Bud break in sugar maple submitted to changing conditions simulating a northward migration

Assisted migration, the human-mediated movement of species and populations, is one adaptive strategy to climate change. Plant phenology affects the survival and distribution of species to local conditions, and its potential modifications need to be explored in the context of assisted migration. We conducted identical experiments in January and April (experiment I and II) and monitored the timing of bud break in sugar maple (<i>Acer saccharum</i> Marshall) under cooling and longer photoperiod to simulate a northward migration. The budbreak in experiment II started 55 days earlier than experiment I. In experiment I, longer photoperiod was more effective than warming in advancing bud break. Compared to experiment II, cooling and long photoperiod had stronger effect in experiment I . Our results demonstrated the significant effect of chilling and confirmed that photoperiod outweighs temperature in initiating bud break when the chilling requirement is unfulfilled. These findings suggest that the future mild winters in the southern range of sugar maple may reduce chilling accumulation and result in the delayed bud break. Sugar maples migrating northward could benefit from longer day lengths, which could partly counteract the delayed effects of colder springs in northern regions, thus ensuring a sufficient growth period.

As Winters Get Warmer, Sugar Maples May Absorb Less Silicon

Rising temperatures that reduce snow cover leave soils vulnerable to frost, reducing silicon uptake by trees, with potential effects on downstream ecosystems.

Reaction of Selected Cultivars of Sugar Maple to Anthracnose in North Alabama

Anthracnose, caused by the fungus Discula campestris, appeared in a planting of 18 sugar maple cultivars in Cullman, AL (USDA Hardiness Zone 7a). Sizable differences in the timing of disease onset and intensification were noted between sugar maple cultivars. On susceptible cultivars, the appearance of reddish-brown lesions 4 to 10 mm in diameter, sometimes with a tan center and yellow border, in June was followed with the initiation of premature defoliation by mid-July. By early fall, the susceptible cultivars Goldspire, Seneca Chief, and Sugar Queen along with the moderately susceptible cultivars Endowment, Fairview, Flax Mill Majesty, Morton, and Sweet Shadow were defoliated and showed no fall color. In contrast, disease onset was delayed, the level of premature defoliation greatly reduced, and fall color display unaffected on the anthracnose resistant cultivars Autumn Blush, Autumn Faith, Fall Fiesta, and Legacy, all of which would be excellent choices for amenity and commercial landscapes in the Mid- and Upper South. Among the representative cultivars of the four resistance classes, total rainfall and mean temperature influenced premature anthracnose-induced defoliation on the susceptible Sugar Queen and moderately resistant Commemoration, but not on the resistant Fall Fiesta or the moderately susceptible Flax Mill Majesty sugar maples. Accepted for publication 28 November 2016.

Sugar content in the sap of birches, hornbeams and maples in southeastern Poland

There is very little data on the sugar content of tree sap in Central Europe. In order to fill this gap we measured sugar content in the spring sap of 55 trees from 8 species (six native and two introduced). Sugar content was measured chromatographically using an HPLC Dionex Ultimate 3000 system and CAD detection. The proportion of sugar was highly genus-specific: maples contained sucrose, birches a mix of glucose, fructose and sucrose and hornbeams glucose and fructose. Acer saccharinum had the sweetest sap (4.0%), followed by A. platanoides (3.2%), A. pseudoplatanus (3.2%), A. negundo (2.9%) and A. campestre (2.8%). Birches were slightly less sweet (Betula pendula 2.5% and B. pubescens 2.6%). Carpinus betulus sap contained only 0.9% sugar. The reported values for birches are higher than those reported in other European studies and the values for maples are similar to those for sugar maples in North America. As southeastern Poland has many large populations of maples and birches, a small-scale sugar syrup industry could become an additional source of income for forest owners.

Small-scale heterogeneity in temperate forest canopy arthropods: stratification of spider and beetle assemblages

Vertical gradients in biotic and abiotic factors may create small-scale spatial variation in arthropod communities, a phenomenon that continues to be understudied. We investigated heterogeneity in the vertical distribution of spider and beetle assemblages in the canopy of sugar maples (Acer saccharum Marshall) (Aceraceae) in a deciduous forest in eastern Canada. Comparisons across four strata (understorey [UN] through upper canopy [UC] crown) documented variation in density, diversity, and species composition. Density of all common families decreased significantly with height and overall species richness of both spiders and beetles was highest in the UN and lowest in the UC crown. We observed greater spatial variation in spider assemblages compared with beetle assemblages and documented differences in spider guild structure: web-spinning spiders were most common in the UN and jumping spiders dominated the canopy. Our results suggest that arthropod assemblages are not homogeneous with respect to vertical space and that heterogeneity exists even at the scale of several metres.

Frequency and Severity of Trunk Decay in Street Tree Maples in Four New York Cities

A proportional random selection of street tree Norway, silver, and sugar maples, and other species among four diameter classes were surveyed in the U.S.’ New York cities of Albany, Buffalo, Rochester, and Syracuse for decay incidence and severity. Decay was determined by drilling sampled trees with a Resistograph and calculating the ratio of sound wood to radius. Overall, 58.3% of the sampled trees had some amount of decay and incidence was highest in sugar maples and in the largest size class trees. However, decay incidence was high (53.2%) even in the smallest diameter tree size class (30.5–45.7cm (12–18 in). Decay severity was greatest in silver maple and in the largest diameter trees, although only 3.2% of the trees sampled had serious decay. The study shows that decay is common in street trees but is seldom severe. It also suggests that decay becomes established early in the life of street trees but is most severe in larger diameter trees and in trees that compartmentalize decay poorly such as silver maple. The frequency and severity of decay in the cities studied indicates that they need to continue to identify and manage trees with decay.

Evaluation of the Fate of Ice Storm-Damaged Urban Maple (Acer) Trees

Annually, ice storms cause millions of dollars of damage to urban trees and infrastructure in the United States and Canada. However, there is limited information to guide judgments on whether to remove ice-damaged trees. This study followed the response of three maple species that were damaged in the 1998 ice storm in northern New York State. Norway (Acer platanoides), silver (A. saccharinum), and sugar maples (A. saccharum) were placed in one of three diameter classes and canopy loss categories and were reevaluated 6 years after the initial damage. Over the 5-year study period, 26.8% of trees were removed, and there was no statistical difference among species, crown loss, or diameter class for these removals. Analysis of a variety of tree health and crown parameters showed that tree species was the most important factor in response, whereas diameter class and crown loss were less important. These results suggest that urban tree managers should consider tree species as an important factor in making removal decisions after an ice storm.