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Climate warming is expected to lengthen the phenological season of deciduous broadleaf trees. Such longer phenological seasons could also lead to higher growth rates. This hypothesis was tested by examining and relating leaf phenology and tree-ring width series of three European deciduous tree species (Betula pendula, Fagus sylvatica, Quercus robur). Leaf onset and fall dates were used to define the duration of the phenological season. Leaf phenological variables were compared with climate and radial growth rates (basal area increment) obtained from nearby sites. This comparison was done in 17 sites located across a wide geographical gradient in Europe (7.12–87.80 °E, 46.14–66.37° N). In general, leaf emergence dates are advancing as spring temperatures rise. In most sites and species, growth variability, phenology (dates of leaf emergence and senescence) and the duration of the phenological season were not related. In the few sites where relationships between growth and phenology were found, they changed through time. These findings indicate that a longer phenological season does not entail higher growth rates in deciduous tree species. Climate warming may trigger an earlier start of the phenological season in some species, which may lead to longer phenological seasons, but not necessarily to enhanced radial growth rates and carbon sequestration in the form of woody tissues.

The cool temperate rainforests of eastern Australia are at risk from anthropogenic climate change with predicted changes in temperature, rainfall, severe weather, basal cloud layer, and droughts. Phenology and litter production are fundamental reproductive and growth processes to document in any ecosystem, yet very few long-term studies exist in Australian rainforests. In this study, long-term datasets are used to describe different phenological and litter production behaviours of tree species in a Nothofagus cool temperate rainforest in New South Wales (NSW), Australia, analysing seasonal and inter-annual climate drivers. Leaf fall at the community level was mostly influenced by Nothofagus moorei, driven by temperature and wind speed, and Ceratopetalum apetalum, driven by temperature, rainfall, and solar radiation. Mean dates of leaf fall at the community level were found to be advancing, correlated with an advance in solar radiation. We also analysed in detail the flowering behaviour of the dominant canopy tree species, N. moorei, which masts with a mean inter-flowering period of 3-4 years in 65% of flowering events. Three of the studied species presented mast flowering, C. apetalum, N. moorei, and Orites excelsus; however, they did not mast in the same years. All species presented strong seasonality in their phenological activity, but seasonality peaked in different months, and were driven by varied climate variables. Supra-annual peaks of flowering and fruiting did not occur at the same time for all species, and climate drivers of inter-annual phenological behaviour were different for each species. Our results show that projected changes in climate will affect species from cool temperate rainforests differently, affecting not only biomass production, but also species reproductive output and forest dynamics. [ABSTRACT FROM AUTHOR]

The cool temperate rainforests of eastern Australia are at risk from anthropogenic climate change with predicted changes in temperature, rainfall, severe weather, basal cloud layer, and droughts. Phenology and litter production are fundamental reproductive and growth processes to document in any ecosystem, yet very few long-term studies exist in Australian rainforests. In this study, long-term datasets are used to describe different phenological and litter production behaviours of tree species in a Nothofagus cool temperate rainforest in New South Wales (NSW), Australia, analysing seasonal and inter-annual climate drivers. Leaf fall at the community level was mostly influenced by Nothofagus moorei, driven by temperature and wind speed, and Ceratopetalum apetalum, driven by temperature, rainfall, and solar radiation. Mean dates of leaf fall at the community level were found to be advancing, correlated with an advance in solar radiation. We also analysed in detail the flowering behaviour of the dominant canopy tree species, N. moorei, which masts with a mean inter-flowering period of 3–4 years in 65% of flowering events. Three of the studied species presented mast flowering, C. apetalum, N. moorei, and Orites excelsus; however, they did not mast in the same years. All species presented strong seasonality in their phenological activity, but seasonality peaked in different months, and were driven by varied climate variables. Supra-annual peaks of flowering and fruiting did not occur at the same time for all species, and climate drivers of inter-annual phenological behaviour were different for each species. Our results show that projected changes in climate will affect species from cool temperate rainforests differently, affecting not only biomass production, but also species reproductive output and forest dynamics.

In September 2022, a leaf spot disease, which later coalesce and result into leaf defoliation of rubber was observed in Tungawan, Zamboanga Sibugay, Philippines. Morpho‐cultural and molecular characterization identified the pathogen as Neopestalotiopsis clavispora. Koch's postulates were fulfilled confirming its pathogenicity to rubber seedlings. To the best of our knowledge, this is the first report of N. clavispora infecting rubber in the Philippines. [ABSTRACT FROM AUTHOR]

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Abstract The litter deposited on the soil surface at various stages of decomposition is important for primary productivity that impacts the microbial communities and soil carbon storage. The objective of this study was to evaluate the accumulation and decomposition of cultural residues of Theobroma grandiflorum (Willd. ex. Spreng) Schum, Paullinia cupana (Mart.) Ducke, Bixa orellana L., and forest in the Amazon region. The study was carried out in the São Francisco settlement, Canutama in the south of Amazonas, in a randomized block experimental design, and the treatments consisted of four areas with different crops: 1 - P. cupana; 2 - T. grandiflorum; 3 - B. orellana; 4 - Native woodland area (forest), in time subdivided plots: 7, 15, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, and 330 days after the distribution of the bags in the field, all with four repetitions. To evaluate the contribution and fractions of litter, conical collectors were used in each area, and collections were performed monthly in the period from March 2020 to February 2021. The estimate of the decomposition rate of the litter was done by quantifying the loss of mass, using litter bags, which allow for a direct analysis of the rate of decay over time. The forest and P. cupana environments presented the highest litter production, and greater deposition when compared to environments cultivated with T. grandiflorum and B. orellana. The forest and B. orellana areas showed the highest speed of decomposition, while the opposite situation occurred under T. grandiflorum and P. cupana cultivation.

In the Cerrado, the sequential chaining of phenological events during the dry season is a pattern observed in many plant species. In this season, many plants completely lose their leaves, and soon after deciduous, there is an expressive production of leaf buds. In this study, we investigated the effect of irrigation and early defoliation on the triggering of leaf budding of the deciduous species Peixotoa tomentosa A.Juss. in the dry season of a seasonal environment with water restrictions. Therefore, we set up an experiment with three groups of plants: control (n = 15), irrigation treatment (n = 15), and removal treatment (n = 15), and after the complete deciduousness of the plants, we carried out phenological monitoring of the development of leaf buds in these plants. From July to August 2022, the leaf budding phenology of the 45 individuals was evaluated twice a week. To test whether there is a difference in the number of leaf buds between treatments, we built generalized linear mixed models (GLMMs). Plants in the removal treatment had a statistically higher number of leaf buds produced than the plants in the irrigation and control groups (P < 0.05). However, the control group and the irrigation treatment did not differ from each other (P > 0.05). We showed that early defoliation influenced the triggering of leaf buds in P. tomentosa, increasing the production of young leaves in their individuals in a seasonal environment with water restrictions. Irrigation was not able to break the dormancy of leaf buds. Our findings contribute to a better understanding of the triggering of vegetative phenophases in deciduous Cerrado plants, showing that leaf fall may play a more important role than rain in the production of leaf buds in the dry season. [ABSTRACT FROM AUTHOR]

Background and Objectives: In kiwifruiy vineyards, the high concentration of bicarbonate ions in irrigation water or soil is one of the main limiting factors on growth and production. The high levels of bicarbonate in irrigation water caused soil alkalinity and reduced the root accessibility to nutrients such as irons. Iron deficiency in kiwifruit vineyards caused leaves chlorosis and therafter, fruits. Fruits with iron deficiency have an unacceptable taste and low shelf life. Iron deficiency is usually more severe in June and July with increasing irrigation frequency. Growing suitable rootstocks that have a high tolerance to soil alkalinity is a good strategy to overcome this problem. Therefore, in this study, the response of seedlings in different populations of kiwifruit from three different species to irrigation water bicarbonate was investigated. Materials and Methods: In this study, the effect of different concentrations of bicarbonate ions in irrigation water (0, 170, 350, and 550 mg L-1) on leaf chlorosis and iron uptake of seedlings of six kiwifruit seed populations (Green 11, Bruno, Red 2, Red 6, Red 22 and Baby kiwi) from three different species (Actinidia deliciosa, A. chinensis and A. arguta) was investigated as a factorial experiment in a completely randomized design with three replications in research greenhouse of faculty of agricultural sciences, University of Guilan. Each replication was one potted seedling. The plants were irrigated with different bicarbonate level for 6 weeks with three days intaervals. Traits such as leaf fall percentage, stem diameter, chlorosis percentage, necrosis percentage, chlorophyll a, b, total chlorophyll, carotenoids and iron content of leaves were measured. Results: The results showed that increasing bicarbonate concentration in irrigation water caused leaf abscission. The highest leaf abscission percentage was observed in Baby kiwi from A. arguta with 16.6% and the lowest one in Bruno (1.19%) from A. deliciosa species as compared to their control, when exposed to high bicarbonate stress. Genotype type, different levels of bicarbonate and their interaction did not show a significant effect on the percentage of stem diameter changes. The Red2 from A. chinensis species seedlings showed the highest leaf chlorosis (38.46%) and the lowest leaf chlorosis was found in Green 11 seedlings from A. deliciosa with 6.95%. With increasing the amount of bicarbonate in irrigation water, the percentage of leaf necrosis also increased. Total leaf chlorophyll and carotenoid content significantly declined in all genotypes with increasing bicarbonate ion content in irrigation water. With increasing bicarbonate ion concentration in irrigation water, leaf iron content significantly decreased. The lowest iron declining percentage compared to the control when seedlings exposed to 170, 350, and 550 (mg L-1) of bicarbonate of irrigation water was found in Bruno from A. deliciosa species with 3.28, 4.29, and 4.72%, respectively. Moreover, the results showed that there is a significant correlation between leaf iron content and chlorophylls content, chlorosis percentage and necrosis percentage. Conclusion: Overall, because of low leaf abscission and higher iron absorption in Bruno seedlings when exposed to high bicarbonate concentration in irrigation water or soil cab be recommend as a souperior rootstock. [ABSTRACT FROM AUTHOR]

The study of vegetative phenology is important to understand adaptation to different environments and potential trade-offs with growth traits. Crown leaf-out and leaf-fall phenology was evaluated on 168 open-pollinated families from 19 Cedrela odorata provenances in an eleven-year-old provenance/progeny trial established in the state of Veracruz, Eastern coast of Mexico. The objectives were: (a) to evaluate the extent of inter- and intra-population genetic variation of leaf phenology traits; (b) to examine the relationship between leaf phenology traits and climate variables at the population level; (c) to estimate the genetic relationships between leaf phenology and growth traits; and (d) to evaluate the accuracy, in terms of genetic control, of using alternative methods to measure leaf phenology in broadleaf trees. The study revealed significant genetic variation in leaf phenology traits both among and within populations. Leaf-out traits showed higher genetic variation than leaf-fall traits. A moderate to large genetic differentiation among Cedrela odorata populations was found; Qst values for leaf-out were 2–6 times higher than those for leaf-fall. Leaf-fall was primarily associated with mean annual temperature, while leaf-out and length of the leafless period were related to annual precipitation and the aridity index of the site of origin. Leaf phenology traits showed moderate to high genetic control (h2i = 0.12–0.67; h2f = 0.27–0.72). However, it was higher for leaf-out traits, so they might play a more important adaptive role. Genetic correlations between leaf phenology and growth traits allow selecting early flushing genotypes within populations to increase adaptation and growth, but caution should be taken when selecting among populations. [ABSTRACT FROM AUTHOR]

The article provides data on the results of studies on the selection of highly productive varieties resistant to spring frosts and clothosporium disease, as well as to the conditions of a hot dry climate, created at the Samarkand scientific station of the Scientific Research Institute of Horticulture, Viticulture, and Winemaking named after Academician M.M. Mirzaev (Uzbekistan). As a result of many years of research, it was revealed that the latest terms of mass flowering were observed in the variety Mulla Sodik (April 09) and hybrid № 4332 (April 12), which is 9-12 days later than the control variety Yubileiny Navoi. Fruit ripening in varieties and hybrids was noted from June 25 to July 10. The varieties Marokand, Mulla Sodik, and hybrid № 4332 were distinguished by their resistance to clothosporium. The largest fruits were cultivar Mulla Sodik (55.8 g) and hybrid No. 4332 (51.3 g). During the research years (2015-2020), the highest yield was obtained for the late-flowering variety Mulla Sodik (14.9 t/ha) and hybrid No. 4332 (15.7 t/ha), which is 24.2-30.8 % higher than the indicators of the control variety Yubileiny Navoi. According to the indicators of the tasting assessment, the fruits of the varieties Mulla Sodik, Marokand (4.6 points), and hybrid № 4332 (4.7 points) stood out. On the basis of the research carried out, the apricot variety Mulla Sodik and hybrid № 4332 were submitted to the State Variety Testing Station of the Republic of Uzbekistan and are recommended for specialized fruit-growing farms. The results of scientific research will contribute to the successful cultivation of apricots, obtaining a constant and high yield, increasing the export of valuable fruits to the countries of the world. [ABSTRACT FROM AUTHOR]

Phenology studies the phases of the life cycle of plants and animals, their temporal occurrence and their relationship with climatic events. While phenological studies in tropical tree species are focused on observations of the reproductive organs (i.e., flowers and fruits), vegetative phenology (i.e., leaves fall and production, and stem growth) remains little explored. Understanding the stem phenology patterns at the intra-annual scale allows us to and identify the causes and the occurrence of wood accumulation in the stems (i.e., carbon accumulation). The trees growing in urban environments and polluted heat islands provide a unique opportunity to understand the phenological responses of trees to climate changes in a global change context. However, the phenology of urban trees rarely has been studied in trees of tropical cities. In this research, we identified the timing and duration of the vegetative phenophases (i.e., stem growth, leaf flushing, and leaf fall) of Fraxinus uhdei (Wenz.) Lingelsh. (Oleaceae) and its relationship with monthly precipitation, in an urban environment. We applied weekly phenological monitoring with band dendrometers and observations of the leaf turnover during 12 months (Oct. 2022 - Nov. 2023) in nine adult trees at the campus of Universidad Nacional de Colombia, Medellín. All individuals showed stem diameter growth synchronously during the least rainy months (December-March: 148±118 mm/month). According to our observations, leaf fall was preceded by leaf flushing, and both phenophases occurred in the rainiest months of the year (August-November: 224±100 mm/month). Fraxinus uhdei showed rhythmic growth, expressed during a few months of the year (i.e., less rainy period) and not year-round as is usually believed for tropical tree species. Although the water deficit usually explains the rhythmic growth of tropical trees, in some ecosystems and species, light is the main limiting factor for plant growth as is suggested by our observations. [ABSTRACT FROM AUTHOR]

Questions: Although past land‐use effects on composition and structure are described for many forest types, forested riparian areas have been overlooked. Riparian areas may contain unique species and high species richness, as well as contribute basal leaf‐litter resources for aquatic fauna. We asked: (a) does past land use alter composition in riparian vs upland areas in wet tropical forest; (b) which vegetation life forms characterize riparian zones; and (c) what is the composition and quantity of leaf litter in riparian zones compared to uplands? Location: Riparian and upland locations in tropical wet forest, Luquillo Forest Dynamics Plot (LFDP), Luquillo Experimental Forest, Puerto Rico. Methods: Stratified random sampling was conducted in riparian and upland areas of LFDP with high and low past land use. Understorey vegetation life form composition and cover were sampled in plots. Leaf‐litter species composition and components were estimated with collecting baskets placed throughout riparian zones and uplands. Results: Ferns and lianas were more abundant in riparian areas than uplands. Ordination of species composition groups was distinct for riparian and upland areas with different past land use when based on leaf litter, but this ordination pattern was not as clear in plot vegetation. Conclusion: Characterized by greater presence of ferns and lianas, riparian zones had higher species richness values and greater leaf litter biomass. Distinct leaf‐litter species composition within riparian and upland areas may result from a combination of different land‐use histories, various plant types, and environmental conditions. Although riparian areas are proportionally a small component of the forested landscape, they are significant contributors to ecosystem process, terrestrial and aquatic linkages, and plant community composition. [ABSTRACT FROM AUTHOR]

Temporal variability of leaf senescence (autumn phenology) was observed in 2020 in 11 European beech (Fagus sylvatica) trees in Tivoli, Rožnik and Šišenski hrib Landscape Park in Ljubljana, Slovenia, and also observed for spring phenology in the same year. General leaf colouring, BBCH94, occurred between 19 and 24 October 2020, with lower inter-individual variability than that of leaf unfolding, BBCH11. The trees had active leaves (time between leaf unfolding and leaf colouring) between 177 and 199 days. In only three trees total leaf fall, BBCH97, occurred before 19 November 2020. Leaf colouring of the tree included in the long-term monitoring program of the Slovenian Environment Agency ARSO occurred on 24 October 2020. This is 7 days later than the 65-year average of the same tree/location and is ascribed to weather conditions. Investigation of tree tissues showed that the width of the last formed tree-ring in the wood varied between 0.39 and 9.61 mm and in the phloem between 0.09 and 0.26 mm, and that the tissues reflect the health condition of the trees.

Litterfall plays a key role in the dynamic of forest ecosystems, ultimately determining forest productivity and carbon and nutrient cycling. Increasing our understanding on the role of structural and environmental factors controlling litterfall amount and seasonality is of paramount importance for modelling and estimating soil carbon sequestration and nutrient cycling under climate change scenarios. However, the effect of climatic conditions on litterfall has been scarcely studied, especially in Mediterranean ecosystems. Here, we used nine years of seasonally collected litterfall data in two contrasting Mediterranean cork oak forests to evaluate the effect of climatic variables on leaf fall and litterfall. First, we isolated the litterfall seasonal trend and the between-sites differences in production by using linear mixed models. Then, we evaluated the effect of climatic variables and whether this effect was site-specific. We found a consistent litterfall seasonal pattern, mainly determined by leaf shedding (70% of litterfall). Leaf fall mainly occurs in spring with a second but much smaller peak in autumn some years. Mean temperature, precipitation and mean wind speed strongly influenced litterfall, but this effect was site-specific. In the forest site located at higher latitude and altitude, leaf fall increased linearly with temperature and showed a positive quadratic response to precipitation. In the water-limited site, leaf fall was reduced as temperature increased and did not respond to precipitation. These results have implications for modelling and predicting soil carbon sequestration, nutrient cycling, and the forest ecosystem productivity. Specifically, carbon and nutrient cycling models can be improved by incorporating idiosyncratic forest sites responses to climatic variability.

Reliable phenological observations are important for studying the response of trees to climate and climate change. National phenological networks were not specifically established to monitor tree phenology within forests, yet they are often used to generalise tree phenological phases at national or regional scales. Our objective was to investigate whether a phenological monitoring network using trees in open areas can accurately predict phenology of European beech (Fagus sylvatica L.) located within forests by using two models: one with correlates of environmental variables and one with interpolated monthly air temperature and sun hours. The first leaf unfolding, general leaf colouring and leaf fall dates from 2004 through 2010 were modelled using data from 47 Slovene National Phenology Network (NPN) stations in open areas and tested on phenological observations within forests using data from the UNECE CRLTAP ICP Forests network. Good agreement was found between predicted and observed first leaf unfolding in the forest, while slightly lower agreement was detected for general leaf colouring and leaf fall. Suggestions for the improvement of national phenological network are discussed in order to better predict beech phenology in forest habitats.

This study aimed to assess the impact of ethrel spraying on cassava leaf abscission at different stages of cultivar development. Two experiments were performed using randomized block designs, with 15 total treatments (three repetitions of five conditions) arranged according to the factorial scheme 3 x 5. Experiment 1 (ethrel application in the vegetative development period) consisted of three seasons (November 2013 and 2014, January and February 2014) and four concentrations of ethrel (1,500, 3,000, 4,500, and 6,000 ppm) and a control (no application); Experiment 2 (application in pre-harvest period) consisted of three periods of ethrel spraying (20, 40, and 60 days before harvest), four ethrel concentrations (1,500, 3,000, 4,500, and 6,000 ppm) and a control (without ethrel). The characteristics evaluated included the number of fallen leaves at 20 and 70 days after application, total leaf dry mass and foliar degreening. The effects of different concentrations and times of application of ethrel were significant during the first seven days. Ethrel application during the second period of vegetative development did not affect the number of fallen leaves over a period of 70 days.

ABSTRACT Evergreen (EG) and deciduous (DEC) species exhibit distinct strategies to overcome dry periods and achieve adequate water status for reproduction and growth. Such particularities may result in distinct reproductive strategies between these groups. Thus, we evaluated the phenology of EG and DEC groups, comparing and differentiating their reproductive phenophases in an area of Brazilian savanna (cerrado sensu stricto), located in Mirador State Park, Maranhão State, by associating these patterns with leaf fall and flushing. Leaf fall, leaf flushing, flowering and fruiting data were monitored between April 2014 and March 2016 for 12 EG and 13 DEC species. To assess differences in flowering and fruiting patterns between EG and DEC, we compared phenological time, activity and intensity, and the duration of phenophases. We found earlier occurrence and longer duration of flowering for EG than for DEC; for fruiting, EG differed from DEC in activity throughout the year, with the intensity being greater for the EG group. These responses may reflect the distinct water-use strategies adopted by the EG and DEC groups, and confirm that differences in their ecophysiological strategies may exert an influence on their reproductive phenology.

This study analyzed the phenological patterns of tree synusia, and their relationships with climate variables, in a forest fragment in the municipality of São Miguel do Oeste, SC. From October 2012 to October 2013, phenological events were evaluated using the number of species in the phenophase and the Fournier intensity index. Individuals of twenty species of trees (in 13 families) were monitored for budding, presence of mature leaves, leaf fall, flowers at anthesis, and presence of immature and mature fruits. The standardized Morisita index was used to test seasonality of the phenophases and the Spearman correlation was used to evaluate the possible relationships of phenophases with temperature and precipitation. Leaf fall was seasonal and had a high negative correlation with temperature. Budding and flowering showed seasonality and high intensity in September. Mature and immature fruits occurred at different times throughout the year. The triggering of the phenophases was correlated with temperature, mainly for the vegetative phenophases.

The spatiotemporal characteristics of litterfall reflect important functional processes in a forest ecosystem, yet seasonal and long‐term patterns in litterfall and relationship between litterfall and climate seasonality have rarely been examined in the aseasonal Southeast Asian tropics. We monitored monthly litterfall and conducted meteorological measurements over 16 years in a lowland mixed dipterocarp forest in Borneo. The total annual litterfall averaged 7.02 Mg ha−1 year−1 and leaf fall contributed 67.9% of total litterfall. Fourier analyses detected a significant annual cycle in monthly leaf fall, although spatial variation was relatively high, and 57.5% of litter traps showed annual cycles at the litter trap level. Rainfall, mean temperature and solar radiation also showed distinct 12‐month cycles. Leaf fall was positively correlated with the daily mean air temperature of the same month, and negatively correlated with rainfall in the previous month. Leaf fall gradually increased during the study period. Our results suggest that a seasonal pattern in community‐level leaf fall is regulated by the annual cycle of meteorological factors, even in this aseasonal environment, which experiences no dry season. Further monitoring and analyses are required to clarify spatial variation and long‐term patterns in litterfall and their mechanisms. The study based on 16‐year measurements of litterfall and meteorology highlighted distinct annual cycles in leaf fall and climatic parameters even in the aseasonal Southeast Asian tropics. Further monitoring is needed to explore the mechanisms for the observed general‐upward trend in leaf production. [ABSTRACT FROM AUTHOR]

Key messageIn an evergreen species with fixed-growth, warming advanced budburst but not leaf appearance and growth, and the further developed abnormal shoots bywarming indicates extended growing season instead of leaf fall.Abstract We investigated the effects of warming and precipitation manipulation on phenology (spring phenology, leaf fall, and abnormal shoot phenology) in Pinus densiflora, which is an evergreen species with fixed-growth. In an open-air nursery, 2-year-old P. densiflora seedlings were planted in April 2013 and treated with 6 treatments (n = 3) [2 temperature levels: + 3 °C (TW) and control (TC); 3 precipitation levels: + 30% (PI), − 30% (PD), and control (PC)]. We observed spring and abnormal shoot phenology in 2014 and 2015, and measured dry weight of fallen leaves in 2015. Phenology was not changed by precipitation manipulation. In spring phenology, budburst was advanced by 9.4-9.6 days under warming, but timing of leaf appearance and growth did not changed. Cumulative weight of fallen leaves was 25.8-28.6% lower in TW plots than in TC plots between July and December 2015. There were no significant differences in occurrence rates of abnormal shoots among plots. 65.7-96.8% of abnormal shoots remained at the budburst stage in TC plots, while abnormal shoots in TW plots further developed to the leaf appearance and growth stages. Abnormal shoot development stopped 10.5-28.8 days later in TW plots than the TC plots in 2014 and 2015. Effects of warming were evident only in budburst, because leaf appearance and growth were affected by fixed-growth characteristics as well as warming. Decreased leaf fall and further developed abnormal shoots could be interpreted as delayed leaf senescence and extended growing season, respectively, for an evergreen species with fixed-growth. [ABSTRACT FROM AUTHOR]

Systemic neonicotinoid insecticides such as imidacloprid are increasingly applied against insect pest infestations on forest trees. However, leaves falling from treated trees may reach nearby surface waters and potentially represent a neonicotinoid exposure source for aquatic invertebrates. Given imidacloprid's susceptibility towards photolysis and high water solubility, it was hypothesized that the leaves' toxicity might be modulated by UV-irradiation during decay on the forest floor, or by leaching and re-mobilization of the insecticide from leaves within the aquatic ecosystem. To test these hypotheses, the amphipod shredder Gammarus fossarum was fed (over 7 d; n  = 30) with imidacloprid-contaminated black alder ( Alnus glutinosa ) leaves that had either been pre-treated (i.e., leached) in water for up to 7 d or UV-irradiated for 1 d (at intensities relevant during autumn in Central Europe) followed by a leaching duration of 1 d. Gammarids' feeding rate, serving as sublethal response variable, was reduced by up to 80% when consuming non-pretreated imidacloprid-contaminated leaves compared to imidacloprid-free leaves. Moreover, both leaching of imidacloprid from leaves (for 7 d) as well as UV-irradiation reduced the leaves' imidacloprid load (by 46 and 90%) thereby mitigating the effects on gammarids' feeding rate to levels comparable to the respective imidacloprid-free controls. Therefore, natural processes, such as UV-irradiation and re-mobilization of foliar insecticide residues in water, might be considered when evaluating the risks systemic insecticide applications in forests might pose for aquatic organisms in nearby streams. [ABSTRACT FROM AUTHOR]

Small-scale farmers in the banana-coffee agro-zone of Central Uganda plant and maintain trees to provide a range of benefits. However, the impact of trees on soil fertility and crop yields is small. On many farms, trees exist in infinite numbers, compositions, with no proper spacing, sequencing and canopy management recommendations. The objectives of this study were to: quantify and compare leaf fall and leaf litter biomass for the dominant tree species subjected to different pruning regimes and during different seasons and determine the nutrient concentrations in leaf litter materials in order to assess their potential to improve soil fertility. A survey was conducted on 30 randomly selected farms to examine and document the tree species. Four tree species were dominant; Ficus natalensis (15.3%), Albizia coriaria (10.2%), Artocarpus heterophyllus (10.0%) and Mangifera indica (9.2%). Experiments such as canopy pruning, collecting leaf fall and weights of pruned leaf biomass were established for the four dominant trees on five randomly selected farms. A total of 120 trees were subjected to three pruning regimes (0%, 25% and 50%). Litter traps (1 m × 1 m) were placed 2 m from the tree trunk to collect falling leaves. Leaf biomass was collected from pruned branches and weighed. Leaf samples were collected from pruned leaves and a composite sample analysed for carbon and nutrient concentrations. Results showed that 40 tree and shrub species belonging to 21 families existed on farms. Leaf fall was highest in the dry season and A. Heterophyllus registered the highest amount. Leaf biomass from pruned trees was heaviest for M. indica (42.4 ±3 kg) in the wet season and at the 50% pruning regime (45.7± 2.1kg). Total nutrient concentrations were in the order A. coriaria>F. natalensis>A.heterophyllus>M.indica. We concluded that F. natalensis and A. Coriaria should be integrated more into the agroforestry system to improve soil fertility. A.heterophyllus and M.indica should be planted on farm boundaries. The 50% pruning regime was the best and should be carried out during the wet season. [ABSTRACT FROM AUTHOR]

Leaf fall is a serious disease of para rubber seedlings, known to cause economic losses in several nurseries of southern Thailand. It is caused by a phytopathogenic fungal-like organism Phytophthora. Chitosan is a biological polymer used as a plant growth stimulator, and used against several phytopathogenic fungi on many crops. This study aimed to determine the effects of chitosan in controlling leaf fall disease of para rubber seedlings caused by Phytophthora palmivora, both in vitro and in vivo. Various concentrations of chitosan were applied on seedlings of para rubber clone RRIM 600. The growth rate of P. palmivora on potato dextrose agar was determined with various chitosan concentrations, and a concentration of 1 mg/ml was sufficient to reduce the radial growth of P. palmivora by about 91% on agar plates. This concentration also reduced the size of necrotic lesions at 24 and 48 hours post inoculation (hpi), but not after 72 hpi. The results suggest that chitosan (i) directly inhibits the growth of P. palmivora, and (ii) reduces the growth rate of necrotic lesions, but may not completely be able to control the leaf fall disease of para rubber seedling.

Efficient methods to monitor forested areas help us to better understand their processes. To date, only a few studies have assessed the usability of multitemporal synthetic aperture radar (SAR) datasets in this context. Here we present an analysis of an unprecedented set of C-band observations of mixed temperate forests. We demonstrate the potential of using multitemporal C-band VV and VH polarisation data for monitoring phenology and classifying forests in northern Switzerland. Each SAR acquisition was first radiometrically terrain corrected using digital elevation model-based image simulations of the local illuminated area. The flattened backscatter values and the local area values were input to a temporal compositing process integrating backscatter values from ascending and descending tracks. The process used local resolution weighting of each input, producing composite backscatter values that strongly mitigated terrain-induced distortions. Several descriptors were calculated to show the seasonal variation of European beech (Fagus sylvatica), oak (Quercus robur, Quercus petraea) and Norway spruce (Picea abies) in C-band data. Using their distinct seasonal signatures, the timing of leaf emergence and leaf fall of the deciduous species were estimated and compared to available ground observations. Furthermore, classifications for the forest types 'deciduous' and 'coniferous' and the investigated species were implemented using random forest classifiers. The deciduous species backscatter was about 1 dB higher than spruce throughout the year in both polarisations. The forest types showed opposing seasonal backscatter behaviours. At VH, deciduous species showed higher backscatter in winter than in summer, whereas spruce showed higher backscatter in summer than in winter. In VV, this pattern was similar for spruce, while no distinct seasonal behaviour was apparent for the deciduous species. The time differences between the estimations and the ground observations of the phenological events were approximately within the error margin (±12 days) of the temporal resolution. The classification performances were promising, with higher accuracies achieved for the forest types (OA of 86% and k = 0.73) than for individual species (OA of 72% and k = 0.58). These results show that multitemporal C-band backscatter data have significant potential to supplement optical remote sensing data for ecological studies and mapping of mixed temperate forests. [ABSTRACT FROM AUTHOR]

The Meckenheim fruit growing region in Western Germany may be affected as a consequence of climate change by lack of chilling, i.e. a cold period in the winter required for tree species to flower in the subsequent spring. As sweet cherry requires high chill, 160 potted trees of three sweet cherry cultivars with threefold different chilling requirements were cultivated in a large experiment over 4 years, either in the orchard or in an unheated greenhouse (simulated climate change). The orchard temperatures in the warmer winter (6.0 °C) exceeded those in the unheated greenhouse (4.7 °C) in the cold winter. Chilling computations for this region showed that cherry trees of low chill cultivar '6000CZ' required 22.3-26.6 chill portions (CP), medium chill cv. 'Brooks' about 37.9-54.4 CP and the high chill cv. 'Schneiders späte Knorpelkirsche' about 54.4-79.3 CP for a natural flowering. Cherry trees cv. '6000CZ' receiving <300 CH, cv. 'Brooks' <500 CH and cv. 'Schneiders späte Knorpelkirsche' <700 CH were unable to flower, equivalent of 50 % of the assumed chilling optimum of the respective cultivar. Maximum chill accumulation in this region is currently achieved, so that warmer winters may reduce the available chill. The beginning of leaf drop was identified as a suitable initiation point for computing chill accumulation. Overall, the work has shown that environmental change has an effect on chilling availability in Meckenheim and possibly other fruit growing regions along 50°N. The insights gained ultimately highlight the need for cross-sectoral, adaptive management practices that jointly target a sustainable regional development. [ABSTRACT FROM AUTHOR]

• Temperature free-air controlled enhancement system was used to simulated warming. • The responses of autumn phenology varied greatly among species to warming. • Extension of growing season was mainly through the advancement of spring phenology. • The temperature sensitivity of budburst declined with increasing temperature. • Warming increased budburst but reduced leaf coloration synchrony among species. Predicting the length of growing season to further warming relies on both spring and autumn phenological responses of different species, but with little experimental evidence under different levels of warming. Here, the timing of spring phenology including budburst and leaf unfolding, and autumn phenology including leaf coloration and leaf fall, were examined in 2-year-old seedlings of three temperate tree species (Fraxinus mandschurica, Quercus mongolica , and Juglans mandshurica) that were grown in the field under warming conditions (W0, ambient; W2, +2°C; W4, +4°C). Our study showed that warming advanced budburst and leaf unfolding by 9 and 8 days in the W2 treatments and by 13 and 15 days in the W4 treatments, respectively, with the magnitude varied greatly among species. However, we found a delayed autumn leaf senescence only for Q. mongolica , for which leaf coloration and leaf fall delayed by 19 and 6 days and by 17 and 12 days in the W2 and W4 treatments, respectively. The temperature sensitivity of budburst declined with increasing temperature in Q. mongolica. The growing season was extended by 7–18 and 10–25 days in W2 and W4, primarily through the advancement of spring phenology. Warming increased budburst synchrony, such that J. mandshurica , which typically has the earliest leaf emergence, lost its growth and competitive advantages over the more phenologically plastic species, F. mandschurica and Q. mongolica. Our results provide new insights into the effects of elevated temperatures on phenological shifts and their potential influences on tree species recruitment and forest structure and composition. [ABSTRACT FROM AUTHOR]

Phenological observations were taken for 13 woody species for two years (Jan 2006 - Dec 2007) in dry deciduous forest of North Gujarat. The phenological behavior of most of the woody species was almost similar in two different years. Leaf initiation started in the month of March with peak April – May before pre-monsoon showers and leaf - fall began in October with a peak in November and December. Flowering in most of the woody species was observed in the month of February continued till May, fruit appearance for these species from March, with a peak of August. In July and August 69% of woody species appeared in fruit ripening stage. While monsoon begins same duration, that allow to the optimal germination of tree species. An observing human impact on selected species facing seasonal threats, more number of species faced cutting during leaf fall period or before on setting of flowers. International Journal of Environment, Volume-2, Issue-1, Sep-Nov 2013, Pages 60-69 DOI: http://dx.doi.org/10.3126/ije.v2i1.9208