Nitrogen deposition and forest expansion in the northern Great Plains

Köchy, Martin; Wilson, Scott D.

doi:10.1046/j.0022-0477.2001.00600.x

Cited by 137 publications

(106 citation statements)

References 57 publications

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“…The rate of woody encroachment into these environments has changed during the past century, increasing in some regions (Archer 1989;Van Auken 2000) and decreasing in others (del Moral 1985;Goldberg and Gross 1988;Inouye et al 1994;Lawson et al 1999). These changes in woody encroachment have been variously attributed to changes in fire frequency, grazing and browsing patterns, dispersal limitation, and resource availability (Archer 1989;Wilson 1993;Inouye et al 1994;Weltzin et al 1997;Davis et al 1999;Van Auken 2000;Kochy and Wilson 2001).…”

Section: Introductionmentioning

confidence: 99%

Non-indigenous grasses impede woody succession

et al. 2005

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With the proliferation of old fields and the decline of native grasslands in North America, non-indigenous grasses, which tend to colonize and dominate North American old fields, have become progressively more abundant. These new grasses can differ from native grasses in a number of ways, including root and shoot morphology (e.g., density of root mat, height of shoots), growth phenology (e.g., cool season vs. warm season growth), and plant-soil-water relations due to differences in photosynthetic physiology (C 3 vs. C 4 ). Woody plants have been slow to colonize some old fields in the prairie-forest border area of North America and it is hypothesized that non-indigenous grasses may be contributing to the poor establishment success of woody plants in this region, possibly through more intense competition for resources. To test this hypothesis, a multi-factorial field experiment was conducted in which water, nitrogen, and grass functional group (non-indigenous C 3 and native C 4 species) were manipulated in a study of survival of oak seedlings. The grass type variously affected some of the different growth measurements, however, the effects of grass type on seedling growth were small compared to the effects on seedling survival. The results showed that when grown under dry conditions, seedlings growing in non-indigenous grasses experienced up to a 50% reduction in survival compared to those growing in native grasses under the same conditions. Analyses of root and shoot competition showed that the cause for the reduced survival in the non-indigenous grasses was due primarily to underground processes. The findings confirmed our initial hypothesis that nonindigenous grasses are likely contributing to the poor establishment success of woody plants in these old fields. However, the explanation for the reduced oak seedling survival in non-indigenous grasses does not appear to be due to reduced resource availability since soil water levels did not differ between nonindigenous and native grass plots and other resource levels measured (light, NO 3 , and NH 4 ) were higher in non-indigenous grass plots under dry conditions. An alternative explanation is that the non-indigenous grasses modify the soil environment in ways that, under dry conditions, are deleterious to emerging oak seedlings. Since current climate projections for the upper Midwest are for hotter and drier summers, the results suggest that the resistance of these old fields to oak encroachment will likely increase in the future.

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Section: Introductionmentioning

confidence: 99%

Non-indigenous grasses impede woody succession

et al. 2005

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“…This was presumably due to higher N input with litter in forests. Total N in forest litter is 10 g/m 2 but only 4 g/m 2 in shrubland (Köchy & Wilson 2001). Decomposition rates are probably similar in both habitats since litter quality estimated by N concentration in forest (0.9%) and shrub 5 litter (1.1%) is similar (Köchy 1999).…”

Section: Soil Nitrogenmentioning

confidence: 90%

“…and measured with an ion-selective electrode (Köchy & Wilson 2001). We Data analysis.-One hundred and three above-surface and 26 belowsurface bags contained N equivalent to >100 kg ha -1 yr -1 .…”

Section: Study Sitesmentioning

confidence: 99%

“…In the ecotone between boreal forest and semi-arid grassland, climate and competition are presumably more important as controls of tree invasion than are fire and grazing (Archer 1994). Deposition of atmospheric N may be expected to increase the competitive ability of woody species and accelerate forest 15 invasion at the northern edge of the prairie (Köchy & Wilson 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Higher rates of N deposition are linked to higher soil N availability (Kazada & Katzensteiner 1993;Köchy & Wilson 2001). The stength of this 20 link varies with soil type and soil N content due to their influence on mineralization and denitrification (Lovett & Rueth 1999;Lemke et al 1998).…”

Section: Introductionmentioning

confidence: 99%

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Variation in nitrogen deposition and available soil nitrogen in a forest–grassland ecotone in Canada

Köchy

Wilson

2005

Landscape Ecol

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word count: 7106Nitrogen deposition and availability, Köchy M., page 2, 2004-05-23 2 AbstractRegional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape-or local-scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National 5Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha -1 yr -1 ). N deposition was on average higher ton clayrich luvisols than on brunisols, and areas burned 1 -15 years previously received more atmospheric N than unburned sites. We suggest that the 10 effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting 15 an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition. 20

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Atmospheric concentrations and deposition of reactive nitrogen in Grand Teton National Park

et al. 2013

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[1] The Grand Teton Reactive Nitrogen Deposition Study (GrandTReNDS) was conducted to provide a more complete look at atmospheric concentrations and deposition fluxes of various reactive nitrogen species in and around Grand Teton National Park (GTNP). Daily measurements of wet deposition, PM 2.5 composition, and gaseous ammonia and nitric acid concentrations were made at three locations. Weekly measurements of gaseous ammonia were made at eight additional sites. Ammonia concentrations were higher at the western sites; the study average ammonia concentration west of GTNP was 35 nmol m À3 and on the east side of the park it was 18 nmol m À3. Concentrations of other measured reactive nitrogen species were lower than NH 3 and fairly similar at all sites, with averages of approximately 9, 1, and 3 nmol m À3 for ammonium, nitrate, and nitric acid, respectively. Wet deposition of ammonium and dry deposition of ammonia were the largest reactive nitrogen deposition pathways, together accounting for 56% and 62% of the nitrogen deposition on the east and west sides of GTNP, respectively. Nitrogen deposition of measured species totaled 2.38 kg N ha À1 west of GTNP at Driggs, ID (6 April to 21 September 2011), 0.85 kg N ha À1 west of GTNP at a high-elevation site (28 July to 21 September 2011) and 1.23 kg N · ha À1 at a location on the east side of GTNP (15 May to 21 September 2011). These measurements highlight the significant inputs of reactive nitrogen to regional ecosystems over the few months studied, the importance of including NH 3 dry deposition in nitrogen deposition budgets, and the need to conduct further research to capture sources and the annual cycle of deposition.

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Nitrogen deposition and forest expansion in the northern Great Plains

Cited by 137 publications

References 57 publications

Non-indigenous grasses impede woody succession

Non-indigenous grasses impede woody succession

Variation in nitrogen deposition and available soil nitrogen in a forest–grassland ecotone in Canada

Atmospheric concentrations and deposition of reactive nitrogen in Grand Teton National Park

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