Fidji Gendron

Comparison of various methods for estimating the mean growing season percent photosynthetic photon flux density in forests

Five methods for estimating the mean growing season percent photosynthetic photon flux density (PPFD) were compared to continuous measurements of PPFD throughout the growing season within a young bigleaf maple stand on Vancouver Island (Canada). Measured PPFD was recorded continuously as 10-min averages over the growing season (May 18-October 14, 1996) using 52 gallium arsenide phosphide photodiodes in the understory and a LI-COR quantum sensor (LI-190SA) in the open. Photodiodes were randomly located on a systematic grid of points and represented a wide range of above canopy openings which were classified into three different types of light environments: closed canopy, gaps of various sizes, and open canopy. Objectives of this study were to compare different methods for estimating the growing season %PPFD and to determine the efficiency of these methods in the three light environments. At each photodiode location, instantaneous light measurements using a Ceptometer on sunny days around noon and a LAI-2000 Plant Canopy Analyzer were made and hemispherical canopy photographs were taken. 10-min averages recorded by the photodiodes during completely overcast sky conditions were used as surrogate values for a method that uses instantaneous measurements on overcast days. Finally, a new light model (LITE) developed to estimate growing season %PPFD in a deciduous canopy was tested. All these five methods provided estimates of growing season %PPFD and are much less time consuming than continuous measurements of %PPFD using photodiodes. The three most accurate (r2>0.89) methods to estimate the growing season %PPFD were the 10 min averages on overcast days, the diffuse non-interceptance calculated using the LAI-2000, and the gap light index (GLI) calculated from the hemispherical canopy photographs. These three methods performed similarly in each type of light environment. Although the relationship between the LITE model and the growing season %PPFD was good (r2=0.79), the model systematically underestimated light transmission. The instantaneous sunny days around noon method was the least efficient method (r2=0.68) for estimating the growing season %PPFD, although replacing instantaneous measures with the mean of two 10-min averages improved r2 to 0.84. Estimates on sunny days tended to be low in low light and high in high light. Practical considerations such as equipment availability, cost, sampling and processing time, sky conditions, and the number of microsites to be sampled should be taken into account in the selection of the suitable method for a particular study.

Temporal variations in the understorey photosynthetic photon flux density of a deciduous stand: the effects of canopy development, solar elevation, and sky conditions

The effects of canopy development, solar elevation, and sky conditions on temporal variation in photosynthetic photon flux density (PPFD) were examined within a 9-year-old bigleaf maple stand on Vancouver Island (Canada). PPFD was measured every second and stored as 10-min averages from 18 May to 14 October 1996, at 52 microsites characterised according to their growing season %PPFD (GSP). PPFD and %PPFD variability was examined at three different temporal levels. Specific days in May, July, and September with clear and overcast sky conditions were selected to separate the effects of canopy development and solar elevation on diurnal and seasonal light variability. Diurnal light variability expressed as the mean of the difference between two consecutive 10-min averages of PPFD and %PPFD decreased with increasing GSP on clear days in May. For clear days in July and September, variability was characterised by arc-shaped relationships with high variability for microsites receiving between 20 and 80% GSP and lower variability for microsites below 20 and above 80% GSP. On overcast days, diurnal variability in PPFD increased with increasing GSP while diurnal variability in %PPFD showed an arc-shape relationship. The coefficient of variation of PPFD and %PPFD decreased with increasing GSP on clear days and sunflecks decreased with decreasing GSP and from May to September. Day-to-day light variability expressed as the mean difference between consecutive daily PPFD increased with increasing GSP while the mean difference between consecutive daily %PPFD was higher for microsites receiving between 20 and 80% GSP. The coefficient of variation for the daily PPFD and %PPFD was higher for microsites receiving <20% GSP compared to other microsites. Seasonal light variability showed that microsites with <50% GSP received up to eight times more light in May than in July on both clear and overcast sky conditions because of canopy development. From July to September in clear sky conditions, decrease in light was variable for microsites receiving <40% GSP; probably because of the position of microsites in relation to the solar track. On overcast days, mean daily PPFD above canopy and in the understorey was 2 to 3 times higher in July than in September while mean daily %PPFD remained stable. The possible effects of the types of diurnal and day-to-day light variability on physiological and morphological responses of understorey plants are discussed.

Bioactive Prairie Plants and Aging Adults: Role in Health and Disease

A burgeoning population of aging adults is associated with the search for substances with medicinal activity, and bioactive plants have always been alluring. The North American continent consists of a large bioregion of prairie grasslands rich in biodiversity and natural botanicals appreciated by indigenous and nonindigenous peoples. This chapter reviews the medicinal/cultural uses and chemical properties of selected prairie plants: Hierochloe odorata , Zizania spp. , Glycyrrhiza lepidota , Astragalus crassicarpus , Helianthus tuberosus , Artemisia ludoviciana , Artemisia scoparia , Asclepias syriaca , Asclepias incarnata , Amelanchier alnifolia , Monarda fistulosa , and Mentha arvensis . Their common names in English, French, and indigenous languages are also given. In addition to their nutritive value, a range of bioactivities have been found in these native plants including antioxidant, antitumor, anti-inflammatory, antimicrobial, and antiviral. Further study of these plants/compounds is warranted and can lead to increased value of complementary and alternative medicines/functional foods, appreciation of ethnobotany, and preservation of prairie grasslands.

Exploring and revitalizing Indigenous food networks in Saskatchewan, Canada, as a way to improve food security

The project discussed in this paper was designed to expand research and instigate revitalization of Indigenous food networks in Saskatchewan, Canada, by exploring the current state of local Indigenous food networks, creating a Facebook page, organizing volunteer opportunities and surveying workshop participants regarding their knowledge and interest in Indigenous foods. The survey included Likert scale questions and qualitative questions. Project activities and survey results are discussed using statistical and qualitative analysis of the themes. Results indicate that participants are very interested in learning more about, and having greater access to, traditional foods and suggest that supporting Indigenous food networks may be an appropriate response to food insecurity in communities. Elders and community members are vital players in Indigenous foods exploration and revitalization in Saskatchewan by passing on traditional education.

A Traditional Elder’s Anti-Aging Cornucopia of North American Plants

All major biomes are represented in the expansive North American continent. The continent has a rich and under-appreciated tradition of indigenous uses of foods and medicines derived from the native plants. This chapter features a discussion regarding the following cornucopia of plants, selected by a Native American/Aboriginal Elder: Indian breadroot (Pediomelum esculentum (Pursh) Rydb.), gumweed (Grindelia squarrosa (Pursh) Dunal), Labrador tea (Ledum spp.), and blueberry (Vaccinium spp.). These plants are selected for discussion due to their use or promise in the prevention/treatment of ailments commonly experienced with aging, and may benefit older adults when consumed. They are presented in a way to illustrate both the traditional uses of the plants (indigenous science) and the evidence in support of their bioactive properties (Western science). This approach to the presentation of these plants will allow readers a greater appreciation of Native North American Traditional Medicine.

Immunomodulatory Ethnobotanicals of the Great Lakes

The demand for new medicinal health products encourages an evidence-based evaluation of many wild plants used in traditional ethnomedicine. In North America, indigenous and non-indigenous people from the Great Lakes have used regional plants as phytotherapies for immune system ailments. Bioactive compounds from plants with immunomodulatory properties may serve as important regulators of immunity and inflammation. Prevention and treatment of chronic human diseases (e.g., obesity, diabetes, cancer, and cardiovascular disease) should target inflammatory and oxidative stress, important driving forces in the disease process. Several North American plants from the Great Lakes region are reviewed for their potential impact upon the human immune system: Pinus strobus, Morus rubra, Urtica dioica, Foeniculum vulgare, and Acorus calamus. The anti-inflammatory, antihistaminic, anti-infectious, and antioxidant properties of these plants are examined in detail. Additional study of these plants is warranted to describe their bioactive compounds and mechanisms of action, to acknowledge Aboriginal contributions to complementary and alternative medicine, and to promote sustainable utilization of the Great Lakes’ flora.

Bioactive Prairie Plants and Aging Adults

A burgeoning population of aging adults is associated with the search for substances with medicinal activity, and bioactive plants have always been alluring. The North American continent consists of a large bioregion of prairie grasslands rich in biodiversity and natural botanicals appreciated by indigenous and nonindigenous peoples. This chapter reviews the medicinal/cultural uses and chemical properties of selected prairie plants: Hierochloe odorata , Zizania spp. , Glycyrrhiza lepidota , Astragalus crassicarpus , Helianthus tuberosus , Artemisia ludoviciana , Artemisia scoparia , Asclepias syriaca , Asclepias incarnata , Amelanchier alnifolia , Monarda fistulosa , and Mentha arvensis . Their common names in English, French, and indigenous languages are also given. In addition to their nutritive value, a range of bioactivities have been found in these native plants including antioxidant, antitumor, anti-inflammatory, antimicrobial, and antiviral. Further study of these plants/compounds is warranted and can lead to increased value of complementary and alternative medicines/functional foods, appreciation of ethnobotany, and preservation of prairie grasslands.

Chapter 21 – Bioactive Prairie Plants and Aging Adults: Role in Health and Disease

A burgeoning population of aging adults is associated with the search for substances with medicinal activity, and bioactive plants have always been alluring. The North American continent consists of a large bioregion of prairie grasslands rich in biodiversity and natural botanicals appreciated by indigenous and nonindigenous peoples. This chapter reviews the medicinal/cultural uses and chemical properties of selected prairie plants: Hierochloe odorata , Zizania spp. , Glycyrrhiza lepidota , Astragalus crassicarpus , Helianthus tuberosus , Artemisia ludoviciana , Artemisia scoparia , Asclepias syriaca , Asclepias incarnata , Amelanchier alnifolia , Monarda fistulosa , and Mentha arvensis . Their common names in English, French, and indigenous languages are also given. In addition to their nutritive value, a range of bioactivities have been found in these native plants including antioxidant, antitumor, anti-inflammatory, antimicrobial, and antiviral. Further study of these plants/compounds is warranted and can lead to increased value of complementary and alternative medicines/functional foods, appreciation of ethnobotany, and preservation of prairie grasslands.