Liana regeneration in secondary and primary forests of Central Amazonia

Lianen sind ein wichtiger Bestandteil tropischer Wälder. Obgleich sie nur im geringen Maße zur Waldbiomasse und -diversität beitragen, haben sie einen großen Einfluss auf die dynamischen Prozesse im Wald. Besonders in gestörten Waldflächen, wie Bestandeslücken, Waldrändern oder Sekundärwäldern, finden sich Lianen in hoher Abundanz. Da Primärwälder immer mehr fragmentiert werden und die Fläche der Sekundärwälder zunimmt, ist zu erwarten, dass die Bedeutung der Lianen in Zukunft steigt. Bisherige Untersuchungen zu Lianengesellschaften konzentrierten sich meist auf die Erhebung von Stammdichten großer kletternder Pflanzen. Dagegen gibt es wenige Informationen über Lianensamen, -keimlinge, -jungpflanzen und vegetative Sprosse (Trieb, Schössling), obwohl Verjüngung in viele ökologische Prozesse unterschiedlichster Skalen einbezogen ist und Hinweise auf die zukünftige Vegetation gibt. Das Wissen über die Verjüngung von Lianen kann für Naturschutz oder Waldbau von Bedeutung sein.Die Ziele dieser Arbeit waren:Die Freilanduntersuchungen wurden in einem Primärwald und zwei regional typischen Sekundärwaldtypen in Amazonien nahe Manaus (Brasilien) durchgeführt. Der Primärwald war tropischer immergrüner Tieflandregenwald. Die zwei Sekundärwaldtypen waren zum einen Vismiawald auf Flächen, die nach Kahlschlag abgebrannt und beweidet wurden, und zum anderen Cecropiawald auf ehemaligen Kahlschlagflächen ohne nachfolgende Beweidung oder intensives Abrennen. Lianenverjüngung, welche Keimlinge, Jungpflanzen und vegetative Sprosse ≤ 1,7 m Länge einschloss, wurde auf 8 10 Probeflächen pro Waldtyp erhoben, auf insgesamt 27 Probeflächen. Der Abstand der Sekundärwaldflächen zum Primärwald betrug zwischen 0,03 und 1,2 km. Bestandesmerkmale wie Kronendeckung, basierend auf hemisphärischen Fotos, Grundfläche des Baumbestandes und die Stammanzahl anderer Wuchsformen wurden auf allen Probeflächen aufgenommen. In der ersten Studie wurden die Dichte und Artenvielfalt von Lianenverjüngung in den drei genannten Waldtypen untersucht. Im Sekundärwald war die Dichte der Lianenverjüngung 50 % geringer als im Primärwald. Der Anteil der Lianen an der Gesamtverjüngung aller holzigen Pflanzen unterschied sich allerdings nicht zwischen den Waldtypen. Die Artenanzahl pro Probefläche war im Primärwald am höchsten und am niedrigsten im Vismiawald. Die aufaddierte Artenanzahl war ähnlich im Cecropia- und Primärwald. Mit zunehmendem Abstand zum Primärwald nahmen der Anteil der Lianen an der Gesamtverjüngung sowie die Artenanzahl ab. Diese Ergebnisse zeigen, dass der Sekundärwaldtyp zwar die Artenvielfalt, nicht aber die Dichte der Lianenverjüngung beeinflusst. Die zweite Untersuchung behandelte die funktionellen Pflanzen- und Blattmerkmale der 26 häufigsten Lianenarten aus der ersten Studie. Funktionelle Merkmale (spezifische Blattfläche, Blattgröße und -form, Pflanzenlänge, Schlankheitsgrad des Stamms und Herbivorie) sowie die Wachstumsrate während eines Jahres wurden pro Art und pro Probefläche evaluiert. Die meisten Primärwaldarten hatten eine ähnliche Form und waren durch kleinen Wuchs und kleine, runde Blätter mit geringer spezifischer Blattfläche gekennzeichnet, während die funktionellen Merkmale der Sekundärwaldarten stark variierten. Die Auswertung der funktionellen Merkmale pro Probefläche bestätigte den Unterschied zwischen Primär- und Sekundärwald. Mit zunehmender Kronendeckung nahm die Herbivorie zu und die Variabilität der Blattgröße ab. Die relative Wachstumsrate nahm mit steigender Kronendeckung ab und war am höchsten im Vismiawald. Aus den Ergebnissen kann man folgern, dass die funktionellen Merkmale der Lianenverjüngung im Primärwald ähnlich waren und sich deutlich von denen im Sekundärwald unterschieden; die Kronendeckung konnte jedoch nur einen Teil dieser Unterschiede erklären. Der dritte Teil der Arbeit stellt die Samen- und Keimungseigenschaften von 20 Lianenarten vor. Biometrische Daten der Samen (Masse, Wassergehalt, längste und kürzeste Achse, die errechnete Austrockungstoleranz basierend auf dem Samen/Schalenverhältnis) wurden erhoben und der Keimlingstyp bestimmt. Zusätzlich wurden Keimversuche zur Untersuchung von Austrocknungstoleranz und Lichtabhängigkeit durchgeführt. Für einen Teil der Arten wurde der Einfluss von 12stündig wechselnden Temperaturen (20/30 °C, 15/35° C, mit 12 Lichtstunden) auf die Keimrate getestet. Die Trockenmasse der Samen unterschied sich 1000-fach zwischen den Arten (0,009 g 10,7 g). Die Arten mit austrocknungssensitiven Samen hatten alle Trockensamenmassen von ≥ 0,27 g. Für fünf Arten mit austrocknungssensitiven Samen wurde bisher in denselben Genera oder in einem Fall in derselben Familie nur von austrocknungstoleranten Samen berichtet. Lichtabhängige Keimung wurde bei drei kleinsamigen Arten gefunden (0,01 0,015 g Samentrockenmasse) und für zwei dieser Arten erstmals beschrieben. Es muss jedoch berücksichtigt werden, dass nur Samen von einer Mutterpflanze pro Art untersucht wurden. Weitere Studien sollten die gefundenen Ergebnisse validieren. Wechselnde Temperatur beeinflusste die Keimung von vier von neun untersuchten Arten: Für alle vier Arten verminderte sich die Keimrate bei täglicher Temperaturschwankung zwischen 15 und 35 °C, bei wechselnde Temperaturen zwischen 20 und 30 °C war die Keimrate je nach Art vermindert, erhöht oder gleichbleibend im Vergleich zu konstanter Temperatur von 25 °C. Samen- und Keimungseigenschaften der untersuchten Arten reichten von typischen Pionier- bis zu Klimaxartenmerkmalen, was bedeutet, dass die Lianenarten in einer Bandbreite von Lebensräumen keimen könnten.Diese Arbeit hat gezeigt, dass die Wuchsform Liane eine weite Bandbreite von Pflanzen- und Samenmerkmalen umfasst, womit die funktionelle Diversität dieser Gruppe unterstrichen wird. Der Erfolg der Lianenverjüngung in gestörten Habitaten ist artspezifisch und von verschiedenen Umweltfaktoren abhängig. Es ist somit schwer vorherzusagen, wann und wie Lianen während der Waldsukzession erfolgreich sind

Liana litter decomposes faster than tree litter in a multispecies and multisite experiment

1. Lianas account for a small fraction of forest biomass, but their contribution to leaf or litter biomass and thus to food webs can be substantial. Globally liana exhibit fast life-history traits. Thus, liana litter may decompose faster than tree litter, and could enhance the decomposition of tree litter (complementarity effect). The differences in decomposition may also vary with mesofauna access or across forest communities. The contribution of these factors to nutrient biogeochemical cycling is poorly understood. 2. We examined the decomposition of litter of 20 liana and 20 tree species of three different tropical forest communities in southern China, over 1 year. (i) We incubated the litter in bags with coarse and fine mesh to distinguish mesofaunal and microfaunal effects. (ii) We used single-species litter bags to compare decomposition rates of lianas and trees, to test which functional traits best explained decomposition, and whether those traits differed between lianas and trees, and among forest types. (iv) We used mixed-species litter bags to test whether liana litter enhances decomposition in litter mixtures. (v) We evaluated how leaf litter nutrients decayed in relation to litter mass. 3. Litter decayed faster in coarse-mesh than fine-mesh bags, but there was no interaction effect with forest type or growth form. Liana litter decayed faster than tree litter in single-species bags with mesofauna access and in mixed bags (liana-only mix, tree-only mix) without mesofauna. Lianas had higher nitrogen content and specific leaf area and lower leaf dry matter content (LDMC) and toughness than trees. Decomposition rate was significantly negatively related to LDMC. Litter of evergreen broadleaved forest decomposed slower than that of other forest types. Liana litter did not enhance the decomposition of tree litter in mixtures. Liana litter released calcium slightly faster than trees. 4. Synthesis: Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry

Chromosome‐level reference genome of the soursop (Annona muricata) : a new resource for Magnoliid research and tropical pomology

The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. To provide resources to breeders and evolutionary researchers, we report a chromosome-level genome assembly of the soursop (Annona muricata). We assembled the genome using 444.32 Gb of DNA sequences (676x sequencing depth) from PacBio and Illumina short-reads, in combination with 10x Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo-chromosomes using Hi-C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb). Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein-coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA-seq and homology-based approaches. Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes. The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome-assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry

Chromosome-level reference genome of the soursop (Annona muricata): A new resource for Magnoliid research and tropical pomology

The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. To provide resources to breeders and evolutionary researchers, we report a chromosome‐level genome assembly of the soursop (Annona muricata). We assembled the genome using 444.32 Gb of DNA sequences (676× sequencing depth) from PacBio and Illumina short‐reads, in combination with 10× Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo‐chromosomes using Hi‐C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb). Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein‐coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA‐seq and homology‐based approaches. Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes. The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome‐assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry

Traits and growth of liana regeneration in primary and secondary forests of Central Amazonia

Question: Do traits of liana regeneration differ among secondary forest types of varying land-use history and primary forest? Location: Eighty kilometers north of Manaus, Brazil. Methods: We compared plant functional traits and growth rates of liana regeneration (<1.7-m length) among two secondary forest types and primary forest. Secondary forest types were: Vismia (on land formerly clear-cut, used for pasture and intensively burned) and Cecropia (no pasture usage or intensive fires after clear-cut). Results: A principal components analysis indicated that most of the primary forest species exhibited a similar habit and were characterized by short shoots and small, round leaves with low specific leaf area, whereas secondary forest species had a broad range of trait values. At the plot level, primary and secondary forest communities were separated mainly by plant length and leaf size. Plant size varied more within secondary than within primary forest plots. The two secondary forest types could not be separated based on the traits of liana regeneration. Relative growth rate (RGR) did not correlate significantly with any measured plant trait, except for a negative relation to initial length. RGR increased with decreasing canopy cover and was highest in Vismia forest plots. Conclusion: Plant functional traits of liana regeneration were more similar in the primary forest and differed substantially from secondary forests, yet canopy cover only partly explained the observed differences. © 2011 International Association for Vegetation Science

Liana litter decomposes faster than tree litter in a multispecies and multisite experiment

Lianas account for a small fraction of forest biomass, but their contribution to leaf or litter biomass and thus to food webs can be substantial. Globally liana exhibit fast life-history traits. Thus, liana litter may decompose faster than tree litter, and could enhance the decomposition of tree litter (complementarity effect). The differences in decomposition may also vary with mesofauna access or across forest communities. The contribution of these factors to nutrient biogeochemical cycling is poorly understood. We examined the decomposition of litter of 20 liana and 20 tree species of three different tropical forest communities in southern China, over 1 year. (i) We incubated the litter in bags with coarse and fine mesh to distinguish mesofaunal and microfaunal effects. (ii) We used single-species litter bags to compare decomposition rates of lianas and trees, to test which functional traits best explained decomposition, and whether those traits differed between lianas and trees, and among forest types. (iv) We used mixed-species litter bags to test whether liana litter enhances decomposition in litter mixtures. (v) We evaluated how leaf litter nutrients decayed in relation to litter mass. Litter decayed faster in coarse-mesh than fine-mesh bags, but there was no interaction effect with forest type or growth form. Liana litter decayed faster than tree litter in single-species bags with mesofauna access and in mixed bags (liana-only mix, tree-only mix) without mesofauna. Lianas had higher nitrogen content and specific leaf area and lower leaf dry matter content (LDMC) and toughness than trees. Decomposition rate was significantly negatively related to LDMC. Litter of evergreen broadleaved forest decomposed slower than that of other forest types. Liana litter did not enhance the decomposition of tree litter in mixtures. Liana litter released calcium slightly faster than trees. Synthesis: Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry

Chromosome-level reference genome of the soursop (Annona muricata): A new resource for Magnoliid research and tropical pomology

The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. To provide resources to breeders and evolutionary researchers, we report a chromosome-level genome assembly of the soursop (Annona muricata). We assembled the genome using 444.32 Gb of DNA sequences (676× sequencing depth) from PacBio and Illumina short-reads, in combination with 10× Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo-chromosomes using Hi-C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb). Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein-coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA-seq and homology-based approaches. Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes. The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome-assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry

The Soursop Genome (Annona muricata L., Annonaceae)

The Annonaceae family contains important tropical crops, but the number of species used commercially is limited, and development of other promising species for cultivation is hindered by a lack of genomic resources to support the building of breeding programmes. The family is part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades have remained unclear. To provide novel resources to both plant breeders and evolutionary research, we described the chromosome-level genome assembly of the soursop (Annona muricata L.), using DNA data generated with PacBio and Illumina short-read technology, in combination with 10XGenomics, BioNano data, and Hi-C sequencing. To disentangle key angiosperm relationships, we reconstructed phylogenomic trees comparing a wider sampling of available angiosperm genomes and reveal that the soursop represents a genomic mosaic supporting different evolutionary histories, with scaffolds almost exclusively supporting singular topologies. However, coalescent methods and a majority of genes support magnoliids as sister to monocots and eudicots, where previously published whole genome-based studies remained inconclusive. The soursop genome highlights the need for more early diverging angiosperm genomes and critical assessment of the suitability of such genomes for inferring evolutionary history. The soursop is the first genome assembled in Annonaceae and supports further studies of floral evolution in magnoliids, whilst providing an essential resource for delineating relationships of major lineages at the base of the angiosperms. Both genome-assisted improvement in promising Annonaceae fruit crops and conservation efforts will be strengthened by the availability of the soursop genome. The genome assembly as a community resource will further strengthen the role of Annonaceae as a model group for research on the ecology, evolution, and domestication potential of tropical species in pomology and agroforestry