dehli: Drought Effect of Habitat Loss on Invertebrates

In alexology/biomonitoR: biomonitoring indices and metrics

Drought Effect of Habitat Loss on Invertebrates

Description

This function calculates the Average Score Per Taxon index following Armitage et al. (1983), Davy-Bowker et al. (2007) and Alba-Tercedor & Sanchez-Ortega (1988) implementations.

Usage

dehli(x, method = "chadd_2017", agg = TRUE, exceptions = NULL, traceB = FALSE)

Arguments

x	Result of aggregate_taxa().
method	The implementation of DEHLI needed to calculate ASPT. The only choice is chadd_2017 (Chadd et al . 2017). Users can provide their own data.frame (see examples) with a column called Taxon and the column of scores called Scores.
agg	This option allows the composite family approach. It can be FALSE, TRUE or a data.frame. If FALSE no aggregation will be performed, while if TRUE aggregation will be performed according to the rules described in Details. A data.frame containing the aggregation rules can be provided by the user. This data.frame needs a column called Taxon containing the taxon to aggregate and a column called Correct_Taxon with the aggregation specifications. agg cannot be TRUE when a data.frame is provided as method.
exceptions	Taxa that need to be excluded from the calculation. This option can be useful, for instance, to exclude an alien species belonging to an autochthonous family.
traceB	If set to TRUE a list as specified below will be returned.

Details

The DEHLI index measures the effect of flow intermittency on the macroinvertebrate community. It assigning weights to taxa on the basis of their likely association with key stages of channel drying. DEHLI is the average score of the taxa receiving a score, similary to aspt.

The follwing composite taxa are used:

1. Philopotamus (inc. Wormaldia)

2. Brachyptera (inc. Rhabdiopteryx)

3. Protonemura (inc. Amphinemura)

4. Protonemura (inc. Nemurella)

5. Habrophlebia (inc. Leptophlebia)

The dehli() function automatically check for parent-child pairs in the scoring system, see the Value section for a definition. All the information used for dehli() calculation can be retrieved with the function show_scores.

Value

If traceB is set to TRUE a list with the following elements will be returned:

• results Result of dehli().

• taxa_df The data.frame used for the calculation containing the abundance of taxa receiving a score.

• composite_taxa Taxa aggregated following the aggregation rules when agg is not NULL.

• exceptions A data.frame containing the changes made by excluding the taxa included in exceptions.

• parent_child_pairs For instance in Spanish ASPT both Ferrissia and Planorbidae receive a score. Abundances of the higher taxonomic level need therefore to be adjusted by subtracting the abundances of the lower taxonomic level.

References

Chadd, R. P., England, J. A., Constable, D., Dunbar, M. J., Extence, C. A., Leeming, D. J., Murray-Bligh Wood J.A., P. J. (2017). An index to track the ecological effects of drought development and recovery on riverine invertebrate communities. Ecological Indicators, 82, 344-356.

See Also

aggregate_taxa bmwp

Examples

data(macro_ex)
data_bio <- as_biomonitor(macro_ex)
data_agr <- aggregate_taxa(data_bio)
dehli(data_agr)
dehli(data_agr)

alexology/biomonitoR documentation built on Oct. 10, 2024, 12:02 a.m.