Abstract
Denmark hosts a large portion of the European dune heaths, a vegetation type that is largely protected under European conventions. Coastal dunes are characterized by a mosaic of habitat types interchanging in both space and time.
This study focuses on a GIS-based method for monitoring the dynamics of dune heath vegetation situated in NW Jutland during a period of 15 years. An orthophoto from 2010 was inspected visually and divided in patches based on differences in color and texture. The results were hereafter verified on ground by means of vegetation analyses based on ground cover estimates. In total four different habitat types were recognized 1) dune heath, 2) shrub-dominated dune slack, 3) graminoid-dominated dune slack and 4) grey dune.
The four habitat types were separated by differences in preference for the five Ellenberg indicator values F (moisture), L (light), R (reaction - pH), S (salt) and N (nitrogen availability). The development of patch dynamics of the four habitat types were subsequently studied on an orthophoto from 1995. During this period of 15 years (1995-2010) the grey dune was reduced by nearly 50 %, a result of the increasing dominance of shrubby vegetation in the dune systems, probably due to increased deposition of atmospheric nitrogen. The results also showed an increase in the total area of the graminoid-dominated dune slacks, possibly due to increase in precipitation and/or closing of drains.
Although the method used in this study is time consuming and not refined for management purposes it is definitely a promising tool for gaining insight in the dynamics of patchy vegetation types at the landscape level. The results clearly show that management actions are needed to preserve the grey dunes and to restore the natural dynamics of the dune system.
This study focuses on a GIS-based method for monitoring the dynamics of dune heath vegetation situated in NW Jutland during a period of 15 years. An orthophoto from 2010 was inspected visually and divided in patches based on differences in color and texture. The results were hereafter verified on ground by means of vegetation analyses based on ground cover estimates. In total four different habitat types were recognized 1) dune heath, 2) shrub-dominated dune slack, 3) graminoid-dominated dune slack and 4) grey dune.
The four habitat types were separated by differences in preference for the five Ellenberg indicator values F (moisture), L (light), R (reaction - pH), S (salt) and N (nitrogen availability). The development of patch dynamics of the four habitat types were subsequently studied on an orthophoto from 1995. During this period of 15 years (1995-2010) the grey dune was reduced by nearly 50 %, a result of the increasing dominance of shrubby vegetation in the dune systems, probably due to increased deposition of atmospheric nitrogen. The results also showed an increase in the total area of the graminoid-dominated dune slacks, possibly due to increase in precipitation and/or closing of drains.
Although the method used in this study is time consuming and not refined for management purposes it is definitely a promising tool for gaining insight in the dynamics of patchy vegetation types at the landscape level. The results clearly show that management actions are needed to preserve the grey dunes and to restore the natural dynamics of the dune system.
| Translated title of the contribution | Study of orthophotos in relation to vegetation dynamics in Danish coastal dunes 1995-2010 |
|---|---|
| Original language | English |
| Journal | Flora og Fauna |
| Volume | 122 |
| Issue | 1+2 |
| Pages (from-to) | 1-12 |
| Number of pages | 12 |
| ISSN | 0015-3818 |
| Publication status | Published - Apr 2016 |