A Late Triassic vegetation record from the Huangshanjie Formation, Junggar Basin, China: possible evidence for the Carnian Pluvial Episode

The Carnian Pluvial Episode (CPE; ∼234‒232 million years ago) is characterized by an accelerated hydrological cycle, global warming and a period of elevated biotic turnover. Using spores and pollen, we reconstruct vegetation and climate changes through a Carnian‒Norian (Upper Triassic) interval of the Huangshanjie Formation from the Junggar Basin, China. Four palynofloras were identified, representing distinct vegetation communities. Among these palynofloras, we observed a prominent shift from a conifer-dominated climax forest community, with common ginkgophytes and bennettites, to a fern-dominated community, suggestive of an environmental perturbation. We interpret this change as a regional shift in vegetation, likely caused by increased humidity, consistent with the CPE. Our records represent the first indication of a possible CPE-induced vegetation response in the Junggar Basin and highlight how this event likely affected floral communities of inland Laurasia.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5738637

Cenopopulation structure of climax forest stands of formation of beech forests in Ukrainian Carpathians

Logging in the mountainous conditions of the Carpathians has transformed the forest cover into a continuous succession system. Climax exemplary communities which are subject to protection and research according to the position of structure and dynamics on the population methodological basis, to have survived on an insignificant area in the reserves and protective categories of forests. The cenopopulation paradigm considers the edificator species (spruce, fir, beech, pine) as a system of interacting geographic, food and elementary populations. The structure of climax uneven-aged coenopopulations of formation of the beech forest is considered as natural climax cenoses that have arisen as a result of endo- or exogenous successions due to climatic and edaphic conditions. Their dynamic equilibrium is supported by the variability of the spatial mosaic structure through the age-old turnover of generations. The distribution of trees by diameter in climax forest stands is characterized by three types: reverse s-shaped, j-shaped and bell-shaped with right-sided asymmetry. The inverse s-type distribution type is the main one and occupies 77 % of trial plots. The types of reverse j-shaped and bell-shaped with right-side asymmetry are encountered respectively in 2 and 21 % of the trial plots. Vertical stratification in climax beech cenoses distinguishes four functional tiers-horizons, or spatial ecological niches. There is a possibility to forecast the directions of successions by species composition in tiers. In mixed dark-coniferous-beech stands, the beech occupies a dominant position, and fir, and especially spruce, a regressive position. The age structure of climax forest stands is presented to 6 age groups: pre-generative - juvenile and imature and virginal; generative – young, middle-aged, ripe and old (overmature). According to number of climax coniferous/beech and beech stands the full-member beech cenpopulations predominate. The age spectra of fir and spruce, maple-sycamore, ash, and elm are usually unequal, or fragmentary. On average, one hectare in climax coniferous/beech and beech stands include 174–235 individuals of generative generation – 42–52 – fir, 5–16 – spruce, 5–10 – maple-sycamore and ash tree. The timber stock in half (50–60 %) is concentrated in overmature and 25 % in mature age condition. Introduction of the population paradigm in forest synecology discover a new opportunity to divide the stand of the age generation and treat them as old-growth forests and virgin forests which form a set of key species of cenopopulations, and also determine the direction of succession.

When the shifting agriculture is gone: functionality of Atlantic Coastal Forest in abandoned farming sites

Slash-and-burn agriculture has been practiced for a very long time by the traditional populations (caiçaras) on Ilha Grande, Rio de Janeiro State, Brazil. After a few years of use the plots are abandoned to fallow. We examined the processes of litter production and decomposition and the relationships between forest lands used by caiçara populations and landscape functionality. Five and 25-year-old forests growing on areas once used for subsistence agriculture were compared to a near-climax forest site. No significant differences between the three areas were noted in terms of litter production over a 2-yr period; the average litter productions were 9,927, 8,707 and 10,031 kg/ha/yr for the 5-year, 25-year and climax forests respectively. N and K nutrient input through litter was greatest in the climax forest; P and Mg input was greatest in the 5-yr forest; and Na greatest in the 25-yr forest. Ground litter accumulation (3,040-3,730 kg/ha/yr) was not significantly different in the three areas. Litter turnover times (1/K) were 0.33, 0.42 and 0.38 for the 5-yr, 25-yr and climax forests respectively. These secondary forests cover almost all of Ilha Grande and demonstrate low species diversity, but they have production and decomposition systems similar to those of mature forests.