Stem CO2 efflux in six co‐occurring tree species: underlying factors and ecological implications

Stem respiration plays a role in species coexistence and forest dynamics. Here we examined the intra‐ and inter‐specific variability of stem CO₂ efflux (E) in dominant and suppressed trees of six deciduous species in a mixed forest stand: Fagus sylvatica L., Quercus petraea [Matt.] Liebl, Quercus pyrenaica Willd., Prunus avium L., Sorbus aucuparia L. and Crataegus monogyna Jacq. We conducted measurements in late autumn. Within species, dominants had higher E per unit stem surface area (E_s) mainly because sapwood depth was higher than in suppressed trees. Across species, however, differences in E_s corresponded with differences in the proportion of living parenchyma in sapwood and concentration of non‐structural carbohydrates (NSC). Across species, E_s was strongly and NSC marginally positively related with an index of drought tolerance, suggesting that slow growth of drought‐tolerant trees is related to higher NSC concentration and E_s. We conclude that, during the leafless period, E is indicative of maintenance respiration and is related with some ecological characteristics of the species, such as drought resistance; that sapwood depth is the main factor explaining variability in E_s within species; and that the proportion of NSC in the sapwood is the main factor behind variability in E_s among species.     

The effects of disturbance on the population structure and regeneration potential of five dominant woody species – in Hugumburda‐Gratkhassu National Forest Priority Area,North‐eastern Ethiopia

Vast areas of forests in North‐eastern Ethiopia have been replaced by cropland, shrub land or grazing areas. Thus, information about how vegetation composition and structure varies with disturbance is fundamental to conservation of such areas. This study aimed to investigate the effects of disturbance on the population structure and regeneration potential of five dominant woody species within forest where local communities harvest wood and graze livestock. Vegetation structure and environmental variables were assessed in 50 quadrats (20 m × 20 m). In most of both disturbed and undisturbed treatments, Juniperus procera was the highest contributor to the basal area of the forest, while that of Olinia rochetiana was the lowest. Analysis of population structure showed high density at lower Diameter at Breast Height (DBH) and low density at higher DBH classes. Undisturbed forest treatments had 84% canopy cover, 22 m mean vegetation height and a density of 1320 trees of dominant species and 1024 seedlings/saplings ha^?1. In disturbed habitats, canopy cover (73%), mean vegetation height (18 m) and density of dominant trees and saplings were significantly lower than in undisturbed habitats. Thus, to ensure species, survival and maintain species diversity managed use of the protected area is essential.     

Life history and population dynamics of a tree species in tropical semi‐arid climate: A case study with Cordia oncocalyx

In semi‐arid climates, plant population dynamics are strongly influenced by the amount and temporal distribution of rainfall. We monitored a population of the tree species Cordia oncocalyx (Boraginaceae) for 24 months in the dry thorny woodland of semi‐arid northeastern Brazil, to investigate which life‐history traits allow this tree to be locally dominant. We used horizontal life tables and a Lefkovitch matrix and tested for relationships among demographic parameters of seedling, infant, juvenile, immature, virginile and reproductive ontogenetic stages with rainfall and canopy openness. Germination and recruitment occurred in the rainy months, and dry‐season mortality occurred only in seedlings (76% and 100%, first and second years, respectively) and infants (3% and 6%). Juveniles showed greater height growth under more open canopies (Spearman correlation coefficient = 0.24), suggesting that light availability influences growth. The population growth rate was λ = 1.0336, and the highest sensitivity occurred in the infant‐juvenile transition. Our results show light as a restrictive growth factor for plants in the juvenile stage and confirm the strong influence of rainfall on the dynamics of trees in a seasonally dry environment. The formation of a persistent seed bank with germination concentrated at the rainfall onset but spreading over the rainy season are strategies that hedge bets before establishment. The formation of a bank of infants, which can resume growth as soon as there is water, hedges bets after establishment. We attribute the positive population growth rate of Cordia oncocalyx to survival strategies allowing bet‐hedging both before and after establishment.     

Canopy disturbance and gap partitioning promote the persistence of a pioneer tree population in a near‐climax temperate forest of the Qinling Mountains,China

An unresolved question of temperate forests is how pioneer tree species persist in mature forests. In order to understand the responsible mechanisms, we investigated a near‐climax mixed temperate forest dominated by Betula albosinensis in the Qinling Mountains of China. Through establishing four 50 m × 50 m plots, we examined the canopy disturbance characteristics and its effects on tree recruitments. We further test the intra‐ and interspecific effects on the recruitment of B. albosinensis. The obtained data demonstrated canopy disturbance was frequent but most small‐sized. The canopy gaps are caused mainly by adult B. albosinensis by snapping. The regeneration of coexistent tree species shows a distinct preference for gap size. B. albosinensis were clumped at the juvenile stage and small scales. B. albosinensis juveniles were positively associated with B. utilis juveniles and negatively associated with the conspecific and B. utilis large trees. In addition, B. albosinensis juveniles showed negative associations with contemporary other tree species. Our results suggested that canopy disturbance caused by canopy trees and gap partitioning among the coexistent tree species are important for the persistence of the mixed forest. As a main gapmaker, B. albosinensis appear to develop a self‐perpetuating life‐history trait and allow them to persist.     

Dampening prey cycle overrides the impact of climate change on predator population dynamics: a long‐term demographic study on tawny owls

Predicting the dynamics of animal populations with different life histories requires careful understanding of demographic responses to multifaceted aspects of global changes, such as climate and trophic interactions. Continent‐scale dampening of vole population cycles, keystone herbivores in many ecosystems, has been recently documented across Europe. However, its impact on guilds of vole‐eating predators remains unknown. To quantify this impact, we used a 27‐year study of an avian predator (tawny owl) and its main prey (field vole) collected in Kielder Forest (UK) where vole dynamics shifted from a high‐ to a low‐amplitude fluctuation regime in the mid‐1990s. We measured the functional responses of four demographic rates to changes in prey dynamics and winter climate, characterized by wintertime North Atlantic Oscillation (wNAO). First‐year and adult survival were positively affected by vole density in autumn but relatively insensitive to wNAO. The probability of breeding and number of fledglings were higher in years with high spring vole densities and negative wNAO (i.e. colder and drier winters). These functional responses were incorporated into a stochastic population model. The size of the predator population was projected under scenarios combining prey dynamics and winter climate to test whether climate buffers or alternatively magnifies the impact of changes in prey dynamics. We found the observed dampening vole cycles, characterized by low spring densities, drastically reduced the breeding probability of predators. Our results illustrate that (i) change in trophic interactions can override direct climate change effect; and (ii) the demographic resilience entailed by longevity and the occurrence of a floater stage may be insufficient to buffer hypothesized environmental changes. Ultimately, dampened prey cycles would drive our owl local population towards extinction, with winter climate regimes only altering persistence time. These results suggest that other vole‐eating predators are likely to be threatened by dampening vole cycles throughout Europe.     

Gap-phase dynamics and coexistence of a long-lived pioneer and shade-tolerant tree species in the canopy of an old-growth coastal temperate rain forest of Chiloé Island, Chile

Aim A major question with regard to the ecology of temperate rain forests in south‐central Chile is how pioneer and shade‐tolerant tree species coexist in old‐growth forests. We explored the correspondence between tree regeneration dynamics and life‐history traits to explain the coexistence of these two functional types in stands apparently representing a non‐equilibrium mixture. Location This study was conducted in northern Chiloé Island, Chile (41.6° S, 73.9° W) in a temperate coastal rain forest with no evidence of stand disruption by human impact. Methods We assessed stand structure by sampling all stems within two 50 × 20 m and four 5 × 100 m plots. A 600‐m long transect, with 20 uniformly spaced sampling points, was used to quantify seedling and sapling densities, obtain increment cores, and randomly select 10 tree‐fall gaps. We used tree‐ring analysis to assess establishment periods and to relate the influences of disturbances to the regeneration dynamics of the main canopy species. Results Canopy emergent tree species were the long‐lived pioneer Eucryphia cordifolia and the shade‐tolerant Aextoxicon punctatum. Shade‐tolerant species such as Laureliopsis philippiana and several species of Myrtaceae occupied the main canopy. The stem diameter distribution for E. cordifolia was distinctly unimodal, while for A. punctatum it was multi‐modal, with all age classes represented. Myrtaceae accounted for most of the small trees. Most tree seedlings and saplings occurred beneath canopy gaps. Based on tree‐ring counts, the largest individuals of A. punctatum and E. cordifolia had minimum ages estimated to be > 350 years and > 286 years, respectively. Shade‐tolerant Myrtaceae species and L. philippiana had shorter life spans (< 200 years). Most growth releases, regardless of tree species, were moderate and have occurred continuously since 1750. Main conclusions We suggest that this coastal forest has remained largely free of stand‐disrupting disturbances for at least 450 years, without substantial changes in canopy composition. Release patterns are consistent with this hypothesis and suggest that the disturbance regime is dominated by individual tree‐fall gaps, with sporadic multiple tree falls. Long life spans, maximum height and differences in shade tolerance provide a basis for understanding the long‐term coexistence of pioneer and shade‐tolerant tree species in this coastal, old‐growth rain forest, despite the rarity of major disturbances.     

Relative influence of habitat structure,species interactions and rainfall on the post‐fire population dynamics of ground‐dwelling vertebrates

The long‐term impacts of wildfires on animal populations are largely unknown. We used time‐series data based on a tracking index, from coastal NSW spanning 28 years after a wildfire, to investigate the relative influence of habitat structure, species interactions and climate on post‐fire animal population dynamics. The fire had an immediate impact on habitat structure, reducing and simplifying vegetation cover, which then underwent post‐fire successional change including an increase and plateau in tree canopy cover; an increase, stabilization and then decline in shrub cover; and an increase in ground litter cover. Population changes of different animal species were influenced by different components of successional change, but there was also evidence that species interactions were important. For example, bandicoots (Isoodon obesulus and Perameles nasuta combined) increased concurrent with an increase in shrub cover then declined at a faster rate than a direct association with senescing shrub cover would suggest, while the feral cat (Felis catus) population changed with the bandicoot population, suggesting a link between these species. Potoroos (Potorous tridactylus) increased 10 years after the fire concurrent with the closing tree canopy, but there was also evidence of a negative association with feral foxes (Vulpes vulpes). Variation in rainfall did not have significant effects on the population dynamics of any species. Our results suggest that changes in habitat structure play a key role in the post‐fire dynamics of many ground‐dwelling animals and hence different fire regimes are likely to influence animal dynamics through their effects on habitat structure. However, the role of predator–prey interactions, particularly with feral predators, is less clear and further study will require manipulative experiments of predators in conjunction with fire treatments to determine whether feral predator control should be integrated with fire management to improve outcomes for some native species.     

Environmental determinants of population divergence in life‐history traits for an invasive species: climate,seasonality and natural enemies

Invasive species cope with novel environments through both phenotypic plasticity and evolutionary change. However, the environmental factors that cause evolutionary divergence in invasive species are poorly understood. We developed predictions for how different life‐history traits, and plasticity in those traits, may respond to environmental gradients in seasonal temperatures, season length and natural enemies. We then tested these predictions in four geographic populations of the invasive cabbage white butterfly (Pieris rapae) from North America. We examined the influence of two rearing temperatures (20 and 26.7 °C) on pupal mass, pupal development time, immune function and fecundity. As predicted, development time was shorter and immune function was greater in populations adapted to longer season length. Also, phenotypic plasticity in development time was greater in regions with shorter growing seasons. Populations differed significantly in mean and plasticity of body mass and fecundity, but these differences were not associated with seasonal temperatures or season length. Our study shows that some life‐history traits, such as development time and immune function, can evolve rapidly in response to latitudinal variation in season length and natural enemies, whereas others traits did not. Our results also indicate that phenotypic plasticity in development time can also diverge rapidly in response to environmental conditions for some traits.     

Dry deposition of ammonia gas drives species change faster than wet deposition of ammonium ions: evidence from a long‐term field manipulation

Although the effects of atmospheric nitrogen deposition on species composition are relatively well known, the roles of the different forms of nitrogen, in particular gaseous ammonia (NH₃), have not been tested in the field. Since 2002, we have manipulated the form of N deposition to an ombrotrophic bog, Whim, on deep peat in southern Scotland, with low ambient N (wet + dry = 8 kg N ha^?1 yr^?1) and S (4 kg S ha^?1 yr^?1) deposition. A gradient of ammonia (NH₃, dry N), from 70 kg N ha^?1 yr^?1 down to background, 3–4 kg N ha^?1 yr^?1 was generated by free air release. Wet ammonium (NH₄⁺, wet N) was provided to replicate plots in a fine rainwater spray (NH₄Cl at +8, +24, +56 kg N ha^?1 yr^?1). Automated treatments are coupled to meteorological conditions, in a globally unique, field experiment. Ammonia concentrations were converted to NH₃‐N deposition (kg N ha^?1) using a site/vegetation specific parameterization. Within 3 years, exposure to relatively modest deposition of NH₃, 20–56 kg NH₃‐N ha^?1 yr^?1 led to dramatic reductions in species cover, with almost total loss of Calluna vulgaris, Sphagnum capillifolium and Cladonia portentosa. These effects appear to result from direct foliar uptake and interaction with abiotic and biotic stresses, rather than via effects on the soil. Additional wet N by contrast, significantly increased Calluna cover after 5 years at the 56 kg N dose, but reduced cover of Sphagnum and Cladonia. Cover reductions caused by wet N were significantly different from and much smaller than those caused by equivalent dry N doses. The effects of gaseous NH₃ described here, highlight the potential for ammonia to destroy acid heathland and peat bog ecosystems. Separating the effects of gaseous ammonia and wet ammonium deposition, for a peat bog, has significant implications for regulatory bodies and conservation agencies.     

Structure and dynamics of a <Emphasis Type="Italic">Castanopsis cuspidata</Emphasis> var. <Emphasis Type="Italic">sieboldii</Emphasis> population in an old-growth,evergreen, broad-leaved forest: The importance of sprout regeneration

The population structure and dynamics of Castanopsis cuspidata var. sieboldii were studied to evaluate vegetative and sapling regeneration in an old-growth, evergreen broad-leaved forest exposed to low-severity typhoon disturbances by annual typhoons on the Tsushima Islands in Japan. The density of individuals 5cm d.b.h. was 38.0ha^–1 in 1990; 7.9% were multiple-stemmed individuals. Over the 7-year study period (1990–1997), the number of individuals decreased, although the number of stems increased. Over 30% of apparently dead individuals were reconstituted by sprouting stems. Compared with sprout regeneration, sapling regeneration rarely occurred and was only observed in canopy gaps. Most individuals had at least one sprout shoot (H 30cm, d.b.h. <5cm), and the number and size of sprout shoots increased as the size of the individuals increased. During the study period, larger individuals with stem breakage tended to produce sprout stems. The density of saplings was 1074ha^–1 and they were more abundant in canopy gaps than under closed canopies, but large saplings were very rare even in canopy gaps. The population of C.cuspidata var. sieboldii consisted primarily of single-stemmed individuals with a few multiple-stemmed individuals providing a sprout bank. Larger individuals responded to the low severity typhoon disturbances and formed sprout stems. Although many saplings were observed, regeneration occurred more often by sprout formation than by growth of saplings. Thus, sprout regeneration is an important mode of regeneration, which allows this pioneer-like species to maintain its population in this forest.     

Comparative population structure of two dominant species,Shinkaia crosnieri (Munidopsidae: Shinkaia) and Bathymodiolus platifrons (Mytilidae: Bathymodiolus), inhabiting both deep‐sea vent and cold seep inferred from mitochondrial multi‐genes

Deep‐sea hydrothermal vents and cold seeps, limited environments without sunlight, are two types of extreme habitat for marine organisms. The differences between vents and cold seeps may facilitate genetic isolation and produce population heterogeneity. However, information on such chemosynthetic fauna taxa is rare, especially regarding the population diversity of species inhabiting both vents and cold seeps. In this study, three mitochondrial DNA fragments (the cytochrome c oxidase submit I (COI), cytochrome b gene (Cytb), and 16S) were concatenated as a mitochondrial concatenated dataset (MCD) to examine the genetic diversity, population structure, and demographic history of Shinkaia crosnieri and Bathymodiolus platifrons. The genetic diversity differences between vent and seep populations were statistically significant for S. crosnieri but not for B. platifrons. S. crosnieri showed less gene flow and higher levels of genetic differentiation between the vent and seep populations than B. platifrons. In addition, the results suggest that all the B. platifrons populations, but only the S. crosnieri vent populations, passed through a recent expansion or bottleneck. Therefore, different population distribution patterns for the two dominant species were detected; a pattern of population differentiation for S. crosnieri and a homogeneity pattern for B. platifrons. These different population distribution patterns were related to both extrinsic restrictive factors and intrinsic factors. Based on the fact that the two species were collected in almost identical or adjacent sampling sites, we speculated that the primary factors underlying the differences in the population distribution patterns were intrinsic. The historical demographics, dispersal ability, and the tolerance level of environmental heterogeneity are most likely responsible for the different distribution patterns.     

Climate warming alters effects of management on population viability of threatened species: results from a 30‐year experimental study on a rare orchid

Climate change is expected to influence the viability of populations both directly and indirectly, via species interactions. The effects of large‐scale climate change are also likely to interact with local habitat conditions. Management actions designed to preserve threatened species therefore need to adapt both to the prevailing climate and local conditions. Yet, few studies have separated the direct and indirect effects of climatic variables on the viability of local populations and discussed the implications for optimal management. We used 30 years of demographic data to estimate the simultaneous effects of management practice and among‐year variation in four climatic variables on individual survival, growth and fecundity in one coastal and one inland population of the perennial orchid Dactylorhiza lapponica in Norway. Current management, mowing, is expected to reduce competitive interactions. Statistical models of how climate and management practice influenced vital rates were incorporated into matrix population models to quantify effects on population growth rate. Effects of climate differed between mown and control plots in both populations. In particular, population growth rate increased more strongly with summer temperature in mown plots than in control plots. Population growth rate declined with spring temperature in the inland population, and with precipitation in the coastal population, and the decline was stronger in control plots in both populations. These results illustrate that both direct and indirect effects of climate change are important for population viability and that net effects depend both on local abiotic conditions and on biotic conditions in terms of management practice and intensity of competition. The results also show that effects of management practices influencing competitive interactions can strongly depend on climatic factors. We conclude that interactions between climate and management should be considered to reliably predict future population viability and optimize conservation actions.     

Environmental dependence of population dynamics and height growth of a subalpine conifer across its vertical distribution: an approach using high‐resolution aerial photographs

Many studies have reported shifts in the altitudinal ranges of plant species in response to recent global warming. However, most studies of tree species have been conducted on a small scale and have focused on tree line ecotones by examining tree rings and age structure on account of the long life spans of the trees. To examine the impact of climate change on forest dynamics at a regional scale, we investigated differences in the population density and canopy height of a Japanese subalpine coniferous species, Abies mariesii, between 1967 and 2003 by analysis of high‐resolution aerial photographs of the Hakkoda Mountains, Honshu, Japan. In 712 plots within the photographs we analyzed which environmental variables (including elevation, aspect, wetness, and distance from moorlands) account for these changes. The population density of A. mariesii decreased below 1000 m a.s.l. and increased above 1300 m a.s.l. It also increased around moorlands, which may provide refugia at low elevations. The rate of increase in canopy height was lowest on the southeastern slopes and on the periphery of the moorlands. The distinct changes in the population density of A. mariesii at its distribution limits probably reflect the responses of the population to climatic changes during three decades. Areas surrounding the moorlands may offer refugia in spite of the poor growing conditions there.     

Contrasting responses to Pleistocene climate changes: a case study of two sister species Allium cyathophorum and A. spicata (Amaryllidaceae) distributed in the eastern and western Qinghai–Tibet Plateau

It has been hypothesized that species occurring in the eastern and the western Qinghai–Tibet Plateau (QTP) responded differently to climate changes during the Pleistocene. Here, we test this hypothesis by phylogeographic analysis of two sister species, Allium cyathophorum and A. spicata. We sequenced two chloroplast DNA (cpDNA) fragments (accD‐psaI and the rpl16 intron) of 150 individuals, and the nuclear (ITS) region of 114 individuals, from 19 populations throughout the distributional ranges of these species. The divergence between the two species was dated at 779 ‐ 714 thousand years before the present and was likely initiated by the most major glaciation in the QTP. Analysis of chlorotype diversity showed that A. spicata, the species occurring in the western QTP, contains much lower genetic diversity (0.25) than A. cyathophorum (0.93), which is distributed in the eastern QTP. Moreover, multiple independent tests suggested that the A. spicata population had expanded recently, while no such expansion was detected in A. cyathophorum, indicating a contrasting pattern of responses to Pleistocene climate changes. These findings highlight the importance of geographical topography in determining how species responded to the climate changes that took place in the QTP during the Pleistocene.     

Egyptian tortoise conservation: A community‐based,field research program developed from a study on a captive population

Local community participation and ex situ conservation has the potential to assist the recovery of the endangered Egyptian tortoise, Testudo kleinmanni. We initiated an in situ community‐based conservation and research program from a captive population of T. kleinmanni. We used a captive population of the Egyptian tortoise to train a member of the local community as a research technician and used his indigenous tracking skills and knowledge of the area to collect activity and dietary data on 28 captive tortoises. We overcame problems with illiteracy by creating a data sheet based on symbols and numbers. This data sheet allowed us to use the indigenous knowledge of various people from the community, and employ them in the future. Our local community approach to data collection, in conjunction with a craft program, made the conservation of the Egyptian tortoise more rewarding to the local community by providing a more sustainable form of income than collecting animals for the pet trade. Our multidimensional approach (local community participation as research technicians, craft program, and trust building) for gaining local support eventually led to the rediscovery of wild Egyptian tortoises in North Sinai, which was significant, as this species was presumed extinct in Egypt. We have now shifted our focus to in situ conservation, using the research and local capacity building template developed from this captive population study. Our template can be used by zoos and conservation organizations with small budgets and collections of native species in natural habitats to create similar captive research programs that can be applied to in situ conservation. Zoo Biol 26:397–406, 2007. © 2007 Wiley‐Liss, Inc.     

A thorough study of a Paratylenchus sp. in glasshouse‐grown lettuce: Characterisation,population dynamics,host plants and damage threshold as keys to its integrated management

In glasshouses practising monoculture of butterhead lettuce in Belgium, high densities of pin nematodes (Paratylenchus spp.) are frequently associated with reduced plant growth. Growers currently apply chemical soil disinfestation measures to manage this problem, although stricter phytosanitary regulations are forcing a shift towards integrated management. Efficient implementation of such management requires knowledge about the factors influencing nematode population dynamics, and the damage threshold for lettuce. The nematode populations in five Belgian glasshouses were monitored for at least 1 year by frequently soil sampling at 0–30 cm and 30–60 cm depth. An undescribed species of Paratylenchus was identified in all glasshouses based on morphological and molecular features. High nematode densities (>20,000 (100 ml soil)^?1) occurred in winter and spring. Chemical soil disinfestation lowered these populations greatly, although up to 14% survived in the deeper soil layer. After soil steaming under negative pressure, no pin nematodes were found. After 2 months of black fallow pin nematode densities were reduced by 50%–76%. Lamb's lettuce, parsley and wild rocket were found to be poor hosts in a pot experiment, while reproduction factors (P_f/P_i) on lettuce cultivars varied between 1 and 3. In three experiments with butterhead lettuce ‘Cosmopolia’ in pots with a series of 9 or 10 densities of Paratylenchus sp. [up to 35,000 (100 ml soil)^?1], no damage to lettuce heads was observed. However, root weight and root quality were reduced, and the corresponding damage thresholds were rather low [1,754 and 362 Paratylenchus sp. (100 ml soil)^?1, respectively]. Management strategies such as crop rotation, soil disinfestation or fallow are recommended to avoid pin nematode population build‐up.     

Inferring the contribution of sexual reproduction,migration and off‐season survival to the temporal maintenance of microbial populations: a case study on the wheat fungal pathogen Puccinia striiformis f.sp. tritici

Understanding the mode of temporal maintenance of plant pathogens is an important domain of microbial ecology research. Due to the inconspicuous nature of microbes, their temporal maintenance cannot be studied directly through tracking individuals and their progeny. Here, we suggest a series of population genetic analyses on molecular marker variation in temporally spaced samples to infer about the relative contribution of sexual reproduction, off‐season survival and migration to the temporal maintenance of pathogen populations. We used the proposed approach to investigate the temporal maintenance of wheat yellow rust pathogen, Puccinia striiformis f.sp. tritici (PST), in the Himalayan region of Pakistan. Multilocus microsatellite genotyping of PST isolates revealed high genotypic diversity and recombinant population structure across all locations, confirming the existence of sexual reproduction in this region. The genotypes were assigned to four genetic groups, revealing a clear differentiation between zones with and without Berberis spp., the alternate host of PST, with an additional subdivision within the Berberis zone. The lack of any differentiation between samples across two sampling years, and the very infrequent resampling of multilocus genotypes over years at a given location was consistent with limited over‐year clonal survival, and a limited genetic drift. The off‐season oversummering population in the Berberis zone, likely to be maintained locally, served as a source of migrants contributing to the temporal maintenance in the non‐Berberis zone. Our study hence demonstrated the contribution of both sexual recombination and off‐season oversummering survival to the temporal maintenance of the pathogen. These new insights into the population biology of PST highlight the general usefulness of the analytical approach proposed.