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How Weed Control Affects <i>Eucalyptus globulus</i> Labill. Productivity – Results from Two Long Term Trials

2022; RELX Group (Netherlands); Linguagem: Inglês

10.2139/ssrn.4180318

1556-5068

Sofia Corticeiro, Paula Maia, Catarina Isabel Gonçalves, Jan Jacob Keizer, Carlos Valente,

Agroforestry and silvopastoral systems

Eucalyptus globulus Labill. is amongst the most extensively planted and economically relevant hardwood species in the world. Several management strategies have been developed to reach the productivity potential of eucalypt plantations in a sustainable manner, thereby contributing to the development of the forest sector while meeting the industrial demands for wood, especially for paper pulp production. Weed control is considered one of most critical management operations for the establishment and growth of eucalypts, and has become a generally applied practice during the last decades. The main objective of this study was to assess the impact of weed control on E. globulus productivity, with the specific objective of doing so for two eucalypt plantations under different edaphoclimatic conditions. The two field experiments were carried out in an operational setting, i.e. in two actively managed eucalypt plantations in the Central Portugal, one located further north, in the province of Beira Litoral, and another further south, in the province of Estremadura. At each experimental site, two types of plots were established according to the treatment application, with or without weed control. Weed control was carried out through herbicide application when vegetation cover occupied at least 50% of the plot area, with a mean height of at least 50 cm. Weed control demonstrated to be effective on diminishing vegetation cover density to a maximum of 79% and 94% in the northmost and in the southmost sites, respectively. Weed control significantly increased eucalypt productivity, by significant increments in height and in diameter at breast height in at least one of the time periods monitored. At the northernmost site, this effect was more pronounced when weed control was performed during the first 3 years following planting. At the southernmost site, however, the effect of weed control only became significant towards the end of the eucalypt rotation cycle, during the 9 th year after planting, when the effect of weed control operations on vegetation was more pronounce. This study demonstrated the need for repeated and time-specific control of the understory vegetation to enhance eucalypt productivity along the first rotation cycle, not just immediately following planting or early establishment.