Abstract
Off-season ecosystem processes is becoming an area of increasing interest, being
important when considering annual nitrogen and carbon budgets. The general assumption that
physiological activity in soil microorganisms as well as vegetation is low during winter may
not be justified. In this field study we show that northern temperate coastal heath vegetation
has a significant uptake potential for nitrogen, both in the form of ammonium and as glycine,
throughout the non-growing season.
We used 15N ammonium and 2*(13C)15N glycine as nutrient tracer. This was injected
into the soil two times during winter and once at spring. The winter temperatures were similar
to those of average winter in the northern temperate region of Europe, with only few days of
soil temperatures below zero and a winter mean of 2.4 °C. The vegetation, consisting of the
evergreen dwarf shrub Calluna vulgaris (L.), the deciduous dwarf shrub Salix arenaria (L.)
and the graminoids Carex arenaria (L.) and Deschampsia flexuosa (L.), showed root uptake
of both forms of nitrogen, both one day after labelling and after a month. Translocation of the
labelled nitrogen to shoots was generally evident after one month and increased as spring
approached, with different translocation strategies in the three plant functional types.
Furthermore, shoot total nitrogen concentration increased in all plant types, but only the
graminoids and, eventually, S. arenaria showed shoot growth during winter. Our study
suggests that plant nitrogen uptake can cause increasing nitrogen concentration in shoot tissue
from fall to spring.
To our knowledge this is one of the first studies of plant nitrogen uptake during nongrowing
season at a temperate heath. Our results show that the nitrogen uptake is in the same
order of magnitude as summer uptake in other types of ecosystems in the temperate/boreal
region. These results suggest that plant nitrogen uptake during winter should be included in
the annual nitrogen budgets of heath ecosystems, and that the view of plant nutrient uptake as
low in this climatic region during winter should be revised. Furthermore, these results should
be taken into account when ecosystem responses to climatic changes such as warming are
evaluated.
| Original language | English |
|---|---|
| Journal | Oecologia |
| ISSN | 0029-8549 |
| Publication status | Published - 2004 |
| Event | The 4th international Conference on Applications of Stable Isotope Techniques to Ecological Studies - Isoecol, New Zealand Duration: 19 Apr 2004 → 23 Apr 2004 |
Conference
| Conference | The 4th international Conference on Applications of Stable Isotope Techniques to Ecological Studies |
|---|---|
| Country/Territory | New Zealand |
| City | Isoecol |
| Period | 19/04/2004 → 23/04/2004 |