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Health and mortality of large trees in Semi-deciduous Atlantic Forest fragments

Published online by Cambridge University Press:  01 October 2026

Juliana Deganello Vieira
Affiliation:
Campus Jacarezinho, Federal Institute of Paraná, Brazil Graduate Program in Biology, State University of Londrina, Brazil
Jessica Oliveira Araujo
Affiliation:
Graduate Program in Biology, State University of Londrina, Brazil
Jose Marcelo Domingues Torezan*
Affiliation:
Graduate Program in Biology, State University of Londrina, Brazil
*
Corresponding author: Jose Marcelo Domingues Torezan; Email: torezan@uel.br
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Abstract

In tropical forests, large trees (LTs; those with a diameter ≥50 cm), can suffer significant abundance decline, especially near the edges of fragments. However, the mechanisms involved with this decline remain poorly understood. The objective of this study was to investigate edge effects on the health of LTs over a four-year interval, and identify the factors driving their mortality. The study was conducted in eight Semi-deciduous Seasonal Atlantic Forest fragments in the northern Paraná state, Brazil. The health of LTs was evaluated along an 0–250 m, edge-interior gradient using 11 indicators compiled into a Health Threat Index (HTI). Four sites had LT health assessed twice (2019 and 2023). A higher incidence of health threats was observed in the first 50 m from the forest edge, with a reduction in the frequency of these indicators with increased distance from the edge. This pattern was stronger in the largest fragment. Among the four re-sampled fragments, three maintained stable HTIs, while one exhibited a decline in LT health. The main indicators associated with LT mortality were liana infestation and the presence of dead crown portions. Liana cutting and other management measures should be tested in order to improve conservation of such important organisms.

Information

Type
Research Article
Copyright
© The Author(s), 2026. Published by Cambridge University Press
Figure 0

Figure 1. Location of the eight Semi-deciduous Seasonal Atlantic Forest fragments in northern Paraná, southeastern Brazil.

Figure 1

Table 1. Features of Semi-deciduous Seasonal Atlantic Forest fragments, in northern Parana state, BrazilTable 1 long description.

Figure 2

Figure 2. Figure 2 long description.Frequency of health indicator scores in large trees (DBH ≥ 50 cm) sampled along an edge-interior gradient (250 m) in eight fragments of Semi-deciduous Seasonal Forest, Paraná, Brazil. (a) 0–50 m from the edge; (b) 50–100 m from the edge; (c) 100–150 m from the edge; (d) 150–200 m from the edge; and (e) 200–250 m from the edge.

Figure 3

Table 2. Generalized linear models (GLMs) fitted to evaluate the effects of fragment size (FS) and edge distance (ED) on the Health Threat Index (HTI) of large trees (DBH ≥ 50 cm) in eight forest fragments from northern Paraná, Brazil. Models with ΔAICc ≤ 2 were considered equally informative and are highlighted in bold (see main text). FS = fragment size; ED = edge distance; df = degrees of freedom; weight = Akaike weightTable 2 long description.

Figure 4

Figure 3. Figure 3 long description.Relationship between the Health Threat Index (HTI) and the distance class from the edge, modelled using a generalized linear models (GLM) with a negative binomial distribution, in eight fragments of the Semi-deciduous Seasonal Forest, Paraná, Brazil. The HTI is a unitary value ranging from 0 to 33 and is represented per tree. PEMG: Mata dos Godoy State Park; BUL: Bule Farm; IBI: Ibicatu State Park; ALV: Alvorada Farm; GRE: São Gregório I Farm; DOR: Doralice Farm; SAN: Santo Antônio Farm; and MOR: Morungaba Farm.

Figure 5

Figure 4. Health Threat Index (HTI) of large trees (DBH ≥ 50 cm) sampled in 2019 and 2023 across 11 transects in four fragments of the Semi-deciduous Seasonal Forest, Paraná, Brazil. The HTI is a unitary value ranging from 0 to 33 and is represented per tree. (a) PEMG: Mata dos Godoy State Park; (b) BUL: Bule Farm; (c) ALV: Alvorada Farm; and (d) SAN: Santo Antônio Farm. Groups that do not share the same letter (above the boxplot) differ significantly (p < 0.05; paired t-test).

Figure 6

Figure 5. Frequency of health indicator grades in large trees (DBH ≥ 50 cm) sampled in 11 transects from four fragments of the Semi-deciduous Seasonal Forest, Paraná, Brazil. (a) Indicator grades in 2019 for trees that remained alive in the 2023 assessment (n = 91); (b) indicator grades in 2019 for trees that died in 2023 (n = 10).

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