Mogelijkheden voor natuurontwikkeling in de Westelijke Veenweidegebieden : Verdergaande bodemdaling of herstel van veengroei?

Het ICES-KIS project ‘Waarheen met het veen?’ is een samenwerkingsverband tussen onderzoeksinstituten, waterbeheerders en beleidsmakers. Het doel van dit project is om de verschillende mogelijkheden voor waterbeheer in de Westelijke Veenweiden te onderzoeken op hun gevolgen voor landschap, landgebruik, milieukwaliteit en natuur. In dit rapport wordt een inleiding gegeven op het project en worden de onderzoeksvragen geformuleerd die betrekking hebben op het deelonderzoek ‘natuurontwikkeling op voormalige landbouwgronden’ van de groep Landschapsecologie van de Universiteit Utrecht (UU). Begeleiding van dit deelonderzoek ligt bij Prof. Dr. Jos Verhoeven (Landscape Ecology, Institute of Environmental Biology, UU) en Dr. A. Barendregt (Environmental Sciences, Faculty of Geosciences, UU). Deze rapportage is de eerste in een reeks van drie tussenrapporten en een eindrapport. In dit rapport wordt overzicht gegeven van het werk dat is gedaan in het afgelopen jaar en worden plannen gepresenteerd voor vervolgonderzoek

Nutrient limitation in species-rich Calthion grasslands in relation to opportunities for restoration in a peat meadow landscape

Questions:Which nutrient(s) limit(s) vegetation productivity in Calthion grasslands? Is phosphorus release a bottleneck for restoration of species-rich Calthion grasslands on rewetted dairy meadows? Location: Three species-rich Calthion grasslands in the Western Peat District in the Netherlands. Methods: We conducted a field fertilization experiment with nitrogen (N), phosphorus (P) and potassium (K) in three existing Calthion grasslands to evaluate the potential for restoration on rewetted dairy meadows. Responses of above-ground biomass, tissue nutrient concentrations and nutrient ratios were determined after 2 yr of fertilization. Results: Biomass increased with fertilization with Nonly and K-only but did not react to P-only additions. Comparisons of tissue nutrient concentrations and nutrient ratios also gave indications of N and K limitation. Conclusions: The strong P release expected after rewetting should not necessarily interfere with restoration of Calthion communities on rewetted dairy meadows. It is concluded that for successful restoration management measures should focus on reducing N and/or K availability. Potassium might be an overlooked bottleneck in the restoration of species-rich grasslands

Data from: Long-term effects of liming on soil physico-chemical properties and micro-arthropod communities in Scotch pine forest

This dataset contains the results of long-term liming on soil micro-arthropods in a stand of Scotch pine on a former drift sand. To counteract the effects of acidification liming was applied in triplicate in increasing quantities from 0 (control), 3, 6, 9 and 18 ton per ha on experimental plots in 1985 and 1986. Soil samples for chemical analyses and soil samples for extraction of soil micro-arthropods were taken in October 2017, 32 years after application. The study site is a 55 years old forest stand of Scotch Pine on a typic quarzipsamment (afforested former drift sand) near de city of Harderwijk, the Netherlands. Soil taxonomy is according to Soil Survey Staff (1999). The forest stand is on a flat plane at 17.5 m above sea level. In 1985 a series of experiments have been conducted here, varying from application of several types of manure (from calves and ducks), a factorial experiment with additions of P, Ca, Mg and K and a range of added carbonated lime in quantities of 3, 6, 9 and 18 ton per ha and an untreated control. All experimental fields are triplicated and 22 x 25 = 550m2 in size. At the start of the experiment pH[CaCl] was around 4.1-4.2 in the mineral soil (mixed top 25 cm) (Hekstra et al. 1990). Carbonated lime for agricultural use, having around 2% Mg, was added in autumn of 1985 (3 ton and all other plots first gift), in autumn 1986 (final gift 6 and 9 ton and second gift 18 ton) and additionally in spring 1987 (final gift to 18 ton). Thinning of the canopy was done in 2001 as regular forest management measure, no other management activities have been conducted ever since. On 16 October 2017 samples have been taken for soil chemical analyses. Each sample has been taken from the mixed top 25 cm mineral soil. We determined organic matter content (weight loss on ignition), pH (in NaCl 0.2 mol per liter), POlsen (plant available P), Cation Exchange Capacity and base saturation (Strontium extraction method). Total quantities of Ca, Mg, Al, Fe, Mn, P, S, Si and Zn (after grinding and extraction with 65% HNO3) were measured with an Inductively Coupled Plasma Spectrophotometer (ICP-OES, ICAP 6300 ARCOS MV, Spectro). NO3-, NH4+ and PO43- concentrations were determined colorimetrically with a Seal auto-analyser III with resp. reagens of salicylate, hydrazin sulphate and ammoniummolybdate/ascorbic acid. Cl- was determined colorimetrically with a Bran+Luebbe auto-analyser III system with mercuritiocynide. Na+ and K+ were determined with a flame spectrophotometer Sherwood Model 420 Flame Photometer. On 17 October 2017, in each of the limed plots and the control plots (green and yellow cadres) four soil cores of 5 cm depth: 100 cm3 content plus litter were sampled and extracted on a Tullgren funnel for 7 days. During that period temperature was increased from 35 to 45 0C. Ethanol 70% was used as conservation fluid and micro-arthropods obtained were put into lactic acid 40% for clarification and identification (Siepel and van de Bund, 1988). Nomenclature and identification for the main groups is according to Weigmann (2006) for Oribatida, Karg (1993) for Gamasina, Karg (1989) for Uropodina and Bretfeld (1999), Potapow (2001), Dunger and Schlitt (2011) and Jordana (2012) for Collembola. Species were grouped to feeding guilds after Siepel & de Ruiter-Dijkman (1993) in herbivorous grazers, herbivorous browsers, fungivorous grazers, fungivorous browsers (grazers feed on the cell walls as well and have resp. cellulase and chitinase activities, browsers on the contents only), opportunistic herbofungivores (plants incl. cell walls and fungal cell contents, i.e. trehalase activity), herbofungivorous grazer (plant and fungal cell walls) and predators (general or specialized on nematods or arthropods). Data files guildData.csv - limeTreatment: number of tons of lime added per hectare - plotNumber: experimental plot identifier - fb: number of individuals in the ‘fungivorous browsers’ category - fg: number of individuals in the ‘fungivorous grazers’ category - hfg: number of individuals in the ‘herbofungivorous grazers’ category - ohf: number of individuals in the ‘opportunistic herbofungivores’ category - hg: number of individuals in the ‘herbivorous grazers’ category - hb: number of individuals in the ‘herbivorous browsers’ category - o: number of individuals in the ‘omnivores’ category - gp: number of individuals in the ‘general predators’ category soilChemistryData.csv - limeTreatment: number of tons of lime added per hectare - plotNumber: experimental plot identifier - organicMatter: soil organic matter percentage, determined by weight loss on ignition - pH: pH in NaCl 0.2 mol.l-1 - Ca: calcium concentration [µmol per kg dry weight] - Mg: magnesium concentration [µmol per kg dry weight] - Al: aluminium concentration [µmol per kg dry weight] - NH4: ammonium concentration [µmol per kg dry weight] - NO3: nitrate concentration [µmol per kg dry weight] - Polsen: plant available phosphorus concentration [µmol per kg dry weight] - Fe: iron concentration [µmol per kg dry weight] - K: kalium concentration [µmol per kg dry weight] - Mn: manganese concentration [µmol per kg dry weight] - S: sulphur concentration [µmol per kg dry weight] - Si: silicon concentration [µmol per kg dry weight] - Zn: zinc concentration [µmol per kg dry weight] - moistureContent: soil moisture content percentage References Bretfeld G (1999) Symphypleona. Synopses on Palaearctic Collembola, Vol. 2 (Dunger), Staatliches Museum für Naturkunde Görlitz Dunger W, Schlitt, B (2011) Tullbergiidae. Synopses on Palaearctic Collembola, Vol. 6/1 (Dunger), Senckenberg Museum of Natural History Görlitz Hekstra A, Dilz K, van Diest A, van den Burg J (1990) Jaarverslag 1989-1990 Bosbemestingsonderzoek in het gemeentebos van Harderwijk. Report [in Dutch] Gemeente Harderwijk, CAS Dronten, LU Wageningen and NMI Den Haag Jordana R (2012) Capbryinae and Entomobryini. Synopses on Palaearctic Collembola, Vol. 7/1 (Dunger), Senckenberg Museum of Natural History Görlitz Karg W (1989) Acari (Acarina), Milben, Unterordnung Parasitiformes (Anactinoichaeta), Uropodina Kramer, Schildkrötchenmilben. Die Tierwelt Deutschlands 67. Teil, VEB Gustav Fischer Verlag, Jena Karg W (1993) Acari (Acarina), Milben, Parasitiformes (Anactinochaeta), Cohors Gamasina Leach, Raubmilben. Die Tierwelt Deutschlands 59. Teil, 2. Überarbeitete Auflage, VEB Gustav Fischer Verlag, Jena Potapow M (2001) Isotomidae. Synopses on Palaearctic Collembola, Vol. 3 (Dunger), Staatliches Museum für Naturkunde Görlitz Siepel H, de Ruiter-Dijkman EM (1993) Feeding guilds of oribatid mites based on carbohydrase enzyme activities. Soil Biol Biochem 25:1491-1497 Siepel H, van de Bund CF (1988) The influence of management practices on the microarthropod community of grassland. Pedobiologia 31:339-354 Soil Survey Staff (1999) Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd Ed. United States Department of Agriculture, Agriculture handbook 436 Weigmann G (2006) Hornmilben (Oribatida). Die Tierwelt Deutschlands 76. Teil, Goecke & Evers, Kelter

De toekomst van ons veenweidelandschap - Over vernatten, optoppen en veenmosteelt

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Data from: Long-term effects of liming on soil physico-chemical properties and micro-arthropod communities in Scotch pine forest

This dataset contains the results of long-term liming on soil micro-arthropods in a stand of Scotch pine on a former drift sand. To counteract the effects of acidification liming was applied in triplicate in increasing quantities from 0 (control), 3, 6, 9 and 18 ton per ha on experimental plots in 1985 and 1986. Soil samples for chemical analyses and soil samples for extraction of soil micro-arthropods were taken in October 2017, 32 years after application. The study site is a 55 years old forest stand of Scotch Pine on a typic quarzipsamment (afforested former drift sand) near de city of Harderwijk, the Netherlands. Soil taxonomy is according to Soil Survey Staff (1999). The forest stand is on a flat plane at 17.5 m above sea level. In 1985 a series of experiments have been conducted here, varying from application of several types of manure (from calves and ducks), a factorial experiment with additions of P, Ca, Mg and K and a range of added carbonated lime in quantities of 3, 6, 9 and 18 ton per ha and an untreated control. All experimental fields are triplicated and 22 x 25 = 550m2 in size. At the start of the experiment pH[CaCl] was around 4.1-4.2 in the mineral soil (mixed top 25 cm) (Hekstra et al. 1990). Carbonated lime for agricultural use, having around 2% Mg, was added in autumn of 1985 (3 ton and all other plots first gift), in autumn 1986 (final gift 6 and 9 ton and second gift 18 ton) and additionally in spring 1987 (final gift to 18 ton). Thinning of the canopy was done in 2001 as regular forest management measure, no other management activities have been conducted ever since. On 16 October 2017 samples have been taken for soil chemical analyses. Each sample has been taken from the mixed top 25 cm mineral soil. We determined organic matter content (weight loss on ignition), pH (in NaCl 0.2 mol per liter), POlsen (plant available P), Cation Exchange Capacity and base saturation (Strontium extraction method). Total quantities of Ca, Mg, Al, Fe, Mn, P, S, Si and Zn (after grinding and extraction with 65% HNO3) were measured with an Inductively Coupled Plasma Spectrophotometer (ICP-OES, ICAP 6300 ARCOS MV, Spectro). NO3-, NH4+ and PO43- concentrations were determined colorimetrically with a Seal auto-analyser III with resp. reagens of salicylate, hydrazin sulphate and ammoniummolybdate/ascorbic acid. Cl- was determined colorimetrically with a Bran+Luebbe auto-analyser III system with mercuritiocynide. Na+ and K+ were determined with a flame spectrophotometer Sherwood Model 420 Flame Photometer. On 17 October 2017, in each of the limed plots and the control plots (green and yellow cadres) four soil cores of 5 cm depth: 100 cm3 content plus litter were sampled and extracted on a Tullgren funnel for 7 days. During that period temperature was increased from 35 to 45 0C. Ethanol 70% was used as conservation fluid and micro-arthropods obtained were put into lactic acid 40% for clarification and identification (Siepel and van de Bund, 1988). Nomenclature and identification for the main groups is according to Weigmann (2006) for Oribatida, Karg (1993) for Gamasina, Karg (1989) for Uropodina and Bretfeld (1999), Potapow (2001), Dunger and Schlitt (2011) and Jordana (2012) for Collembola. Species were grouped to feeding guilds after Siepel & de Ruiter-Dijkman (1993) in herbivorous grazers, herbivorous browsers, fungivorous grazers, fungivorous browsers (grazers feed on the cell walls as well and have resp. cellulase and chitinase activities, browsers on the contents only), opportunistic herbofungivores (plants incl. cell walls and fungal cell contents, i.e. trehalase activity), herbofungivorous grazer (plant and fungal cell walls) and predators (general or specialized on nematods or arthropods). Data files guildData.csv - limeTreatment: number of tons of lime added per hectare - plotNumber: experimental plot identifier - fb: number of individuals in the ‘fungivorous browsers’ category - fg: number of individuals in the ‘fungivorous grazers’ category - hfg: number of individuals in the ‘herbofungivorous grazers’ category - ohf: number of individuals in the ‘opportunistic herbofungivores’ category - hg: number of individuals in the ‘herbivorous grazers’ category - hb: number of individuals in the ‘herbivorous browsers’ category - o: number of individuals in the ‘omnivores’ category - gp: number of individuals in the ‘general predators’ category soilChemistryData.csv - limeTreatment: number of tons of lime added per hectare - plotNumber: experimental plot identifier - organicMatter: soil organic matter percentage, determined by weight loss on ignition - pH: pH in NaCl 0.2 mol.l-1 - Ca: calcium concentration [µmol per kg dry weight] - Mg: magnesium concentration [µmol per kg dry weight] - Al: aluminium concentration [µmol per kg dry weight] - NH4: ammonium concentration [µmol per kg dry weight] - NO3: nitrate concentration [µmol per kg dry weight] - Polsen: plant available phosphorus concentration [µmol per kg dry weight] - Fe: iron concentration [µmol per kg dry weight] - K: kalium concentration [µmol per kg dry weight] - Mn: manganese concentration [µmol per kg dry weight] - S: sulphur concentration [µmol per kg dry weight] - Si: silicon concentration [µmol per kg dry weight] - Zn: zinc concentration [µmol per kg dry weight] - moistureContent: soil moisture content percentage References Bretfeld G (1999) Symphypleona. Synopses on Palaearctic Collembola, Vol. 2 (Dunger), Staatliches Museum für Naturkunde Görlitz Dunger W, Schlitt, B (2011) Tullbergiidae. Synopses on Palaearctic Collembola, Vol. 6/1 (Dunger), Senckenberg Museum of Natural History Görlitz Hekstra A, Dilz K, van Diest A, van den Burg J (1990) Jaarverslag 1989-1990 Bosbemestingsonderzoek in het gemeentebos van Harderwijk. Report [in Dutch] Gemeente Harderwijk, CAS Dronten, LU Wageningen and NMI Den Haag Jordana R (2012) Capbryinae and Entomobryini. Synopses on Palaearctic Collembola, Vol. 7/1 (Dunger), Senckenberg Museum of Natural History Görlitz Karg W (1989) Acari (Acarina), Milben, Unterordnung Parasitiformes (Anactinoichaeta), Uropodina Kramer, Schildkrötchenmilben. Die Tierwelt Deutschlands 67. Teil, VEB Gustav Fischer Verlag, Jena Karg W (1993) Acari (Acarina), Milben, Parasitiformes (Anactinochaeta), Cohors Gamasina Leach, Raubmilben. Die Tierwelt Deutschlands 59. Teil, 2. Überarbeitete Auflage, VEB Gustav Fischer Verlag, Jena Potapow M (2001) Isotomidae. Synopses on Palaearctic Collembola, Vol. 3 (Dunger), Staatliches Museum für Naturkunde Görlitz Siepel H, de Ruiter-Dijkman EM (1993) Feeding guilds of oribatid mites based on carbohydrase enzyme activities. Soil Biol Biochem 25:1491-1497 Siepel H, van de Bund CF (1988) The influence of management practices on the microarthropod community of grassland. Pedobiologia 31:339-354 Soil Survey Staff (1999) Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd Ed. United States Department of Agriculture, Agriculture handbook 436 Weigmann G (2006) Hornmilben (Oribatida). Die Tierwelt Deutschlands 76. Teil, Goecke & Evers, Kelter

Data from: Long-term effects of liming on soil physico-chemical properties and micro-arthropod communities in Scotch pine forest

This dataset contains the results of long-term liming on soil micro-arthropods in a stand of Scotch pine on a former drift sand. To counteract the effects of acidification liming was applied in triplicate in increasing quantities from 0 (control), 3, 6, 9 and 18 ton per ha on experimental plots in 1985 and 1986. Soil samples for chemical analyses and soil samples for extraction of soil micro-arthropods were taken in October 2017, 32 years after application. The study site is a 55 years old forest stand of Scotch Pine on a typic quarzipsamment (afforested former drift sand) near de city of Harderwijk, the Netherlands. Soil taxonomy is according to Soil Survey Staff (1999). The forest stand is on a flat plane at 17.5 m above sea level. In 1985 a series of experiments have been conducted here, varying from application of several types of manure (from calves and ducks), a factorial experiment with additions of P, Ca, Mg and K and a range of added carbonated lime in quantities of 3, 6, 9 and 18 ton per ha and an untreated control. All experimental fields are triplicated and 22 x 25 = 550m2 in size. At the start of the experiment pH[CaCl] was around 4.1-4.2 in the mineral soil (mixed top 25 cm) (Hekstra et al. 1990). Carbonated lime for agricultural use, having around 2% Mg, was added in autumn of 1985 (3 ton and all other plots first gift), in autumn 1986 (final gift 6 and 9 ton and second gift 18 ton) and additionally in spring 1987 (final gift to 18 ton). Thinning of the canopy was done in 2001 as regular forest management measure, no other management activities have been conducted ever since. On 16 October 2017 samples have been taken for soil chemical analyses. Each sample has been taken from the mixed top 25 cm mineral soil. We determined organic matter content (weight loss on ignition), pH (in NaCl 0.2 mol per liter), POlsen (plant available P), Cation Exchange Capacity and base saturation (Strontium extraction method). Total quantities of Ca, Mg, Al, Fe, Mn, P, S, Si and Zn (after grinding and extraction with 65% HNO3) were measured with an Inductively Coupled Plasma Spectrophotometer (ICP-OES, ICAP 6300 ARCOS MV, Spectro). NO3-, NH4+ and PO43- concentrations were determined colorimetrically with a Seal auto-analyser III with resp. reagens of salicylate, hydrazin sulphate and ammoniummolybdate/ascorbic acid. Cl- was determined colorimetrically with a Bran+Luebbe auto-analyser III system with mercuritiocynide. Na+ and K+ were determined with a flame spectrophotometer Sherwood Model 420 Flame Photometer. On 17 October 2017, in each of the limed plots and the control plots (green and yellow cadres) four soil cores of 5 cm depth: 100 cm3 content plus litter were sampled and extracted on a Tullgren funnel for 7 days. During that period temperature was increased from 35 to 45 0C. Ethanol 70% was used as conservation fluid and micro-arthropods obtained were put into lactic acid 40% for clarification and identification (Siepel and van de Bund, 1988). Nomenclature and identification for the main groups is according to Weigmann (2006) for Oribatida, Karg (1993) for Gamasina, Karg (1989) for Uropodina and Bretfeld (1999), Potapow (2001), Dunger and Schlitt (2011) and Jordana (2012) for Collembola. Species were grouped to feeding guilds after Siepel & de Ruiter-Dijkman (1993) in herbivorous grazers, herbivorous browsers, fungivorous grazers, fungivorous browsers (grazers feed on the cell walls as well and have resp. cellulase and chitinase activities, browsers on the contents only), opportunistic herbofungivores (plants incl. cell walls and fungal cell contents, i.e. trehalase activity), herbofungivorous grazer (plant and fungal cell walls) and predators (general or specialized on nematods or arthropods). Data files guildData.csv - limeTreatment: number of tons of lime added per hectare - plotNumber: experimental plot identifier - fb: number of individuals in the ‘fungivorous browsers’ category - fg: number of individuals in the ‘fungivorous grazers’ category - hfg: number of individuals in the ‘herbofungivorous grazers’ category - ohf: number of individuals in the ‘opportunistic herbofungivores’ category - hg: number of individuals in the ‘herbivorous grazers’ category - hb: number of individuals in the ‘herbivorous browsers’ category - o: number of individuals in the ‘omnivores’ category - gp: number of individuals in the ‘general predators’ category soilChemistryData.csv - limeTreatment: number of tons of lime added per hectare - plotNumber: experimental plot identifier - organicMatter: soil organic matter percentage, determined by weight loss on ignition - pH: pH in NaCl 0.2 mol.l-1 - Ca: calcium concentration [µmol per kg dry weight] - Mg: magnesium concentration [µmol per kg dry weight] - Al: aluminium concentration [µmol per kg dry weight] - NH4: ammonium concentration [µmol per kg dry weight] - NO3: nitrate concentration [µmol per kg dry weight] - Polsen: plant available phosphorus concentration [µmol per kg dry weight] - Fe: iron concentration [µmol per kg dry weight] - K: kalium concentration [µmol per kg dry weight] - Mn: manganese concentration [µmol per kg dry weight] - S: sulphur concentration [µmol per kg dry weight] - Si: silicon concentration [µmol per kg dry weight] - Zn: zinc concentration [µmol per kg dry weight] - moistureContent: soil moisture content percentage References Bretfeld G (1999) Symphypleona. Synopses on Palaearctic Collembola, Vol. 2 (Dunger), Staatliches Museum für Naturkunde Görlitz Dunger W, Schlitt, B (2011) Tullbergiidae. Synopses on Palaearctic Collembola, Vol. 6/1 (Dunger), Senckenberg Museum of Natural History Görlitz Hekstra A, Dilz K, van Diest A, van den Burg J (1990) Jaarverslag 1989-1990 Bosbemestingsonderzoek in het gemeentebos van Harderwijk. Report [in Dutch] Gemeente Harderwijk, CAS Dronten, LU Wageningen and NMI Den Haag Jordana R (2012) Capbryinae and Entomobryini. Synopses on Palaearctic Collembola, Vol. 7/1 (Dunger), Senckenberg Museum of Natural History Görlitz Karg W (1989) Acari (Acarina), Milben, Unterordnung Parasitiformes (Anactinoichaeta), Uropodina Kramer, Schildkrötchenmilben. Die Tierwelt Deutschlands 67. Teil, VEB Gustav Fischer Verlag, Jena Karg W (1993) Acari (Acarina), Milben, Parasitiformes (Anactinochaeta), Cohors Gamasina Leach, Raubmilben. Die Tierwelt Deutschlands 59. Teil, 2. Überarbeitete Auflage, VEB Gustav Fischer Verlag, Jena Potapow M (2001) Isotomidae. Synopses on Palaearctic Collembola, Vol. 3 (Dunger), Staatliches Museum für Naturkunde Görlitz Siepel H, de Ruiter-Dijkman EM (1993) Feeding guilds of oribatid mites based on carbohydrase enzyme activities. Soil Biol Biochem 25:1491-1497 Siepel H, van de Bund CF (1988) The influence of management practices on the microarthropod community of grassland. Pedobiologia 31:339-354 Soil Survey Staff (1999) Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd Ed. United States Department of Agriculture, Agriculture handbook 436 Weigmann G (2006) Hornmilben (Oribatida). Die Tierwelt Deutschlands 76. Teil, Goecke & Evers, Kelter

Reassessing the role of phospholipase D in the Arabidopsis wounding response.

Plants respond to wounding by means of a multitude of reactions, with the purpose of stifling herbivore assault. Phospholipase D (PLD) has previously been implicated in the wounding response. Arabidopsis (Arabidopsis thaliana) AtPLDalpha1 has been proposed to be activated in intact cells, and the phosphatidic acid (PA) it produces to serve as a precursor for jasmonic acid (JA) synthesis and to be required for wounding-induced gene expression. Independently, PLD activity has been reported to have a bearing on wounding-induced MAPK activation. However, which PLD isoforms are activated, where this activity takes place (in the wounded or non-wounded cells) and what exactly the consequences are is a question that has not been comprehensively addressed. Here, we show that PLD activity during the wounding response is restricted to the ruptured cells using (32)P(i)-labelled phospholipid analyses of Arabidopsis pld knock-out mutants and PLD-silenced tomato cell-suspension cultures. pldalpha1 knock-out lines have reduced wounding-induced PA production, and the remainder is completely eliminated in a pldalpha1/delta double knock-out line. Surprisingly, wounding-induced protein kinase activation, AtLOX2 gene expression and JA biosynthesis were not affected in these knock-out lines. Moreover, larvae of the Cabbage White butterfly (Pieris rapae) grew equally well on wild-type and the pld knock-out mutants