Biogeography of Two Southwest American Oaks in Relation to Atmospheric Dynamics

Neilson, Ronald P.; Wullstein, L. H.

doi:10.2307/2844738

Cited by 129 publications

(83 citation statements)

References 48 publications

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“…Paleoecological studies have indicated that the distributions of piñon and juniper species have been dynamic over the last 10,000 years, undergoing considerable northwards expansion during the Holocene, to approximately their modern distributions (Betancourt 1987;Betancourt et al 1990;Lanner and Van Devender 1998;van Devender 1987). There is some evidence to suggest that this was associated with a shift in the North American monsoon (Neilson and Wullstein 1983) and changes in temperature that allowed establishment of plants on the Colorado Plateau (Betancourt 1987;Malusa 1992). Furthermore, isotopic evidence from P. edulis needles from the last 40,000 years indicates that P. edulis persistence is tightly coupled to the presence of summer rain (Pendall et al 1999).…”

Section: Discussionmentioning

confidence: 94%

Seasonal variations in moisture use in a piñon–juniper woodland

et al. 2007

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In water-limited environments of the intermountain region of North America, summer precipitation may play a role in the structure and function of aridland communities and ecosystems. This study examined the potential reliance on summer precipitation of two widespread, coexisting woody species in the southwestern United States, Pinus edulis Englmn. (Colorado piñon) and Juniperus osteosperma (Torr) Little (Utah juniper). The current distributions of P. edulis and J. osteosperma are highly suggestive of different dependencies on summer rainfall. We hypothesized that P. edulis was dependent on summer precipitation, utilizing summer precipitation even during extremely dry summers, whereas J. osteosperma was not dependent, using summer precipitation only when amounts were above some minimum threshold. Using sap flux and stable isotopic methods to assess seasonal water sources and water use efficiency, we examined the response of these two species to seasonal variations in moisture at a site located near the northern limits of the North American monsoon. Both sap flux and isotopic results indicated that P. edulis was responsive to summer rain, while J. osteosperma was not. Following summer rain events, sap flux density increased in P. edulis for several days, but not in J. osteosperma. Isotopic evidence indicated that P. edulis took up summer-derived moisture to a greater extent than J. osteosperma. Values of the natural abundance stable isotope ratio of carbon of leaf soluble carbohydrates increased over the summer for P. edulis, indicative of assimilation at higher water use efficiency, but were invariant for J. osteosperma. Our results supported the hypothesis that P. edulis and J. osteosperma are differentially sensitive to summer precipitation and are discussed in the light of potential changes in the seasonality of precipitation associated with climate change.

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Section: Discussionmentioning

confidence: 94%

Seasonal variations in moisture use in a piñon–juniper woodland

et al. 2007

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“…The distributions of species may also be explained differently at different scales. For example, oak seedling mortality at local scales decreases with increasing precipitation, whereas mortality at regional scales is lowest in the drier latitudes (Neilson and Wulstein 1983). Therefore, predicting across scales requires that the changes in the relative importance of parameters with scale be understood.…”

Section: Understanding the Importance Of Parameters At Different Scalesmentioning

confidence: 99%

Predicting across scales: Theory development and testing

1989

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Landscape ecologists deal with processes that occur at a variety of temporal and spatial scales. The ability to make predictions at more than one level of resolution requires identification of the processes of interest and parameters that affect this process at different scales, the development of rules to translate information across scales, and the ability to test these predictions at the relevant spatial and temporal scales. This paper synthesizes discussions from a workshop on 'Predicting Across Scales: Theory Development and Testing' that was held to discuss current research on scaling and to identify key research issues.

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“…This suggests that summer drought was the proximate cause of death in these cases (cf. Neilson & Wullstein, 1983).…”

Section: Observed Causes Of Mortalitymentioning

confidence: 99%

Demography of Betula pubescens ssp. tortuosa sown in contrasting habitats close to the birch tree-limit in Central Sweden

Kullman

1986

Vegetatio

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Seeds of mountain birch (Betula pubescens Ehrh. ssp. tortuosa (Ledeb.) Nyman) were sown on permanent plots in three contrasting habitats close to the birch tree-limit in Central Sweden. The habitats differed mainly in regard to the length of the growth period, as determined by the pattern of local snow-accumulation. Germination success, seedling demography (1981)(1982)(1983) and related aspects of the early stages were studied. Germination was found to start shortly after snowmelt in the year after ripening, in all three habitats. The conclusion is that germination is not the crucial phase of the life-cycle. In the habitat with the longest growth period, and where spontaneous birch stands are present, mortality mainly occurred in summer, evidently caused by soil drought. With shortening of the growth period, however, mortality during the winter became increasingly important. Survival was clearly correlated with the length of the growth period and the autumn height of seedlings. Factors which affect ecesis determine the altitude of the tree-limit and the long-term stability of the mountain birch forest ecosystem.

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Biogeography of Two Southwest American Oaks in Relation to Atmospheric Dynamics

Cited by 129 publications

References 48 publications

Seasonal variations in moisture use in a piñon–juniper woodland

Seasonal variations in moisture use in a piñon–juniper woodland

Predicting across scales: Theory development and testing

Demography of Betula pubescens ssp. tortuosa sown in contrasting habitats close to the birch tree-limit in Central Sweden

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