Effects of shading, nutrient application and warming on leaf growth and shoot densities of dwarf shrubs in two arctic-alpine plant communities

Graglia, Enrico; Jonasson, Sven; Michelsen, Anders; Schmidt, Inger Kappel

doi:10.1080/11956860.1997.11682395

Cited by 70 publications

(82 citation statements)

References 17 publications

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“…In combination with the moderate effects caused by addition of labile C and the consequent microbial immobilization of nutrients (leading, for example, to slight decreases in the concentrations of N and K in leaves and in current-year stem biomass only), our data suggest that this species may be more limited by other factors, such as growing-season length and temperature, than by nutrients at this subarctic heath. This behaviour is similar to that of other dwarf shrubs without a main arctic-alpine distribution (Graglia et al, 1997). The independence of inorganic nutrient supply may be due to large nutrient stores in the stems which serve as a buffer against shorter-term fluctuations in the availability of soil nutrients, and also to the intense colonization of roots by ericoid mycorrhizal fungi which promote nutrient uptake in organic form.…”

Section: Seasonal Changes In Plant Nutrient Demand : Effects Of Nutrimentioning

confidence: 50%

Differential responses of grass and a dwarf shrub to long‐term changes in soil microbial biomass C, N and P following factorial addition of NPK fertilizer, fungicide and labile carbon to a heath

et al. 1999

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Microbial immobilization may decrease the inorganic nutrient concentrations of the soil to the extent of affecting plant nutrient uptake and growth. We have hypothesized that graminoids with opportunistic nutrient-acquisition strategies are strongly influenced by nutrient limitation imposed by microbes, whereas growth forms such as dwarf shrubs are less affected by the mobilization-immobilization cycles in microbes. By adding NPK fertilizer, labile C (sugar) and fungicide (benomyl) over a 5 yr period in a fully factorial design, we aimed to manipulate the sink-source potential for nutrients in a non-acidic heath tundra soil. After 2 yr, N and P accumulated in the microbial biomass after fertilization with no change in microbial C, which suggests that nutrients did not limit microbial biomass growth. After 5 yr, microbial C was enhanced by 60 % in plots with addition of labile C, which points to C-limitation of the microbial biomass. Microbial biomass N and P tended to increase following addition of labile C, by 10 and 25 %, respectively. This caused decreased availability of NH % + and P, showing close microbial control of nutrient availability. The most common graminoid, Festuca ovina, responded to fertilizer addition with a strong increase, and to labile C addition with a strong decrease in cover, providing the first direct field evidence that nutrient limitation imposed by immobilizing microbes can affect the growth of tundra plants. Also in support of our hypothesis, following addition of labile C the concentrations of N and K in leaves and that of N in roots of F. ovina decreased, whilst the demand of roots for P increased. In contrast, the most common dwarf shrub, Vaccinium uliginosum, was only slightly sensitive to changes in resource availability, showing no cover change after 4 yr addition of labile C and fertilizer, and little change in leaf nutrient concentrations. We suggest that the differential responses of the two growth forms are due to differences in storage and nutrient uptake pathways, with the dwarf shrub having large nutrient storage capacity and access to organic forms of N through its mycorrhizal association. While the fungicide had no effect on ericoid mycorrhizal colonization of roots or symbiotic function inferred from plant "&N natural abundance, it decreased microbial biomass C and N after 2 yr. Throughout the fifth season, the availability of soil NO $ − and inorganic P was decreased with no change in microbial biomass C, N or P, suggesting a negative impact of benomyl on N and P mineralization.

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Section: Seasonal Changes In Plant Nutrient Demand : Effects Of Nutrimentioning

confidence: 50%

Differential responses of grass and a dwarf shrub to long‐term changes in soil microbial biomass C, N and P following factorial addition of NPK fertilizer, fungicide and labile carbon to a heath

et al. 1999

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“…Although rates of leaf-based net gas exchange were only modestly enhanced in the deciduous shrubs following nutrient addition, this was nonetheless associated with an increased mass of individual shoots, but not with higher leaf area per shoot. Reports of experimental fertilization in (sub)arctic heath communities have, similarly, shown increased mass of current-year shoots in dwarf shrubs from fertilized plots whereas leaf area, number of leaves per shoot and LMR did not always change accordingly (Karlsson 1985;Graglia et al 1997). Higher concentrations of foliar nutrients in the fertilized plots were accompanied by a lower SLM in E. hermaphroditum and V. uliginosum, but not in V. myrtillus.…”

Section: Effects Of Fertilizationmentioning

confidence: 72%

Nutrient and carbon relations in subalpine dwarf shrubs after neighbour removal or fertilization in northern Italy

et al. 2002

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Two subalpine dwarf-shrub heath communities with differing levels of soil nutrient availability were subjected to a 3-year experimental manipulation, including nutrient addition or removal of one of the two co-dominant species from each community. The main objective of our study was to assess the relative importance of interspecific competition versus nutrient limitation in relation to soil fertility. We also aimed to investigate if and to what extent current-year shoot size, leaf-based rates of net photosynthesis and foliar nutrient status accounted for the observed changes in the aboveground biomass of the shrubs. At the end of the experiment, neighbour removal increased the aboveground biomass of all shrubs, especially in the more fertile community, while fertilization did not. We concluded that: (1) competition is more effective than nutrient limitation in structuring the vegetation of subalpine heathlands; and (2) competition intensity is stronger in the more fertile community. The observed patterns of variations in aboveground biomass were not consistently related to net photosynthetic rates, size of individual shoots and foliar nutrient status. Hence, we also concluded that the growth response of dwarf shrubs to altered environmental conditions is primarily determined by developmental plasticity.

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“…In previous studies of warming effects on plant communities, the performance of dominant component species or functional types has been measured in various regions; for example, that of graminoids, deciduous and evergreen shrubs, and mosses in a moist tussock tundra (Chapin et al 1995), rhizomatous sedges in a wet tundra in arctic Alaska (Shaver et al 1998), and evergreen and deciduous shrubs, graminoids, and forbs in a subalpine heath and an alpine fellfield in northern Sweden (Graglia et al 1997(Graglia et al , 2001Molau 2001). In Japanese alpine fellfields, deciduous and evergreen shrub species are major components of the communities (Kudo and Suzuki 2002;Wada et al 2002).…”

Section: Introductionmentioning

confidence: 99%

“…However, the changing patterns of nutrient availability caused by global warming are difficult to predict (Callaghan and Jonasson 1995;Rustad et al 2001). On the other hand, several studies have demonstrated that warming without increased nutrient supply could influence the growth and production of tundra plants (Parsons et al 1994;Graglia et al 1997;Hobbie and Chapin 1998;Press et al 1998;Molau 2001;Rustad et al 2001). Mid-latitude alpine ecosystems contain the southern margins of ranges of many circumpolar arctic species, and their climate conditions are rather different from those of arctic regions, including greater fluctuation of seasonal temperatures, contrasting day-night temperatures throughout the summer, high precipitation, strong winds, and high variation of snow distribution in alpine regions (Billings 1973;Körner 1999).…”

Section: Introductionmentioning

confidence: 99%

Warming effects on growth, production, and vegetation structure of alpine shrubs: a five-year experiment in northern Japan

Kudo

Suzuki

2003

Oecologia

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Warming effects on shoot growth, production, reproductive activity, and vegetation structure of alpine shrubs were measured over 5 years in a mid-latitude alpine fellfield in northern Japan. Open-top chambers (OTC) increased the daily mean air-temperature by 1.5-2.3 degrees C throughout the growing season but the effect on soil temperature was small. Two evergreen species, Ledum palustre and Empetrum nigrum, tended to increase their annual shoot production and aboveground-mass accumulation in the OTCs, whereas flower production did not differ. Two deciduous species, Vaccinium uliginosum and Arctous alpinus, increased their flower production in the OTCs, whereas the vegetative growth and mass accumulation did not change. No significant differences in vegetative and flower production were detected in Vaccinium vitis-idaea between the OTCs and control plots. The shoot survival and growth in terms of height of most species increased in the OTCs relative to the control treatment, and the growth rate was significantly different among species. As a result, interspecific competition seemed to be accelerated in the OTCs, and the less competitive V. vitis-idaea was suppressed by other plant species. The response to the warming observed in this study was rather different from that seen in arctic and subarctic plants even within the same species, indicating that the warming effect may cause different responses between arctic and mid-latitude alpine ecosystems. We concluded that the artificial warming over 5 years accelerated the growth of a few restricted species and lead to the change in vegetation structure in the mid-latitude alpine ecosystem.

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Effects of shading, nutrient application and warming on leaf growth and shoot densities of dwarf shrubs in two arctic-alpine plant communities

Cited by 70 publications

References 17 publications

Differential responses of grass and a dwarf shrub to long‐term changes in soil microbial biomass C, N and P following factorial addition of NPK fertilizer, fungicide and labile carbon to a heath

Differential responses of grass and a dwarf shrub to long‐term changes in soil microbial biomass C, N and P following factorial addition of NPK fertilizer, fungicide and labile carbon to a heath

Nutrient and carbon relations in subalpine dwarf shrubs after neighbour removal or fertilization in northern Italy

Warming effects on growth, production, and vegetation structure of alpine shrubs: a five-year experiment in northern Japan

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