Banca de DEFESA: ANDRÉ YURI SANTOS PORTIOLE BELO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDRÉ YURI SANTOS PORTIOLE BELO
DATE: 05/05/2025
TIME: 08:00
LOCAL: Google Meet (https://meet.google.com/yy b-jjky-tny)
TITLE:

Dynamics of litter decomposition in habitats: species interactions, litter diversity and functional responses to biotic and abiotic factors

KEY WORDS:

litter decomposition; synergistic and antagonistic non-additive effects; habitat heterogeneity; functional attributes; biotic-abiotic gradients; SLA; interspecific interactions; photodegradation

PAGES: 95
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Litter decomposition is an essential ecological process for nutrient cycling, regulated by complex interactions between biotic and abiotic factors, whose context-dependent modulation is still poorly understood. Here, we investigate how spatial heterogeneity, seasonality, and leaf litter quality and functional diversity influence decomposition dynamics in habitats with distinct factors that modulate decomposition. Using experimental approaches based on the use of litterbags, we evaluate: (1) the contextdependence of the non-additive effects of leaf litter mixtures of inquiline species on the decomposition of a keystone species, (2) the interactive role of habitat diversity and leaf litter diversity in decomposition, and (3) the ability of litter functional attributes (i.e., traits) to predict decomposition under conditions where the process is more determined by abiotic vs. biotic factors. In chapter 1, we evaluated how the decomposition of the key habitat-forming species Encholirium spectabile (Macambira-de-flecha) is affected by the litter of tenant species in three habitat conditions associated with E. spectabile thickets— inside, on the edge of, and outside the E. spectabile —under seasonal variation in sequences of dry and rainy regimes. The results indicated that within the E. spectabile (microclimate with lower and more stable temperatures), mixtures with litter of tenant species accelerated the decomposition of E. spectabile in the seasonal sequence in which the litter begins and ends to decompose during the dry season. This possibly occurred because the mixture provided greater complementarity to the litter of the habitat-forming species, as the habitat provided better conditions for the establishment of decomposers during dry periods. At the edge of the E. spectabile (with intermediate temperature and light variation), under the same seasonal sequence, the decomposition of E. spectabile was also accelerated, indicating complementarity between biotic decomposition and photodegradation. Outside the E. spectabile (high temperature variation and constant light), the decomposition of the E. spectabile litter was inhibited (i.e., slowed down) in the presence of the litter of the inquiline species, both in the seasonal sequence in which the litter begins and ends to decompose in the dry season and in the rainy season. This is due to a possible interference of the release of inhibitory compounds to the decomposers, as well as to shading that hindered the photodegradation process. In chapter 2, we tested how the effects of leaf litter diversity are modulated by habitat diversity. Contrary to our hypotheses, our results demonstrated that at the assemblage level (i.e., total decomposition of all species in a mixture), positive effects of mixing on decomposition occurred when the detritus decomposed in a single habitat where similar environmental factors prevailed and negative effects occurred when the litter decomposed in different habitats where the greatest diversity (variability) of environmental factors occurred. Thus, showing that habitat diversity generated effects that may have nullified or diminished patterns of complementarity of the litter mixture. On the other hand, at the species-specific level the interaction between habitat and litter diversity varied depending on the litter quality. Species with higher SLA tended to have antagonistic effects, compared to species with lower SLA in more diverse habitats. These results reveal possible mechanisms dependent on habitat diversity, in addition to those described by detritus diversity alone. Finally, in chapter 3, we identify the chemical and physical traits that best predict decomposition in habitats dominated by biotic factors vs. biotic factors. abiotic factors, as well as those that best predict the relative difference in decomposition rates of different species between shaded and sun-exposed habitats. We observed that, in habitats where biotic factors predominate over decomposition (shaded habitats under vegetation), decomposition was associated with traits related to palatability for decomposers. In habitats under strong influence of abiotic factors (sunexposed and vegetation-free habitats), in addition to chemical traits, physical traits were critical for litter decomposition. However, contrary to what we expected, the traits that best explained the difference between decomposition in habitats are not linked only to the habitat that most influenced litter decomposition. In summary, the results of the three chapters demonstrate that the non-additive effects of mixing and the relevance of specific traits are highly dependent on the environmental context, being modulated by the interaction between detritus diversity, habitat heterogeneity and environmental factors. Through these results, we observe the importance of integrating spatial, seasonal and spatial scales.

COMMITTEE MEMBERS:
Presidente - 1714892 - ADRIANO CALIMAN FERREIRA DA SILVA
Externo à Instituição - ALBERT LUIZ SUHETT - UFRRJ
Externo à Instituição - JAQUEIUTO DA SILVA JORGE
Interna - 1434166 - LUCIANA SILVA CARNEIRO
Externa à Instituição - MERY INGRID GUIMARÃES DE ALENCAR