Linking the spatiotemporal variation of litterfall to standing vegetation biomass in Brazilian savannas

Abstract

Aims Litterfall at a global scale is affected by climate, edaphic features, and vegetation structure, with litter production increasing from grasslands to forests following the rise in standing biomass. However, at landscape scales, the same relationship between litter production and vegetation structure has rarely been studied and comparisons of litterfall patterns between adjacent, structurally distinct communities are lacking. Here we use a standardized methodology to describe the structural differences among four savanna physiognomies and analyze their relationship with changes in litterfall across the Cerrado. Methods We evaluated the woody vegetation structure and composition in 48 sites, equally distributed across four physiognomies, and monitored the monthly litter production from April 2014 to March 2015. Important Findings Results showed that the density, basal area, cylindrical volume, and aboveground biomass of woody vegetation differ among physiognomies, increasing consistently from cerrado ralo, cerrado típico, cerrado denso, and cerradão. Indeed, we found a strong and positive relationship between aboveground biomass and annual litter production, with litter yield increasing from 0.9 to 8.4 Mg ha-1 across different physiognomies, following the increment in vegetation structure. Monthly production was seasonal and similar among vegetation types, increasing during the dry season. Leaves comprised the dominant fraction (approx. 85%) and litterfall seasonality primarily resulted from the concentration of leaf shedding during dry months. However, the temporal pattern of litterfall throughout the year showed a gradual reduction in the seasonality from open to closed vegetation types, likely following the decrease of deciduous species abundance in the plant community. Our results showed that changes in vegetation structure may affect spatial and temporal litterfall patterns in different physiognomies, which co-occur across the Cerrado landscape, with potential implications for the overall functioning of this ecosystem. Moreover, these findings highlight the use of standardized methods as essential to correctly compare litterfall patterns among different environments.

Topsoil physical properties under a riparian forest in Central Brazil: infiltration and penetration resistance

“…Our resistance to penetration was lower compared to a nearby savana (regionally known as "Cerrado típico") in the same area (Murta et al 2020). Such difference of soil penetration resistance in the riparian forest compared to a savanna might be attributed to the higher and more continuous addition of litter year-round in the forest compared to the savanna (Costa et al 2020). For example, Aquino et al (2016) measured an average of 6 ton ha -1 year -1 in a riparian forest whereas Valenti et al ( 2008) found 0.6 ton ha -1 year -1 in a savana.…”

Multitemporal lidar captures heterogeneity in fuel loads and consumption on the Kaibab Plateau

“…Litter accumulates on the soil until litterfall equals decomposition and accumulation stabilizes around a mean steady state (Ewel et al 1976 ). Note as well that both decomposition and litterfall are complex processes mainly driven by climate, aboveground biomass, site, and soil conditions (Prescott 2002 ; Bezkorovaynaya 2005 ; Krishna and Mohan 2017 ; Neumann et al 2018 ; Costa et al 2020 ). Changes to these can alter the system feedbacks and affect the accumulation process which would explain the fluctuation of fuel loads over the asymptote after a long time since fire (Fig.…”

Aerial Biomass Estimation in the Cerrado Biome Using Canopy Height Data

“…The values of aboveground forest biomass were assessed according to the proportions of live and dead forest biomass, both above and below the ground. A total of 67 documents were reviewed based on the search criteria used, and 16 were selected for the analyses of the present study; see Figure 2 [2,[4][5][6]8,9,[11][12][13][14][16][17][18][19]27,28].…”

“…The second evaluated sample set used the geographic location of statistical parameters related to inventoried populations from 29 forest fragments in different phytophysiognomies, measured at different times, and distributed across the 16 scientific articles found in the Cerrado systematic review [2,[4][5][6]8,9,[11][12][13][14][16][17][18][19]27,28]. Classifications of shrubland, savanna, and forest formations were determined according to the authors' classifications in the articles.…”

“…Research carried out in the field to quantify plant biomass in transition zones between biomes is rare but essential for understanding carbon stocks in the different types of vegetation [17]. According to [18], surface litter biomass in tropical forests is affected by many variables, such as climate, edaphic and vegetation structure, with a rising litter production from grasslands to forests. This fact can further increase the variability of the relationship between the proportions of biomass parts, making it difficult to standardize the dynamics of biomass between herbaceous, shrub, and forest vegetation structures of different phytophysiognomies.…”