O estrato herbáceo-arbustivo do cerrado sensu stricto é menos resiliente que o estrato arbóreo após o desmatamento e raspagem do solo superficial: O papel do banco de gemas e sementes na regeneração natural

Abstract

The Cerrado is recognized for its resilience due to a series of evolutionary adaptations that enable persistence under unique environmental conditions, such as prolonged droughts and natural fire regimes. Among these adaptations is the ability to resprout from buds located in both the aerial and underground structures of plants. Anthropogenic disturbances can reduce species resilience, as these often occur at intensities beyond what plants have evolved to withstand, leading to local extinctions in many cases. This study aimed to understand the recovery of the plant community in a cerrado stricto sensu area undergoing natural regeneration for 2 years and to identify the regeneration sources (resprouting or seed) involved in this process. The study was conducted in a typical Cerrado area in Catalão (Goiás). Half of the area had experienced vegetation suppression and had been regenerating naturally for two years, while the other half remained intact, with no recent anthropogenic intervention. We compared species richness, structure, and composition between the suppressed area and the reference area through 10 sample plots, each measuring 20m x 50m, and used the line-intercept method to measure cover through transects. To investigate regeneration strategies, we excavated tree individuals in randomly selected 10m x 10m plots within each sample plot and herb-shrub layer individuals (shrubs, subshrubs, lianas, palms, grasses, and herbs) in randomly selected sampling units within the transects. The natural regeneration area showed significant differences in species richness and composition compared to the reference area, with the herb-shrub layer being the most severely affected. Structurally, the same pattern was observed, with low cover and a high incidence of exposed soil in the regenerating area, creating a favorable habitat for the proliferation of easily dispersed exotic species. The primary regeneration strategy for the tree layer was resprouting from stems and, more notably, from underground bud-bearing structures, such as the root collar, soboles, and bud-bearing roots, the latter two being diffuse underground systems capable of both resprouting and vegetative propagation. In the herb-shrub layer, resprouting primarily occurred from xylopodium, with less frequent resprouting from soboles and bud-bearing roots. However, seed regeneration played an important role, highlighting the severity of the disturbance, which significantly damaged the bud bank in underground structures, which are generally fewer and more superficial in the life forms present in this layer. Although the Cerrado is recognized as a resilient ecosystem, its savanna environments rely on a persistent bud bank for regeneration and are not adapted to survive anthropogenic disturbances, which can lead to significant species diversity losses, particularly in the herb-shrub layer, responsible for various ecosystem functions in the biome.