Dendroclimatic Analysis of White Spruce at its Southern Limit of Distribution in the Spruce Woods Provincial Park, Manitoba, Canada

Abstract

We examined the radial growth-climate association of a disjunct population of white spruce (Picea glauca (Moench) Voss) at its southern limit of distribution. Forty-four white spruce tree islands were sampled over four mixed-grass prairie preserves in the Spruce Woods Provincial Park located in the forestprairie boundary of southwestern Manitoba. Reduced radial growth occurred during the 1910s, 1930s, early 1960s, and the late 1970s to the early 1980s and corresponded to periods of drought on the Canadian prairies, and the Great Plains of the United States. Correlation and response function coefficients indicated that conditions in the summer and fall of the previous year (t-1), and the summer of the current year (t) strongly influenced white spruce growth. Growth was positively correlated with August-September (t-1) and May-June-July (t) precipitation and moisture index (precipitation minus potential evapotranspiration). Radial growth was positively associated with June-July-August (t) river discharge. Growth was most correlated with maximum and mean temperature compared with minimum temperature. Precipitation and maximum temperature accounted for the greatest variation in radial growth (61%). The results suggest that white spruce growth is sensitive to climatic fluctuations because growth is restricted by moisture deficiency exacerbated by temperature-induced drought stress.Keywords: aspen parkland, climate change, dendroclimatology, drought stress, mixed-grass prairie, Picea glauca (Moench) Voss, prairie-forest boundary, response function. RÉ SUMÉL'association entre l'accroissement radial et le climat fut examinée chez une population disjointe d'épinette banche croissant à sa limite sud de distribution. Quarante-quatre épinettes ont été échantillonnées dans quatre réserves de la prairie d'herbes mixtes du Parc Provincial Spruce Woods situé au sud-ouest du Manitoba, à l'interphase entre la forêt et la prairie. De faibles accroissements radiaux furent observés au cours des années 1910, 1930, au début des années 1960 et de la fin des années 1970 au début des années 1980. Ces épisodes correspondent tous à des périodes de sécheresse survenues dans les prairies canadiennes et les grandes plaines américaines. Les coefficients de corrélation et des fonctions de réponse ont démontré que les conditions encourues durant l'été et l'automne antérieurs (t-1) à la formation du cerne et durant l'été de la formation du cerne (t) influencent fortement la croissance radiale de l'épinette blanche. L'accroissement fut positivement corrélé aux précipitations des mois de août-septembre (t-1) et des mois de Mai-Juin-Juillet (t) de même qu'à un indice d'humidité (précipitation moins évapotranspiration potentielle). L'accroissement radial fut positivement associé aux débits fluviaux des mois de Juin-Juillet-Août (t). La croissance était aussi plus fortement corrélée aux températures maximales et moyennes qu'aux températures minimales. Les précipitations et les températures maximales ont expliqué 61% de la variation de la crois...

Climatic Sensitivity of a Mixed Forest Association of White Spruce and Trembling Aspen at Their Southern Range Limit

“…The weak response to monthly precipitation as well as the lack of correlation with the annualized periods of precipitation suggest that white spruce trees benefited from the moderated microclimate of aspen groves. These results are very much in contrast to white spruce growing in pure tree island stands which had a strong and direct association with precipitation [24]. The reduced effect of drought stress on white spruce supports the stress gradient hypothesis in which facilitative interactions between tree species are expected under harsher environmental conditions [6][7][8][9].…”

“…Therefore, temperature induced drought stress during the summer of the current year can negatively affect growth, and this was also observed in white spruce growing in pure stands [24,39]. It is unclear why growth was negatively correlated with the spring and early growing season months as well as the annualized periods of river discharge.…”

“…Furthermore, drought stress has also been shown to limit white spruce growth at its northern range limit [18,19]. In the Canadian prairies, dendroclimatological studies of white spruce have also been undertaken where climatic moisture deficiency has been identified as the principal factor that controls the southern distribution limit of coniferous tree species [20][21][22][23][24][25].…”

Growth of White Spruce, <em>Picea glauca</em>, Seedlings in Relation to Microenvironmental Conditions in a Forest-Prairie Ecotone of Southwestern Manitoba

“…The prevailing regional climate of the aspen parkland and mixed-grass prairie in southwestern Manitoba is characterized by low precipitation, high summer temperatures, and dry winds, any of which may be limiting factors to plant distribution and growth (Coupland 1950). For instance, previous studies which examined the radial growth-climate association of White Spruce [Picea glauca (Moench) Voss] in the aspen parkland region demonstrated that growth was restricted by moisture deficiency exacerbated by temperature-induced drought stress (Chhin et al 2004).…”

The relationship between climate and outbreak dynamics of Dothistroma needle blight in northwest British Columbia, Canada.

“…Autoregressive modeling, therefore, makes observations independent to meet the condition of most statistical analyses. Furthermore, autoregressive modeling removes low-frequency variation and enhances the common growth signal, which is usually best correlated with yearly climatic fluctuations (Linderholm et al 2003, Chinn et al 2004). …”