Mediterranean Riparian Forest Research Articles

Leaf Litter Dynamics and Nitrous Oxide Emission in a Mediterranean Riparian Forest

Mediterranean riparian zones can experience severe drought periods that lead to low soil moisture content, which dramatically affects their performance as nitrate removal systems. In the Mediterranean riparian zone of this study, we determined that N2O emission was practically nil. To understand the role of forest floor processes in nitrogen retention of a Mediterranean riparian area, we studied leaf litter dynamics of two tree species, London planetree [Platanus × acerifolia (Aiton) Willd.] and alder [Alnus glutinosa (L.) Gaertn.], for two years, along with soil nitrogen mineralization rates. Annual leaf litter fall equaled 562.6 ± 10.1 (standard error) g dry wt. m−2, 68% of which was planetree and 32% of which was alder. The temporal distribution of litterfall showed a two-peak annual cycle, one occurring in midsummer, the other in autumn. Planetree provided the major input of organic nitrogen to the forest floor, and the amount of planetree leaves remaining on the forest floor was equivalent to approximately four years of stock. Leaf litter decomposition was three times higher for alder (decay coefficient [k] = 1.13 yr−1) than for planetree (k = 0.365 yr−1). Mineralization rates showed a seasonal pattern, with the maximum rate in summer (1.92 mg N kg−1 d−1). Although the forest floor was an important sink for nitrogen due to planetree leaf accumulation, 7.5% of this leaf litter was scoured to the streambed by wind. This loss was irrelevant for alder leaves. Due to the litter quality, the forest floor of this Mediterranean riparian forest acts as a nitrogen sink.

Leaf Litter Dynamics and Nitrous Oxide Emission in a Mediterranean Riparian Forest

Mediterranean riparian zones can experience severe drought periods that lead to low soil moisture content, which dramatically affects their performance as nitrate removal systems. In the Mediterranean riparian zone of this study, we determined that N2O emission was practically nil. To understand the role of forest floor processes in nitrogen retention of a Mediterranean riparian area, we studied leaf litter dynamics of two tree species, London planetree [Platanus x acerifolia (Aiton) Willd.] and alder [Alnus glutinosa (L.) Gaertn.], for two years, along with soil nitrogen mineralization rates. Annual leaf litter fall equaled 562.6 +/- 10.1 (standard error) g dry wt. m(-2), 68% of which was planetree and 32% of which was alder. The temporal distribution of litterfall showed a two-peak annual cycle, one occurring in midsummer, the other in autumn. Planetree provided the major input of organic nitrogen to the forest floor, and the amount of planetree leaves remaining on the forest floor was equivalent to approximately four years of stock. Leaf litter decomposition was three times higher for alder (decay coefficient [k] = 1.13 yr(-1)) than for planetree (k = 0.365 yr(-1)). Mineralization rates showed a seasonal pattern, with the maximum rate in summer (1.92 mg N kg(-1) d(-1)). Although the forest floor was an important sink for nitrogen due to planetree leaf accumulation, 7.5% of this leaf litter was scoured to the streambed by wind. This loss was irrelevant for alder leaves. Due to the litter quality, the forest floor of this Mediterranean riparian forest acts as a nitrogen sink.

Response of a Mediterranean Riparian Forest to a 1 in 400 Year Flood, Ouveze River, Drome-Vaucluse, France

Response of a Mediterranean Riparian Forest to a 1 in 400 Year Flood, Ouveze River, Drome-Vaucluse, France

Response of a Mediterranean Riparian Forest to a 1 in 400 Year Flood, Ouveze River, Drome‐Vaucluse, France

This study provides original data concerning the impact of an exceptional 400-year flood on the riparian forest of a six order French Mediterranean river. Both the restricting effects of the forest on the flood and the hydraulic behaviour of the forest during the flood were studied. Twenty-five per cent of the riparian forest was destroyed or profoundly altered as the flood waters enlarged the channel which was initially less than 200 m wide. However, the forest also reduced the flow capacity of the floodplain (lateral reduction of high water level). It also reduced lateral mineral fluxes (lateral reduction of sediment granulometry) and organic deposition (lateral reduction of coarse woody debris mass). However, the lateral extension and topographic accretion of the forest reduces the flood evacuation capacity of the bed and thereby increases the risk of flooding. Future legislation will have to take into account the nature of antropogenic activity in the area of the study. © 1997 by John Wiley & Sons, Ltd.

Response of a Mediterranean Riparian Forest to a 1 in 400 Year Flood, Ouveze River, Drome‐Vaucluse, France

Response of a Mediterranean Riparian Forest to a 1 in 400 Year Flood, Ouveze River, Drome‐Vaucluse, France