Chronicles of an announced landscape disaster and lessons for the future: spatial modelling of the plane tree Canker stain

Assessing the effects of landscape structure on the relationship between species diversity and functional diversity

Can epidemic control be achieved by altering landscape connectivity in agricultural systems?

The studies of woody organs-affecting diseases of Platanus × acerifolia can be hampered by the finding of fungi whose identification is difficult with mycological techniques. In a previous study on Platanus × acerifolia affected by severe cankers, Fomitiporia mediterranea/punctata-like fungi, not associated with fruit bodies and Libertella sp. were recovered. Due to the severity of the associated symptoms, a characterization of fungal ribosomal DNA genes was undertaken in the present study, aimed to specific identification of the pathogens. From DNA of Fomitiporia-vegetative isolates and Fomitiporia-fruit body isolates, included in the study for comparison (from fruit body on plane trees typical of F. mediterranea/punctata), and Libertella sp., DNA fragments were amplified in polymerase chain reaction (PCR) with the use of ITS5/ITS4 and 5.8S-R/LR7 primer pairs. Sequence alignments showed that Fomitiporia-vegetative/fruit body isolates had highly homologous ITS5/ITS4 sequences, with a nucleotide identity of 98–100%. All the Fomitiporia isolates from plane tree showed 97–100% and 91–94% of nucleotide identity respectively with ITS5/ITS4 sequences of known strains of F. mediterranea and F. punctata, extracted from GenBank. The strong similarity of these identity ranges with those obtained within F. mediterranea (98–100%) and between the two Fomitiporia species (90–94%) confirms the identification of the isolates from plane tree as F. mediterranea. Sequence comparison between Libertella sp. from plane tree and known strains of Eutypa lata/L. blepharis showed 94–99% of nucleotide identity. The comparison with eight additional species of Eutypa showed 90–93% of nucleotide identity. As previously reported for the different taxa within Diatrypaceae, also ITS5/ITS4 sequence of Libertella sp. from plane tree exhibited 11-bp tandem repeats motifs. Results of sequence alignments, of phylogenetic trees, and of the putative restriction map, identify the Fomitiporia isolates of this work as F. mediterranea, and the isolates of Libertella sp. as E. lata/L. blepharis. For comparative purposes, ITS5/ITS4 sequences of Spongipellis pachyodon and Fomes fomentarius from plane tree, were also obtained in this work.

ivanova H., Bernadovicova S., Pastircakova k.: The influence of selected climatological characteristics on antracnose disease development in plane trees. ekologia (Bratislava), vol. 29, no. 4, p. 430-440, 2010. The plane tree (Platanus sp.) is one of frequently used ornamental trees in Slovak urban areas. The population of London plane in the Slovak Republic has not been affected so far by important dangerous pathogens common to warmer regions of Europe. However, in recent years the health state of plane trees has been significantly deteriorating. During 2004–2008, reappearances of anthracnose on Platanus × hispanica M u n c h h . were recorded. The causal agens of the disease, microscopical fungi of genus Apiognomonia [A. veneta (S a c c . & S p e g . ) H o h n .], were isolated from symptomatic leaves and twigs, with characteristic spots and lesions sampled from affected host trees growing in the urban environment at the selected localities (Nitra, Komarno, Piesťany). The spreading of fungi basically depends on meteorological conditions, for example air humidity and precipitation, active solar radiation and air temperature. In this study, climatological parameters, air temperature and annual precipitation with their influence on the incidence of Apiognomonia anthracnose on plane trees growing in urban settings are presented. Our results show that plane population damage can be irreversible and very considerable in consequence of repeated climatically unfavourable years, resulting in the subsequent development of A. veneta infection.

Urban London plane tree dieback linked to fungi in the Botryosphaeriaceae

Karabağlar (Muğla, Turkey) is one of those settlements that over time has come to blend well with its natural assets. Not only are the man-made and natural components of this seasonal settlement unique, and in harmony with one another, but they have also persisted throughout the centuries despite much adversity. Previous research has revealed how two landscape components particular to the area, namely irim and kesik, have resulted in a remarkable character. Further inquiry into other aspects of Karabağlar will help in the depiction of its original layout, taking into account the wealth of landscape elements and structures that have a couple of millennia, or more, of historical precedent. The originality of the spatial layout of a yurt setting, the lifestyle that is generated around a coffeehouse, in addition to a masjid and plane trees, all deserve attention as a system of diverse values worthy of conservation.

Indicating atmospheric sulfur by means of S-isotope in leaves of the plane, osmanthus and camphor trees

During the last decade the conservation of biodiversity in agricultural landscapes has been greatly emphasized. Intensification of agricultural production and practices, as well as land abandonment, have been considered as major threats (Solbrig, 1991), by making drastic changes in landscape structure and composition. The agricultural landscape is a shifting mosaic of crops, pastures, fallow lands and woody areas. Landscape elements exhibit their own disturbance regime, which depends on the practices used by farmers and thus interact with insects at several spatio-temporal scales. Changes at regional and long-term scales are the most documented and the most predictive (Baker, 1989; Rackham, 1986; Odum and Turner, 1990; Meeus, 1995; Crumley and Marquardt, 1987). A recent trend in western Europe is a decrease of the area covered by non-cultivated elements such as hedgerows, woodlots, heathlands, within intensive agricultural landscapes (Agger and Brandt, 1988; Bunce and Hallam, 1993; Burel and Baudry, 1990; Morant et al., 1995). In the mean time large tracks of farmland are abandoned. Thus the contrast between different regions increases. The changes within rural landscapes result in an increase in fragmentation of many elements and affect insect populations by reducing available habitats or seasonal refuges for many species. At a finer scale, farmers make decisions on crop succession in their farming system and on management practices for field boundaries and non-productive areas; this creates a changing landscape mosaic. Changes in agricultural landscapes can only be predicted through the knowledge of how farmers will change the land use pattern under different circumstances. Two levels must be considered: 1) changes in the type of production (e.g. from dairy production to cereals) and 2) changes in the techniques of production (e.g. feeding dairy cows with hay or maize silage). If, at a broad regional scale, relationships between the type of farming systems and landscape can be established, it becomes very fuzzy at the landscape scale, relating to, the scales of individual and population dispersal. Deffontaines et al. (1995) provide examples of two farms, in the Pays d’Auge, where the most productive one has more grassland and less annual forage crops. In all cases, the within farm land use diversity is striking, it results from both physical and spatial constraints and the requirements of the system of production (e.g. winter/summer forage). Many factors, out of the agricultural sector, also affect land use and landscape patterns, as in multi-job farms (Laurent et al., 1994). Trajectories of households as well as changes within farm systems are barely related at the individual farm scale. The major consequence from a landscape ecological point of view is that landscape changes cannot be derived from current landscape patterns (Burel and Baudry, 1990). More specifically, abandonment or dereliction of grassland is a stochastic process at the landscape scale, although deterministic at the farm scale.

The London plane tree (Platanus × hispanica) is a long-lived drought tolerant tree, able to adapt to urban conditions and tolerate pollution, which is often grown as a park and avenue tree in Central Europe. In July and August 2022, branches from 20-year-old plane trees with large, dark-brown to red- brown lesions (Figure 1) extending from the bark (Figure 2a-b) to the heartwood (Figure 2c-d) were observed along an avenue in Cottbus, Germany. More than 100 trees (about 60% of the total) were diseased. Trees on the eastern side of the road, which were more exposed to sunlight, were significantly more affected than those on the west side, where sunlight exposure was reduced by larger trees in an adjacent park. Infected branches of different sizes (diameter 3–10 cm) were collected from four individual plane trees, with five samples being taken from each tree. From each branch, nine diseased samples were taken from the sapwood and heartwood, surface-sterilised and incubated on synthetic nutrient-poor agar (Sifin Diagnostics GmbH, Germany) for six days at 24 ±2°C under daylight conditions. Based on morphological characteristics, described in Crous and Groenewald (2017), Querciphoma minuta (syn. Q. carteri), a species within the Camarosporium complex was identified from all the samples. Conidiomata were medium brown, pycnidia, globose to eustromatic with 1–3 papillate ostioles, 150–250μm diameter (Figure 3a), with verruculose, septate setae with obtuse ends (Figure 3b-d). Conidia were solitary, hyaline, smooth, broadly ellipsoidal, aseptate and 4–6 × 3,5 μm in size. To confirm the identification, genomic DNA was extracted from four isolates and the internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers (White et al., 1990). All consensus sequences (GenBank Accession Nos. OQ186736, OQ186741, OQ190053 and OQ190054) were identical. BLAST searches revealed 100 % sequence identity to Querciphoma minuta (KX359604.1, KF251209.1 and MN833930.1). A pathogenicity test was performed using two isolates (22-784B, 22–1121) on twenty healthy plane tree seedlings (Platanus × hispanica), 120 to 150 cm in height. Wounded stems were inoculated with mycelial plugs taken from the margin of a seven-day colony growing on potato dextrose agar (PDA) (sterile PDA agar plugs were used as controls) and sealed with plastic film. After six weeks of incubation at 24°C ±2°C and 75% humidity in the greenhouse, necrosis and vascular discolouration appeared on almost 98% of the sites inoculated with mycelium (Figures 4a-b and 5a-c), but not on the sites inoculated with sterile agar plugs (Figures 4c-d and Figure 5d). Necrosis extended mainly longitudinally from the inoculation point, causing brown to dark brown discolouration of the wood (Figure 3j). Lesions varied considerably, ranging from 1 to 5.3 cm in length for both isolates. Fungi were reisolated from all stem lesions and identified as above. Querciphoma minuta was confirmed in 85% of the inoculated sites, but in none of the controls, thus fulfilling Koch's postulates. Querciphoma minuta was until now known only to occur in oak, causing dieback (Carter 1941), or associated with veteranisation wounds in living oak trunks (Menkis et al., 2022). It is also pathogenic when associated with Coraebus florentinus in declining oak forests (Pinna et al., 2019). In 2022, Q. minuta was also found in Quercus petraea displaying dieback and large stem lesions in Spremberg, Germany (LELF, unpublished). Nevertheless, much remains to be discovered about the ecology of this fungus. This is the first report of Q. minuta as a potential canker pathogen of plane, suggesting that the pathogen has a larger host range of and a greater impact as a plant pathogen than previously suspected. T. Pfannenstill, M. Schemmel and R. Wichmann (LELF, P4, Plant Health Control) are gratefully acknowledged for sampling assistance. We thank C. Tielesch (LELF) and T. Wille (JKI) for laboratory assistance and T. Gaskin for language editing.

Urban trees emit a wide range of biogenic Volatile Organic Compounds (bVOC). Some of these bVOC, like isoprene can react with atmospheric oxidants to form secondary compounds, such as ozone (O3) and secondary organic aerosols (SOA), which have impacts on air quality and climate. In addition, isoprene emissions are strongly influenced by environmental factors and urban sites are known as stressful environment, characterized for example by water scarcity. However, little is known on the contribution of urban trees to air quality, notably during drought periods. In a semi-controlled experiment, fourteen young plane trees (Platanus x hispanica, known as a strong isoprene emitter) were grown in containers, in an urban site (at Vitry-sur-Seine, near Paris), since 2020. In June 2022, half the trees were subjected to drought by total rainfall exclusion and by withholding watering. A comprehensive characterization of tree response to drought, including plant morphology (leaf density and area), water status (i.e., leaf water potential, δ13C isotopic composition) and physiology (stomatal conductance, net photosynthesis, leaf pigment contents, stress molecular markers, chlorophyll fluorescence) analyses, was undertaken along with the characterization of bVOC emissions by an original leaf scale method (portable GC-MS coupled to a leaf chamber). All together, these parameters provided relevant information on the relation between bVOC emissions and plant morphology, its water use efficiency and photosynthetic energy conversion. Shortly after the onset of drought, the isoprene emissions of the plane trees remained unchanged even though typical responses to drought stress were observed, such as partial stomatal closure leading to a decrease in carbon assimilation. With the progression of drought stress, progressive leaf shedding occurred. When almost completely defoliated, the trees emitted lower amounts of isoprene emissions likely due to disruption of the photosynthetic energy conversion process. Despite the moderate decrease in absolute isoprene emissions rates (as expressed per dry leaf mass) induced by the drought treatment on plane trees with nearly zero gas exchange, total emissions were strongly affected because defoliation significantly reduced the total leaf area. We emphasize that this phenomenon should be taken into account in atmospheric models especially in species highly subjected to drought induced defoliation. Here, a simple parameterisation of this effect on plane tree-bVOC emissions is proposed.

Disposition polynomials and plane trees

Data on allergic rhinitis and respiratory health metrics are limited for South Africa, with grass pollen as a key outdoor aeroallergen. Exotic trees such as plane trees and ragweed produce highly allergenic pollen, dominating indigenous trees and weeds. Pollen allergy prevalence data is lacking in cities of North-West province such as Potchefstroom. This study aimed to (i) assess the prevalence of allergies to major aeroallergens, including Poaceae (grasses), Cupressus/Hesperocyparis (cypresses), Platanus (plane tree), Ulmus (elm), Quercus (oak), Betula (birch), Olea (olive), Artemisia (sagebrush), Amaranthus (amaranth), Plantago (plantain), Morus (mulberry), and Ambrosia (ragweed), along with fungal spores such as Alternaria, Cladosporium, and Penicillium/Aspergillus, and (ii) investigate the monthly incidence of major aeroallergens and reactivity levels in sensitized adults in Potchefstroom. Skin prick tests (SPTs) were performed on 202 adults aged 18-64 years with confirmed allergic symptoms during a field campaign at North-West University (NWU)'s Potchefstroom campus. A test panel of grass, weed, tree, and fungal spore extracts previously identified via aerobiological monitoring was used. Symptom scores were recorded using ISAAC questionnaires; Spearman's statistical correlation between symptom frequency and monthly aeroallergen concentrations were analyzed. Among the participants, 184 (91%) exhibited positive SPT reactions: 104 (57%) are monosensitized to pollen, 45 (24%) to fungal spores, and 35 (19%) are polysensitized. Aeroallergen prevalence was higher in females (73%) than in males (27%). The most common pollen allergens were Cynodon dactylon (Bermuda grass) (85%), Zea mays (maize) (46%), Platanus spp. (plane tree) (35%), and Ulmus campestris (field elm) (33%). Among fungal spores, Alternaria was the most common (93%), followed by Cladosporium (27%). A significant and positive statistical correlation was found between allergic rhinitis symptoms and monthly pollen concentrations of Betula, Morus, Platanus, and Quercus. This pilot study linked aeroallergens detected in Potchefstroom with allergy profiles of local residents. The findings highlight the need for more comprehensive regional studies that integrate allergen testing with aerobiological data. Raising awareness and implementing health strategies are essential for managing allergic rhinitis in South Africa. More affordable and available SPTs kits, adapted to allergy prevalence in South Africa, are strongly suggested.

A polynomial with exactly two critical values is called a generalized Chebyshev polynomial (or Shabat polynomial). A polynomial with exactly three critical values is called a Zolotarev polynomial. Two Chebyshev polynomials f and g are called Z-homotopic if there exists a family pα, α\( \epsilon \) [0, 1], where p0 = f, p1 = g, and pα is a Zolotarev polynomial if α\( \epsilon \) (0, 1). As each Chebyshev polynomial defines a plane tree (and vice versa), Z-homotopy can be defined for plane trees. In this work, we prove some necessary geometric conditions for the existence of Z-homotopy of plane trees, describe Z-homotopy for trees with five and six edges, and study one interesting example in the class of trees with seven edges.

The combinatorics of RNA plays a central role in biology. Mathematical biologists have several commonly-used models for RNA: words in a fixed alphabet (representing the primary sequence of nucleotides) and plane trees (representing the secondary structure, or folding of the RNA sequence). This paper considers an augmented version of the standard model of plane trees, one that incorporates some observed constraints on how the folding can occur. In particular we assume the alphabet consists of complementary pairs, for instance the Watson-Crick pairs A-U and C-G of RNA. Given a word in the alphabet, a valid plane tree is a tree for which, when the word is folded around the tree, each edge matches two complementary letters. Consider the graph whose vertices are valid plane trees for a fixed word and whose edges are given by Condon, Heitsch, and Hoos's local moves. We prove this graph is connected. We give an explicit algorithm to construct a valid plane tree from a primary sequence, assuming that at least one valid plane tree exists. The tree produced by our algorithm has other useful characterizations, including a uniqueness condition defined by local moves. We also study enumerative properties of valid plane trees, analyzing how the number of valid plane trees depends on the choice of sequence length and alphabet size. Finally we show that the proportion of words with at least one valid plane tree goes to zero as the word size increases. We also give some open questions.

Old and young leaves on plane trees