Composition, phenology and restoration of campo rupestre mountain grasslands, Brazil

Composição, fenologia e restauração dos campos rupestres Brasil. As mudanças ambientais globais, principalmente as mudanças de uso da terra, afetam profundamente o funcionamento dos ecossistemas e a biodiversidade e já alteraram muitos serviços ecossistêmicos. Essas perdas enfatizam a necessidade de se preservar ecossistemas intocados; no entanto, quando os programas de conservação não são suficientes, a restauração das áreas que foram destruídas ou perturbadas pode melhorar os esforços de conservação e mitigar os danos. Este trabalho trata dos campos rupestres, campos neotropicais encontrados em altitudes, incluídos no Cerrado, que possuem uma grande biodiversidade com um alto grau de endemismo e, assim como outros ecossistemas de montanhas, fornecem serviços ecossistêmicos valiosos, tais como filtragem da água e áreas de lazer. Eles foram e ainda estão sendo impactados por atividades humanas, tais como obras de engenharia civil, pedreiras e minas. O primeiro objetivo do presente trabalho foi descrever o ecossistema de referência, a fim de definir claramente um objetivo de restauração para monitorar o progresso e o sucesso da restauração. Mostramos que campos rupestres são compostos por pelo menos duas comunidades vegetais distintas (campos arenoso e pedregoso), cada uma com composição e estrutura específicas e apresentando grande biodiversida de. Vários padrões fenológicos ocorrem nas comunidades herbáceas de campos rupestres: a maioria das espécies florescem e frutificam durante a estação chuvosa, quando algumas espécies reproduzem durante a estação seca mas outros padrões podem ser observados. Durante o nosso levantantamento fenológico de 2 anos, algumas espécies dominantes de Poaceae, entre outros, não foram observadas reproduzindo, o que implica possibilidades limitadas de dispersão em áreas degradadas. A vegetação de campos rupestres não é resiliente após um grande distúrbio: vários anos depois do distúrbio, espécies nativas quase não são encontradas em áreas degradadas, os solos estão completamente alterados e os bancos de sementes recompõem apenas espécies ruderais. De acordo com o modelo dos filtros, uma comunidade local é o resultado de um conjunto regional de espécies selecionadas por três filtros: um filtro de dispersão, um filtro abiótico e um filtro biótico. A atuação sobre os diferentes filtros para influenciar a comunidade de planta s foi o núcleo de nossas intervenções de restauração. Aplicamos, então, três protocolos de restauração in-situ (a transferência de feno, a translocação de espécies e translocação do placa de vegetação) para restaurar os dois tipos de campos. A transferência de feno não permite a restauração da vegetação de campos rupestres devido à alteração do solo e, principalmente, por causa da baixa qualidade das sementes. De fato, estudos mostram que algumas Xyridaceae e Velloziaceae têm uma germinação alta, enquanto algumas espécies dominantes, como Poaceae, Cyperaceae ou Asteraceae, têm sementes sem embrião, inviáveis ou dormentes, o que torna a semeadura uma técnica pouca eficiente. Não há evidências de que o fogo aumenta a germinação das espécies de campos rupestres . A translocação de espécies foi bem sucedida para apenas uma espécie, Paspalum erianthum; para as outras, danos nas raizes provavelmente impediram a sobrevivência. A translocação de placa de vegetação finalmente foi o método mais bem sucedido, uma vez que numerosas espécies foram reintroduzidas em áreas degradadas. No entanto, devido à baixa resiliência dos campos rupestres de onde as placas foram retiradas, a translocação de placa de vegetação apenas pode ser considerada no caso de resgate de habitat, em circunstâncias em que a destruição completa do habitat é inevitável. Face à dificuldade de se restaurar os campos rupestres, a proteção e a conservação dos mesmos deve ser uma prioridade.Composition, phenology and restoration of campo rupestre mountain grasslands - Brazil. Global environmental changes, especially land-use changes, have profound effects on both ecosystem functioning and biodiversity, having already altered many ecosystem services. These losses emphasize the need to preserve what remains; however when conservation programs are not sufficient, restoring areas that have been destroyed or disturbed can improve conservation efforts and mitigate damages. This work focuses on campos rupestres, Neotropical grasslands found at altitudes, which are part of the Cerrado (Brazilian savannas). They host a great biodiversity with a high level of endemism and, like other mountain ecosystems, provide valuable ecosystem services, such as water purification and recreational services. They have been and still are being impacted by human activities, such as civil engineering construction, quarrying or mining. The first objective of this thesis was to describe the reference ecosystem in order to aim for a clear restoration target and to monitor progress and success. We show that campos rupestres are composed of at least two distinct plant communities (i.e. sandy and stony grasslands), each having a specific composition and structure, hosting a great biodiversity. Several phenolo gical patterns occur among the herbaceous communities: the majority of species flowers and fruits appear during the rainy season but other patterns can be observed. During our 2-year survey, some dominant species belonging to Poaceae, among others, were not observed reproducing, which implies limited chances to disperse on degraded areas. Campo rupestre vegetation is not resilient following a strong disturbance: several years after the disturbance, almost no native species are encountered on the degraded areas, soils are completely altered and seed bank recomposes only with non-target ruderal species. According to the filter model, a local community is a subset of the regional species pool determined by a set of dispersal, abiotic and biotic filters. Acting on the different filters to influence the plant community was the core of our restoration interventions. We then applied three in-situ restoration protocols (hay transfer, species translocation and turf translocation) to restore both kinds of grassland. Hay transfer does not allow the restoration of campo rupestre vegetation because of soil alteration and mainly because of poor seed quality. Indeed, germination studies show that, while some Xyridaceae and Velloziaceae have a high germinability, some dominant Poaceae, Cyperaceae or Asteraceae species have embryoless, unviable or dormant seeds, which makes seeding less efficient. There is no evidence that fire-related cues enhance germination in campos rupestres. Species translocation is successful for only one species, Paspalum erianthum; for the others, root damages probably impede survival. Finally, turf translocation is the most successful method, since numerous species are re -introduced on degraded areas. However due to the low resilience of pristine campos rupestres where turfs are taken from, turf translocation can only be considered in the case of habitat rescue, in circumstances when complete habitat destruction is otherwise unavoidable. Face to the difficulty to restore these peculiar grasslands, the protection and the conservation of campos rupestres must be made a high priority

Relation entre les traits fonctionnels des végétaux des ravines marneuses et leurs capacités à résister au déracinement

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Composição, fenologia e restauração dos campos rupestres – Brasil

Global environmental changes, especially land-use changes, have profound effects on both ecosystem functioning and biodiversity, having already altered many ecosystem services. These losses emphasize the need to preserve what remains; however when conservation programs are not sufficient, restoring areas that have been destroyed or disturbed can improve conservation efforts and mitigate damages. This work focuses on campos rupestres, Neotropical grasslands found at altitudes, which are part of the Cerrado (Brazilian savannas). They host a great biodiversity with a high level of endemism and, like other mountain ecosystems, provide valuable ecosystem services, such as water purification and recreational services. They have been and still are being impacted by human activities, such as civil engineering construction, quarrying or mining. The first objective of this thesis was to describe the reference ecosystem in order to aim for a clear restoration target and to monitor progress and success. We show that campos rupestres are composed of at least two distinct plant communities (i.e. sandy and stony grasslands), each having a specific composition and structure, hosting a great biodiversity. Several phenological patterns occur among the herbaceous communities: the majority of species flowers and fruits appear during the rainy season but other patterns can be observed. During our 2-year survey, some dominant species belonging to Poaceae, among others, were not observed reproducing, which implies limited chances to disperse on degraded areas. Campo rupestre vegetation is not resilient following a strong disturbance: several years after the disturbance, almost no native species are encountered on the degraded areas, soils are completely altered and seed bank recomposes only with non-target ruderal species. According to the filter model, a local community is a subset of the regional species pool determined by a set of dispersal, abiotic and biotic filters. Acting on the different filters to influence the plant community was the core of our restoration interventions. We then applied three in-situ restoration protocols (hay transfer, species translocation and turf translocation) to restore both kinds of grassland. Hay transfer does not allow the restoration of campo rupestre vegetation because of soil alteration and mainly because of poor seed quality. Indeed, germination studies show that, while some Xyridaceae and Velloziaceae have a high germinability, some dominant Poaceae, Cyperaceae or Asteraceae species have embryoless, unviable or dormant seeds, which makes seeding less efficient. There is no evidence that fire-related cues enhance germination in campos rupestres. Species translocation is successful for only one species, Paspalum erianthum; for the others, root damages probably impede survival. Finally, turf translocation is the most successful method, since numerous species are re-introduced on degraded areas. However due to the low resilience of pristine campos rupestres where turfs are taken from, turf translocation can only be considered in the case of habitat rescue, in circumstances when complete habitat destruction is otherwise unavoidable. Face to the difficulty to restore these peculiar grasslands, the protection and the conservation of campos rupestres must be made a high priorityLes changements globaux, notamment les changements d'usage des terres, modifient profondément le fonctionnement des écosystèmes et la biodiversité et, ont déjà impacté de nombreux services écosystémiques. La disparition de ces écosystèmes souligne la nécessité de préserver les zones intactes, et la restauration des zones détruites ou perturbées peut permettre de venir en appui aux efforts de conservation et minimiser les dommages. Ce travail a pour objet d’étude les campos rupestres, des pelouses néotropicales d’altitude, faisant partie du Cerrado (savane brésilienne), qui recèlent une importante biodiversité et qui, comme bien d'autres écosystèmes de montagne, fournissent de précieux services écosystémiques tels que la filtration de l’eau. Ils ont été, et sont encore, grandement affectés par les activités humaines (les travaux de génie civil, les carrières ou les mines). Le premier objectif de cette thèse était de décrire l'écosystème de référence, afin de définir clairement un objectif de restauration et mesurer les progrès et le succès de la restauration. Nous avons montré que les campos rupestres sont composés d'au moins deux communautés végétales distinctes (une avec un substrat caillouteux et l’autre avec un substrat sableux), chacune ayant une composition en espèces et une structure particulières ainsi qu’une grande biodiversité. La phénologie reproductive varie au sein des communautés herbacées: la majorité des espèces fleurissent et fructifient pendant la saison des pluies, d'autres se reproduisent en revanche durant la saison sèche. Tout au long de nos 2 années de suivis phénologiques, certaines espèces dominantes, notamment des Poaceae, n'ont pas été observées en fleur impliquant une dispersion limitée de ces espèces vers les zones dégradées. Les communautés végétales de campos rupestres ne sont pas résilientes aux fortes perturbations: plusieurs années après, presque aucune des espèces cibles n’ont été trouvées en zones dégradées, les sols ont complètement été modifiés et les banques de graines ne se sont recomposées qu’avec des espèces rudérales non désirées. Selon le modèle des filtres, une communauté résulte d’un pool régional d’espèce sélectionné par un ensemble de filtres : de dispersion, abiotique et biotique. Les interventions de restauration mises en place avaient pour but d’agir sur ces différents filtres afin de diriger la dynamique des communautés végétales. Nous avons mis en place trois protocoles de restauration in-situ (le transfert de foin, la translocation d’espèce et la translocation de plaque de végétation) pour restaurer les deux types de communautés de campos rupestres identifiées. Le transfert de foin n’a pas permis la restauration des communautés végétales de campos rupestres en raison de l’importante altération des sols et, surtout, à cause de la mauvaise qualité des graines. En effet, nos études de germination ont montré que, alors que certaines espèces de Xyridaceae et Velloziaceae germent très bien, certaines espèces dominantes de Poaceae, de Cyperaceae ou d’Asteraceae ont des graines soit vides, soit non viables, soit dormantes ; le semis se révèle alors peu efficace. Nous n’avons pas mis en évidence d’effet positif du feu sur la germination des espèces de campos rupestres. La translocation d'espèces s’avère un succès pour une seule espèce, Paspalum erianthum. Pour les autres, les dommages causés au niveau des racines lors de la translocation limitent probablement leur survie. Enfin la translocation de plaques de végétation s’avère être la méthode la plus efficace permettant à de nombreuses espèces d’être réintroduites en zones dégradées. En raison de la faible résilience des campos rupestres dans lesquels les plaques de végétation ont été prélevées, cette méthode ne peut être envisagée que pour sauver des habitats dans le cas extrême où leur destruction est inévitable. Face à la difficulté de restaurer les campos rupestres, leur protection et leur conservation doit être une priorit

Restaurer les savanes et les écosystèmes herbacés tropicaux

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Vegetation composition and structure of some Neotropical mountain grasslands in Brazil

The description and understanding of plant communities is fundamental for the implementation of conservation or restoration programs, especially when these communities are highly threatened and need to be restored. Campos rupestres, some Neotropical mountain grasslands located in central Brazil and part of the Cerrado biome (covering 2 million km2) host unique plant communities, currently threatened by quarrying and mining. The grassy matrix of campos rupestres, has long been considered a rich mosaic under the control of local topography and the nature of substrate, but this affirmation has not been well studied. We analyzed whether plant communities varied in relation to edaphic factors within the stony substrate and the sandy substrate of this grassy matrix. We selected 5 sites where occur both grasslands on stony substrate and on sandy substrate, and we carried out vegetation surveys and soil analyses. We counted 222 plant species within our communities, among which 38.6% are exclusively found on campos rupestres. Our results show that both soil-types are strongly acidic, nutrient poor and exhibit a seasonal variation. Phosphorus increases and pH and organic carbon decrease during the dry season. Stony soils are slightly richer in nutrients than sandy soils and differences in soil granulometry and composition have led to the formation of distinct plant communities. Some species are confined to either one or the other grassland-type, which makes the plant composition of each community unique. Variations in edaphic factors generate heterogeneous grasslands favorable to a high plant diversity. Conservation programs and restoration actions have to maintain or recreate this heterogeneity. The presence of distinct plant communities implies that different strategies might be adopted to improve the restoration of these ecosystems. © 2015, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg

No recovery of campo rupestre grasslands after gravel extraction: implications for conservation and restoration

International audienceOld‐growth grasslands, including savannas and tropical grasslands, need centuries to assemble; they are therefore expected to have low resilience to anthropogenic activities that disturb the soil (e.g. cultivation, quarrying, mining, etc.). Understanding which parameters restrict the natural recovery of degraded ecosystems is a major prerequisite for planning an effective restoration program. This study was designed to evaluate the recovery of an old‐growth grassland, the campo rupestre, after a major disturbance: gravel extraction. In 2010 (i.e. 8 years after the degradation), we analyzed soil characteristics, seed bank, and vegetation composition in degraded sites consisting of sandy or gravel substrates, as well as in reference sites of sandy and gravel grasslands. At degraded sites, soils contained lower concentrations of the main nutrients, and seed banks consisted mainly of nontarget species. Seed banks of reference grasslands were poor in species and in seeds. Eight years after the degradation, plant communities at degraded sites were still very different from those at the reference sites, with ruderals and almost no target species. Altered soil conditions, low capacity of campo rupestre species to form seed banks, and the probable restriction of seed dispersal from the target species in nearby campo rupestre considerably limited the establishment of campo rupestre plant communities in degraded areas. Time is essential for old‐growth grassland assemblage and, even with the presence of a propagule source in the surroundings, the assembly of campo rupestre plant communities in degraded sites will take centuries. Therefore, human intervention is necessary to rapidly reestablish the main species

Restoration of rupestrian fields, physiognomy of Cerrado threatened by land use changes

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