Ellen G. Denny

RESPONSE OF SUGAR MAPLE TO CALCIUM ADDITION TO NORTHERN HARDWOOD FOREST

Watershed budget studies at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, have demonstrated high calcium depletion of soil during the 20th century due, in part, to acid deposition. Over the past 25 years, tree growth (especially for sugar maple) has declined on the experimental watersheds at the HBEF. In October 1999, 0.85 Mg Ca/ha was added to Watershed 1 (W1) at the HBEF in the form of wollastonite (CaSiO3), a treatment that, by summer 2002, had raised the pH in the Oie horizon from 3.8 to 5.0 and, in the Oa horizon, from 3.9 to 4.2. We measured the response of sugar maple to the calcium fertilization treatment on W1. Foliar calcium concentration of canopy sugar maples in W1 increased markedly beginning the second year after treatment, and foliar manganese declined in years four and five. By 2005, the crown condition of sugar maple was much healthier in the treated watershed as compared with the untreated reference watershed (W6). Following high seed production in 2000 and 2002, the density of sugar maple seedlings increased significantly on W1 in comparison with W6 in 2001 and 2003. Survivorship of the 2003 cohort through July 2005 was much higher on W1 (36.6%) than W6 (10.2%). In 2003, sugar maple germinants on W1 were approximately 50% larger than those in reference plots, and foliar chlorophyll concentrations were significantly greater (0.27 g/m2 vs. 0.23 g/m2 leaf area). Foliage and fine-root calcium concentrations were roughly twice as high, and manganese concentrations twice as low in the treated than the reference seedlings in 2003 and 2004. Mycorrhizal colonization of seedlings was also much greater in the treated (22.4% of root length) than the reference sites (4.4%). A similar, though less dramatic, difference was observed for mycorrhizal colonization of mature sugar maples (56% vs. 35%). These results reinforce and extend other regional observations that sugar maple decline in the northeastern United States and southern Canada is caused in part by anthropogenic effects on soil calcium status, but the causal interactions among inorganic nutrition, physiological stress, mycorrhizal colonization, and seedling growth and health remain to be established.

Standardized phenology monitoring methods to track plant and animal activity for science and resource management applications

Phenology offers critical insights into the responses of species to climate change; shifts in species’ phenologies can result in disruptions to the ecosystem processes and services upon which human livelihood depends. To better detect such shifts, scientists need long-term phenological records covering many taxa and across a broad geographic distribution. To date, phenological observation efforts across the USA have been geographically limited and have used different methods, making comparisons across sites and species difficult. To facilitate coordinated cross-site, cross-species, and geographically extensive phenological monitoring across the nation, the USA National Phenology Network has developed in situ monitoring protocols standardized across taxonomic groups and ecosystem types for terrestrial, freshwater, and marine plant and animal taxa. The protocols include elements that allow enhanced detection and description of phenological responses, including assessment of phenological “status”, or the ability to track presence–absence of a particular phenophase, as well as standards for documenting the degree to which phenological activity is expressed in terms of intensity or abundance. Data collected by this method can be integrated with historical phenology data sets, enabling the development of databases for spatial and temporal assessment of changes in status and trends of disparate organisms. To build a common, spatially, and temporally extensive multi-taxa phenological data set available for a variety of research and science applications, we encourage scientists, resources managers, and others conducting ecological monitoring or research to consider utilization of these standardized protocols for tracking the seasonal activity of plants and animals.

Evidence for a Rising Cloud Ceiling in Eastern North America

Abstract Data from 24 airport weather stations along the north–south axis (35°–45°N) of the Appalachian Mountains are used to show a significant rising trend in cloud-ceiling height over the past three decades. The mean change in cloud-ceiling height was 4.14 ± 1.03 m yr−1 [mean ± 1 SE (standard error), p ≤ 0.001] across all stations. The trend was negative (−2.22 ± 0.67 m yr−1) for the six stations south of 37.5°N, but positive (6.26 ± 0.89 m yr−1) for the 18 stations north of this latitude. Mean ceiling height for broken cloud cover was higher and rising faster than mean ceiling height for overcast cloud cover. There were strong seasonal patterns that varied between the northernmost and southernmost stations; differences were most pronounced during the spring and summer months. Some of the potential ecological effects on high-elevation forests, where the transition from deciduous to coniferous forest is thought to be controlled by the height of the cloud base, are discussed.

Lilac and honeysuckle phenology data 1956-2014

The dataset is comprised of leafing and flowering data collected across the continental United States from 1956 to 2014 for purple common lilac (Syringa vulgaris), a cloned lilac cultivar (S. x chinensis ‘Red Rothomagensis’) and two cloned honeysuckle cultivars (Lonicera tatarica ‘Arnold Red’ and L. korolkowii ‘Zabeli’). Applications of this observational dataset range from detecting regional weather patterns to understanding the impacts of global climate change on the onset of spring at the national scale. While minor changes in methods have occurred over time, and some documentation is lacking, outlier analyses identified fewer than 3% of records as unusually early or late. Lilac and honeysuckle phenology data have proven robust in both model development and climatic research.

Estimating the onset of spring from a complex phenology database: trade-offs across geographic scales

Phenology is an important indicator of ecological response to climate change. Yet, phenological responses are highly variable among species and biogeographic regions. Recent monitoring initiatives have generated large phenological datasets comprised of observations from both professionals and volunteers. Because the observation frequency is often variable, there is uncertainty associated with estimating the timing of phenological activity. “Status monitoring” is an approach that focuses on recording observations throughout the full development of life cycle stages rather than only first dates in order to quantify uncertainty in generating phenological metrics, such as onset dates or duration. However, methods for using status data and calculating phenological metrics are not standardized. To understand how data selection criteria affect onset estimates of springtime leaf-out, we used status-based monitoring data curated by the USA National Phenology Network for 11 deciduous tree species in the eastern USA between 2009 and 2013. We asked, (1) How are estimates of the date of leaf-out onset, at the site and regional levels, influenced by different data selection criteria and methods for calculating onset, and (2) at the regional level, how does the timing of leaf-out relate to springtime minimum temperatures across latitudes and species? Results indicate that, to answer research questions at site to landscape levels, data users may need to apply more restrictive data selection criteria to increase confidence in calculating phenological metrics. However, when answering questions at the regional level, such as when investigating spatiotemporal patterns across a latitudinal gradient, there is low risk of acquiring erroneous results by maximizing sample size when using status-derived phenological data.

Differential aluminum and calcium concentrations in the tissues of ten Cornus species1

RICHARDSON, A. D., E. G. DENNY, J. A. FORBUSH, T. G. SICCAMA, AND K. S. HUNTER (Yale University, School of Forestry and Environmental Studies, 370 Prospect St., New Haven, CT 06511). Differential aluminum and calcium concentrations in the tissues of ten Cornus species. J. Torrey Bot. Soc. 128: 000-000. 2001.-In both ornamental and forested environments, dogwood anthracnose has caused widespread dieback and decline of Cornus florida L., flowering dogwood, since the late 1970s. Early observations of this disease were more or less simultaneous with the peak of acid rain in North America. Aluminum is known to be toxic to some plants at low concentrations, and soil availability of Al, and hence plant uptake, may be increased by acid rain. Experimental treatment with simulated acid precipitation has been shown to increase the severity of anthracnose infection. In a preliminary study, we observed surprisingly high levels of Al in C. florida wood. Suspecting a possible link between Al and anthracnose, we hypothesized that Al concentrations would be higher in anthracnose-susceptible Cornus species. We also hypothesized that anthracnose-infected C. florida would have higher levels of foliar Al than uninfected trees. Finally, we hypothesized that if there was indeed a link between acid rain and anthracnose via Al uptake and toxicity, that younger wood should have higher concentrations of Al than older wood, reflecting increased soil availability of Al. To investigate the first hypothesis, we collected tissue samples from ten Cornus species from locations across North America for chemical analysis. The four large-bracted species, C. florida, C. nuttallii Aud., C. kousa (Buerger ex Miq.) Hance and C. canadensis L., accumulated Al at concentrations an order of magnitude greater than any of the small-bracted species we studied. However, C. florida and C. nuttallii are known to be highly susceptible to infection by dogwood anthracnose, while C. kousa and C. canadensis are considered resistant to infection. To investigate the second hypothesis, we collected leaves from infected and uninfected trees growing on the same site; Al concentrations in leaves from uninfected trees were actually 432 ppm higher than those from infected trees, suggesting that Al toxicity is not likely a factor in the severity of anthracnose infection. To investigate the third hypothesis, we examined tissue chemistry of both old and young wood. We found that Al concentrations in C. florida wood decreased from older wood to younger wood, contrary to what we would expect if Al availability (and hence plant uptake) had increased as a consequence of acid rain.

Digitization protocol for scoring reproductive phenology from herbarium specimens of seed plants

Premise of the Study Herbarium specimens provide a robust record of historical plant phenology (the timing of seasonal events such as flowering or fruiting). However, the difficulty of aggregating phenological data from specimens arises from a lack of standardized scoring methods and definitions for phenological states across the collections community. Methods and Results To address this problem, we report on a consensus reached by an iDigBio working group of curators, researchers, and data standards experts regarding an efficient scoring protocol and a data‐sharing protocol for reproductive traits available from herbarium specimens of seed plants. The phenological data sets generated can be shared via Darwin Core Archives using the Extended MeasurementOrFact extension. Conclusions Our hope is that curators and others interested in collecting phenological trait data from specimens will use the recommendations presented here in current and future scoring efforts. New tools for scoring specimens are reviewed.

The Plant Phenology Ontology: A New Informatics Resource for Large-Scale Integration of Plant Phenology Data

Plant phenology – the timing of plant life-cycle events, such as flowering or leafing out – plays a fundamental role in the functioning of terrestrial ecosystems, including human agricultural systems. Because plant phenology is often linked with climatic variables, there is widespread interest in developing a deeper understanding of global plant phenology patterns and trends. Although phenology data from around the world are currently available, truly global analyses of plant phenology have so far been difficult because the organizations producing large-scale phenology data are using non-standardized terminologies and metrics during data collection and data processing. To address this problem, we have developed the Plant Phenology Ontology (PPO). The PPO provides the standardized vocabulary and semantic framework that is needed for large-scale integration of heterogeneous plant phenology data. Here, we describe the PPO, and we also report preliminary results of using the PPO and a new data processing pipeline to build a large dataset of phenology information from North America and Europe.

Phenological Implications of Warming Temperatures and Extreme Climatic Events

More than 140 phenology researchers traveled from 6 continents and 21 countries to convene and deliver more than 100 oral presentations and more than 30 posters at the University of Wisconsin-Milwaukee School of Continuing Education Conference Center in downtown Milwaukee at the second interdisciplinary international conference on phenology. The study of recurring plant and animal life-cycle stages, phenology is especially sensitive to variation and change in the environment and climate.

Towards global data products of Essential Biodiversity Variables on species traits

Essential Biodiversity Variables (EBVs) allow observation and reporting of global biodiversity change, but a detailed framework for the empirical derivation of specific EBVs has yet to be developed. Here, we re-examine and refine the previous candidate set of species traits EBVs and show how traits related to phenology, morphology, reproduction, physiology and movement can contribute to EBV operationalization. The selected EBVs express intra-specific trait variation and allow monitoring of how organisms respond to global change. We evaluate the societal relevance of species traits EBVs for policy targets and demonstrate how open, interoperable and machine-readable trait data enable the building of EBV data products. We outline collection methods, meta(data) standardization, reproducible workflows, semantic tools and licence requirements for producing species traits EBVs. An operationalization is critical for assessing progress towards biodiversity conservation and sustainable development goals and has wide implications for data-intensive science in ecology, biogeography, conservation and Earth observation.Essential Biodiversity Variables (EBVs) are intended to provide standardized measurements for reporting biodiversity change. Here, the authors outline the conceptual and empirical basis for the use of EBVs based on species traits, and highlight tools necessary for creating comprehensive EBV data products.