Resource limitation of compensatory responses in ecosystem processes after biodiversity loss
Data files
Jul 26, 2024 version files 904.93 MB
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Cover_measurements_2009.2017.csv
13.04 KB
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Dry_weight_09_2017.csv
1.49 KB
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Flux.data.2009.2017.csv
21.71 KB
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Photos.zip
904.89 MB
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README.md
4.44 KB
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Treatments.csv
624 B
Abstract
Biodiversity loss may result in a decline in important ecosystem processes. The effect of biodiversity loss on ecosystem functioning is determined by the functional contribution of the species lost and the compensatory responses of the remaining species. It is unknown to what extent the strength of the compensatory response of the remaining species depends on resource availability. Here we evaluate how the primary production of an assemblage of salt marsh plants responds to a realistic sequence of species loss in a 7-year experiment, with and without the addition of fertiliser. We found near-full compensation of progressive species loss in gross community primary production by the extinction-resistant species with fertiliser as long as one species (Triglochin maritima) remained. Without fertiliser, at least 4 species, including the particularly abundant species Plantago maritima, were needed to maintain gross community primary production. These results suggest that the magnitude of the compensation by extirpation-resistant species for the decline in ecosystem processes associated with progressive biodiversity loss depends on the resource context, and that compensation after the loss of plant species can be accelerated by increasing resource availability. Ultimately, full compensation appears to be limited by the presence and abundance of species in the remaining community that possess traits that allow them to compensate for the species lost. These findings suggest that the conclusions of a large body of biodiversity-ecosystem experiments cannot be used for informing the management of natural systems, because they do not simulate realistic extinction sequences, and therefore cannot quantify the potential for compensation of ecosystem services in the real world.
https://doi.org/10.5061/dryad.12jm63z6j
We evaluate how the primary production of an assemblage of salt marsh plants responds to a realistic sequence of species loss in a 7-year experiment, with and without the addition of fertiliser. The cover per plant species and the primary production were quantified in most years, and photos were taken of the plots in each year. We quantified the biomass at the end of the experiment.
Description of the data and file structure
The file Treatments.csv specifies what species richness and fertiliser treatment was allocated to each plot number. The column Treat indicates the treatment level, which defines the species richness treatment SR. ‘Control’ means that the species richness was not manipulated. For the other treatments, species were removed on a species-by-species basis following the derived extirpation sequence (Salicornia ramosissima J. Woods, < Puccinellia maritima (Huds.) Parl. < Armeria maritima (Mill.) < Limonium humile Mill. < Plantago maritima L. < Aster tripolium L. < Triglochin maritima L., from least to most extirpation resistant). Plot indicates the plot number, which is used to match across the different data files. The column Fertiliser indicates if the plot was fertilised (“Fertiliser”) or not (“None”) from 2013 onwards.
The file Flux.data.2009.2017.csv gives the estimated gross community production (GCP, mmol CO2 uptake m-2 h-1) for each plot for each measurement, for all years in which this was measured. Plot indicates the plot number, which is used to match across the different data files. Year indicates when the measurement was taken, as a decimal year. Month is the month in which the measurement was taken. GCP indicates the gross community production in mmol CO2 uptake m-2 h-1). The column Treat indicates the treatment level, which defines the species richness treatment SR. ‘Control’ means that the species richness was not manipulated. For the other treatments, species were removed on a species-by-species basis following the derived extirpation sequence (Salicornia ramosissima J. Woods, < Puccinellia maritima (Huds.) Parl. < Armeria maritima (Mill.) < Limonium humile Mill. < Plantago maritima L. < Aster tripolium L. < Triglochin maritima L., from least to most extirpation resistant). Plot indicates the plot number, which is used to match across the different data files The column Fertiliser indicates if the plot was fertilised (“Fertiliser”) or not (“None”) from 2013 onwards.
The file Cover measurements 2009.2017.csv gives the cover by plant species for each date at which this was quantified. Cover was quantified at 49 points, and the numbers indicate the number of points at which a plant species was found. Multiple plant species can be found at a single point. Date gives the date of the measurement as dd/mm/yyyy. Plot indicates the plot number, which is used to match across the different data files. The following columns (Salicornia, Puccinellia, Armeria, Limonium, Plantago, Aster, Triglochin, Spergularia, Halimione, Bare, Algal mat) give the number of points at which a plant species was found. Bare indicates that no plant or algal mat was present under a point.
The file Dry_weight_09_2017.csv gives the dry weight per plant species in g per plot at the final harvest in September 2017. Plot indicates the plot number, which is used to match across the different data files. Total gives the total dry weight for all plant species combined per plant species in g per plot. The following columns (Salicornia, Puccinellia, Armeria, Limonium, Plantago, Aster, Triglochin, Halimione, Spergularia_marina) give the total dry weight per plant species in g per plot.
There are 9 folders with photos of every plot taken between 2011 and 2017. The size of the square aluminum frame in the photos is 40 by 40 cm. The folders are labelled as Photosddmmyy, while the filename for the photos indicates the plot number. A few photos are missing because they were mistakenly not taken during the survey. A single replicate per treatment/fertiliser combination for the 2017 photos is presented in the paper, and these photos are not included in this submission for copyright reasons.
We evaluate how the primary production of an assemblage of salt marsh plants responds to a realistic sequence of species loss in a 7-year experiment, with and without the addition of fertiliser.
Following a previous study by Davies et al. (2012) on algal impact in salt marshes, this paper investigates how plant communities respond to the gradual loss of species caused by increasing fucoid algae deposits. Ninety 1-m2 experimental plots spaced ~ 3 m apart were established in an area of transitional low salt marsh in the Cefni estuary, Anglesey, Wales, UK (53°10′12″ N: 4°23′39″ W). In June 2009, the undisturbed assemblage of salt marsh plants was manipulated. A central 40 x 40 cm area of each of 32 plots was randomly allocated to a stage in the extirpation sequence of species in response to increased volumes of fucoid algae deposited on the marsh surface (see Davies et al., 2012). Species were removed on a species-by-species basis following the derived extirpation sequence (Salicornia ramosissima J. Woods, < Puccinellia maritima (Huds.) Parl. < Armeria maritima (Mill.) < Limonium humile Mill. < Plantago maritima L. < Aster tripolium L. < Triglochin maritima L., from least to most extirpation resistant).
The experiment lasted for 7 years from 2009 to 2017. To quantify whether compensation was context-dependent, and limited by nutrient availability, half the plots for each treatment (n = 2 per treatment) where fertilised in 2013 while the rest of the plots (n = 2 per treatment) were left unfertilised. Fertilisation was carried out by spreading 50g of Osmocote slow release fertiliser pellets per 40x40 cm plot on 07/05/2013. These pellets were not visible anymore in 2015 and therefore the treatment was repeated on 28/05/2015. The experiment was finished after 7 years in 2017.
During every summer growth season, one or more samples were collected for each replicate treatment plot in each year to provide an average value of gross community productivity and % cover per plant species over the peak of each growing season. At the end of the experiment in 2017, the biomass of each plant species in each plot was also measured destructively.
Gross community productivity (GCP, a measure of primary production) was quantified once or more in every year during June, July, August, and/or September (dates given in SM). Gross community productivity (GCP) was estimated as CO2 flux recorded using an LI-840 CO2/H20 gas analyser (LI-COR Biosciences, Lincoln, NE, USA) connected to a clear plexiglass chamber (0.09 m2 internal base area, 0.19 m high, internal volume = 17.1 litres). GCP was estimated using the rate of CO2 flux recorded during consecutive light and dark measurements representing net community productivity (NCP, CO2 utilization by photosynthesis plus CO2 production by respiration) and community respiration (CR, CO2 production during respiration), respectively. GCP was then estimated as GCP = NCP - CR and expressed at the community level as mmol CO2 uptake m-2 h-1. CO2 flux measurements were recorded in a stratified random order between 10:00 h and 14:00 h BST during a neap tidal cycle on days with low cloud cover to minimize imprecision caused by the effect of abiotic factors on photosynthetic rates. In addition, GCP measurements were recorded only where light levels exceeded 700 µmol PPFD m-2 s-1, a previously observed threshold above which variation in ambient light level has minimal impacts on primary production in this salt marsh community.
Total dry-weight biomass by species was measured at the end of the experiment in September 2017 by clipping all vegetation at the soil level. Species biomass could only be estimated before the end of the experiment as this required destructive sampling. To estimate a proxy for total community biomass before the end of the experiment, the abundance of each species in each plot was assessed as % cover using a 0.3 x 0.3 m point quadrat (49 point intersections) in July and/or August. The vegetation cover and GCP were not measured in 2015.