The potential of natural regeneration of rocky outcrop vegetation on rupestrian field soils in "Serra do Cipó", Brazil

An area's innate potential to regenerate represents a crucial factor for its conservation and management. The seed rain and seed bank are important agents in the regeneration process. Seed banks are particularly important in communities where there is a high proportion of obligate seeders. Rocky outcrops are habitats where most part of the plant species depends on their seeds to reproduce and maintain viable populations. Therefore, seed banks ought to be important in this vegetation physiognomy. We test the hypotheses that the seed bank of the rocky outcrops found in the rupestrian fields of "Serra do Cipó", Brazil, is richer in species and denser than those formed on different vegetation physiognomies neighboring the outcrops. We then compared species abundance, species richness and composition in the rocky outcrops' seed banks with those of sandy and peaty bogs, forests, gallery forests, and "cerrados". Furthermore, we report on the natural regeneration potential of these soils by assessing a greenhouse study on seedling emergence. Soil samples were collected from 0 to 5 and 5 to 10 cm of depth. Rocky outcrops had the poorest in species and less dense seed bank and showed segregation in species composition. Emergence was greater in the most superficial layer. However, soils on rocky outcrops showed the greatest proportion of endemic threatened species in their seed banks, demonstrating their importance for biodiversity conservation of the "Serra do Cipó" rupestrian fields.

Influence of soil properties on the abundance of plant species in ferruginous rocky soils vegetation, southeastern Brazil

Ferruginous "campos rupestres" are a particular type of vegetation growing on iron-rich primary soils. We investigated the influence of soil properties on plant species abundance at two sites of ferruginous "campos rupestres" and one site of quartzitic "campo rupestre", all of them in "Quadrilátero Ferrífero", in Minas Gerais State, southeastern Brazil. In each site, 30 quadrats were sampled to assess plant species composition and abundance, and soil samples were taken to perform chemical and physical analyses. The analyzed soils are strongly acidic and presented low fertility and high levels of metallic cations; a principal component analysis of soil data showed a clear segregation among sites due mainly to fertility and heavy metals content, especially Cu, Zn, and Pb. The canonical correspondence analysis indicated a strong correlation between plant species abundance and soil properties, also segregating the sites.

Floristic and vegetation structure of a granitic grassland in Southern Brazil

A floristic and structural survey of a natural grassland community was conducted on Morro do Osso, a granitic hill in Porto Alegre, RS, Brazil. Structural data were surveyed in 39 one square meter plots placed over two major grassland areas. An accidental fire has occurred in one of the areas approximately one year prior to our survey, leading to further analysis of parameters differences between sites. The floristic list contains 282 species, whereas the structural survey has found 161 species. Families with highest accumulated importance values were Poaceae, Asteraceae and Fabaceae. The diversity and evenness indexes were 4.51 nats ind-1 and 0.86, respectively. Cluster analysis denoted two groups coinciding with the areas distinguished by the fire disturbance. A similarity analysis between our data and two other data sets from nearby granitic hills resulted in 28% to 35% similarity, with equivalent species-family distribution and many common dominant species, corroborating the concept of a continuous flora along the South Brazilian granitic hills.

The coastal restinga vegetation of Pará, Brazilian Amazon: a synthesis

The present article reviews studies (some unpublished) of the vegetation of coastal sandy soils (restinga) along the coast of Pará State, northern Brazil. A total of 411 higher plant species are reported; Fabaceae, Poaceae, Cyperaceae, Rubiaceae and Myrtaceae are the most species-rich families. Nearly half of the restinga species (48%) are terrestrial herbs; palms, trees and shrubs account for 39% of the species, the remainder being lianas and epiphytes. Species are frequently wide-spread and occur in coastal areas of Southeastern Brazil as well as at inland sites in the Amazon region. Only two species appear to be exclusively coastal; whereas other species appear to exhibit a preference for sandy soils. Plant assemblages are commonly classified by means of "formations" associated with certain habitats but current data do not allow the description of well-defined plant associations. The species composition at different sites along the Pará coast does not show any clear regional grouping pattern. Seasonal changes in the composition of restinga vegetation are most probably linked to variation in ground water level. Restinga forest is mostly low and open; among the dominant tree species are Humiria balsamifera Aubl., Pouteria ramiflora (Mart.) Radlk., Anacardium occidentale L., Byrsonima crassifolia (L.) Kunth, and Tapirira guianensis Aubl.

Plant-plant associations and population structure of four woody plant species in a patchy coastal vegetation of Southeastern Brazil

We examined plant population structure and interspecific associations for juveniles and adults of four woody species (Andira legalis (Vell.) Toledo, Clusia hilariana Schltdl., Protium icicariba (DC.) Marchand and Vernonia crotonoides Sch. Bip. ex Baker) in a patchy vegetation on a sandy coastal plain (restinga) in SE - Brazil. We found 101 vegetation patches in a 0.5 ha grid and these were divided into two distinct size classes, with large patches (> 20 m²) containing the majority of adult individuals of the species studied. The most abundant species, P. icicariba (465 individuals) and C. hilariana (312), had actively regenerating populations, whereas A. legalis (20) and V. crotonoides (338) showed evidence of intermittent regeneration. The regeneration niches of the four species differed as did their investment in vegetative reproduction: for instance, 81% of C. hilariana seedlings were found growing inside tank-bromeliads contrasting with only 3% of P. icicariba in this habitat. Additionally, 28% of regenerants of C. hilariana originated vegetatively, contrasting with only 6% for P. icicariba. All significant associations between species found in the study were positive. There was a positive association between adults of C. hilariana and P. icicariba, as well as between adults of C. hilariana and juveniles of both. This suggests that P. icicariba is successfully establishing under the canopy of C. hilariana and highlights the role of C. hilariana in generating vegetation cover that will be later dominated by other woody plant species, as an important process for maintenance of plant diversity in this restinga vegetation.

Reproductive biology of Protium spruceanum (Burseraceae), a dominant dioecious tree in vegetation corridors in Southeastern Brazil

We investigated the reproductive biology of Protium spruceanum (Benth.) Engler in vegetation corridors of secondary Atlantic forest in Lavras, southern Minas Gerais State, Brazil. The reproductive phenology was investigated fortnightly over a one year period. Floral biology studies involved pollen viability analysis, nectar production, stigmatic receptivity, pollen tube growth, visiting insect species and visit rates. The small, pale yellowish flowers (0.3-0.4 cm diameter) are functionally unisexual and organized in dense inflorescences (ca. 45 flowers). P. spruceanum presented annual flowering between September and November. Staminate flowers supplied a high percentage of viable pollen (90.6%) and relatively abundant nectar (x = 4.5 μL). Pistillate flowers produced only nectar to flower visitors (x = 4.0 μL). The effective pollinators were Apis mellifera and Trigona sp. (Hymenoptera, Apidae). Pollen tubes of cross-pollinated flowers were observed entering the ovaries 48 h after pollination. The fruiting season is from October to March, with a peak in November, coinciding with the rainfall peak. Ecological implications of these findings, and alternative arguments to explain the high genetic diversity at regional landscape are discussed.

Impacts of the Belo Monte hydroelectric dam construction on pioneer vegetation formations along the Xingu River, Pará State, Brazil

There is an important pioneer vegetation formation along the Xingu River in the area where the Belo Monte hydroelectric dam is being constructed that is highly adapted to a seasonally fluctuating water levels. The aim of this study was to examine the habitat and flora of the pioneer formations in the Belo Monte area. The area was divided in three sections for study purposes (Reservoir, Low Flow, and Control) that were expected to experience different degrees of impact from the dam project. The calculations of habitat losses were based on satellite imagery classifications, and a total of 111 plots were established in the three areas for vegetation sampling. Habitat losses of the pioneer formations will total 89.7% when the project is fully functional. Forty-five of the 72 recorded species are restricted to single areas. Species richness and diversity were significantly lower in the control area. The completion of the Belo Monte reservoir will result in habitat reductions and will consequently reduce the richness and diversity of pioneer formations. Studies suggest monitoring the populations located in the reduced flow area to determine possible impacts resulting from changes in the regional hydrological cycle caused by the Xingu River dam.

Influence of edaphic variables on the floristic composition and structure of the tree-shrub vegetation in typical and rocky outcrop cerrado areas in Serra Negra, Goiás State, Brazil

The present study analyzed the influence of edaphic variables on the floristic compositions and structures of the arboreal and shrub vegetation of typical cerrado (TC) and rocky outcrop cerrado (RC) communities in the Serra Negra mountain range in Piranhas Municipality, Goiás State, Brazil. Ten 20×50m plots were established in each community, and all individuals with minimum diameters ³5cm measured at 30cm above soil level were sampled. Composite soil samples were collected at 0-20cm depths in each plot for physical and chemical analyses. The proportions of above-ground rock cover work also estimated in each RC plot. A total of 2,009 individuals (83 species, 69 genera, and 34 families) were recorded. Qualea parviflora was the only species consistently among the 10 most structurally important taxa in both communities, and was considered a generalist species. The observed and estimated species richnesses were greater in RC than in TC, although plant basal areas and heights did not differ between them. There were positive correlations between rock cover×plant density and rock cover×basal areas. TWINSPAN and PCA analysis separated the TC and RC plots, and three RC habitat specialist species (Wunderlichia mirabilis, Norantea guianensis, and Tibouchina papyrus) were identified. Soil variables were found to have greater effects on the species compositions of the TC and RC sites than the geographic distances between sampling plots. According to CCA analysis, the exclusive (or more abundant species) of each community were correlated with soil variables, and these variables therefore determined the selection of some species and influenced the differentiation of the vegetation structures of the communities studied.

The tree-shrub vegetation in rocky outcrop cerrado areas in Goiás State, Brazil

We describe the floristic composition of the tree-shrub vegetation in 10 areas of rocky outcrop cerrado in Goiás State, Brazil. Ten 20×50m plots (totaling 1ha) were established and all of the individuals with diameters at 30cm above soil level (DB30) ³5cm were included in the sampling. Comparative analyses of the flora were realized using similarity indices (Sørensen and Czekanowski), classification analysis (TWINSPAN), and the Mantel test. A total of 13,041 tree-shrub individuals were sampled, distributed among 219 species, 129 genera and 55 families. Fabaceae was the most well-represented family, followed by Myrtaceae, Melastomataceae, Vochysiaceae, Malphigiaceae, and Rubiaceae. Fully 42.3% of the comparisons evaluated by the Sørensen index were >0.50, while all the values were <0.50 for the Czekanowski index, with the exception of Jaraguá and Mara Rosa areas. The TWINSPAN classification generated four divisions and, in general, only the differences in the size of the population were responsible for the groupings. The Mantel test indicated that there was no relationship between floristic similarity and the distances between the areas (r=0.32, P=0.05). It therefore appears that the areas of rocky outcrop cerrado in Goiás State are relatively floristically homogeneous and that they are principally distinguished by the differences in the sizes of the populations of their dominant species, and the presence of exclusive species in certain areas.

Microalgal vegetation in the selected Mangrove Ecosystem of Kerala.

Department of Marine Biology, Cochin University of Science & Technology

Vegetation changes in a river oasis on the southern rim of the Taklamakan Desert in China between 1956 and 2000

The indigenous vegetation surrounding the river oases on the southern rim of the Taklamakan Desert has drastically diminished due to overexploitation as a source of fodder, timber and fuel for the human population. The change in the spatial extent of landscape forms and vegetation types around the Qira oasis was analyzed by comparing SPOT satellite images from 1998 with aerial photographs from 1956. The analysis was supplemented by field surveys in 1999 and 2000. The study is part of a joint Chinese-European project with the aim of assessing the current state of the foreland vegetation, of gathering information on the regeneration potential and of suggesting procedures for a sustainable management. With 33 mm of annual precipitation, plants can only grow if they have access to groundwater, lakes or rivers. Most of the available water comes into the desert via rivers in the form of seasonal flooding events resulting from snow melt in the Kun Lun Mountains. This water is captured in canal systems and used for irrigation of arable fields. Among the eight herbaceous and woody vegetation types and the type of open sand without any plant life that were mapped in 2000 in the oasis foreland, only the latter, the oasis border between cultivated land and open Populus euphratica forests and Tamarix ramosissima-Phragmites australis riverbed vegetation could be clearly identified on the photographs from 1956. The comparison of the images revealed that the oasis increased in area between 1956 and 2000. Shifting sand was successfully combated near to the oasis borders but increased in extent at the outward border of the foreland vegetation. In contrast to expectations, the area covered with Populus trees was smaller in 1956 than today due to some new forests in the north of the oasis that have grown up since 1977. Subfossil wood and leaf remnants of Populus euphratica that were found in many places in the foreland must have originated from forests destroyed before 1956. In the last 50 years, the main Qira River has shifted its bed significantly northward and developed a new furcation with a large new bed in 1986. The natural river dynamics are not only an important factor in forming the oasis’ landscape but also in providing the only possible regeneration sites for all occurring plant species. The conclusion of the study is that the oasis landscape has changed considerably in the last 50 years due to natural floodings and to vegetation degradation by human overexploitation. The trend towards decreasing width of the indigenous vegetation belt resulting from the advancing desert and the expansion of arable land is particularly alarming because a decrease in its protective function against shifting sand can be expected in the future.

The role of ligneous vegetation for livestock nutrition in the sub-Sahelian and Sudanian zones of West Africa: Potential effects of climate change

Climate change and variability in sub-Saharan West Africa is expected to have negative consequences for crop and livestock farming due to the strong dependence of these sectors on rainfall and natural resources, and the low adaptive capacity of crops farmers, agro-pastoralist and pastoralists in the region. The objective of this PhD research was to investigate the anticipated impacts of expected future climate change and variability on nutrition and grazing management of livestock in the prevailing extensive agro-pastoral and pastoral systems of the Sahelian and Sudanian zones of Burkina Faso. To achieve this, three studies were undertaken in selected village territories (100 km² each) in the southern Sahelian (Taffogo), northern Sudanian (Nobere, Safane) and southern Sudanian (Sokouraba) zone of the country during 2009 and 2010. The choice of two villages in the northern Sudanian zone was guided by the dichotomy between intense agricultural land use and high population density near Safane, and lower agricultural land use in the tampon zone between the village of Nobere and the National Park Kaboré Tambi of Pô. Using global positioning and geographical information systems tools, the spatio-temporal variation in the use of grazing areas by cattle, sheep and goats, and in their foraging behaviour in the four villages was assessed by monitoring three herds each per species during a one-year cycle (Chapter 2). Maximum itinerary lengths (km/d) were observed in the hot dry season (March-May); they were longer for sheep (18.8) and cattle (17.4) than for goats (10.5, p<0.05). Daily total grazing time spent on pasture ranged from 6 - 11 h with cattle staying longer on pasture than small ruminants (p<0.05). Feeding time accounted for 52% - 72% of daily time on pasture, irrespective of species. Herds spent longer time on pasture and walked farther distances in the southern Sahelian than the two Sudanian zones (p<0.01), while daily feeding time was longer in the southern Sudanian than in the other two zones (p>0.05). Proportional time spent resting decreased from the rainy (June - October) to the cool (November - February) and hot dry season (p<0.05), while in parallel the proportion of walking time increased. Feeding time of all species was to a significantly high proportion spent on wooded land (tree crown cover 5-10%, or shrub cover >10%) in the southern Sahelian zone, and on forest land (tree crown cover >10%) in the two Sudanian zones, irrespective of season. It is concluded that with the expansion of cropland in the whole region, remaining islands of wooded land, including also fields fallowed for three or more years with their considerable shrub cover, are particularly valuable pasturing areas for ruminant stock. Measures must be taken that counteract the shrinking of wooded land and forests across the whole region, including also active protection and (re)establishment of drought-tolerant fodder trees. Observation of the selection behaviour of the above herds of cattle and small ruminant as far as browse species were concerned, and interviews with 75 of Fulani livestock keepers on use of browse as feed by their ruminant stock and as remedies for animal disease treatment was undertaken (Chapter 3) in order to evaluate the consequence of climate change for the contribution of browse to livestock nutrition and animal health in the extensive grazing-based livestock systems. The results indicated that grazing cattle and small ruminants do make considerable use of browse species on pasture across the studied agro-ecological zones. Goats spent more time (p<0.01) feeding on browse species than sheep and cattle, which spent a low to moderate proportion of their feeding time on browsing in any of the study sites. As far as the agro-ecological zones were concerned, the contribution of browse species to livestock nutrition was more important in the southern Sahelian and northern Sudanian zone than the southern Sudanian zone, and this contribution is higher during the cold and hot dry season than during the rainy season. A total of 75 browse species were selected on pasture year around, whereby cattle strongly preferred Afzelia africana, Pterocarpus erinaceus and Piliostigma sp., while sheep and goats primarily fed on Balanites aegyptiaca, Ziziphus mauritiana and Acacia sp. Crude protein concentration (in DM) of pods or fruits of the most important browse species selected by goats, sheep and cattle ranged from 7% to 13% for pods, and from 10% to 18% for foliage. The concentration of digestible organic matter of preferred browse species mostly ranged from 40% to 60%, and the concentrations of total phenols, condensed tannins and acid detergent lignin were low. Linear regression analyses showed that browse preference on pasture is strongly related to its contents (% of DM) of CP, ADF, NDF and OM digestibility. Interviewed livestock keepers reported that browse species are increasingly use by their grazing animals, while for animal health care use of tree- and shrub-based remedies decreased over the last two decades. It is concluded that due to climate change with expected negative impact on the productivity of the herbaceous layer of communal pastures browse fodder will gain in importance for animal nutrition. Therefore re-establishment and dissemination of locally adapted browse species preferred by ruminants is needed to increase the nutritional situation of ruminant stock in the region and contribute to species diversity and soil fertility restoration in degraded pasture areas. In Chapter 4 a combination of household surveys and participatory research approaches was used in the four villages, and additionally in the village of Zogoré (southern Sahelian zone) and of Karangasso Vigué (northern Sudanian zone) to investigate pastoralists’ (n= 76) and agro-pastoralists’ (n= 83) perception of climate change, and their adaptation strategies in crop and livestock production at farm level. Across the three agro-ecological zones, the majority of the interviewees perceived an increase in maximum day temperatures and decrease of total annual rainfall over the last two decades. Perceptions of change in climate patterns were in line with meteorological data for increased temperatures while for total rainfall farmers’ views contrasted the rainfall records which showed a slight increase of precipitation. According to all interviewees climate change and variability have negative impacts on their crop and animal husbandry, and most of them already adopted some coping and adaptation strategies at farm level to secure their livelihoods and reduce negative impacts on their farming system. Although these strategies are valuable and can help crop and livestock farmers to cope with the recurrent droughts and climate variability, they are not effective against expected extreme climate events. Governmental and non-governmental organisations should develop effective policies and strategies at local, regional and national level to support farmers in their endeavours to cope with climate change phenomena; measures should be site-specific and take into account farmers’ experiences and strategies already in place.

Interrelatedness of grazing livestock with vegetation parameters and farmers’ livelihoods in the Mahafaly region, southwestern Madagascar

The study aims to get deeper insight into the highly extensive system of animal husbandry in the Mahafaly region of southwestern Madagascar. It tries to understand the major drivers for pastoral dynamics, land and resource use along a gradient in altitude and vegetation to consider the area’s high spatial and temporal heterogeneity. The study also analyzes the reproductive performance of local livestock as well as the owners’ culling strategies to determine herd dynamics, opportunities for economic growth, and future potential for rural development. Across seasons, plateau herds from both livestock species covered longer distances (cattle 13.6±3.02 km, goats 12.3±3.48 km) and were found further away from the settlements (cattle 3.1±0.96 km, goats 2.8±0.98 km) than those from the coastal plain (walking_dist: cattle 9.5±3.25 km, goats 9.2±2.57 km; max_dist: cattle 2.6±1.28 km, goats 1.8±0.61 km). Transhumant cattle were detected more vulnerable through limited access to pasture land and water resources compared to local herds. Seasonal water shortage has been confirmed as a key constraint on the plateau while livestock keeping along the coast is more limited by dry season forage availability. However, recent security issues and land use conflicts with local crop farmers are gaining importance and force livestock owners to adapt their traditional grazing management, resulting in spatio-temporal variation of livestock numbers and in the impending risk of local overgrazing and degradation of rangelands. Among the 133 plant species consumed by livestock, 13 were determined of major importance for the animals’ nutrition. The nutritive value and digestibility of the natural forage, as well as its abundance in the coastal zone, substantially decreased over the course of the dry season and emphasized the importance of supplementary forage plants, in particular Euphorbia stenoclada. At the same time, an unsustainable utilization and overexploitation of its wild stocks may raise the pressure on the vegetation and pasture resources within the nearby Tsimanampetsotsa National Park. Age at first parturition was 40.5±0.59 months for cattle and 21.3±0.63 months for goats. Both species showed long parturition intervals (cattle 24.2±0.48 months, goats 12.4±0.30 months), mostly due to the maintenance of poorly performing breeding females within the herds. Reported offspring mortality, however, was low with 2.5% of cattle and 18.8% of goats dying before reaching maturity. The analysis of economic information revealed higher than expected market dynamics, especially for zebus, resulting in annual contribution margins of 33 € per cattle unit and 11 € per goat unit. The application of the PRY Herd Life model to simulate herd development for present management and two alternate scenarios confirmed the economic profitability of the current livestock system and showed potential for further productive and economic development. However, this might be clearly limited by the region’s restricted carrying capacity. Summarizing, this study illustrates the highly extensive and resources-driven character of the livestock system in the Mahafaly region, with herd mobility being a central element to cope with seasonal shortages in forage and water. But additional key drivers and external factors are gaining importance and increasingly affect migration decisions and grazing management. This leads to an increased risk of local overgrazing and overexploitation of natural pasture resources and intensifies the tension between pastoral and conservation interests. At the same time, it hampers the region’s agronomic development, which has not yet been fully exploited. The situation therefore demonstrates the need for practical improvement suggestions and implication measures, such as the systematic forestation of supplemental forage plant species in the coastal zone or a stronger integration of animal husbandry and crop production, to sustain the traditional livestock system without compromising peoples’ livelihoods while at the same time minimizing the pastoral impact on the area’s unique nature and environment.

GRASS GIS for the distinction of vegetation from buildings using LiDAR altimetric data

La tecnología LiDAR (Light Detection and Ranging), basada en el escaneado del territorio por un telémetro láser aerotransportado, permite la construcción de Modelos Digitales de Superficie (DSM) mediante una simple interpolación, así como de Modelos Digitales del Terreno (DTM) mediante la identificación y eliminación de los objetos existentes en el terreno (edificios, puentes o árboles). El Laboratorio de Geomática del Politécnico de Milán – Campus de Como- desarrolló un algoritmo de filtrado de datos LiDAR basado en la interpolación con splines bilineares y bicúbicas con una regularización de Tychonov en una aproximación de mínimos cuadrados. Sin embargo, en muchos casos son todavía necesarios modelos más refinados y complejos en los cuales se hace obligatorio la diferenciación entre edificios y vegetación. Este puede ser el caso de algunos modelos de prevención de riesgos hidrológicos, donde la vegetación no es necesaria; o la modelización tridimensional de centros urbanos, donde la vegetación es factor problemático. (...)