DOI: 10.5061/dryad.cvdncjt3h
title: Agent‐based modeling of the effects of forest dynamics, selective logging, and fragment size on epiphyte communities

description: Forest canopies play a crucial role in structuring communities of vascular
 epiphytes by providing substrate for colonization, by locally varying
 microclimate, and by causing epiphyte mortality due to branch or tree
 fall. However, as field studies in the three-dimensional habitat of
 epiphytes are generally challenging, our understanding of how forest
 structure and dynamics influence the structure and dynamics of epiphyte
 communities is scarce. Mechanistic models can improve our understanding of
 epiphyte community dynamics. We present such a model that couples
 dispersal, growth, and mortality of individual epiphytes with substrate
 dynamics, obtained from a three-dimensional functional-structural forest
 model, allowing the study of forest-epiphyte interactions. After
 validating the epiphyte model with independent field data, we performed
 several theoretical simulation experiments to assess how (1) differences
 in natural forest dynamics, (2) selective logging, and (3) forest
 fragmentation could influence the long-term dynamics of epiphyte
 communities. The proportion of arboreal substrate occupied by epiphytes
 (i.e. saturation level) was tightly linked with forest dynamics and
 increased with decreasing forest turnover rates. While species richness
 was, in general, negatively correlated with forest turnover rates, low
 species numbers in forests with very low turnover rates were due to
 competitive exclusion when epiphyte communities became saturated. Logging
 had a negative impact on epiphyte communities, potentially leading to a
 near-complete extirpation of epiphytes when the simulated target diameters
 fell below a threshold. Fragment size had no effect on epiphyte abundance
 and saturation level but correlated positively with species numbers.
 Synthesis: The presented model is a first step towards studying the
 dynamic forest-epiphyte interactions in an agent-based modelling
 framework. Our study suggests forest dynamics as key factor in controlling
 epiphyte communities. Thus, both natural and human-induced changes in
 forest dynamics, e.g. increased mortality rates or the loss of large
 trees, pose challenges for epiphyte conservation.
description: These
 epiphyte data were collected in Panama and Ecuador. In Panama, an area of
 ca. 0.9 ha was sampled using a gondola attached to a construction crane.
 In Ecuador, an area of 25x40 m was sampled using single rope climbing
 techniques. For each individual epiphyte in these areas, the x, y, and z
 position (i.e., the height above ground) was identified. If possible,
 individuals were identified to the species level. In Ecuador, the total
 plant height was measured. In Panama, the leaf size (for Orchids: the stem
 length) was measured.
description: <b><i>Panama</i></b> Field site - San Lorenzo, Panama Reference - Zotz, G., Schultz, S., 2008. The vascular epiphytes of a lowland forest in Panama - species composition and spatial structure. Plant Ecol. 195, 131-141. Data use - Data are released into the public domain under a Creative Commons Zero license waiver. When you use the data in your publication, you should cite the reference given above. If the data set is a major part of the data analyzed in your study, you may consider inviting the data holder as collaborator. <i>Description of columns</i> individualID: A unique identifier for each individual epiphyte speciesCode: A unique six-digit code for each epiphyte species. For all individuals that could only be identified to the family level, the family name is provided (e.g. Orchidaceae, Ferns, Araceae). The few individuals that could not be identified to the family level are marked as “None”. X: X-position in cm (relative to a reference point) Y: Y-position in cm (relative to a reference point) Z: Z-position in cm (height above ground) size: Length of the longest leaf. For orchids, the maximum stem length was measured. Unit: cm. lifeForm: Holoepiphyte, Hemiepiphyte, or nomadic vine <b><i>Ecuador</i></b> Field site – Tiputini Biodiversity Station, Ecuador Reference – Kreft, H., N. Koster, W. Kuper, J. Nieder, Barthlott, W., 2004. Diversity and biogeography of vascular epiphytes in Western Amazonia, Yasuni, Ecuador. Journal of Biogeography 31,1463-1476. Data use - Data are released into the public domain under a Creative Commons Zero license waiver. When you use the data in your publication, you should cite the reference given above. If the data set is a major part of the data analyzed in your study, you may consider inviting the data holder as collaborator. <i>Description of columns</i> individualID: A unique identifier for each individual epiphyte speciesID: A unique identifier for each epiphyte species. All individuals that could not be identified to the species level are marked as “NA”. X: X-position in cm (relative to a reference point) Y: Y-position in cm (relative to a reference point) Z: Z-position in cm (height above ground) plantHeight: Height of the individual in cm