Database stats

The following provides an overview of the content of the Living Planet Database (LPD) as of 5th June 2018. If you think you have or know of any data which could be added to the LPD, please get in touch with us at [email protected].

Number of populations and species

Database growth over time

Figure 1 Data accumulation since the online database was established. All previous data were transferred from the offline version of the database.

Since the online database was established the time and date of entry are saved with the record, enabling us to track how many populations and species are being added over time. There are now 3,903 species from 19,278 populations in the database (Figure 1). The relatively steady increase over time has been punctuated by two steep increases in records which coincide with the completion of certain reports and projects.

Number of species and populations by class Birds are the dominant class in the database, contributing the majority of species and almost half of populations (Figure 2). Fish1 form a similar portion of the species in the database.

1 Fish aren’t technically one class but a group comprising the following classes. Actinoptergyii, Cephalaspidomorphi, Myxini, Sarcopterygii, Elasmobranchii and Holocephali (with the latter two sometimes joined as Chondrichthyes). These different classes are combined for ease of interpretation.

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b) a)

Figure 2 Pie charts showing the number of a) species and b) populations in the Living Planet Database by class.

Looking at the representation of classes in the LPI in more detail, Figure 3 shows how the number of species in the database compares to the total estimated number of species in the world. Birds once again have the highest representation of any class, followed by mammals, while reptiles have the lowest representation followed by amphibians and fish (Figure 3). Birds are the best-studied class so one reason for the high representation achieved is that there are many publications about different bird species.

Figure 3 Graph showing the number of species in the Living Planet Database (solid bars) as a subset of the total number of species in the class based on figures from the relevant taxonomic authorities (hollow bars).

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Number of species and populations by system Terrestrial species form the bulk of records in the LPI, though at the population level marine and terrestrial are more evenly matched (Figure 4). Considering that freshwater systems cover a substantially smaller portion of the world’s surface, it is not surprising that fewer species and populations from that system are contained in the LPI.

Figure 4 Pie charts showing the distribution of a) species and b) populations in the Living Planet Database across the terrestrial, marine and freshwater system.

Time-series length

The majority of records cover 3-5 years of population data (Figure 5). There are over 3,000 records with the minimum amount of population data, 2 years. There is an unusual jump, in an otherwise decreasing trend in the number of populations with longer time series, with many records running from 1970 to 2011-2015.This is likely due to the large proportion of time-series stemming from long- term monitoring programmes such as the North American Breeding Bird Survey.

Figure 5 Bar chart showing the distribution of populations according to their length.

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Temporal distribution of data

The number of populations and species which have a data point in a given year rises steadily from 1970, reaching a peak of >11,000 and > 2,600 – respectively - in the 1990s. After this point, numbers drop rapidly. As research on wildlife population change is still ongoing in more recent years, this reduction in the number of contributing populations and species is mainly due to a lag in the publication of collected data. In addition, data are published at such a rate so as to create a backlog of time-series to be entered into the database, and newer data sources are unlikely to be added unless they are in line with the current focus of data collection.

Figure 6 The number of populations and species which have a data point in a given year.

Data sources

The majority of population records were sourced from peer-reviewed scientific journals (Figure 7). Secondary sources are those where an article or report uses population information from another typically referenced source. These are the second most common data source. Other sources include expert judgements, other unspecified sources and population records from an unknown source.

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Figure 7 Pie chart showing the distribution of population sources in the database.

Distribution

There is an unequal spatial distribution of populations in the LPI, with more populations coming from Europe and North America than anywhere else for both terrestrial & freshwater, and marine systems (Figure 8). These two regions alone account for 10,909 populations – over half of all populations in the database. The figures also highlight the large gaps in distribution for both terrestrial and freshwater, and for marine populations.

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a)

b)

Figure 8 Map of a) terrestrial & freshwater, and b) marine populations in the Living Planet Database. Only populations monitored in a specific location are plotted on the map.

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Current data gaps

The records which are currently contained in the LPD have been added opportunistically using published data, with data entry often following the focus of projects in progress. There is also a bias in available data from particular regions and species groups and from publications in the English language. If we compare the number of species currently represented in the LPD with the number of known vertebrate species globally, we can identify gaps in coverage. This provides an opportunity to target data entry towards these taxonomic and geographic gaps. Table 1 and 2 present the biggest data gaps in the LPD split into systems, classes and biogeographic realms. Overall, fish are the most underrepresented group in the database, followed by reptiles. If you think you have data which could be used to address these gaps, please get in touch with us at [email protected].

Table 1 The top 5 least well represented group/realm combinations in the Living Planet Database for terrestrial and freshwater systems. RANK REALM CLASS 1 Neotropical FW fish 2 Indo-Malaya FW fish 3 Neotropical Reptilia 4 Afrotropical FW fish 5 Afrotropical Reptilia

Table 2 The top 4 least well represented group/realm combinations in the Living Planet Database for the marine system. RANK REALM CLASS 1 Tropical and Sub-tropical Indo-Pacific Fish 2 S.Temperate and Antarctic Fish 3 Atlantic Tropical and Sub-tropical Fish 4 Arctic Fish

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