DOI: 10.5061/dryad.6ck1816
title: Data from: Related plant species respond similarly to chronic anthropogenic disturbance: implications for conservation decision-making

description: 1. Many developing countries harbor inordinate numbers of species that
 face little-understood, gradual changes in their environment, such as
 chronic anthropogenic disturbance (CAD, a high frequency but low intensity
 form of disturbance). These countries also lack the resources to study
 each species, so conservation practices have had to be generalized
 assuming that complete taxonomic groups (e.g., cacti or cetaceans) may be
 managed in the same way. This could be justified if closely related
 species respond similarly to threatening factors. We assessed if relatives
 respond similarly to CAD and whether this affects phylogenetic diversity.
 To determine if such patterns occur in different systems, we studied a
 semiarid grassland and tropical dry forest in Mexico. 2. Species’ identity
 and abundance was recorded in 59 sites differing in CAD intensity.
 Disturbance response indices were calculated for each species. Nested
 ANOVAs coupled with null models were applied to determine if
 generalizations within taxa are justified and which taxonomic level (using
 APG IV system) explained the most variation in disturbance response among
 species. We obtained phylogenetic trees using molecular data for the
 grassland and published phylogenies for the tropical forest. Phylogenetic
 signal was measured with Pagel’s λ, whereas community mean phylogenetic
 distance was regressed on CAD. 3. Higher taxonomic levels explained more
 variation among species than expected by chance, indicating that related
 species respond similarly to CAD. However, only species in the same genus
 behaved similarly enough (explaining over 80 % of the accumulated
 variance) to make generalizations reliable. This is the result of an
 underlying, if modest, phylogenetic signal in CAD responses. 4. Mean
 phylogenetic distance decreased with CAD in the grassland but not the
 tropical dry forest. This suggests that CAD was a stronger environmental
 filter in the grassland but weak in the tropical dry forest, where it was
 less intense. Policy implications. Species inform us about how their
 relatives respond to CAD, supporting the idea that generalizations in
 management are possible; however, this procedure is seemingly reliable
 only within genera, and not within orders or families. CAD may reduce
 phylogenetic diversity, perhaps leading to ecosystem function
 loss.27-Feb-2018
description: Abundance and chronic
 anthropogenic disturbance at two vegetation typesData for species
 abundance and chronic anthropogenic disturbance (CAD) in a semiarid
 grassland and a tropical dry forest. The file contains two sections, one
 for each vegetation type. All data correspond to abundances, except column
 labeled CAD. Semiarid grassland The semiarid grassland is in Concepción
 Buenavista, Oaxaca, southern Mexico, at an elevation of 2275 m a.s.l.
 Annual precipitation is 530·3 mm, and mean temperature is 16·3 °C. Data
 come from 21 0·5 ha sites. In each site, eight 1 × 1 m quadrats were
 randomly chosen, and in each one we randomly selected 20 0·1 × 0·1 m
 squares. In the latter, we quantified the abundance of all vascular
 plants. Tropical dry forest The tropical dry forest is located in La
 Cañada, Oaxaca. Its elevation ranges from 580 m a.s.l. to 850 m a.s.l.
 Precipitation ranges from 473 to 515 mm in annual precipitation and mean
 temperature ranges from 25·2 to 26·2 °C.Data comprise vascular plant
 abundances for 38 sites with 3 transects each, measuring 50 × 10 m for
 trees and 50 × 4 m for shrubs and small succulents. Chronic anthropogenic
 disturbance The chronic anthropogenic disturbance (CAD) index is based on
 14 metrics that measure disturbance values for human activities,
 livestock, and land degradation, the sum of which provides an estimate of
 total CAD. The index runs from zero in pristine sites to slightly over 100
 in extremely degraded communities where even soil has been almost
 completely lost. Metrics for human activities comprise fuelwood
 extraction, human trails density, human trail surface, settlement
 proximity, contiguity to activity cores, land use and wildfires. Metrics
 for livestock raising comprise goat droppings, cattle droppings, browsing,
 livestock trail density and soil compaction. Finally, land degradations
 metrics comprise erosion, presence of soil islands and totally modified
 surfaces. Each metric was measured in 3 different transects and averaged
 to obtain a single value for each site. See Martorell and Peters (2005,
 2008) for more details.MartorellMartinezAbundanceCAD.csv