Data from: Related plant species respond similarly to chronic anthropogenic disturbance: implications for conservation decision-making
Martínez-Blancas, Alejandra, National Autonomous University of Mexico
Paz, Horacio, National Autonomous University of Mexico
Salazar, Gerardo A., National Autonomous University of Mexico
Martorell, Carlos, National Autonomous University of Mexico
Published Mar 07, 2019 on Dryad.
Cite this dataset
Martínez-Blancas, Alejandra; Paz, Horacio; Salazar, Gerardo A.; Martorell, Carlos (2019). Data from: Related plant species respond similarly to chronic anthropogenic disturbance: implications for conservation decision-making [Dataset]. Dryad. https://doi.org/10.5061/dryad.6ck1816
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
Abundance and chronic anthropogenic disturbance at two vegetation types
Data 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.
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.