A spatial regression procedure for evaluating the relationship between AVHRR-NDVI and climate in the northern Great Plains

Abstract On the basis of snowfall observations from 1929 to 1999, positive (negative) snowfall anomalies are associated with wetter (drier) than normal conditions during the summer [July–August (JJA)] in the northern Great Plains. The five driest summers are associated with negative snowfall anomalies during the preceding winter (−66.7 mm) and spring (−62.4 mm) that cover most of the study region (∼85%). Snowfall anomalies during the late spring (April–May) are more important for determining summer moisture conditions than snowfall anomalies in fall [September–November (SON)] or winter [December–February (DJF)]. The link between snowfall anomalies and summer moisture conditions appears to be, at least partly, through soil moisture since positive (negative) snowfall anomalies are associated with wetter (drier) soils, a later (earlier) date of snowmelt, cooler (warmer) air temperatures, and more (less) evaporation during spring and summer. However, the relationship between spring snowfall and summer moisture conditions is only statistically significant when the moisture anomaly index (Z), which accounts for both temperature and precipitation, is used to characterize summer moisture conditions and the signal is weak when just considering precipitation (e.g., standardized precipitation index). Results also indicate that the strength of the relationship between winter/spring snowfall and summer moisture varies significantly over space and time, which limits its utility for seasonal forecasting.

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RELATIONSHIP OF CHLOROGENIC ACID CONCENTRATION IN SUNFLOWER ACHENES TO BIRD PREDATION OF SUNFLOWER

Canadian Journal of Plant Science ◽

10.4141/cjps86-002 ◽

1986 ◽

Vol 66 (1) ◽

pp. 11-17 ◽

Cited By ~ 1

Author(s):

D. E. PARFITT ◽

G. J. FOX ◽

J. D. BROSZ

Keyword(s):

Chlorogenic Acid ◽

Great Plains ◽

Passer Domesticus ◽

Northern Great Plains ◽

Bird Predation ◽

Xanthocephalus Xanthocephalus ◽

Helianthus Annus ◽

Bird Damage ◽

Relationship Of ◽

The Relationship

Blackbird feeding on sunflower is a significant problem in parts of the Northern Great Plains. Therefore, experiments were initiated to determine the relationship of chlorogenic acid (CA) in sunflower achenes to bird predation and the amount of variability for CA in sunflower genotypes. Eight inbred sunflower (Helianthus annuus L.) genotypes with variable levels of resistance to blackbird (Agelaius phoeniceus L. and Xanthocephalus xanthocephalus Bonaparte) and house sparrow (Passer domesticus L.) predation were evaluated at two locations in 1979 and 1980 for seed and hull CA. Differences were observed among inbred sunflower genotypes for CA concentration in both hull and seed. However, no significant correlation between percent CA in seed and mean percent bird damage over the four tested environments was observed. An unexpected positive correlation for hull CA and bird damage was found, however. Achene samples were taken from three positions within the sunflower head (outside, middle and inside) from seven inbred lines at three sampling dates. Genotype influenced CA level in both achene components while sampling date influenced CA level in the seed only. Position of achenes within the sunflower head did not influence CA concentration of either hull or seed. Thus, it is unlikely that the CA concentration of physiologically mature sunflower achenes (hull or seed) causes the observed bird predation pattern (edge to center) on sunflower heads. CA concentration is not apparently related to bird damage.Key words: Sunflower, bird feeding, chlorogenic acid, Helianthus annus L., blackbird

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Tamarisk (Tamarixspp.) Establishment in its Most Northern Range

Invasive Plant Science and Management ◽

10.1614/ipsm-d-10-00036.1 ◽

2011 ◽

Vol 4 (1) ◽

pp. 58-65 ◽

Cited By ~ 8

Author(s):

Erik A. Lehnhoff ◽

Fabian D. Menalled ◽

Lisa J. Rew

Keyword(s):

Great Plains ◽

Storage Time ◽

Storage Period ◽

Water Levels ◽

Regulated River ◽

Northern Great Plains ◽

Riparian Areas ◽

Greenhouse Study ◽

The Relationship ◽

Hydrologic Conditions

AbstractTamarisk, a shrub or small tree native to Eurasia, was introduced to North America in the early 1800s and is now naturalized throughout many riparian areas of the southwestern United States, where extensive research has been conducted. It is a more recent invader to the northern Great Plains, and fewer studies have been conducted on tamarisk ecology and management in this area. The objectives of this research were to investigate the overwintering potential of tamarisk seeds in Montana and the relationship between hydrologic conditions and historic tamarisk establishment. Emergence of seedlings from seeds stored for different time periods at a range of temperatures was evaluated in a greenhouse study. Emergence rates declined after a 7-d storage period, but storage time had no effect on subsequent emergence rates, and seeds stored at −14 C and 5 C had greater emergence rates than those stored at 20 C and 35 C. Patterns in tamarisk establishment were assessed through age and hydrologic data collected from a reservoir (Fort Peck), a regulated river (Bighorn), and an unregulated river (Yellowstone) in Montana. These data indicated that tamarisk establishment at the reservoir was closely related to historic water levels, whereas establishment on rivers was not related to flow. However, data from the rivers indicated that recruitment differed between regulated and unregulated rivers, with the regulated river having less recruitment after the period of initial colonization than the unregulated river. Our results show that tamarisk seeds have the ability to overwinter in Montana and can establish under a range of flow conditions, indicating potential recolonization of sites after tamarisk removal.

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