Temporal trends in pollination of the Poaceae family.
| Reference (publication date) | Region (number of sites) | Study period | Methodology | Trend identification technique | PIn (grains per cubic meter of air per decade and significance) | PSS (days per decade and significance) | PSD (days per decade and significance) |
|---|---|---|---|---|---|---|---|
| [16] (2016) | N Italy (1) | 1990–2004 | Hirst-type | Linear regression | – | Slightly + | No trend |
| [18] (2014) | Europe (13) | 1990–2009 | Hirst-type | Linear regression | + or – (ns, except Leiden and Legnano) | – in 7 of 10 sites (ns, except Reykjavik and Strasbourg) | + or – (* in 3 sites of 13, ns at the other 7) |
| [19] (2022) | United Kingdom (6) | 1995–2020 | Hirst-type | Linear regression | No trend | Locally – (* to **) | |
| [20] (2010) | NW Italy (1) | 1981–2007 | Hirst-type | Linear regression | – ns | – (9.6; ns) | No trend |
| [22] (2019) | France (7) | 1987–2018 | Hirst-type | Linear & polynomial regression | – overall, except in Lyon, often with a phase of increase until 1999–2002 | +, stationary, or –, depending on the site | –, stationary, or +, depending on the site |
| [23] (2021) | Central Germany (4) | 1998–2017 | Hirst-type | Cochran-Armitage test for trend | No trend | ||
| [24] (2005) | Austria (2) | 1980–2001 | Hirst-type | Linear regression | + (~2,400 in valley area, ~700 at higher altitude) | – (4.5 in valley area, 2.6 at higher altitude) | |
| [25] (2018) | Brussels (1) | 1982–2015 | Hirst-type | Local regression method (LOESS) | – | ||
| [26] (2003) | Switzerland (1) | 1979–1999 | Hirst-type | Linear regression | No trend | – (6.7; *) | No trend |
| [27] (2025) | Texas, USA (1) | 2009–2023 | Hirst-type | Least square regression | – (0.4; ns) | ||
| [28] (2021) | Benelux (5) | 1981–2020 | Hirst-type | Linear regression | – in all sites; * in 4 of 5 | – in the 5 sites; * in 4 of 5 | + at the 5 sites; * at only 1 |
| [30] (2014) | Catalonia (8) | 1994–2011 | Hirst-type | Linear regression + non-parametric test | – | ||
| [31] (1998) | Basel (1) | 1969–1996 | Hirst-type | Linear regression | + (**) | No trend | |
| [34] (2008) | Switzerland (3) | 1969–2007 | Hirst-type | Linear regression | + (1969–1990; **), then – (1991–2007; * in Basel) | – (1.8 to 3.2), but + (11) in Locarno | |
| [35] (2021) | Basel (1) | 1969–2020 | Hirst-type | Linear regression | – (~1.5) | ||
| [36] (2016) | Spain (12) | 1994–2013 | Hirst-type | Linear regression | + at 8 out of 12 sites | ||
| [37] (2021) | Basel (1) | 1969–2018 | Hirst-type | Linear regression | – (ns) | No trend | – (~3.7; **) |
| [38] (2021) | Switzerland (14) | 1990–2020 | Hirst-type | Linear regression + LOESS | + (ns) | ||
| [40] (2018) | Brussels (1) | 1982–2015 | Hirst-type | Linear regression + Mann-Kendall test | – (*) | – (*) | |
| [41] (2019) | Switzerland (6) | 1985–2014 | Hirst-type | Bayesian statistics | – in recent years in 3 of the sites | ||
| [42] (2011) | Germany (10) | 1988–2009 | Hirst-type | Linear regression + Mann-Kendall test | + in NE (~700) and S (~635), – in NW (~2,180) | – in S (9) | + in S (~11) |
| [43] (2024) | United Kingdom (2) | 1970–2021 | Hirst-type | Generalized additive model for time series | – from the late 1970’s to early 1990’s; + thereafter | – prior to 1990, + thereafter | |
| [44] (2016) | Stockholm (1) | 1973–2013 | Hirst-type | Linear regression | + (~35; ns) | – (~0.6; ns) | + (3; **) |
| [45] (2011) | S Poland (1) | 1991–2008 | Hirst-type | Linear regression | + (*) | – (**) | |
| [47] (2021) | Bavaria (8) | 1989–2018 | Hirst-type | Linear regression | – (*; ** in Munich) | – (** in Munich) | + |
| [50] (2003) | W Europe (5) | 1968–2001 (partly) | Hirst-type | Linear regression | + in 2 sites, – in 3 others; ns everywhere | ||
| [51] (2024) | NE Italy (20) | 2001–2022 | Hirst-type | Theil-Sen estimator | + (685) | – (6.3) | + (12.5) |
| [52] (2021) | France (6) | 1987–2021 | Hirst-type | Variable | – (~530) | ||
| [55] (2015) | USA (50) | 1994–2010 | Unspecified | Linear regression | + everywhere (2.75 to 79.6; ns except in the Central region) | – in 5 of 9 regions (1.8 to 5.3); + in 3 regions; ns except in the Central region | – in 7 regions out of 9 (1.2 to 11.5); + in the NE (5.9; *) |
| [56] (2012) | Europe (97) | 1977–2009 (partially) | Hirst-type | Linear regression | – (ns) | ||
| [57] (2020) | N & Central Italy (9) | 2000–2016 | Hirst-type | Non-parametric Mann-Kendall test | No trend | – | – |
| [58] (2020) | Basel (1) | 1969–2018 | Hirst-type | Linear regression | – (~1.2) | ||
| [59] (2021) | Georgia, USA (1) | 1992–2018 | Rotorod | Linear regression | No trend | – (14.2) | – (4.0) |
| [61] (2021) | Austria (1) | 1993–2017 | Hirst-type | Linear regression | – (~1,000) | – | No trend |
| [62] (2025) | N Italy (1) | 1997–2023 | Hirst-type | Linear regression | + ns | – (3.6; *) | + (12.1; **) |
| [63] (2024) | Switzerland | 1990–2023 | Hirst-type | Unspecified | + (~588) | – (~2) | |
| [73] (2002) | W of the NL (1) | 1969–2000 | Hirst-type | Linear regression | – (~2) | ||
| 2000s–2090s | Modelling | Unspecified | – (1.1) | ||||
| [74] (2025) | Iberian Peninsula (12) | 1994–2023 | Hirst-type | Linear regression | – (119 on average, but up to 1,588 in Badajoz) | – (1.3) | |
| [81] (2007) | Thessaloniki (1) | 1987–2005 | Hirst-type | Linear regression | + (~600) | No trend | No trend |
| [82] (2024) | Rome (1) | 1997–2016 | Hirst-type | Linear regression | No trend | ||
| [83] (2002) | Central Italy (1) | 1982–2001 | Hirst-type | Linear regression | – (3.0; *) | – (6.0; *) | |
| [85] (2021) | Slovakia (1) | 2002–2019 | Hirst-type | Linear regression + Mann-Kendall test | – | ||
| [90] (2024) | N Italy (1) | 1989–2018 | Hirst-type | Linear regression + Mann-Kendall test | + (*) | – (***) | No trend |
| [91] (2016) | S Spain (1) | 1996–2010 | Hirst-type | Linear regression + local regression method (LOESS) | + (~15,500; ***) | ||
| [92] (2021) | Oklahoma, USA (1) | 1996–2020 | Hirst-type | Linear regression | – (ns) | – (*) | + |
| [93] (2023) | Andalusia (1) | 1998–2020 | Hirst-type | Linear regression + Mann-Kendall test + Sen’s slope estimation | + (1,027; ns) | – (2; ns) | |
| [94] (2018) | S Spain (1) | 1994–2016 | Hirst-type | Z coefficient estimation + Mann-Kendall test | + (~750; ns) | – (ns) | + (ns) |
| [95] (2022) | Madrid (1) | 1979–2018 | Hirst-type | Linear regression | No trend | – (~1; ns) | – (~0.75; ns) |
| [96] (2025) | SW Spain (1) | 1993–2022 | Hirst-type | Linear regression + Mann-Kendall test + Theil-Sen estimator | No trend | + (*) | – (***) |
| [100] (2011) | NW Italy (1) | 1981–2010 | Hirst-type | Linear regression | + (**) | No trend | No trend |
| [109] (2019) | NW Spain (1) | 1997–2016 | Hirst-type | Mann-Kendall test + Theil-Sen estimator | No trend | ||
| [113] (1993) | London (1) | 1961–1990 | Hirst-type | Unspecified | – from the early 1960s to the mid-1980s | +, especially in the 1980s–1990s | – (4.3) |
| [114] (2017) | Central Italy (1) | 1982–2014 | Hirst-type | Linear regression | – (~1,450; ***) | – (~4.1; ***) | No trend |
| [115] (2009) | NW Spain | 1993–2007 | Hirst-type | Linear regression | – (**) | – but varies according to the site and the method used to define the season | Generally – |
| [116] (2017) | Central Italy (1) | 1982–2014 | Hirst-type | Linear regression | – (1,620; ***) | – (4.0; ***) | No trend |
| [117] (2014) | Experiment | + 50% with elevated CO2 | |||||
| [118] (2010) | Andalusia (8) | 1982–2008 | Hirst-type | Linear regression | + (** at 2 of 8 sites) | – (more or less, * or ns) | + (more or less, * or ns) |
| [119] (2014) | W Poland (1) | 1996–2011 | Hirst-type | Mann-Kendall test + Sen’s slope estimator | No trend | – (10.3; *) | + (30.0; **) |
| [120] (2024) | Portugal (1) | 2001–2021 | Hirst-type | Linear regression + Kruskal–Wallis test | No trend | No trend | No trend |
| [121] (2000) | NW Italy (1) | 1981–1997 | Hirst-type | Linear regression | No trend | ||
| [122] (1999) | United Kingdom (3) | 1961–1993 | Hirst-type | Unspecified (linear regression) | Contrasting schemes depending on the site and the decade | – in Cardiff and Derby, + in London | |
| [123] (2023) | Denmark (2) | 1825–2014 | Herbaria | Linear regression | – but varies according to species | + but varies according to species | |
| 1977–2019 | Hirst-type | Linear regression | – (2.5; ***) | + (4.4; **) | |||
| [124] (2000) | W Europe (4) | 1976–1997 | Hirst-type | Unspecified (linear regression) | – in Austria and the NL, + in S Finland virtually stable in London |
The grey backgrounds correspond to studies that have made projections about the future. +: trend towards increased pollen concentration (PIn), earlier onset of pollination (PSS), or longer pollen season (PSD); –: trend towards decreased pollen concentration (PIn), later onset of pollination (PSS), or shorter pollen season (PSD); *: p < 0.05; **: p < 0.01; ***: p < 0.001. PIn: pollen integral; PSS: pollen season start date; PSD: pollen season duration; N: north; ns: non-significant; NW: northwest; LOESS: locally estimated scatterplot smoothing; NE: northeast; S: south; W: west; SW: southwest; NL: Netherlands.