Dating and reconstruction of the growth of small plants and the influence of ecological and climate variables

Abstract

Cerrado grasslands were naturally rare in the State of São Paulo before land conversion and, currently, only small fragments remain. However, despite their small size, these fragments are home to a rich diversity of small plants, including endemic and/or endangered species. Therefore, deepening our knowledge about plant diversity in these remnants becomes crucial for their preservation. Furthermore, this allows us to highlight the important role of these ecosystems in carbon sequestration and storage and, consequently, better understand how climate change is affecting the carbon cycle in these environments. The present project has four main objectives: (1) Determine the age and reconstruct the growth of small plant species, using dendrochronology (growth ring analysis), and infer the age and conservation status of the ecosystems in which they inhabit; (2) Characterize the anatomical structure of wood and growth rings, enabling the creation of descriptive sheets, dichotomous key and guides for the identification of small plant species; assembly of wood library and collection of histological slides of small plant species collected as a complement to the herbarium exsiccates; (3) Application of X-ray densitometry to characterize growth rings and evaluate the Carbon sequestered each year in the wood of small plants and its relationship with biodiversity and climate change; (4) Dendroecology and the assessment of fire events, the effectiveness of forest restoration treatments, the historical reconstruction (30 years) of woody encroachment over grasslands. Sampling of small plant species will be carried out in at least six Conservation Units (CU) using different methodologies. In the laboratory, the description of the macro and microscopic anatomical structure of wood and other organs of small plant species will be carried out, followed by analysis of the microdensity of the growth rings by X-ray densitometry, with the delimitation of the growth rings, determination of the density, volume, wood mass and C increment. Dendrochronology and dendroecology analyzes use growth ring width and microdensity profiles with the application of specific software, with models being built associating growth ring parameters with the variables climate change, C fixation, history of fires, grassland replacement by forests, etc., in addition to the reconstruction of the climate and extreme weather events. Interactive identification keys for small plant species by anatomical structure will be elaborated and made available online. The study areas can be grouped by similarity and type of vegetation, with the attributes of the plant community and set of indicator species as input for management and conservation.