Increment in eucalyptus diameter as affected by seasonality and production system

Helio Tonini,Vanderley Porfirio Da Silva,Marina Moura Morales,Ciro Augusto De Souza Magalhaes

doi:10.1590/s1678-3921.pab2021.v56.02544

Helio Tonini, Vanderley Porfirio Da Silva + Show 2 more

Open Access

https://doi.org/10.1590/s1678-3921.pab2021.v56.02544

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Abstract

Abstract: The objective of this work was to assess the current monthly increment in diameter of eucalyptus (Eucalyptus grandis x Eucalyptus urophylla) trees in response to different production systems, climatic factors, and thinning. The trees were evaluated in four production systems: monoculture and crop-forestry, livestock-forestry, and crop-livestock-forestry integration. The increment in diameter of 80 trees was measured monthly from May 2015 to May 2019. The effect of the climatic variables was determined through correlation and multiple regression analyses. The increment in current monthly diameter is seasonal and highly dependent on accumulated rainfall. The adopted modeling allowed concluding that both water shortage and excess (30 and 475 mm per month, respectively) decreased tree growth in diameter. The trees in the integrated systems showed a higher growth in diameter than those under monoculture, and intercropping with crops resulted in a greater diameter growth than that with pasture. Thinning accelerates the growth of the remaining trees, with an effect of higher magnitude and longer duration in the integrated production systems.

Highlights

In the past ten years, the area occupied by integrated crop-livestock-forestry (CLF) systems in Brazil increased by 10 million hectares, reaching the current 11.5 million hectares (ILPF em números, 2016)
The silvopastoral, agroforestry, and agrosilvopastoral systems account for 17% or for approximately 2 million hectares of the CLF area (ILPF em números, 2016), which is significant since 9 million hectares are planted with forests in the country (IBÁ, 2020)
The highest values were recorded between February and March, with a mean current monthly increment in diameter (CMI) value of 2.7 mm, reducing to a mean value of 0.5 mm when rainfall started to decrease in May (Figure 1)

Summary

Introduction

In the past ten years, the area occupied by integrated crop-livestock-forestry (CLF) systems in Brazil increased by 10 million hectares, reaching the current 11.5 million hectares (ILPF em números, 2016). The silvopastoral, agroforestry, and agrosilvopastoral systems account for 17% or for approximately 2 million hectares of the CLF area (ILPF em números, 2016), which is significant since 9 million hectares are planted with forests in the country (IBÁ, 2020). To understand the reaction of trees to short-term changes in environmental conditions, it is crucial to continuously monitor stem radial variations throughout the year (Deslauriers et al, 2007). These variations allow assessing growth based on seasonality and its association with both climatic conditions and effects of silvicultural treatments (Sette Junior et al, 2012)

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