Silvia Diana Matteucci

Urbanization and the consumption of fertile land and other ecological changes: the case of Buenos Aires:

This paper describes the conflict between agriculture and urban development in the Pampa Ondulada, the eco-region where the city of Buenos Aires is located and which is one of the world’s richest and most productive agricultural areas. It describes and analyzes the ecological changes brought about by urban expansion in peri-urban and rural areas between 1869 and 1991 and the form that these have taken. It also includes an analysis of the soil types where this expansion has taken place. The paper ends with a discussion of the lack of control over the continued expansion of the urban agglomeration including that caused by the closed settlements now favoured by middle and upper-income groups and the speculative parcelling of land in advance of its development.

Sustainable Development and Urban Growth in the Argentine Pampas Region

This article describes the conflict between rural and urban development in the Pampa Ondulada (Rolling Pampas), the ecological region in which the city of Buenos Aires is located, which is one of the worlds richest and most productive agricultural areas. It describes the ecological changes brought by urban growth in periurban and rural areas between 1869 and 1991. It also includes an analysis of the social and economical changes during the past decade (1991-2001) and their effect on ecological services. The article ends with a discussion of the lack of planning over the expansion process of the urban agglomeration, including the so-called suburbia settlements of the middle and upper classes and the speculative pricing of land in advance of its development.

Forest conservation: Remember Gran Chaco

TROPICAL AND SUBTROPICAL dry forests around the globe are experiencing rapid clearing and concomitant biodiversity loss ([ 1 ][1]). In their Research Article “Plant diversity patterns in neotropical dry forests and their conservation implications” (23 September 2016, p. [1383][2]), DRYFLOR et al

Spatial and seasonal dynamic of abundance and distribution of guanaco and livestock: insights from using density surface and null models.

Monitoring species abundance and distribution is a prerequisite when assessing species status and population viability, a difficult task to achieve for large herbivores at ecologically meaningful scales. Co-occurrence patterns can be used to infer mechanisms of community organization (such as biotic interactions), although it has been traditionally applied to binary presence/absence data. Here, we combine density surface and null models of abundance data as a novel approach to analyze the spatial and seasonal dynamics of abundance and distribution of guanacos (Lama guanicoe) and domestic herbivores in northern Patagonia, in order to visually and analytically compare the dispersion and co-occurrence pattern of ungulates. We found a marked seasonal pattern in abundance and spatial distribution of L. guanicoe. The guanaco population reached its maximum annual size and spatial dispersion in spring-summer, decreasing up to 6.5 times in size and occupying few sites of the study area in fall-winter. These results are evidence of the seasonal migration process of guanaco populations, an increasingly rare event for terrestrial mammals worldwide. The maximum number of guanacos estimated for spring (25951) is higher than the total population size (10000) 20 years ago, probably due to both counting methodology and population growth. Livestock were mostly distributed near human settlements, as expected by the sedentary management practiced by local people. Herbivore distribution was non-random; i.e., guanaco and livestock abundances co-varied negatively in all seasons, more than expected by chance. Segregation degree of guanaco and small-livestock (goats and sheep) was comparatively stronger than that of guanaco and large-livestock, suggesting a competition mechanism between ecologically similar herbivores, although various environmental factors could also contribute to habitat segregation. The new and compelling combination of methods used here is highly useful for researchers who conduct counts of animals to simultaneously estimate population sizes, distributions, assess temporal trends and characterize multi-species spatial interactions.

Multiple-purposes land mapping and resources inventory

A land classification and resources inventory of Falcón State was undertaken with the aim of gathering baseline information to help in development planning. The study area, located in northwestern Venezuela, comprises an ecologically diverse region, due both to its varied geomorphology and to its history of human occupation. A landscape approach was used. On the basis of photointerpretation, examination of existing literature, and field work, uniform land units (physiognomic units) were delineated and described in terms of landform, soil, vegetation, drainage pattern, and climate. These were grouped in homogeneous units (HU) on the basis of their potential natural vegetation through the delimitation of climax complexes. The last hierarchy, the land systems, comprise the geomorphogenetically related HU. The results are presented at different levels of generalization and integration, in verbal and cartographic descriptions, and they are stored in standardized formats to ensure ease of comprehension and handling and to meet different needs. This report describes the methods employed for the survey and data presentation, and discusses its applicability and limitations.

Spatial and temporal patterns at small scale in Austrocedrus chilensis diseased forests and their effect on disease progression

Austrocedrus chilensis is an endemic conifer of Patagonia that suffers a widespread mortality whose causes are a topic of discussion. Since Phytophthora austrocedrae is the most probable cause, we proposed that the spatial and temporal patterns of disease at small scale should reflect pathogen behavior. We aimed at characterizing the spatial and temporal patterns of diseased trees in different soil types and the effect of microsite variability on diseased trees spatial pattern. The spatial pattern of disease was influenced by soil type and tree density. In clay soils with low disease incidence (ca. 25%), the spatial pattern was random and not influenced by abiotic microsite conditions. When disease incidence increased (ca. 70%), concurring with denser plots, the spatial pattern was clustered, as a result of an infection process, and it was independent of microsite variability. In soils with better drainage conditions, that is, alluvial soils with volcanic ash input and coarse textured volcanic soils, the disease was clustered and associated with flat microtopographies. The progression of the disease at small scale was influenced by soil, precipitation and tree density. The spatial and temporal patterns of disease progression were associated with a contagion process and with environmental variables that affect drainage, coinciding with Phytophthora biology and requirements. Our results concur in pointing at Phytophthora as the cause of A. chilensis disease in the study area. Management practices should be urgently applied in order to minimize the spread of the inoculum.

Applying cost-distance analysis for forest disease risk mapping: Phytophthora austrocedrae as an example

AbstractCost-distance model analyzes the relative difficulty in reaching each spot of the landscape for the object or species under study. It calculates the effective distance, which is the Euclidian distance modified by the friction to movement through different landscape elements. This work deals with the application of cost-distance analysis in forest pathology, considering Austrocedrus chilensis root rot caused by Phytophthora austrocedrae as an example. In this case, cost-distance analysis was used to determine the relative difficulty for the pathogen to reach healthy forest patches from the patches that are presently diseased. Friction values were assigned on the basis of abiotic conditions, biological characteristics of the pathogen and host presence. Since cattle may be a vehicle for Phytophthora dispersion, three hypothetical situations of ranching were considered. Cost-distance application resulted useful to define minimum risk areas for conservation purposes. In the study case, minimum risk area strongly varied in response to cattle presence. This study provided valuable information for A. chilensis disease management and showed one of the broad applications of cost-distance analysis in forestry.

Desertification Maps of Falcon State, Venezuela

Maps are presented of the desertification status and degree of hazard in Falcon State, Venezuela, comprising 24,750 sq. km of land, and the criteria employed for their compilation are described. The information used for the compilation of the maps was obtained from the results of a regional survey recently conducted by the Authors. Degree of slope, landform, and soil texture, were employed to assess the physical fragility of the different landscapes, which were expressed as classes of inherent vulnerability. The classes of desertification hazard were obtained from the combination of degrees of plant cover and of inherent vulnerability. The results show that more than 42% of the area of Falcon State has already undergone deterioration, and that 41% is under severe or very severe desertification hazard. The subhumid climatic zone is more critical than the semiarid, both because of inherent vulnerability and of its human occupation pattern. The aim of the present paper is to get Falcon State incorporated in the world inventory of land under desertification hazard, and to call public and governmental attention to the seriousness and extent of the desertification threat—in Venezuela and also in other countries that face similar problems, whether or not they realize their danger.

Regional patterns of ecosystem functional diversity in the Argentina Pampas using MODIS time-series

The characterization of ecosystem functioning is significant for different purposes such as biodiversity conservation and ecosystem services. A key aspect of ecosystem functioning is carbon gains, since it represents the energy available for upper trophic levels. In this sense, remote-sensing methods have allowed the study of ecosystem dynamics and spatial distribution at different spatial and temporal scales. The objectives were to describe the regional patterns of ecosystem functional diversity and to establish the importance of interannual variability in the definition of Ecosystem Functional Types (EFTs) in the Argentina Pampas. EFTs were obtained from carbon gains using a set of seven functional attributes and their interannual variations, which were retrieved from 14-year NDVI time-series. An ISODATA technique was applied to all the analyzed variables, and the clusters that best separate in the n-dimensional space were selected using discriminant analysis. The Argentina Pampas shows a high heterogeneity in the spatial patterns of ecosystem functional attributes. The annual integral of NDVI (i-NDVI, a linear estimator of net primary productivity), a complex of ecosystem functional attributes that describe the interannual variability, and the annual relative range of NDVI (RREL, ecosystem seasonality) had the highest relevance to distinguish nine EFTs in the study area. This study shows a novel approach for mapping ecosystem functioning, which reveals the importance of interannual variations. This methodology includes the effects of climate variability on ecosystem dynamics, thus enhancing our understanding of ecosystem functional diversity. The results obtained represent a baseline scenario to evaluate the effects of both land use change and climate variability on ecosystem functioning from a temporal perspective.