Article

Oceanic and temperate rainforest climates and their epiphyte indicators in Britain

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Abstract

A biogeographic zone with high oceanicity is a well described feature of the European Atlantic region. This oceanic zone intersects with a zone of European temperate rainforest that has received increasing conservation recognition. Although having a degree of spatial overlap, the terminology applied to these different zones is not synonymous. Temperate rainforest is one example of an oceanic system, alongside others such as blanket bog or liverwort heath. Conversely, oceanic systems provide one type of climatic setting suitable to the development of temperate rainforest, alongside other and contrasting landscapes such as the orographic climate of continental mountains. Zones of high oceanicity and temperate rainforest are both strongly represented in the British Isles, and this study examines the degree of spatial overlap in Britain for standard definitions of each. Lichen epiphyte indicators associated with zones of oceanic woodland or temperate rainforest were quantified, and subsequently tested for conservation priority Atlantic oakwoods (Annex 1 Habitat Code 91A0: old sessile oak woods with _Ilex_ and _Blechnum_ in the British Isles). Discrepancies between oceanic woodland and temperate rainforest led to slightly different sets of indicator species that could be applied in biodiversity and habitat quality assessments. The definition of oceanic systems appeared to include warmer and lowland situations for example in coastal Wales and south-west England. In contrast, temperate rainforest extended to cooler upland areas in north-eastern Scotland. The species indicators for oceanic and temperate rainforest were nevertheless effective in identifying sites with different conservation priorities, such as for protection or restoration.

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... The hydration source and frequency differ among habitats (Gauslaa, 2014) and constitute ecological constraints to species' ranges (Lid en et al., 2010). Thus, climate-specific hydrological patterns often shape lichens' distribution (Giordani and Incerti, 2008;Ellis, 2016). ...
... All species often cooccur on trunks in broad-leaved forests, while L. pulmonaria also abundantly grows on conifer branches in boreal rainforests of Norway (Holien and Tønsberg, 1996) and humid temperate forests of western North America (Goward and Spribille, 2005). A ranking of the British epiphytic lichens' dependency on various measures of oceanity (Ellis, 2016), classified all three as indicators of oceanic temperate rainforests; L. virens had the strongest association to an oceanic climate, L. pulmonaria the weakest. Owing to their spectacular appearance and widespread decline, these lichens have been featured as flagship species in the conservation of old forests, and are model species in ecological (e.g. ...
... By contrast, vapor uptake in the more attached and compact L. virens is likely restricted to the upper thallus surface, and hampered by a thicker boundary layer (Larson, 1979). The different uptake rates could elucidate their divergent geographical distributions: the fast L. pulmonaria also grow in inland sites with strong nocturnal cooling; the slower L. virens is restricted to rainy coastal sites (Ellis, 2016) with less diurnal temperature fluctuations. Although the thick L. amplissima had the slowest water uptake rate per thallus dry mass and as RWC, it took up water per unit area at the fastest rate. ...
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Although water is essential for photosynthetic activation in lichens, rates of vapor uptake and activation in humid air, which likely influence their niche preferences and distribution ranges, are insufficiently known. This study simultaneously quantifies rehydration kinetics and PSII reactivation in sympatric, yet morphologically and functionally distinct cephalolichens (Lobaria amplissima, L. pulmonaria, L. virens). High-temporal resolution monitoring of rehydrating thalli by automatic weighing combined with chlorophyll fluorescence imaging of maximal PSII efficiency (FV/FM) was applied to determine species-specific rates of vapor uptake and photosynthetic activation. The thin and loosely attached growth form of L. pulmonaria rehydrates and reactivates faster in humid air than the thick L. amplissima, with L. virens in between. This flexible hydration strategy is consistent with L. pulmonaria’s wide geographical distribution stretching from rainforests to continental forests. By contrast, the thick and resupinate L. amplissima reactivates slowly in humid air but stores much water when provided in abundance. This prolongs active periods after rain, which could represent an advantage where abundant rain and stem flow alternates with long-lasting drying. Understanding links between morphological traits and functional responses, and their ecological implications for species at risk, is crucial to conservation planning and for modelling populations under various climate scenarios.
... Its growth form and low STM likely facilitate uptake of water vapor, meaning lower dependency on the rare occurrences of liquid water. These opportunistic traits may explain why L. pulmonaria is reported to be less associated with wet rain forest climate than L. amplissima and L. virens (Ellis, 2016). ...
... An earlier light-susceptibility study of sympatric populations of the three study species showed that L. virens was substantially more susceptible to high light while desiccated than L. amplissima and L. pulmonaria (Gauslaa and Solhaug, 1996). These findings are consistent not only with the strong association between L. virens and rain forest climates (Ellis, 2016), but also with its higher tendency to grow on lower parts of the trunks in more shaded sites than the two other species (Asplund et al., 2010). By contrast, L. amplissima with the thickest thalli (high STM), higher light saturation point (Gauslaa and Solhaug, 1996), and a higher lower-height-distribution limit on trunks than the two other species (Asplund et al., 2010), had the highest initial and maximal Ф PSII (Table 1). ...
Article
By fluorescence imaging, we quantified how hydration traits and thallus size determine the duration of photosynthetic activity during drying in light and darkness for sympatric populations of three epiphytic old forest cephalolichens differing in specific thallus mass (STM) and growth form. Maximal PS II efficiency (FV/FM) during drying in darkness and effective PSII yield (ФPSII) during drying in light (200 μmol m⁻² s⁻¹) was repeatedly monitored in lichens under controlled conditions, using chlorophyll fluorescence imaging with simultaneous recordings of wet mass. STM shaping the water holding capacity (WHC), water content in percent at start (WC), and water loss rate per thallus area (WLR) in combination determined the duration of active periods during desiccation between (r²adj = 0.86) and within species (r²adj = 0.60-0.92). Lobaria pulmonaria with the lowest STM and the most upright growth form experienced the shortest active periods, Lobaria amplissima with the highest STM and the most prostrate growth form had the longest periods. Across the more compact species (L. amplissima, L. virens), WLR strongly declined with thallus size, but weakly in the loosely attached L. pulmonaria. ФPSII, a proxy of photosynthesis, exhibited suprasaturation depression at maximal hydration. Fluorescence imaging allowed a rapid, non-invasive evaluation of the contribution of various functional traits to active periods in entire thalli during desiccation. A thick, prostrate growth form prolongs active periods by maximizing water storage, whereas a thin, loosely attached growth form uses a more flexible hydration strategy with shorter active periods.
... Excess hydration often causes depression of photosynthesis in lichens (Lange & Green 1996). A low WHC external may reduce the risk of prolonged suprasaturation in cephalolichens studied, and might explain not only why such lichens were much less damaged than a range of chlorolichens during a prolonged, very wet period (Gauslaa 2002) but also why these cephalolichens often characterize rainforests (Ellis 2016). ...
... Larsson & Gauslaa 2011;MacDonald & Coxson 2013) whereas the other two cephalolichens are more restricted to trunks, with stem flow feeding these prostrate lichens with water. The more oceanic distribution of L. amplissima and L. virens, for example in Britain (Ellis 2016) and Norway (see maps generated in Timdal (2017)), is consistent with a stronger dependency of these species on rain. ...
Article
This study aims to quantify the size-dependency of important hydration traits in Lobaria amplissima, L. pulmonaria and L. virens sampled in sympatric populations on deciduous tree trunks in southern Norway, and to discuss possible implications of species-specific traits for the ecological niches of these old forest cephalolichens. Traits measured were thallus size (area and mass), specific thallus mass (STM), internal (WHC internal ) and external water-holding capacity (WHC external ), and water content (WC) after shaking and after blotting. Lobaria amplissima had the highest WHC internal , 2·6 times higher than L. pulmonaria with the lowest WHC internal . WHC internal , driven by STM, strongly depended on size. WHC external was 28% ( L. virens) to 47% ( L. pulmonaria ) of the WHC internal . Unlike WHC internal , WHC external did not depend on thallus area, meaning that WHC external is proportionally higher for smaller compared with larger thalli. The most widespread species, L. pulmonaria , benefits from a flexible hydration strategy due to low STM, facilitating the use of more diverse water sources than the other two species that depend more on rain, particularly L. amplissima with the highest STM and thus relatively high WHC internal . For L. virens , a combination of less specialized hydration traits and a low tolerance to higher light intensity probably jeopardizes its survival outside rainforest habitats.
... The lichen diversity in southwestern Norway and Scotland shows some similarities. These areas share many species of lichen with temperate rainforest and oceanic distribution patterns (Ellis 2016). For the genus Usnea, all temperate and oceanic species in Britain listed by Ellis (2016) -apart from U. rubicunda -are known from southern Norway (Clerc 1987(Clerc , 2011. ...
... These areas share many species of lichen with temperate rainforest and oceanic distribution patterns (Ellis 2016). For the genus Usnea, all temperate and oceanic species in Britain listed by Ellis (2016) -apart from U. rubicunda -are known from southern Norway (Clerc 1987(Clerc , 2011. Considering the high abundance and dominance of the oceanic species U. flammea, U. fragilescens, and U. cornuta in many coastal deciduous forests in southwestern Norway, it has been surprising that the otherwise widespread U. rubicunda in western Europe (Fos & Clerc 2000, James 2003 was not known in Norway. ...
Article
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The western temperate-tropical fruticose species lichen Usnea rubicunda Stirt. is reported as new to Scandinavia from a locality in Farsund municipality, Vest-Agder, south-west Norway. The fungal barcode marker, nrITS, shows a 99.8–100 % similarity with British specimens, and the known small Norwegian population is assumed to have recently immigrated from Britain, possibly a response to global warming. Details on morphology, habitat, and population characteristics of the Norwegian occurrence are given.
... De Not.). This is primarily a western European species with a preference for temperate rainforest climates (Ellis 2016), but was recently reported (in the form of a new subspecies) from north-west America (Cornejo et al. 2017). Its primary photobiont belongs to the green-algal genus Dictyochloropsis (Dal Grande et al. 2014), presently referred to as Symbiochloris reticulata (Škaloud et al. 2016), while its secondary cyanobacterial photobiont (Nostoc) occurs as invisible smaller internal cephalodia, sometimes with additional fruticose and spectacular external cephalodia (Jordan 1970). ...
... With respect to the wetting capability of dewfall, maximal dewfall rates seem to be <0·04 mm h -1 (Xiao et al. 2013) and a good, average nocturnal dewfall is just 0·2 mm (as reviewed by Gauslaa 2014), which would not be enough for L. amplissima. Therefore, L. amplissima with external cephalodia should have an advantage in a rainy climate with relatively frequent showers of >2 mm rainfall, consistent with their preference for rainforest climates (Ellis 2016). Only under such conditions can they fully benefit from their large WHC internal , allowing long active periods after rain has ended. ...
Article
Hydration traits determine much of a lichen’s distribution pattern along a climatic gradient but the mechanisms involved are still incompletely known. A higher abundance of large external cephalodia in wet oceanic than in drier climates has previously been reported in Lobaria amplissima . This study aims to quantify how much more rain L. amplissima thalli with external cephalodia would need to fill their internal water holding capacity (WHC internal ) than thalli without. The mean WHC internal was 1·8 times higher in thalli with external cephalodia than in those without. The WHC internal when converted to mm rain needed to saturate an average specimen was 1·37 mm (min–max: 0·55–3·8 mm) for a cephalodiate thallus, whereas an average thallus without external cephalodia needed just 0·76 mm (min–max: 0·36–1·3 mm). Known dewfall rates and rates of water uptake from humid air are far below what is needed to saturate even the cephalodiate thallus with the lowest WHC internal , implying a stronger dependency on rain for thalli with external cephalodia. Thus, the observed trends in this study are consistent with earlier reports of decreasing frequency of external cephalodia from wet to drier climates.
... Isles (Mercer, 2009). Like many other UK upland sites, it was once dominated by the 'Atlantic' oak woodlands unique to the NW European coastal fringe and part of the 'temperate rainforest bioclimatic zone' (Ellis, 2016), characterized by a distinct and internationally significant assemblage of epiphytic lichens and understory bryophytes (Ratcliffe, 1968 (Sansom, 1999), numbers have now stabilized (Silcock et al., 2012). Furthermore, uncertainty over the configuration of post-Brexit farm subsidy such as UK Environmental Land Management Schemes (Defra, 2020) petraea L. individuals due to widespread hybridization (Petit et al., 2003) and the difficulty of distinguishing young trees (Boratynski et al., 2008). ...
Article
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Abstract Woodland expansion is widely advocated for the mitigation of climate change and its impacts. This is supported by ambitious targets for increasing tree cover in the United Kingdom and elsewhere to aid carbon storage, flood mitigation and biodiversity provision. However, it remains unclear whether natural tree establishment can supply demand for expanded treescapes in remote, anthropogenically modified upland landscapes. We assessed natural establishment of NW‐European native oak (Quercus robur, Q. petraea) saplings (
... Climate change is expected to result in a set of nonanalogue climatic conditions with no counterpart in the present-day [112,113], bringing into question model projection (extrapolation) from the baseline climate (used to develop and test species bioclimatic response) to climate change scenarios. Significantly, this nonanalogue situation appears to apply to ecosystems that have globally important lichen diversity, such as European temperate rainforest [114,115]. ...
Article
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This paper provides an overview of bioclimatic models applied to lichen species, supporting their potential use in this context as indicators of climate change risk. First, it provides a brief summary of climate change risk, pointing to the relevance of lichens as a topic area. Second, it reviews the past use of lichen bioclimatic models, applied for a range of purposes with respect to baseline climate, and the application of data sources, statistical methods, model extents and resolution and choice of predictor variables. Third, it explores additional challenges to the use of lichen bioclimatic models, including: 1. The assumption of climatically controlled lichen distributions, 2. The projection to climate change scenarios, and 3. The issue of nonanalogue climates and model transferability. Fourth, the paper provides a reminder that bioclimatic models estimate change in the extent or range of a species suitable climate space, and that an outcome will be determined by vulnerability responses, including potential for migration, adaptation, and acclimation, within the context of landscape habitat quality. The degree of exposure to climate change, estimated using bioclimatic models, can help to inform an understanding of whether vulnerability responses are sufficient for species resilience. Fifth, the paper draws conclusions based on its overview, highlighting the relevance of bioclimatic models to conservation, support received from observational data, and pointing the way towards mechanistic approaches that align with field-scale climate change experiments.
... For example, while OTF climate space is extensive in the southwestern fringe of Europe, these European oceanic forests generally have a simple structure, have fewer and largely deciduous tree species, lianas are not prominent, and palms and tree ferns are lacking. In the British Isles 'oceanic temperate rainforest' or 'oceanic woodland' dominated by pine, birch and oak is recognised as a type, although less extensive than our broader concept as it takes > 1400 mm annual rainfall as a criterion (Ellis 2016). Likewise, the northwestern coastal belt of North America has its 'coastal temperate rainforest' (Alaback 1996) which climatically falls within the OTF but, with its heavy conifer dominance and deciduous subordinate angiosperm trees, lacks any close resemblance to New Zealand forests. ...
... As poikilohydric organisms, lichens show a high selectivity for certain hydration sources and can influence ecosystem functioning by their substantial harvest of non-rainfall water (Stanton et al., 2014a;Stanton et al., 2014b;Pypker et al., 2017;Wang et al., 2017). Functional hydration traits in lichens exhibit notable variations across macro- (Ellis and Coppins, 2006) and microclimatic gradients (Merinero et al., 2014), and lichens' dependency on certain climates widely vary among species (Ellis, 2016). A diversity in morphological, anatomical and physiological lichen traits, in part reflects adaptations to exploit niche-specific water sources such as rain (Larson, 1981), dew (Kappen et al., 1980;Lakatos et al., 2012) and humid air (Lange and Tenhunen, 1982;Lange et al., 1986). ...
... However, L. virens is often restricted to more sheltered positions on the trunk closer to the ground [2]. Also in Britain, L. virens is strongly associated with a high level of oceanity (Amman's index of hydrothermy), whereas L. pulmonaria is not [7]. Worldwide, L. virens is only known in Western Europe and Macaronesia. ...
Article
Lichens are considered freezing tolerant, although few species have been tested. Growth, a robust measure of fitness integrating processes in all partners of a lichen thallus, has not yet been used as a viability measure after freezing. We compared relative growth rates (RGR) after freezing with short-term viability measures of photo- and mycobiont functions in the coastal Lobaria virens and the widespread L. pulmonaria to test the hypothesis that low temperature shapes the coastal distribution of L. virens. Hydrated thalli from sympatric populations were subjected to freezing at -10, -20 and -40 °C for 5 h. The rate of cooling and subsequent warming was 5 °C h-1. Short-term viability measures of photobiont (maximal photosystem II efficiency, effective PSII yield) and mycobiont viability (conductivity index), as well as subsequent RGR, were assessed. The exotherms showed that L. virens froze at -3 °C; L. pulmonaria, at -4 °C. Freezing significantly impaired short-term viability measures of both photo- and mycobiont, particularly in the coastal species. Lobaria pulmonaria grew 2.1 times faster than L. virens, but the short-term damage after one freezing event did not affect the long-term RGR in any species. Thereby, short-term responses were impaired by freezing, long-term responses were not. While the lacking RGR-responses to freezing suggest that freezing tolerance does not shape the coastal distribution of L. virens, the significant reported adverse short-term effects in L. virens may be aggravated by repeated freezing-thawing cycles in cold winters. In such a perspective, repeated freezing may eventually lead to reduced long-term fitness in L. virens.
... Associated biodiversity may have global trends that do not conform to standard latitudinal models for animals or vascular plants, e.g. mid-latitudinal peak diversity for ectomycorrhizal fungi (Tedersoo and Nara 2010;Tedersoo et al. 2012), or examples of unique assemblages in highly disjunct mid-latitudinal ecosystems such as for lichen epiphytes in oceanic temperate rainforest (DellaSala 2011;Ellis 2016). ...
Article
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Directly observed biodiversity data have a limited temporal span of c. 100–150 years. Consequently, for a region such as temperate Western Europe, our knowledge of species distributions is restricted to a period impacted by the process of massive industrialisation. There is a danger of shifted baselines in terms of conservation policy and targets. Here we present a novel source of high resolution archaeobotanical information for lichen epiphyte bioindicators; these data can reconstruct species distributions for the pre-industrial European landscape. We compare these historic records to a species’ post-industrial distribution and environmental response, quantifying the spatial trend and causes of biodiversity loss. The results indicate regional extinction rates of c. 76% in response to habitat loss and industrial pollution. We propose pre-industrial baselines that would better represent biodiversity restoration for temperate regions (net gain), and which would be equitable with advocacy for species and habitat protection in the present-day tropics (no net loss).
... We selected 14 epiphytic lichen species that were easily located and identified under field conditions, which had contrasting physiologies and dispersal modes (Table 1), and which are expected to be indicators of old-growth woodland (zecological continuity) for Scotland's western zone of oceanic climate (Ellis, 2016). Thus, the species are used as indicators within either: (i) the Revised ...
Article
European landscape conservation includes the recognition of inter-related ‘ancient’ and ‘old-growth’ woodland. Ancient woodland is defined by its temporal continuity, which can be measured through its consistent occurrence on historic maps over a period of time, typically several centuries. Old-growth woodland has attributes of both temporal continuity and structural complexity; European old-growth woodland is now extremely rare and a valuable conservation resource. Indicator species provide recognition of old-growth woodland, through traits that are sensitive to its defining features: (i) dispersal limitation demanding temporal continuity of suitable habitat prior to colonisation (as is associated with ancient woodland), and/or (ii) specialist niches associated with old and senescent trees (which may or may not be found in ancient woodland, depending on its past management). To test the response of indicators to each of these features, niche models were developed for lichen epiphytes in an ancient and structurally diverse woodland stand, thus corresponding to ‘old-growth’ condition. Models were projected for the ancient and an adjacent regenerated stand. There was less suitable habitat in the regenerated stand, and a lower proportion of suitable habitat was occupied. Nevertheless, indicators had colonised from the ancient to the regenerated stand within 50 years. Viewed against the background of previous work, we conclude that landscape context - the spatial relationship between ancient and regenerated woodland - is critical to the interpretation of indicators, which are perhaps better conceptualised as markers of threat and conservation value than independent measures of woodland history.
... Here, we studied the reintroduction potential for two lichens in the genus Lobaria s. lat.: Lobaria amplissima (¼ Ricasolia amplissima) and Lobaria pulmonaria. Lobaria amplissima is primarily a western European species associated with temperate oceanic and suboceanic climate (Ellis, 2016), but was recently recorded (as a new subspecies) from northwest America (Cornejo et al., 2017). By contrast, L. pulmonaria is considered a globally widespread forest lichen. ...
Article
We studied the potential to use reintroduction of two declining N-fixing flagship lichens to identify factors affecting failure or success in SW Swedish sites that had experienced substantially reduced acidification. After transplanting the critically endangered Lobaria amplissima ± external cephalodia and its near-threatened associate Lobaria pulmonaria onto tree trunks, seasonal growth rates were quantified. We added a phosphorus treatment, using site as a random factor. Growth was positive in winter, and negative in summer, particularly in L. amplissima. Reintroduction of L. amplissima was unsuccessful because gastropods caused significant loss, evidenced by grazing marks. Acer platanoides, a high-pH host, had more grazing than the more acidic Quercus petraea. Gastropods preferred the cephalodia, resulting in substantial loss of the cephalodiate L. amplissima. Phosphorus fertilization had no effects. The widespread L. pulmonaria grew faster than the rare L. amplissima that lost its local growth potential due to aggravated gastropod grazing.
... The absence of shade-tolerant species in many woodlands, the wide ecological amplitude of native trees in Britain, and the humid oceanic climate of western Britain has led to the development of associated communities that are both unique to Britain and of high conservation value globally. These comprise species-rich assemblages of ferns, mosses and liverworts, and include both the richest communities of oceanic bryophytes in Europe (Averis et al., 2012) and a correspondingly diverse oceanic lichen flora (Ellis, 2016). British woods are also globally important for vernal herbaceous plants, some of which benefit from the lack of shade tolerant trees. ...
Article
Both plantation forests and native woodlands are currently facing challenges in the form of rapid climatic change and unprecedented increases in damage by exotic pests and diseases. To combat these problems it has been proposed that a range of novel exotic tree species (non-native species that have not yet undergone thorough operational testing or previously been grown at a forestry scale) should be grown as part of an adaptive management strategy, and that non-native (including novel) species should be introduced into native woodland. Justifications for this policy are that novel exotic species are required to maintain forest productivity under climate change, to create a more diverse, and by implication more resilient forest, and to substitute for native species threatened by introduced pests and pathogens. Here we examine these arguments in the context of British forestry, where there is a long history of utilising non-native species. On the basis of this documented experience we conclude that in the commercial sector of British forestry, where production is the main objective, there are strong arguments for undertaking a programme of rigorous testing and domestication of a very limited number of the most promising novel exotics which, in addition to good timber and growth, also have attributes that will allow the development of more naturalistic silvicultural systems and a move away from current clear-fell regimes. However this must be undertaken within a comprehensive risk assessment framework, where candidate species are rigorously screened both for any biosecurity threats, and their potential for causing ecological damage if they become invasive outside their initial planting sites. Widespread planting of candidate species should only be recommended after the completion of full species and provenance trials, and when reliable sources of appropriately adapted seed have been established. Conversely where conservation of biodiversity is an objective we find no support for introduction of any non-native species. This is based on the greater ecological and economic risk they pose compared to the use of native species. Use of non-natives is likely to lead to an increase rather than a decrease in pest and disease problems, and to hinder rather than support the retention of threatened native tree species and their associated biodiversity.
... During rainy periods, there is a higher chance for suprasaturation in the two chlorolichens that have much more external water than the cephalolichen (Table 1). This may explain why Lobaria pulmonaria, unlike the two widespread chlorolichens, is associated with rainforest climate (Ellis 2016) where less suprasaturation depression of CO 2 uptake would be a competitive advantage. ...
Article
Nine populations of Lobaria pulmonaria were sampled in forests along a natural light-shade gradient. The two most sun-exposed populations were darkly melanic, the two from the most shaded sites were unpigmented, and the remaining five were intermediately pigmented. Susceptibility was measured as depressions in photosystem II quantum yield after (1:) a continuous exposure of air-dry thalli to 24 hrs of either 1200 ♂mol photons m-2 s-1 at ambient temperatures or 48 °C in darkness respectively, followed by (2:) a 48 hrs recovery in the hydrated state at low light and 16 °C. Populations were significantly different (ANOVA), the 2 melanic populations were the most light- and heat-resistant, the 2 pale populations were the most susceptible. However, the difference in susceptibility was not large, considering the huge difference in irradiance of their contrasting habitats. Also darkly melanic specimens can be considered highly susceptible to both heat and strong light, as only 24 hrs of each factor reduced F/FM considerably. The severe photoinhibition suggests that logging-induced rises in light can affect remaining specimens either lethally shortly after logging, or chronically by reduced photosynthesis causing small investments in growth and reproduction. The higher water holding capacities found in populations from more light-exposed habitats were considered to be insufficient to fully compensate for the higher evaporative demands of such habitats.
... Thus far, we have some understanding of how lichen traits vary in relation to elevational (Nascimbene & Marini, 2015;Roos et al., 2019) and fog gradients (Stanton, 2015), macroclimate (Ellis & Coppins, 2006;Marini et al., 2011;Nascimbene & Marini, 2015), forest structure (Marini et al., 2011) and environmental disturbances such as fire (Nelson, McCune, Roland, et al., 2015). Lichen functional traits are also informative environmental and bioclimatic indicators (Ellis, 2016;Giordani et al., 2012;Koch et al., 2013;Nelson, McCune, & Swanson, 2015). ...
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Aim Functional traits offer a window into how organisms are adapted, and might acclimate, to environmental pressures. Despite being important in ecosystem function, lichens are underrepresented in trait-based research; understanding how lichen functional traits vary with climate and habitat availability will be useful in predicting how communities will respond to climate change, for example, in wetter and warmer boreal and arctic ecosystems. Here, we assess the influence of macroclimate and forest availability on the spatial distribution of lichen traits across Norway. Location Norwegian mainland. Taxon Lichens. Methods We used relative trait frequency (RTF) data from LIAS gtm, a database combining trait information from LIAS (A Global Information System for Lichenized and Non-Lichenized Ascomycetes) and GBIF (Global Biodiversity Information Facility) species observations. The 20 traits included photobiont types, growth forms, cortical features and reproductive modes. Nonparametric multiplicative regression (NPMR) models were used to explore the relationships between the environmental predictors of precipitation, temperature and forest availability. Results All traits showed significant relationships with the three environmental predictors. Photobiont type and reproductive mode traits produced the strongest models and revealed ecologically meaningful biogeographical patterns. Trebouxioid species peaked in colder, drier upland regions, while trentepohlioid lichens displayed an affinity for wetter and warmer climates and had a western and southern distribution. Cyanolichens increased with increasing precipitation and were strongly coastal. Sorediate and isidiate lichens were positively related to temperature, the former also increasing with forest cover. The above responses were consistent with the physiological and habitat requirements of the associated lichens. The remaining traits had weaker responses. Main conclusions Discrete traits (i.e. photobiont type and reproductive mode) with relatively low ecological plasticity reflect clear functional environmental responses at the large scale. By contrast, growth form and thallus structural features—proxies for continuous variables—are too variable within each given category to show observable distribution patterns.
... Temperate Oceanic Connections-Lichens restricted to oceanic areas of the northern hemisphere have been the subject of considerable study, particularly in Europe (Suza 1934;Degelius 1935Degelius , 1959Golubkova 1994;Jørgensen 1996;Goward and Ahti 1997;Bjelland 2001;Ellis 2016). Nonetheless, the presence of a sizable element of such oceanic species disjunct in the southern Appalachian Mountains, especially in the Smokies, has been underappreciated. ...
Article
000 new field collections generated, the park checklist now includes 920 species, a 129% increase over estimates made two decades ago. Nearly a quarter of the lichens reported in the park are known from only a single occurence whereas only 7% of the lichens are known from 20 or more occurences. An assessment of commonness/rarity for all 920 species indicates that nearly half of the park's lichens should be considered to be infrequent, rare, or exceptionally rare. We assessed the distributions of all 920 species and found that 54 are endemic to the southeastern United States, 30 are endemic to the southern Appalachians, and eight occur nowhere else than within the confines of the national park. We discuss biogeographical affinities of the park's lichen biota as a whole, delimiting six regional "floristic" connections. Our 11 years of research have resulted in the discovery of several species presumed to be extinct or near-extinct. We make one new combination (Fuscopannaria frullaniae) and describe five species as new to science, each commemorating National Park Service staff instrumental to the completion of the study: Heterodermia langdoniana, Lecanora darlingiae, Lecanora sachsiana, Leprocaulon nicholsiae, and Pertusaria superiana.
... Nevertheless, E. pedicellatum was surpassed by Pectenia plumbea (Fig. 8) with its average of a 2.1 mm thick hypothallus of rhizohyphae (> 10 times thicker than the thallus itself consisting of cortex, photobiont, and medulla layers), which acted as a sponge and shaped WHC total (Gauslaa and Solhaug, 1998). Pectenia plumbea is rare in North America, but more widespread in wet, coastal parts of Europe; much of its European distribution is within oceanic parts of the temperate region where it is classified as a rainforest species (Ellis, 2016), extending to subtropical Macaronesia and wetter parts of the Mediterranean region (Jørgensen and James, 1990). Large P. plumbea thalli may require as much as > 3 mm rain to fill their WHC total (Fig. 9), inferring that as many as approximately 40 rainy days (< 50 % of the rainy days in summer; Fig. 7) may not be able to fill the WHC total of such thalli. ...
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Erioderma pedicellatum, an enigmatic boreal cyanolichen epiphyte is sympatric with the widespread pantropical cyanolichen Coccocarpia palmicola in cool and damp forests in Atlantic parts of Canada. After sampling co-occurring specimens of these lichens in Newfoundland, we quantified important hydration traits. We hypothesized that 1: these lichens restricted to wet forests have higher internal water holding capacity (WHCinternal) than what humid air and dewfall can provide, and 2: the rare E. pedicellatum has higher WHCinternal and / or WHCtotal than the widespread C. palmicola. Both hypotheses were supported: Mean WHCinternal across a wide thallus size range was 0.26 and 0.35 mm H2O in C. palmicola and E. pedicellatum, respectively; corresponding mean WHCtotal were 0.73 and 0.86 mm. These high WHC-levels could only be filled by liquid hydration sources. Because WHC strongly increased with thallus size, larger specimens needed even more water (1.7 mm), emphasizing these species’ dependency on rain and thus wet forests.
... Bermuda tested a new rapid assessment tool which has the potential to accelerate assessments across the UKOTs (Bachman, Walker, Bárrios, Copeland, & Moat, 2020). There is one approved Red List for non-lichenized fungi in Britain (Ainsworth et al., 2013) (James, Hawksworth, & Rose, 1977) and the UK has international responsibility for the conservation of 30 of these species (Ellis, 2016;Woods & Coppins, 2012). These communities are now highly fragmented due to habitat loss through land-use inten- Among more widespread threats like climate change and pollution, ash dieback presents a new serious threat for epiphytic lichens. ...
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This review summarizes current knowledge of the status and threats to the plants and fungi of Great Britain and the UK Overseas Territories (UKOTs). Although the body of knowledge is considerable, the distribution of information varies substantially, and we highlight knowledge gaps. The UK vascular flora is the most well studied and we have a relatively clear picture of its 9,001 native and alien taxa. We have seedbanked 72% of the native and archaeophyte angiosperm taxa and 78% of threatened taxa. Knowledge of the UKOTs flora varies across territories and we report a UKOTs flora comprising 4,093 native and alien taxa. We have conserved 56% of the native flora and 51% of the threatened vascular plants in Kew's Millennium Seed Bank, UK. We need a better understanding of the conservation status of plants in the wild, and progress toward completion or updating national red lists varies. Site‐based protection of key plant assemblages is outlined, and progress in identifying Important Plant Areas analyzed. Knowledge of the non‐vascular flora, especially seaweeds remains patchy, particularly in many UKOTs. The biggest gaps overall are in fungi, particularly non‐lichenized fungi. Considerable investment is needed to fill these knowledge gaps and instigate effective conservation strategies.
... During rainy periods, there is a higher chance for suprasaturation in the two chlorolichens that have much more external water than the cephalolichen (Table 1). This may explain why Lobaria pulmonaria, unlike the two widespread chlorolichens, is associated with rainforest climate (Ellis 2016) where less suprasaturation depression of CO 2 uptake would be a competitive advantage. ...
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Main conclusion During desiccation, both apparent electron transport rate (ETRapp) and photosynthetic CO2 uptake peak when external water has evaporated. External water, causing suprasaturation, weakens the strong correlation between ETRapp and CO2 uptake. Abstract Lichens are poikilohydric organisms passively regulated by ambient conditions. In theory, apparent electron transport rate (ETRapp), estimated by photosystem II yield measured in light (ΦPSII), is a proxy of photosynthetic CO2 uptake. Hydration level, however, is a complicating factor, particularly during suprasaturation that strongly reduces CO2 diffusion. Here, the cephalolichen Lobaria pulmonaria and two chlorolichens Parmelia sulcata and Xanthoria aureola were excessively hydrated before photosynthetic CO2 uptake and ΦPSII using imaging fluorescence tools were simultaneously measured while drying at 200 µmol photons m⁻² s⁻¹. CO2 uptake peaked when hydration had declined to a level equivalent to their respective internal water holding capacity (WHCinternal) i.e., the water per thallus area after blotting external water. CO2 uptake and ETRapp in all species were highly correlated at hydration levels below WHCinternal, but weaker at higher hydration (chlorolichens) or absent (cephalolichen). Yet, at a specimen level for the two chlorolichens, the correlation was strong during suprasaturation. The CO2 uptake—ETRapp relationship did not differ between measured species, but may vary between other lichens because the slope depends on cortical transmittance and fraction of electrons not used for CO2 uptake. For new lichen species, calibration of ETRapp against CO2 uptake is therefore necessary. At intrathalline scales, ΦPSII during drying initially increased along thallus margins before reaching maximum values in central portions when hydration approached WHCinternal. WHCinternal represents the optimal hydration level for lichen photosynthesis. In conclusion, ETRapp is an easily measured and reliable proxy of CO2 uptake in thalli without external water but overestimates photosynthesis during suprasaturation.
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This chapter updates and replaces the previous Woodland SSSI Selection Guidelines chapter (Nature Conservancy Council 1989). It was prepared by Suzanne Perry and Emma Goldberg (Natural England), Jim Latham (Natural Resources Wales) and Jeanette Hall and Kate Holl (Scottish Natural Heritage) and provides detailed guidance for use in selecting woodlands, wood pasture and parkland and veteran tree sites throughout Great Britain to recommend for notification as Sites of Special Scientific Interest. It should be used in conjunction with Part 1 of the SSSI Selection Guidelines published in 2013 (Bainbridge et al 2013, http://jncc.defra.gov.uk/PDF/SSSI_Guidelines_Pt1_Dec2013(2).pdf), which details the overarching rationale, operational approach and criteria for selection of SSSIs. The revised chapter has been subjected to appropriate levels of evidence quality assurance. It is compliant with the JNCC Evidence Quality Assurance Policy 2014, and has been subjected to external peer review by Keith Kirby.
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For over 40 years there has been conflict between hill-farmers and conservationists over the way that the Commons of Dartmoor have been farmed and the impacts that this has had on the moor’s habitats, wildlife, peat and archaeology. This thesis looks at the attitudes of the various stakeholder groups involved via the use of semi-structured interviews. It uses Narrative Policy Analysis and the Narrative Policy Framework to construct and analyse a series of stakeholder narratives in an attempt to understand why the issues are so contested and the search for consensus has been so elusive. It shows how the dominant policy narrative has evolved over time and how this has been impacted by a series of competing counter narratives, in particular those focusing on grazing intensity and vegetation burning techniques. It details how restrictions to farming methods have impacted on traditional hill-farming practices and have led to a series of unintended consequences. As a result, further counter narratives have emerged, which either seek consensus between all the stakeholders or promote specific interests in an attempt to favour the wildlife, the archaeology, the hydrology or a re-wilded landscape. It shows that the issues on Dartmoor are complex and nuanced and it is suggested that historically some of the leading narratives have been too narrow in their focus and as a result may have missed other important causal factors such as atmospheric pollution and climate change. Hill-farming and as a result the traditional practices which have created the moorland landscapes for which Dartmoor is famous, are under considerable pressure as a result of changes to subsidy payments as a result of the UK’s decision to leave the EU, the economic prospects for hill-farming generally and climate change. This narrative approach to the environmental and hill-farming conflicts on Dartmoor has identified areas which should be addressed so the moor’s special character can be conserved and enhanced as a pastoral landscape, at least in part, into the future.
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Systematic data collection for direct statistical analysis of biodiversity trends tends to be focused on charismatic fauna and flora such as birds or vascular plants. When subsequently applied by conservation agencies in summary metrics tracking habitat and species protection, these patterns in biodiversity loss or gain can fail to capture outcomes for groups that have a prominent importance in habitat composition, diversity and ecological function, such as algae, bryophytes, lichens and other fungi. Such species are primarily recorded on an ad hoc basis by taxonomic specialists, yielding noisy data that present problems in robustly identifying trends. This study explored the use of ad hoc field-recorded data as a potential source of biodiversity information, by comparing the pattern of recording for carefully selected indicator species with those for benchmark or control species as a proxy for recording effort. Focusing on Scotland’s internationally important epiphytic lichens, and especially ‘old-growth’ indicator species, British Lichen Society data revealed a decline in the extent of these species in Scotland, relative to recording effort, over a period of five decades. A recent slowing in the rate of decline is observed but remains to be confirmed. The long-term decline is consistent with the effect of land use intensification, resulting in small and isolated populations that are vulnerable to extinction debt. We caution that remedial protection and monitoring for such populations remains vital as a complement to Scotland’s larger scale ambition for increased woodland extent and connectivity.
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Modelling strategies for predicting the potential impacts of climate change on the natural distribution of species have often focused on the characterization of a species’ bioclimate envelope. A number of recent critiques have questioned the validity of this approach by pointing to the many factors other than climate that play an important part in determining species distributions and the dynamics of distribution changes. Such factors include biotic interactions, evolutionary change and dispersal ability. This paper reviews and evaluates criticisms of bioclimate envelope models and discusses the implications of these criticisms for the different modelling strategies employed. It is proposed that, although the complexity of the natural system presents fundamental limits to predictive modelling, the bioclimate envelope approach can provide a useful first approximation as to the potentially dramatic impact of climate change on biodiversity. However, it is stressed that the spatial scale at which these models are applied is of fundamental importance, and that model results should not be interpreted without due consideration of the limitations involved. A hierarchical modelling framework is proposed through which some of these limitations can be addressed within a broader, scale-dependent context.
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I analyze some criticisms made about the application of alpha-inflation correction procedures to repeated-test tables in ecological studies. Common pitfalls during application, the statistical properties of many ecological datasets, and the strong control of the tablewise error rate made by the widely used sequential Bonferroni procedures, seem to be responsible for some 'illogical' results when such corrections are applied. Sharpened Bonferroni-type procedures may alleviate the decrease in power associated to standard methods as the number of tests increases. More powerful methods, based on controlling the false discovery rate (FDR), deserve a more frequent use in ecological studies, especially in those involving large repeated-test tables in which several or many individual null hypotheses have been rejected, and the most significant p-value is relatively large. I conclude that some reasonable control of alpha inflation is required of authors as a safeguard against striking, but spurious findings, wh
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The United States Environmental Protection Agency's Community Multiscale Air Quality (CMAQ) regional-scale model is used to study concentrations and dry deposition of nitrogen species in North Carolina (NC) during the summer season. Each modelled and measured species featured a similar diurnal trend. A process budget analysis (production and removal evaluation) of NO, NO 2 , and NO Y depicted the model's capability to evaluate various process contributions. Dry deposition of NH 3 contributed 34.2 &PlusMinus; 57.9 µg N m -2 hr -1 ; whereas HNO 3 contributed slightly larger dry deposition of nitrogen, 35.2 &PlusMinus; 16.0 µg N m -2 hr -1 , in NC. NH 4 + and NO 3 - hourly-averaged wet deposition fluxes were calculated as 37.3 &PlusMinus; 19.7 µg N -2 hr -1 and 40.6 &PlusMinus; 11.8 µg N m -2 hr -1 , respectively. Examination of total nitrogen deposition during the summer season in NC found that NH 3 contributes approximately 50% of the dry deposition and NO 3 - contributes approximately 50% of the wet deposition.
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This review positions the biodiversity response to climate change within a social-sciences risk-based framework, integrating the parameters of hazard, exposure, and vulnerability. It uses lichen epiphytes as a case study. In treating human-induced climate change as a hazard, the exposure of lichen epiphytes is considered as their sensitivity to spatial climatic variation, while also seeking congruence between bioclimatic models and observational data supporting distributional change. Improved understanding of exposure could be generated through functional response models, and climate sensitivity should be carefully interpreted against co-occurring hazards (pollution, habitat degradation). Where negative impacts result from exposure to climate change, species vulnerability may be reduced through adaptive forest management. This opportunity is based on a cross-scale interaction between microhabitat specificity and macroclimatic setting. Certain stand types (e. g., old-growth stands) offer greater opportunity for establishment and growth in suboptimal climates, because high microhabitat heterogeneity generates a broader spectrum of microclimatic niches, which buffer an unsuitable macroclimate. Lichen epiphyte vulnerability will nevertheless be dependent on an amalgam of ecological processes considered at the stand scale, including trophic interactions, acclimation, and evolutionary adaptation, and at the landscape scale, including gene flow and dispersal limitation. A trait-focused approach could provide an opportunity to generalize these processes.
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In this paper evidence from those British hepatics with discontinuous distribution outside the British Isles is assessed in relation to the history of the British flora. The difficulties of interpreting distribution data for bryophytes are discussed. British hepatics showing disjunction in their world distribution are classified in six groups: (1) The Mediterranean Element, centered on the Mediterranean region. (2) The Disjunct-Temperate Element, found in temperate Asia, western Europe and North America. (3) The American Element, found in western Europe and North America. (4) The Boreal-Tropical Element, found in scattered stations in the north temperate regions and in some part of the Tropics. (5) The Macaronesian-Tropical Element, found in western Europe, Macaronesia (Azores, Madeira and Canary Islands) and commonly also in some part of the Tropics. (6) Other Disjunct Species. The composition of these elements is given in detail. It is shown that within the British Isles the Mediterranean Element is centered in the south of Britain. The remaining elements have markedly western distributions in Britain and Ireland. The possibility of bias in the known distributions, due to unequal collecting, is considered. Such bias is unlikely to be important except within Ireland. The pattern of distribution of these western species, taken together, accords well with areas having a high value of Amann's index of hygrothermy. Examples are quoted of non-British species of hepatics and of British species of other groups of plants which have similar world distribution patterns. It is concluded that the hepatics considered do not form a homogeneous group. From our present knowledge their distribution patterns all appear to be explicable in terms of post-Glacial climatic change without invoking in situ survival through glaciation.
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Characterising future risk to biodiversity across multiple drivers is fraught with uncertainty.•Scenario planning can help identify robust conservation decisions.•A scenarios approach was demonstrated for climate change and tree disease.•Impacts were spatially and temporally variable, highlighting the need for local planning.•Increasing tree diversity can support resilience of dependent organisms, e.g. epiphytes.
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The main types of ombrotrophic mire vegetation in Scotland are described with reference to selected mire sites of national importance. The range of variation is controlled by two main environmental gradients, climate and altitude. In particular the degree of oceanicity is crucial, influencing both the vegetation and the hydro-morphology of individual mires. The framework described provided the basis for selection of 31 nationally important mire sites in Scotland identified in the Nature Conservation Review in 1977. Protection of these sites has been successful, except for two sites now afforested. Current threats to Scottish peatlands mainly relate to lowland raised mires.
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The construction of a global system of eco-climatic regions is a worthwhile aim in spite of the considerable reservations that must be expressed concerning climatic classifications in general. It would appear possible to find closely corresponding biogeographical boundaries and regions by means of climatic parameters and indices at least within floristically relatively homogeneous areas of different continents. Such an eco-climatic system would not only be of value as an important frame of reference for primary research, but also have applications in agricultural and forestry research. -from Author
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Atlantic oakwoods are the oceanic oak-dominated woodlands that fringe the western coast of Britain and Ireland and, due to their high humidity and rich and luxuriant lower plant assemblages, have been regarded as ‘temperate rainforest’. However, unlike the similarly iconic Caledonian pinewoods, Atlantic oakwoods have no formal designation or associated woodland classification type, which gives some uncertainty to the extent of the oakwoods habitat on its fringes. This paper examines the various elements central to the concept of an ‘Atlantic oakwood’ and discuses their occurrence in Great Britain.
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The oceanic bryophyte element of the vegetation of British and Irish Atlantic oakwoods is not only the richest bryophyte flora in Europe, it is also one of the richest bryophyte floras in the world. The oceanic climate and the buffering provided by the tree canopy are critical in maintaining the constant humidity and equable temperatures which provide the basis for this diversity. Though the initial impression of these woodlands is of a homogeneous green carpet over both rocks and trees, most good woodlands will have over 200 different species of moss and liverwort, many of which are very specific as regards micro-habitat. Within the woodlands, a recently glaciated landscape gives much exposed rock of different aspect, texture and chemistry, and also turbulent burns in deep ravines which enhance the humidity. These niches are exploited by different bryophyte communities which may contain a number of species that are very rare in European terms and for which we have a special responsibility. Any management plans for these woodlands should take account of this variety of micro-habitat, and monitoring of the effects on bryophyte populations of any resulting change in the structure of ground vegetation is vital.
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The Northern Hepatic Mat is a community of liverworts which have an Atlantic distribution in Europe. Eleven of these are Northern Atlantic species, confined to the north and west of Britain and Ireland and rare elsewhere in the world. The number of these liverworts recorded in 10 km squares in Scotland can be predicted from the combined effects of rainfall, temperature, humidity and topography, which account for 43% of the variance. Several 10 km squares in Scotland which are apparently suitable for many of the 11 species have fewer records than the model predicts. It is likely that some of these are under-recorded and would be worth further bryological exploration.
Article
Aim To quantify the interaction between climate and woodland continuity in determining the bioclimatic response of lichen epiphytes. Location Northern Britain (Scotland). Methods Indicator-species analysis was used to pre-select lichen epiphytes along parallel gradients in climate and the extent of old-growth woodland. Nonparametric multiplicative regression was used to describe in a predictive model the individualistic response of selected species, which were projected based on climate-change scenarios and contrasting patterns of simulated woodland loss or gain. Species with a similar response were grouped using a novel application of cluster analysis to summarize the potentially huge number of projected outcomes. Projected patterns of occurrence under climate-change scenarios were examined for different levels of old-growth woodland extent. Results Forty-two lichen species were statistically significant indicator species in oceanic woodlands, and old-growth indicators under suboptimal climatic conditions. Responses to climate-change scenarios were contrasting, with one group comprising species projected to increase in extent in response to climate warming, and other response groups projected to decrease in occurrence, possibly in response to shifting rainfall patterns. The occurrence of all response groups had a positive relationship with old-growth woodland extent. Main conclusions An ‘oceanic’ biogeographical group of epiphytes identified using the baseline climatic and present-day woodland setting comprised species with a cyanobacterial photobiont or tropical phytogeographical affinities. However, within this group the individual species responses to climate-change scenarios were contrasting. Additionally, group responses may be poorly matched with simple ecological traits. However, the studied interaction between climate and habitat continuity suggests that the impact of climate change might be offset for certain lichen epiphytes by appropriate management of woodland resources, for example, expansion of native woodland around remnant old-growth stands.
Article
ROSE, F., 1988. Phytogeographical and ecological aspects of Lobarion communities in Europe. The Lobarion communities in Europe are reviewed on the basis of field surveys by the author from south-west Norway to the Pyrenees, Tuscany and Austria. Lobarion communities are still widespread in most montane forests, but in the lowlands are now largely restricted to the Atlantic coastal zone, evidently through forest management practices and air pollution. Evidence for the decline is discussed and causes are reviewed. The major species occurring in these communities in different regions of Europe are tabulated and this reveals interesting geographical patterns. The alliance is appropriately divided into three associations, one being newly proposed here for southern European communities with species drawn from the Xanthorion.
Article
Aim  To quantify the role of multiple biodiversity drivers – pollution, woodland structure and climate – controlling lichen epiphyte composition and diversity.Location Scotland, north-west Europe.Methods  Four compatible datasets were assembled: site-scale species distribution data (response) and base-line modelled data on climate, pollution loads and extent of old-growth woodland (explanatory variables). First, partial-canonical correspondence analysis was used: (1) to compare the importance of environmental variables to pure spatial effects and (2) to partition the importance of environmental variables in explaining species composition. Secondly, patterns of species richness were investigated using multiple least-squares regression.Results  Old-growth woodland was the most important control of species richness. Pollution was the most important explanatory variable for species composition. The impact of pollution on composition (and to a lesser extent on richness) is explained: (1) By recovery of lichens with declining SO2 pollution, although with epiphyte composition shifted by the recent effects of N-pollution and (2) By the limited spatial extent of severe pollution, and generally low-to-moderate pollution loads across our study area, combined with the positive effect of old-growth woodland extent in controlling species richness. The effect of climate and old-growth woodland on species composition covaried, supporting an interaction between habitat quality and climatic setting, which may be important in understanding the epiphyte response to climate change.Conclusions  Advances in conservation planning will likely require an integrated approach to understanding simultaneous effects of multiple drivers, providing opportunities for integrated management strategies. Our study provides a preliminary example of this approach by combining three key biodiversity drivers into a single framework for lichen epiphytes. Thus, reducing pollution loads may make old-growth woodland that currently exists in a polluted landscape available for colonization, thereby extending the available habitat for epiphytes, and facilitating an effective species response to climate change.
Article
Monthly or annual 5 km × 5 km gridded datasets covering the UK are generated for the 1961–2000 period, for 36 climatic parameters. As well as the usual elements of temperature, rainfall, sunshine, cloud, wind speed, and pressure, derived temperature variables (such as growing-season length, heating degree days, and heat and cold wave durations) and further precipitation variables (such as rainfall intensity, maximum consecutive dry days, and days of snow, hail and thunder) are analysed. The analysis process uses geographical information system capabilities to combine multiple regression with inverse-distance-weighted interpolation. Geographic and topographic factors, such as easting and northing, terrain height and shape, and urban and coastal effects, are incorporated either through normalization with regard to the 1961–90 average climate, or as independent variables in the regression. Local variations are then incorporated through the spatial interpolation of regression residuals. For each of the climatic parameters, the choice of model is based on verification statistics produced by excluding a random set of stations from the analysis for a selection of months, and comparing the observed values with the estimated values at each point. This gives some insight into the significance, direction, and seasonality of factors affecting different climate elements. It also gives a measure of the accuracy of the method at predicting values between station locations. The datasets are being used for the verification of climate modelling scenarios and are available via the Internet. © Crown Copyright 2005. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
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MaxEnt is a program for modelling species distributions from presence-only species records. This paper is written for ecologists and describes the MaxEnt model from a statistical perspective, making explicit links between the structure of the model, decisions required in producing a modelled distribution, and knowledge about the species and the data that might affect those decisions. To begin we discuss the characteristics of presence-only data, highlighting implications for modelling distributions. We particularly focus on the problems of sample bias and lack of information on species prevalence. The keystone of the paper is a new statistical explanation of MaxEnt which shows that the model minimizes the relative entropy between two probability densities (one estimated from the presence data and one, from the landscape) defined in covariate space. For many users, this viewpoint is likely to be a more accessible way to understand the model than previous ones that rely on machine learning concepts. We then step through a detailed explanation of MaxEnt describing key components (e.g. covariates and features, and definition of the landscape extent), the mechanics of model fitting (e.g. feature selection, constraints and regularization) and outputs. Using case studies for a Banksia species native to south-west Australia and a riverine fish, we fit models and interpret them, exploring why certain choices affect the result and what this means. The fish example illustrates use of the model with vector data for linear river segments rather than raster (gridded) data. Appropriate treatments for survey bias, unprojected data, locally restricted species, and predicting to environments outside the range of the training data are demonstrated, and new capabilities discussed. Online appendices include additional details of the model and the mathematical links between previous explanations and this one, example code and data, and further information on the case studies.
Article
Aim To produce a statistical stratification of the European environment, suitable for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent, and to provide strata for modelling exercises and reporting. Location A ‘Greater European Window’ with the following boundaries: 11° W, 32° E, 34° N, 72° N. Methods Twenty of the most relevant available environmental variables were selected, based on experience from previous studies. Principal components analysis (PCA) was used to explain 88% of the variation into three dimensions, which were subsequently clustered using an ISODATA clustering routine. The mean first principal component values of the classification variables were used to aggregate the strata into Environmental Zones and to provide a basis for consistent nomenclature. Results The Environmental Stratification of Europe (EnS) consists of 84 strata, which have been aggregated into 13 Environmental Zones. The stratification has a 1 km2 resolution. Aggregations of the strata have been compared to other European classifications using the Kappa statistic, and show ‘good’ comparisons. The individual strata have been described using data from available environmental databases. The EnS is available for noncommercial use by applying to the corresponding author. Main conclusions The Environmental Stratification of Europe has been constructed using tried and tested statistical procedures. It forms an appropriate stratification for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent and for the provision of strata for modelling exercises and reporting at the European scale.
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