Compatibility of grafting in the melon cv. bônus No. 2, and effects on production

Twelve rootstocks were evaluated: 1) pumpkin 'Big Power' (Cucurbita ntoschata); 2) pumpkin 'Seca' (Cucurbita moschata); 3) bottle gourd 'Longa' (Lagenaria siceraria); 4) 'Cachi' (Lagenaria siceraria); 5) bottle gourd 'Marimba' (Lagenaria siceraria); 6) 'Mogango' (Cucurbita maxima); 7) pumpkin 'Kirameki' (Cucurbita moschata); 8) pumpkin 'Caravela' (Cucurbita moschata); 9) pumpkin 'Shelper' (Cucurbita moschata); 10) 'Gherkin' (Cucumis anguria); 11) 'Loofah' (Luffa cylindrica); and 12) pumpkin 'Goianinha' (Cucurbita moschata) with respect to compatibility with melon yield, and the production and quality of fruits from cv. Bônus No. 2, non-grafted and grafted with 9 of these rootstocks (1, 2, 4, 5, 6, 7, 9, 10 and 11). The bottle gourd 'Marimba' provided the highest percentage of grafting success between the vine and rootstock. The rootstocks 1, 2, 3, 4 and 7 did not differ from bottle gourd 'Marimba', therefore also indicating good compatibility with the melon cv. Bônus No. 2. For height of the plants, it was shown in the first evaluation that rootstock 5 produced a greater height of the plant, differing only from rootstocks 7, 8, 9, 10 and 11 and non-grafted cv. Bônus No. 2. In the second evaluation, 'Big Power' showed the greatest value for height of the plant, differing only from combinations with 'Cachi', 'Mogango', 'Shelper' and 'Loofah'. With regard to number of leaves, in the first evaluation rootstocks 3, 4 and 6 had the greatest number of leaves, but in the second 4, 9 and 11 had the greatest. For dry weight of the stem, the greatest value was obtained with 'Mogango' in the first evaluation and with 'Big Power' in the second. For leaf area of the plants, a difference was found among the treatments only in the first evaluation, where the combination with bottle gourd 'Longa' showed a greater leaf area, but did not differ from the combinations with rootstocks 1, 4, 5 and 6. Differences were demonstrated among the treatments only for the transverse diameter of the fruit, where the combination with rootstock bottle gourd 'Marimba' showed the greatest value, differing only from the combination with 'Gherkin'. There were no significant differences for the mean longitudinal diameter, pulp thickness and total soluble solids among the treatments studied.

Analisi dei parametri vegetazionali e dei caratteri funzionali di specie guida come strumenti di studio di comunità prative

Lo studio condotto si propone l’approfondimento delle conoscenze sui processi di evoluzione spontanea di comunità vegetali erbacee di origine secondaria in cinque siti all’interno di un’area protetta del Parco di Monte Sole (Bologna, Italia), dove, come molte aree rurali marginali in Italia e in Europa, la cessazione o riduzione delle tradizionali pratiche gestionali negli ultimi cinquant’anni, ha determinato lo sviluppo di fitocenosi di ridotto valore floristico e produttivo. Tali siti si trovano in due aree distinte all’interno del parco, denominate Zannini e Stanzano, selezionate in quanto rappresentative di situazioni di comunità del Mesobrometo. Due siti appartenenti alla prima area e uno appartenente alla seconda, sono gestiti con sfalcio annuale, i rimanenti non hanno nessun tipo di gestione. Lo stato delle comunità erbacee di tali siti è stato valutato secondo più punti di vista. E’ stata fatta una caratterizzazione vegetazionale dei siti, mediante rilievo lineare secondo la metodologia Daget-Poissonet, permettendo una prima valutazione relativa al numero di specie presenti e alla loro abbondanza all’interno della comunità vegetale, determinando i Contributi Specifici delle famiglie principali e delle specie dominanti (B. pinnatum, B. erectus e D. glomerata). La produttività è stata calcolata utilizzando un indice di qualità foraggera, il Valore Pastorale, e con la determinazione della produzione di Fitomassa totale, Fitomassa fotosintetizzante e Necromassa. A questo proposito sono state trovate correlazioni negative tra la presenza di Graminacee, in particolare di B. pinnatum, e i Contributi Specifici delle altre specie, soprattutto a causa dello spesso strato di fitomassa e necromassa prodotto dallo stesso B. pinnatum che impedisce meccanicamente l’insediamento e la crescita di altre piante. E’ stata inoltre approfonditamente sviluppata un terza caratterizzazione, che si propone di quantificare la diversità funzionale dei siti medesimi, interpretando le risposte della vegetazione a fattori globali di cambiamento, sia abiotici che biotici, per cogliere gli effetti delle variazioni ambientali in atto sulla comunità, e più in generale, sull’intero ecosistema. In particolare, nello studio condotto, sono stati proposti alcuni caratteri funzionali, cosiddetti functional traits, scelti perché correlati all’acquisizione e alla conservazione delle risorse, e quindi al trade-off dei nutrienti all’interno della pianta, ossia: Superficie Fogliare Specifica, SLA, Tenore di Sostanza Secca, LDMC, Concentrazione di Azoto Fogliare, LNC, Contenuto in Fibra, LFC, separato nelle componenti di Emicellulosa, Cellulosa, Lignina e Ceneri. Questi caratteri sono stati misurati in relazione a tre specie dominanti: B. pinnatum, B. erectus e D. glomerata. Si tratta di specie comunemente presenti nelle praterie semi-mesofile dell’Appennino Settentrionale, ma caratterizzate da differenti proprietà ecologiche e adattative: B. pinnatum e B. erectus sono considerati competitori stress-toleranti, tipicamente di ambienti poveri di risorse, mentre D. glomerata, è una specie più mesofila, caratteristica di ambienti produttivi. Attraverso l’analisi dei traits in riferimento alle diverse strategie di queste specie, sono stati descritti specifici adattamenti alle variazioni delle condizioni ambientali, ed in particolare in risposta al periodo di stress durante l’estate dovuto a deficit idrico e in risposta alla diversa modalità di gestione dei siti, ossia alla pratica o meno dello sfalcio annuale. Tra i caratteri funzionali esaminati, è stato identificato LDMC come il migliore per descrivere le specie, in quanto più facilmente misurabile, meno variabile, e direttamente correlato con altri traits come SLA e le componenti della fibra. E’ stato quindi proposto il calcolo di un indice globale per caratterizzare i siti in esame, che tenesse conto di tutti questi aspetti, riunendo insieme sia i parametri di tipo vegetativo e produttivo, che i parametri funzionali. Tale indice ha permesso di disporre i siti lungo un gradiente e di cogliere differenti risposte in relazione a variazioni stagionali tra primavera o autunno e in relazione al tipo di gestione, valutando le posizioni occupate dai siti stessi e la modalità dei loro eventuali spostamenti lungo questo gradiente. Al fine di chiarire se le variazioni dei traits rilevate fossero dovute ad adattamento fenotipico dei singoli individui alle condizioni ambientali, o piuttosto fossero dovute a differenziazione genotipica tra popolazioni cresciute in siti diversi, è stato proposto un esperimento in condizioni controllate. All’interno di un’area naturale in UK, le Chiltern Hills, sono stati selezionati cinque siti, caratterizzati da diverse età di abbandono: Bradenham Road MaiColtivato e Small Dean MaiColtivato, di cui non si conosce storia di coltivazione, caratterizzati rispettivamente da vegetazione arborea e arbustiva prevalente, Butterfly Bank 1970, non più coltivato dal 1970, oggi prateria seminaturale occasionalmente pascolata, Park Wood 2001, non più coltivato dal 2001, oggi prateria seminaturale mantenuta con sfalcio annuale, e infine Manor Farm Coltivato, attualmente arato e coltivato. L’esperimento è stato condotto facendo crescere i semi delle tre specie più comuni, B. sylvaticum, D. glomerata e H. lanatus provenienti dai primi quattro siti, e semi delle stesse specie acquistati commercialmente, nei cinque differenti tipi di suolo dei medesimi siti. Sono stati misurati quattro caratteri funzionali: Massa Radicale Secca (DRM), Massa Epigea Secca (DBM), Superficie Fogliare Secca (SLA) e Tenore di Sostanza Secca (LDMC). I risultati ottenuti hanno evidenziato che ci sono significative differenze tra le popolazioni di una stessa specie ma con diversa provenienza, e tra individui appartenenti alla stessa popolazione se fatti crescere in suoli diversi. Tuttavia, queste differenze, sembrano essere dovute ad adattamenti locali legati alla presenza di nutrienti, in particolare N e P, nel suolo piuttosto che a sostanziali variazioni genotipiche tra popolazioni. Anche per questi siti è stato costruito un gradiente sulla base dei quattro caratteri funzionali analizzati. La disposizione dei siti lungo il gradiente ha evidenziato tre gruppi distinti: i siti più giovani, Park Wood 2001 e Manor Farm Coltivato, nettamente separati da Butterfly Bank 1970, e seguiti infine da Small Dean MaiColtivato e Bradenham Road MaiColtivato. L’applicazione di un indice così proposto potrebbe rivelarsi un utile strumento per descrivere ed indagare lo stato della prateria e dei processi evolutivi in atto, al fine di meglio comprendere e dominare tali dinamiche per proporre sistemi di gestione che ne consentano la conservazione anche in assenza delle tradizionali cure colturali.

Interactive effects of mycorrhizae and a root hemiparasite on plant community productivity and diversity

Plant communities can be affected both by arbuscular mycorrhizal fungi (AMF) and hemiparasitic plants. However, little is known about the interactive effects of these two biotic factors on the productivity and diversity of plant communities. To address this question, we set up a greenhouse study in which different AMF inocula and a hemiparasitic plant (Rhinanthus minor) were added to experimental grassland communities in a fully factorial design. In addition, single plants of each species in the grassland community were grown with the same treatments to distinguish direct AMF effects from indirect effects via plant competition. We found that AMF changed plant community structure by influencing the plant species differently. At the community level, AMF decreased the productivity by 15-24%, depending on the particular AMF treatment, mainly because two dominant species, Holcus lanatus and Plantago lanceolata, showed a negative mycorrhizal dependency. Concomitantly, plant diversity increased due to AMF inoculation and was highest in the treatment with a combination of two commercial AM strains. AMF had a positive effect on growth of the hemiparasite, and thereby induced a negative impact of the hemiparasite on host plant biomass which was not found in non-inoculated communities. However, the hemiparasite did not increase plant diversity. Our results highlight the importance of interactions with soil microbes for plant community structure and that these indirect effects can vary among AMF treatments. We conclude that mutualistic interactions with AMF, but not antagonistic interactions with a root hemiparasite, promote plant diversity in this grassland community.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2004)

This data set contains aboveground community biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in 2004 just prior to mowing (during peak standing biomass in late May and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in four rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2007)

This data set contains aboveground community biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in 2007 just prior to mowing (during peak standing biomass in early June and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in four (May) or three (August) rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2006)

This data set contains aboveground community biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in 2006 just prior to mowing (during peak standing biomass in early June and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in four rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

AMS radiocarbon dates and pollen analysis of ODP Hole 175-1078C

ODP Site 1078 situated under the coast of Angola provides the first record of the vegetation history for Angola. The upper 11 m of the core covers the past 30 thousand years, which has been analysed palynologically in decadal to centennial resolution. Alkenone sea surface temperature estimates were analysed in centennial resolution. We studied sea surface temperatures and vegetation development during full glacial, deglacial, and interglacial conditions. During the glacial the vegetation in Angola was very open consisting of grass and heath lands, deserts and semi-deserts, which suggests a cool and dry climate. A change to warmer and more humid conditions is indicated by forest expansion starting in step with the earliest temperature rise in Antarctica, 22 thousand years ago. We infer that around the period of Heinrich Event 1, a northward excursion of the Angola Benguela Front and the Congo Air Boundary resulted in cool sea surface temperatures but rain forest remained present in the northern lowlands of Angola. Rain forest and dry forest area increase 15 thousand years ago. During the Holocene, dry forests and Miombo woodlands expanded. Also in Angola globally recognised climate changes at 8 thousand and 4 thousand years ago had an impact on the vegetation. During the past 2 thousand years, savannah vegetation became dominant.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2003)

This data set contains aboveground community biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in 2003 just prior to mowing (during peak standing biomass in late May and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in four rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Species-specific plant height along the plant diversity gradient in the Jena Experiment (Main Experiment, year 2002)

This data set contains measurements of species-specific plant height: vegetative height (non-flowering indviduals) and regenerative height (flowering individuals) measured for all sown species separetly in 2002. Data was recorded in the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the Main Experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. In 2002, plant height was recorded two times: in late July (vegetative height) and just before biomass harvest during peak standing biomass in late August (vegetative and regenerative height). For each plot and each sown species in the species pool, 3 plant individuals (if present) from the central area of the plots were randomly selected and used to measure vegetative height (non-flowering indviduals) and regenerative height (flowering individuals) as stretched height. Provided are the means over the three measuremnts per plant species per plot.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2005)

This data set contains aboveground community biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in 2005 just prior to mowing (during peak standing biomass in late May and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in three (in May 2005) and four (August 2005) rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2002)

This data set contains aboveground community biomass (Sown plant community, measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested in September 2002 just prior to mowing (during peak standing biomass) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in one rectangle of 0.2 x 0.5 m per large plot. The location of the rectangle was assigned prior to harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangle within plots were identical for all plots. The harvested biomass was sorted into categories: in 2002 only individual species for the sown plant species were separated and processed. All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Distribution of pollen and spores in sediments of ODP Hole 175-1078C

The distribution of pollen in marine sediments is used to record vegetation change on the continent. Generally, a good latitudinal correspondence exists between the distribution patterns of pollen in the marine surface sediments and the occurrence of the source plants on the adjacent continent. To investigate land-sea interactions during deglaciation, we compare proxies for continental (pollen assemblages) and marine conditions (alkenone-derived sea surface temperatures) of two high-resolution, radiocarbon-dated sedimentary records from the tropical southeast Atlantic. The southern site is located West of the Cunene River mouth; the northern site is located West of the Angolan Huambe Mountains. It is inferred that the vegetation in Angola developed from Afroalpine and open savannah during the last Glacial maximum (LGM) via Afromontane Podocarpus forest during Heinrich Event 1 (H1), to an early increase of lowland forest after 14.5 ka. The vegetation record indicates dry and cold conditions during the LGM, cool and wet conditions during H1 and a gradual rise in temperature starting well before the Younger Dryas (YD) period. Terrestrial and oceanic climate developments seem largely running parallel, in contrast to the situation ca. 5° further South, where marine and terrestrial developments diverge during the YD. The cool and wet conditions in tropical West Africa, South of the equator, during H1 suggest that low-latitude insolation variation is more important than the slowdown of the thermohaline circulation for the climate in tropical Africa.

Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, time series since 2002)

This data set comprises a time series of aboveground community plant biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice a year just prior to mowing (during peak standing biomass twice a year, generally in May and August; in 2002 only once in September) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in up to four rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned by random selection of new coordinates every year within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Pollen analysis of sediment cores from the mouth of the river Congo to Walvis Bay and Lüderitz

The distribution of pollen in marine sediments is used to record vegetation changes over the past 30,000 years on the adjacent continent. A transect of marine pollen sequences from the mouth of the river Congo (~5°S) to Walvis Bay and Lüderitz (~25°S) shows vegetation changes in Congo, Angola and Namibia from the last glacial period into the Holocene. The comparison of pollen records from different latitudes provides information about the latitudinal shift of open forest and savannahs (Poaceae pollen), the extension of lowland forest (rain forest pollen) and Afromontane forest (Podocarpus pollen), and the position of the desert fringe (pollen of Caryophyllaceae, Chenopodiaceae and Amaranthaceae). High Cyperaceae pollen percentages in sediments from the last glacial period off the mouth of the river Congo suggest the presence of open swamps rather than savannah vegetation in the Congo Basin. Pollen from Restionaceae in combination with Stoebe-type pollen (probably from Elytropappus) indicates a possible northwards extension of winter rain vegetation during the last glacial period. The record of Rhizophora (mangrove) pollen is linked to erosion of the continental shelf and sea-level rise. Pollen influx is highest off river mouths (10-2000 grains year**-1 cm**-2), close to the coast (300-6000 grains year**-1 cm**-2), but is an order of magnitude lower at sites situated far from the continent (<10 grains year**-1 cm**-2).