Diversity or Redundancy in Leaf Physiological and Anatomical Parameters in a Species Diverse, Bottomland Hardwood Forest?

Research Highlights: Bottomland hardwood forests exhibit seasonal flooding, are species diverse, and provide numerous ecosystem services including floodwater storage, wildlife habitat and nutrient mitigation. However, data are needed to adequately predict the potential of individual species to achieve these services. Background and Objectives: In bottomland hardwood forests, increasing tree species richness may increase functional diversity unless species exhibit an overlap in physiological functioning. Therefore, the objectives of this study were to (1) compare physiological and anatomical leaf parameters across species, (2) determine if leaf anatomical and nutrient properties were correlated with physiological functioning, (3) determine intra-species variability in leaf stomatal properties and determine how whole crown metrics compare with leaves measured for gas exchange and (4) measure soil nitrogen for evidence of denitrification during inundation periods. Materials and Methods: We measured gas exchange, leaf nutrients and anatomical properties in eight bottomland hardwood species including Carya ovata, Fraxinus pennsylvanica, Quercus michauxii, Quercus nigra, Quercus pagoda, Quercus phellos, Ulmus alata and Ulmus americana. Additionally, we quantified soil ammonium and nitrate content during winter inundated conditions to compare with non-inundation periods. Results: We found that leaf-level water use parameters displayed greater variability and diversity across species than photosynthesis and leaf nitrogen parameters, but green ash and shagbark hickory exhibited generally high leaf N concentrations and similar physiological functioning. Elms and oaks displayed larger variability in leaf physiological functioning. Stomatal density was significantly correlated with photosynthetic capacity and tree-level water use and exhibited high intra-species variability. Conclusions: This bottomland hardwood forest contains more diversity in terms of water use strategies compared with nitrogen uptake, suggesting that differences in species composition will affect the hydrology of the system. Green ash and shagbark hickory exhibit higher leaf nitrogen concentrations and potential for nutrient mitigation. Finally, leaf anatomical parameters show some promise in terms of correlating with leaf physiological parameters across species.

Cryphonectria parasitica. [Distribution map].

A new distribution map is provided for Cryphonectria parasitica (Murrill) M.E. Barr. Ascomycota: Diaporthales. Hosts: Chestnut (Castanea spp.), Italian alder (Alnus cordata), apple (Malus domestica), Quercus spp., Castanopsis spp., Acer spp., staghorn sumac (Rhus typhina) and shagbark hickory (Carya ovata). Information is given on the geographical distrution in Europe (Albania, Austria, Belgium, Bosnia-Herzegovina, Bulgaria, Croatia, Czech Republic, France, Corsica, Mainland France, Germany, Greece, Mainland Greece, Hungary, Italy, Mainland Italy, Sardinia, Sicily, Macedonia, Netherlands, Poland, Portugal, Azores, Madeira, Mainland Portugal, Romania, Russia, Southern Russia, Serbia, Slovakia, Slovenia, Spain, Mainland Spain, Switzerland, Ukraine), Asia (Azerbaijan, China, Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Jiangsu, Jiangxi, Liaoning, Shaanxi, Shandong, Yunnan, Zhejiang, Georgia, India, Uttar Pradesh, Uttarakhand, Iran, Japan, Honshu, Korea Democratic People's Republic, Korea Republic, Taiwan, Turkey), Africa (Tunisia), North America (Canada, British Columbia, Ontario, USA, Arkansas, California, Connecticut, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Massachussetts, Michigan, Minnesota, Mississippi, New Hampshire, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Tennessee, Texas, Virginia, Washington, West Virginia, Wisconsin), Oceania (Australia, Victoria).

Nut Selection by Captive Blue Jays: Importance of Availability and Implications for Seed Dispersal

We assessed dietary preference of 14 captive Blue Jays (Cyanocitta cristata) for different food types under different conditions of availability. In four separate feeding trials, we provisioned jays with the following: Trial 1, two nuts each of white oak (Quercus alba), pin oak (Q. palustris), black oak (Q. velutina), northern red oak (Q. rubra), and shagbark hickory (Carya ovata); Trial 2, two small and two large red oak acorns; Trial 3, two germinating and two nongerminating white oak acorns; and Trial 4, one large red oak acorn, one large white oak acorn, and one shagbark hickory nut. We used discrete choice models to describe selection under conditions of changing choice sets. Blue Jays displayed a clear preference for pin oak and strong avoidance of red oak acorns when alternative foods were available. White oak and black oak acorns were selected intermediately. Shagbark hickory nuts were never used. Correlation coefficients suggested that preference was inversely related to seed size and the proportion of seed consisting of hard seed coat. In the absence of alternative food items, small red oak acorns were readily taken, whereas large red oak acorns were mostly avoided but still used by some birds. These results highlight the importance of considering food availability when making conclusions about preference, and lend support to the hypothesis that Blue Jays can be important dispersers of even less-preferred oak species. We discuss the potential as well as the limitations for Blue Jays to act as seed dispersers, with respect to postglacial range expansion of fagaceous tree species, and in the context of present-day dispersal in regions where forests are highly fragmented.

Cryphonectria parasitica. [Descriptions of Fungi and Bacteria].

A description is provided for Cryphonectria parasitica. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Particularly Castanea dentata (American chestnut); other Castanea spp., Acer spp. Quercus spp., Carya ovata (shagbark hickory) and Rhus typhina (staghorn sumach), (30, 550; 33, 569; 34, 759; 42, 709; 43, 2426; 48, 946; 54, 1012; 56, 410; 57, 1569). DISEASE: Chestnut Blight. GEOGRAPHICAL DISTRIBUTION: Asia (China, India (Uttar Pradesh), Japan, Korea, Turkey, USSR (Caucasus); Europe (Belgium, France, Greece, Hungary, Italy, Portugal, Spain, Switzerland, USSR (Ukraine), Yugoslavia); N. America (Canada (British Colombia, Ontario), USA (E. including Florida, California, Oregon and Washington) (CMI Map 66, ed. 4, 1973) TRANSMISSION: The slimy conidia are spread in water and carried long distances by birds and insects. The ascospores are air dispersed; acospore discharge has been described (59, 471).