Responses in Microbes and Plants to Changed Temperature, Nutrient, and Light Regimes in the Arctic

Abstract

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Initial effects of experimental warming on above- and belowground components of net ecosystem CO2 exchange in arctic tundra

“…In addition, we measured treatment effects on above-and belowground components of plant biomass/nutrient content. This study differs from previous studies on the effects of warming on C balance in mesic/moist tundra (Chapin et al 1995;Christensen et al 1997;Hobbie and Chapin 1998;Jones et al 1998;Jonasson et al 1999) in several major ways. First, it is a short-term study requiring a destructive harvest to determine the initial warming responses not just of GEP and ER, but also of respiration from belowground.…”

“…Soil temperatures are generally warmer in tussock than inter-tussock areas (Table 1; Chapin et al 1979). Long-term warming and fertilisation studies indicate that tundra ecosystems are more responsive to increased nutrient availability than to warmer temperatures (Chapin et al 1995;Jonasson et al 1999). Consequently, the strong nutrient limitation at our site (Chapin et al 1995) suggests that the enhanced tussock leaf nutrient pools (Table 3) and vascular plant primary production in manipulated tussocks resulted from higher soil nutrient availability associated with warming of tussock soils.…”

Balancing positive and negative plant interactions: how mosses structure vascular plant communities

“…Indeed, nitrogen is commonly suggested to be the more important limiting factor in arctic ecosystems (Chapin et al 2002;Jonasson et al 1999;Richardson et al 2002). In our study, however, soil temperature was far more important than nutrient availability in determining the biomass of Alopecurus.…”

Response of NDVI, biomass, and ecosystem gas exchange to long-term warming and fertilization in wet sedge tundra

“…Gross ecosystem production (GEP, always positive), defined as the rate of plant photosynthesis, is calculated as the difference between NEP and ER: GEP=NEPER. For both a and b, means shown below with the same letter are not statistically different at the P 0.05 level of significance range of tundra types (e.g., Henry et al 1986;Jonasson et al 1996Jonasson et al , 1999Press et al 1998;Robinson et al 1998). In a meta-analysis of these past studies, Dorfmann and Woodin (2002) showed that increased nutrient availability consistently caused the greatest changes in aboveground biomass in tundra vegetation, that increased air temperature frequently also increased biomass, and that minor reductions in PAR had little effect while major reductions in PAR caused significant reductions in aboveground biomass and plant growth.…”