Large old trees increase growth under shifting climatic constraints: Aligning tree longevity and individual growth dynamics in primary mountain spruce forests

In a world of accelerating changes in environmental conditions driving tree growth, tradeoffs between tree growth rate and longevity could curtail the abundance of large old trees (LOTs), with potentially dire consequences for biodiversity and carbon storage. However, the influence of tree-level tradeoffs on forest structure at landscape scales will also depend on disturbances, which shape tree size and age distribution, and on whether LOTs can benefit from improved growing conditions due to climate warming. We analyzed temporal and spatial variation in radial growth patterns from ~5000 Norway spruce (Picea abies [L.] H. Karst) live and dead trees from the Western Carpathian primary spruce forest stands. We applied mixed-linear modeling to quantify the importance of LOT growth histories and stand dynamics (i.e., competition and disturbance factors) on lifespan. Finally, we assessed regional synchronization in radial growth variability over the 20th century, and modeled the effects of stand dynamics and climate on LOTs recent growth trends. Tree age varied considerably among forest stands, implying an important role of disturbance as an age constraint. Slow juvenile growth and longer period of suppressed growth prolonged tree lifespan, while increasing disturbance severity and shorter time since last disturbance decreased it. The highest age was not achieved only by trees with continuous slow growth, but those with slow juvenile growth followed by subsequent growth releases. Growth trend analysis demonstrated an increase in absolute growth rates in response to climate warming, with late summer temperatures driving the recent growth trend. Contrary to our expectation that LOTs would eventually exhibit declining growth rates, the oldest LOTs (>400 years) continuously increase growth throughout their lives, indicating a high phenotypic plasticity of LOTs for increasing biomass, and a strong carbon sink role of primary spruce forests under rising temperatures, intensifying droughts, and increasing bark beetle outbreaks.     

Decomposing trends in bird populations: Climate,life histories and habitat affect different aspects of population change

Aim

Despite the complexity of population dynamics, most studies concerning current changes in bird populations reduce the trajectory of population change to a linear trend. This may hide more complex patterns reflecting responses of bird populations to changing anthropogenic pressures. Here, we address this complexity by means of multivariate analysis and attribute different components of bird population dynamics to different potential drivers.

Location

Czech Republic.

Methods

We used data on population trajectories (1982–2019) of 111 common breeding bird species, decomposed them into independent components by means of the principal component analysis (PCA), and related these components to multiple potential drivers comprising climate, land use change and species' life histories.

Results

The first two ordination axes explained substantial proportion of variability of population dynamics (42.0 and 12.5% of variation in PC1 and PC2 respectively). The first axis captured linear population trend. Species with increasing populations were characterized mostly by long lifespan and warmer climatic niches. The effect of habitat was less pronounced but still significant, with negative trends being typical for farmland birds, while positive trends characterized birds of deciduous forests. The second axis captured the contrast between hump-shaped and U-shaped population trajectories and was even more strongly associated with species traits. Species migrating longer distances and species with narrower temperature niches revealed hump-shaped population trends, so that their populations mostly increased before 2000 and then declined. These patterns are supported by the trends of total abundances of respective ecological groups.

Main Conclusion

Although habitat transformation apparently drives population trajectories in some species groups, climate change and associated species traits represent crucial drivers of complex population dynamics of central European birds. Decomposing population dynamics into separate components brings unique insights into non-trivial patterns of population change and their drivers, and may potentially indicate changes in the regime of anthropogenic effects on biodiversity.     

SruI restriction endonuclease from Selenomonas ruminantium

Abstract Sru I, specific restriction endonuclease, has been characterized from Selenomonas ruminantium isolated from the rumen of fallow deer. Results from the study demonstrate that S. ruminantium 18D possesses a type II restriction endonuclease, which recognizes the sequence 5'-TTT↓AAA-3'. The recognition sequence of Sru I was identified using digestions on pBR322, pBR328, pUC18, M13mp18RF, pACYC184 and λDNA. The cleavage patterns obtained were compared with computer-derived data. Sru I recognises the palindromic hexanucleotide sequence and cleaves DNA after the third T in the sequence, producing blunt ends. The purification and characterization of restriction endonuclease Sru I presented here is the first described for Selenomonas ruminantium spp. and demonstrates that this microorganism pocesses a DNA-cleaving enzyme with the same specificity as Dra I or Aha III.     

DNA fingerprinting of red clover (Trifolium pratense L.) with Jeffrey's probes: detection of somaclonal variation and other applications

Summary DNA fingerprints generated by the Jeffreys' probes, 33.6 and 33.15, indicated the presence of minisatellite-like sequences in the red clover genome. The fingerprints generated by probe 33.6 gave less background and fewer but better defined bands than those obtained with probe 33.15. Assay of a regenerative somaclonal variant (F49R) by DNA fingerprinting with probe 33.6 detected mutation that was unlinked to the regenerative trait. The fingerprints obtained under the applied conditions also demonstrated genetic stability of consecutive generations of the regenerants in tissue culture. DNA fingerprints of F₁ plants revealed that each polymorphic band was inherited from either one or the other parent. Both probes distinguished individual-specific genotypes in seven cultivars of red clover. Greater variability in DNA fingerprints was detected between (V=0.899) than within (0.417≤V≤0.548) cultivars.     

Spatial patterns of trees in natural forests of East-Central Europe

The analysis of spatial patterns is one of the ways to estimate the role of competition among trees in forest dynamics. Three hypotheses concerning distribution patterns in old-growth stands were tested: (1) fine-scale spatial patterns of trees are regular; (2) patterns do not differ significantly from a random distribution, and (3) spatial patterns at larger scales are clumped because of site heterogeneity. Old-growth forest stands in Poland and the Czech Republic were analysed with a modified Ripley K function, using distribution maps of tree stems. Fine-scale spatial patterns (with distances among trees not exceeding 15 m) were usually intermediate between random and regular. Trends towards a regular distribution occurred more often among dead than among live individuals. No significant relationships between tree species were found at smaller scales; however, at larger scales (distances from 15–25 m) negative associations between some species were found. This reflects site heterogeneity rather than any direct influence of one tree species upon another.     

Annotated chromosome numbers of selected asiaticPotentilla species

Chromosome numbers are reported for 19 collections representing 16 AsiaticPotentilla taxa. The first chromosome records are reported forP. desertorum Bunge var.arnavatensis Wolf (2n=28),P. festiva Soják (2n=28),P. griffithii Hook f. subsp.beauvaisii (Cardot) Soják (2n=42),P. micropetala D. Don subsp.byssitecta (Soják) Měsí?ek etSoják (2n=14),P. mollissima Lehm. (2n=28),P. moorcroftii Wall. exLehm. (2n=42),P. multicaulis Bunge (2n=14),P. [x]omissa Soják (2n=35, 56, 70) andP. stanjukoviczii Ovcz. exKoczk. (2n=14). Counts differing from those previously recorded are given forP. algida Soják (2n=56) andP. flagellaris Willd. exSchlecht. (2n=42). Chromosome numbers of the following species were confirmed:P. [x]agrimonioides Bieb. (2n=42),P. chinensis Ser. in DC. (2n=14),P. fragarioides L. (2n=14),P. lineata Trev. (2n=14) andP. sericea L. (2n=28). Taxonomy is briefly discussed. A new combinationP. micropetala D. Don subsp.byssitecta (Soják) Měsí?ek etSoják stat. nov. is proposed.     

Cultivation of lymphatic cells in protein-free medium and chemical study of the products

Rabbits immunized withBrucella suis within a period of one week formed antibodies in high titres. These antibodies were of a macroglobulin character only. Cells from the spleen and popliteal lymph nodes were cultivatedin vitro in protein-free medium, in which the only macromolecular substance was dextran or carbowax. Physico-chemical analysis of secretion products was not succesful, since under the given cultivation conditions the cells started to disintegrate from the outset and the medium contained nucleic acids as well as proteins. Some of these substances were present in particles of the size of different subcellular particles. After cultivation of spleen and lymph node cells, antibodies were detected by an agglutination test in media containing dextran and carbowax. When particles substantially larger than the antibody molecule were removed by ultracentrifugation, the agglutination antibody titre in the medium fell.     

Antibody binding capacity of different peptide chains isolated from digested and purified horse diphtheria antitoxin

In commercial digested and purified horse diphtheria antitoxin, which is formed largely of the gamma globulin fragment with the sedimentation coefficient 5.3 S, the reactive disulphide bonds were destroyed by S-sulphonation. Gel filtration on Sephadex G-100 in 0.05 M formic acid with 6 M urea showed that the molecule of the S-sulphonated preparation dissociated into chains similar in character to the peptide chains of native horse antitoxins. Antibody activity was still partly maintained even after treatment with 6 M urea. On mixing the two types of chains isolated by gel filtration, antibody activity was recovered, the amount of antibody protein determined in the mixed fractions being greater than the sum of the amounts in the separate fractions. The neutralizing activity of the mixed fractions tested against toxinin vivo was also greater than the sum of the activity of the separate fractions.