Modelling of the spread of Dothistroma septosporum in Europe

Abstract

Dothistroma needle blight (DNB), a disease affecting several pine species, is currently generating great concern in Europe. Caused by Dothistroma pini and Dothistroma septosporum, DNB affects pine needles and causes premature defoliation, which results in growth reduction and, in extreme cases, mortality. The disease has increased in importance in Europe over the last 20 years, with an increase in the number of observations of DNB in regions with large areas of Pinus sylvestris in northern Europe. This article presents a cell-based spatiotemporal model for predicting the likelihood and intensity of the future spread of D. septosporum in Europe. Here, "spread" includes both invasion of new regions and infection of healthy stands within already-colonized regions. Predicted spread depends on the availability of host species, climatic suitability of different regions to D. septosporum and dispersal of sexual and asexual spores from infected trees to surrounding forests via water splash, mist and wind. Longdistance spread through transport of infected seedlings is also included in the model. Simulations of spread until 2007 and 2015 were used to validate the model. These simulations produced similar patterns of spread to those observed in Europe.Simulations for 2030 suggested that additional and new outbreaks are likely to occur in Scotland, southern Norway, southern and central Sweden, northern parts of Germany and Poland, Estonia, Latvia and south-west Finland. Preventing the delivery of infected seedlings would be an effective method for reducing the spread of D. septosporum in the Nordic countries, Scotland and Ireland, the Baltic countries, and parts of Germany, Poland and Belarus. In these states, prevention of transport of infected seedlings can reduce the probability of additional spread by 15%-40%.

Scenario analyses on the effects of fertilization, improved regeneration material, and ditch network maintenance on timber production of Finnish forests

“…Our study ignored the expected growth increase of boreal forests under the climate change (Kellomäki et al 2008). It also ignored the expected increases in various potential abiotic and biotic risks to forests, which could at least partly cancel the expected increase in forest productivity under climate change (Valinger and Lundqvist 1992;Peltola et al 2010;Pukkala et al 2014b;Subramanian et al 2016;Thom and Seidl 2016;Möykkynen et al 2017;Reyer et al 2017). For example, the higher share of Norway spruce might lead to a larger risk of biotic and abiotic damages (Kellomäki et al 2008;Peltola et al 2010;Subramanian et al 2016;Thom and Seidl 2016).…”

Optimized cellular automaton for stand delineation

“…CA are self-organizing systems, which have been used for many purposes (Von Neumann 1966;Wolfram 2002). In forestry, CA have been used for land allocation and planning (Strange et al 2001;, and for simulating the spread of pests and pathogens (Möykkynen and Pukkala 2014;Möykkynen et al 2015Möykkynen et al , 2017.…”

Occurrence of Dothistroma needle blight in Lithuania and Belarus: The risk posed to native Scots Pine forests

“…The current increase in the incidence, range and severity of DNB and other pine needle diseases in Europe may be caused by global climate change (Adamson et al., 2018; Drenkhan et al., 2016; Jánošíková‐Hečková et al., 2018; Mesanza et al., 2019; Mullett et al., 2018; Ondrušková et al., 2017). Over the past two decades, climatic conditions seem to become increasingly favourable for DNB outbreaks in the Northern Hemisphere, and the risk of this disease to Scots pine forests in the boreal region may increase significantly in the future (Möykkynen, Fraser, Woodward, Brown, & Pukkala, 2017; Sturrock et al., 2011; Watt, Ganley, Kriticos, & Manning, 2011; Watt et al., 2009; Woods et al., 2016). Dothistroma needle blight is particularly sensitive to temperature and water availability, the optimal conditions for the development and sporulation of the pathogen is a combination of temperature 15–20/10–12°C (days/nights) with constant humidity and an average daily relative humidity above 90% (Dvorak, Drapela, & Jankovský, 2012; Woods et al., 2016).…”

“…A model of the possible impact of climate change on the composition of tree species in Lithuania for 2061–2090 (Ozolinčius et al., 2014) has shown that by the end of this century the climate may become less suitable for Pinus sylvestris and other conifers, and warming of the climate will negatively affect their resistance to diseases and pests. Models of D. septosporum distribution for 2030 in Europe (Möykkynen et al., 2017) also showed that new DNB outbreaks may occur in the future in the Nordic and Baltic countries, Scotland and Ireland, including northern Germany, Poland and Belarus, in regions covered by extensive areas of Scots pine forests, especially where P. sylvestris is planted in monocultures.…”