Biodiversity and Ecosystem Functioning in Mediterranean-Climate California

Keeley, Jon E.; Swift, Camm C.

doi:10.1007/978-3-642-78881-9_3

Cited by 35 publications

(31 citation statements)

References 136 publications

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“…The fire extension and frequency occurring nowadays in some Mediterranean areas create a new ecological situation that can enhance desertification processes ͑Vallejo 1997͒. This is especially the case for 'hot spots' where fire frequency is high enough to prevent the vegetation from developing to a mature stage, thus causing some fire-sensitive species to decrease or even disappear ͑Zedler et al 1983;Trabaud 1992;Keeley and Swift 1995;Russel-Smith et al 1998͒.…”

Section: Introductionmentioning

confidence: 97%

Effects of fire recurrence in Quercus coccifera L. shrublands of the Valencia Region (Spain): I. plant composition and productivity

Delitti

Ferran

Trabaud³

et al. 2005

Plant Ecol

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The purpose of this study was to determine whether fire recurrence modifies the regeneration capacity of Quercus coccifera garrigues in the Valencia region ͑eastern Spain͒. We studied several areas with different fire recurrences ͑1, 2 and 3 fires in 16 years͒, all of which had sustained a common last fire in 1994. Three-and-a-half years after the last fire, differences between the 3 fire recurrences were not detected with respect to total plant cover and Q. coccifera cover, with a mean value between 92 and 76%. On the most frequently burned sites, herbaceous and subshrub species cover showed a tendency to increase, while that of the obligate seeding shrub, Ulex parviflorus, decreased with both fire frequency and shorter last-fire interval. The most recurrently burned areas with the shortest last-fire intervals presented higher species richness, which mainly affected the herbaceous and subshrub species group, and of these, the hemichryptophytes. The major effect of fire recurrence was the significant decrease in stem and total biomass of Q. coccifera in the three studied sites. Three-and-a-half years after the fire, the mean total biomass values were around 1500, 1000 and 700 g. m -2 in the garrigues with 1, 2 and 3 fires respectively. Stem production was more affected than leaf production. Leaf area index values showed the same pattern as leaf biomass. Recurrent fires also caused a decrease in net primary production measured the fourth year after fire. The results point to the fact that fire recurrence can cause depletion in garrigue productivity and recovery capacity in southern areas, in contrast with the high resilience observed in northern Mediterranean garrigues.

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Section: Introductionmentioning

confidence: 97%

Effects of fire recurrence in Quercus coccifera L. shrublands of the Valencia Region (Spain): I. plant composition and productivity

Delitti

Ferran

Trabaud³

et al. 2005

Plant Ecol

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“…In this context, gaps are closely related to our understanding of how forests function in their natural state and to what extent their natural structure can be modified through management (Keeley and Swift 1995).…”

Section: Introductionmentioning

confidence: 99%

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

2006

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Changes in soil chemical and microbiological parameters in small (185 m 2 ) and medium (410 m 2 ) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.

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“…On the contrary, in semiarid grazing ecosystems, irreversible vegetation changes may occur when herbivore number is high in grazing managed systems in comparison with self-regulating natural systems ( Van de Koppel and Rietkerk, 2000). Thus, the relation between grazing impact and ecosystem functioning is complex and what role species diversity plays in determining ecosystem function remains unanswered (Keeley and Swift, 1995;Troumbis and Memtsas, 2000).…”

Section: Introductionmentioning

confidence: 99%

Change in plant spatial patterns and diversity along the successional gradient of Mediterranean grazing ecosystems

Alados¹,

El-Aich

Papanastasis³

et al. 2004

Ecological Modelling

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In this study, we analyze the complexity of plant spatial patterns and diversity along a successional gradient resulting from grazing disturbance in four characteristic ecosystems of the Mediterranean region. Grazing disturbance include not only defoliation by animals, but also associated disturbances as animal trampling, soil compaction, and mineralization by deposition of urine and feces. The results show that woodland and dense matorral are more resistant to species loss than middle dense and scattered matorral, or grassland. Information fractal dimension declined as we moved from a dense to a discontinuous matorral, increasing as we moved to a more scattered matorral and a grassland. In all studied cases, the characteristic species of the natural vegetation declined in frequency and organization with grazing disturbance. Heliophyllous species and others with postrate or rosette twigs increased with grazing pressure, particularly in dense matorral. In the more degraded ecosystem, only species with well-adapted traits, e.g., buried buds or unpalatable qualities showed a clear increase with grazing. Indeed, the homogeneity of species distribution within the plant community declined monotonically with grazing impact. Conversely, the spatial organization of the characteristic plants of each community increased in the better-preserved areas, being also related to the sensitivity of the species to grazing impact. The degree of autocorrelation of plant spatial distribution at the species level and the information fractal dimension at the community level allow us to quantify the degree of degradation of natural communities and to determine the sensitivity of key species to disturbance.

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Biodiversity and Ecosystem Functioning in Mediterranean-Climate California

Cited by 35 publications

References 136 publications

Effects of fire recurrence in Quercus coccifera L. shrublands of the Valencia Region (Spain): I. plant composition and productivity

Effects of fire recurrence in Quercus coccifera L. shrublands of the Valencia Region (Spain): I. plant composition and productivity

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

Change in plant spatial patterns and diversity along the successional gradient of Mediterranean grazing ecosystems

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