Testudo graecaL.)

“…The modification of the original scrubland vegetation by anthropogenic activities produces strong shifts in the spatial configuration of the natural landscapes, as well as on their physical (e.g., rainfall and temperature) and biological environments (e.g., vegetation structure, species diversity and resources availability) (Patz et al, 2004; Qian & Ricklefs, 2006; Amo, López & Martín, 2007; Janin, Léna & Joly, 2011; Suzán et al, 2012; Pringle, 2016). These environmental shifts may occur at multiple spatial and temporal scales, which affect complex species interactions, including host-oxyurid interactions of any kind (e.g., positive, negative and/or neutral) in the case of herbivorous reptiles (Harvell et al, 2002; Amo, López & Martín, 2007; Tylianakis, Tscharntke & Lewis, 2007; Janin, Léna & Joly, 2011; Benavides et al, 2012; Benítez-Malvido et al, 2016; Benítez-Malvido, Lázaro & Ferraz, 2018; Hernández-Martínez et al, 2019). Although our findings represent the standing incidence of adult oxyurids in T. graeca tortoises (i.e., a single observation in time), we detected that changes in landscape configuration, exemplified by the amount of suitable habitat, influenced some aspects of host-oxyurid interactions as revealed by differences in oxyurid infestation levels, oxyurid species ecological evenness, tortoises’ growth rates and by differences in the networks’ structure.…”