Modeling the dynamics of herbage production and intake in complex grasslands

Studies in grassland management and ecology have always been challenging because of the large amount and great variation of the entities representing and affecting the system. Despite that, we were able to progress significantly in range experimentation in the Campos, in Southern Brazil. Along past...

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Main Author: Wallau, Marcelo Osório
Other Authors: Carvalho, Paulo Cesar de Faccio
Format: Others
Language:English
Published: 2017
Subjects:
Online Access:http://hdl.handle.net/10183/164622
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spelling ndltd-IBICT-oai-www.lume.ufrgs.br-10183-1646222019-01-22T02:06:36Z Modeling the dynamics of herbage production and intake in complex grasslands Wallau, Marcelo Osório Carvalho, Paulo Cesar de Faccio Pastagem nativa Ingestão Pastejo Produção animal Native grasslands Mechanistic modeling Prey model Grazing behaviour Studies in grassland management and ecology have always been challenging because of the large amount and great variation of the entities representing and affecting the system. Despite that, we were able to progress significantly in range experimentation in the Campos, in Southern Brazil. Along past thirty years, a large amount of data and information was generated, from vegetation production to components of intake. In an attempt to integrate the information available, seeking for a deeper understanding of the functioning of native grasslands, we propose adapting a mechanistic vegetation model, aggregated of a spatialized grazing component to create PampaGraze. This model was developed for temperate perennial grasslands, and was adapted and tested for subtropical, C4-dominated grasslands of the Campos of Southern Brazil (Chapter III). Despite the limited capacity of field data for validating, the model was able to relatively well simulate the trends in vegetation production along the year and seasons, while overpredicting herbage production during peak growing season. The structure of the model as it is did not allow for an accurate simulation slow-growing, tussock-forming species. Further, we developed and integrated a grazing model, based on a hybrid approach of the classical mechanistic equations of the prey model (STEPHENS & KREBS, 1986), and experimental data on foraging behaviour measured on native grasslands (Chapter IV). The model was very successful on predicting the components of intake, and responded well to variation of components in relation to changes in vegetation and to selectivity pressures, compared to available literature. Regardless of the limitations on the vegetation model, we were able to further explore the relationships of components of intake, identifying possible major limitations for herbage consumption, thus animal performance, in native grasslands. A significant progress was achieved with this thesis, but still long ways to go with this project. A list of suggestions for further developments can be found in Chapter V. We identified the emergent needs for field studies on parameters and morphogenesis, for improving predictions of the vegetation model, as well as structural points of the model that could be addressed for better representation of natural phenomena. This thesis is the first step towards a more detailed and reliable tool for studying and predicting the behaviour of vegetation dynamics and animal production in sub-tropical grasslands. This can allow us to explore relationships and scenarios beyond our experimental capacity, and investigate the connectivity of the system, as well as each mechanism separately. The stage has been set, awaiting further developments. 2017-08-01T02:36:33Z 2017 info:eu-repo/semantics/publishedVersion info:eu-repo/semantics/doctoralThesis http://hdl.handle.net/10183/164622 001027430 eng info:eu-repo/semantics/openAccess application/pdf reponame:Biblioteca Digital de Teses e Dissertações da UFRGS instname:Universidade Federal do Rio Grande do Sul instacron:UFRGS
collection NDLTD
language English
format Others
sources NDLTD
topic Pastagem nativa
Ingestão
Pastejo
Produção animal
Native grasslands
Mechanistic modeling
Prey model
Grazing behaviour
spellingShingle Pastagem nativa
Ingestão
Pastejo
Produção animal
Native grasslands
Mechanistic modeling
Prey model
Grazing behaviour
Wallau, Marcelo Osório
Modeling the dynamics of herbage production and intake in complex grasslands
description Studies in grassland management and ecology have always been challenging because of the large amount and great variation of the entities representing and affecting the system. Despite that, we were able to progress significantly in range experimentation in the Campos, in Southern Brazil. Along past thirty years, a large amount of data and information was generated, from vegetation production to components of intake. In an attempt to integrate the information available, seeking for a deeper understanding of the functioning of native grasslands, we propose adapting a mechanistic vegetation model, aggregated of a spatialized grazing component to create PampaGraze. This model was developed for temperate perennial grasslands, and was adapted and tested for subtropical, C4-dominated grasslands of the Campos of Southern Brazil (Chapter III). Despite the limited capacity of field data for validating, the model was able to relatively well simulate the trends in vegetation production along the year and seasons, while overpredicting herbage production during peak growing season. The structure of the model as it is did not allow for an accurate simulation slow-growing, tussock-forming species. Further, we developed and integrated a grazing model, based on a hybrid approach of the classical mechanistic equations of the prey model (STEPHENS & KREBS, 1986), and experimental data on foraging behaviour measured on native grasslands (Chapter IV). The model was very successful on predicting the components of intake, and responded well to variation of components in relation to changes in vegetation and to selectivity pressures, compared to available literature. Regardless of the limitations on the vegetation model, we were able to further explore the relationships of components of intake, identifying possible major limitations for herbage consumption, thus animal performance, in native grasslands. A significant progress was achieved with this thesis, but still long ways to go with this project. A list of suggestions for further developments can be found in Chapter V. We identified the emergent needs for field studies on parameters and morphogenesis, for improving predictions of the vegetation model, as well as structural points of the model that could be addressed for better representation of natural phenomena. This thesis is the first step towards a more detailed and reliable tool for studying and predicting the behaviour of vegetation dynamics and animal production in sub-tropical grasslands. This can allow us to explore relationships and scenarios beyond our experimental capacity, and investigate the connectivity of the system, as well as each mechanism separately. The stage has been set, awaiting further developments.
author2 Carvalho, Paulo Cesar de Faccio
author_facet Carvalho, Paulo Cesar de Faccio
Wallau, Marcelo Osório
author Wallau, Marcelo Osório
author_sort Wallau, Marcelo Osório
title Modeling the dynamics of herbage production and intake in complex grasslands
title_short Modeling the dynamics of herbage production and intake in complex grasslands
title_full Modeling the dynamics of herbage production and intake in complex grasslands
title_fullStr Modeling the dynamics of herbage production and intake in complex grasslands
title_full_unstemmed Modeling the dynamics of herbage production and intake in complex grasslands
title_sort modeling the dynamics of herbage production and intake in complex grasslands
publishDate 2017
url http://hdl.handle.net/10183/164622
work_keys_str_mv AT wallaumarceloosorio modelingthedynamicsofherbageproductionandintakeincomplexgrasslands
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