María Vanessa Lencinas

Spatial patterns of cultural ecosystem services provision in Southern Patagonia

AbstractContextAlthough there is a need to develop a spatially explicit methodological approach that addresses the social importance of cultural ecosystem services for regional planning, few studies have analysed the spatial distribution on the cultural ecosystem services based on social perceptions. ObjectiveThe main objective of this study was to identify cultural ecosystem service hot-spots, and factors that characterize such hot-spots and define the spatial associations between cultural ecosystem services in Southern Patagonia (Argentina).MethodsThe study was carried out in Southern Patagonia (243.9 thousand km2) located between 46° and 55° SL with the Andes mountains on the western fringe and the Atlantic Ocean on the eastern fringe of the study area. The study region has a range of different vegetation types (grasslands, shrub-lands, peat-lands and forests) though the cold arid steppe is the main vegetation type. We used geo-tagged digital images that local people and visitors posted in the Panoramio web platform to identify hot-spots of four cultural ecosystem services (aesthetic value, existence value, recreation and local identity) and relate these hot-spots with social and biophysical landscape features.ResultsAesthetic value was the main cultural service tagged by people, followed by the existence value for biodiversity conservation, followed by local identity and then recreational activity. The spatial distribution of these cultural ecosystem services are associated with different social and biophysical characteristics, such as the presence of water bodies, vegetation types, marine and terrestrial fauna, protected areas, urbanization, accessibility and tourism offer. The most important factors are the presence of water in Santa Cruz and tourism offer in Tierra del Fuego.ConclusionsOur results demonstrate that this methodology is useful for assessing cultural ecosystem services at the regional scale, especially in areas with low data availability and field accessibility, such as Southern Patagonia. We also identify new research challenges that can be addressed in cultural ecosystem services research through the use of this method.

Changes in Understory Species Diversity during the Nothofagus pumilio Forest Management Cycle

Human commercial activities must be compatible with sustainable management to achieve species conservation in the natural environment. After harvesting, diversity and abundance of understory species differ substantially from the pre-harvest situation. Have knowledge of the changes that logging produces in all components of the system allows us to develop management alternatives with reduced impacts. The objective of this work was to evaluate changes in density, biomass and diversity of understory species along a forest shelterwood cut system management cycle in aNothofagus pumilio forest. Six forest management situations (postharvesting stands and different phases of forest development) were sampled in a pureN. pumilio forest of Tierra del Fuego (Argentina) of middle-high site class (fromclass I toIII). Species number, density and biomass were modified substantially after a shelterwood cut. These were being greatest after cutting and falling substantially when the forest canopy closes during theinitial growth phase, returning to values similar to this virgin forest when themature phase was reached. The impact of the forest management on understory species diversity is analyzed and discussed. The silvicultural practices applied toN. pumilio forest in Tierra del Fuego permit the introduction of alien flora to the system, and produce great changes during the forest management cycle.

Conservation value of timber quality versus associated non-timber quality stands for understory diversity in Nothofagus forests

Conservation strategies of forested landscapes must consider biodiversity of the included site types, i.e. timber-quality forests and associated non-timber-quality stands. The objectives were to characterize forest overstory structure in timber-quality versus associated non-timber-quality stands; and to compare their understory communities. Six forest types were sampled in Nothofagus forests of Tierra del Fuego (Argentina): two timber-quality N. pumilio forests, and four associated non-timber-quality stands (edge, N. antarctica, wetlands and streamside forests). Overstory structure and understory vegetation (species richness, frequencies, cover and biomass) were characterized during spring and summer seasons. Analysis of variance and multivariates were carried out. Overstory structure differed across the site types, with higher tree size, canopy closure and tree volume in timber-quality stands. Fifty-one understory plant species were observed, but understory variables varied with site types, especially wetlands (highest native and exotic richness, cover and biomass, and 25% of exclusive species). Site types were grouped in three: N. antarctica stands, streamside stands and the other N. pumilio forests according to multivariate analysis. Forty three percent of plants were distributed in all site types, and all timber-quality forest understory species were present in some associated non-timber-quality stands. Timber-quality N. pumilio forests have a marginal value for understory conservation compared to associated non-timber-quality stands, because these last include all the plants observed in timber-quality forests and also possess many exclusive species. Therefore, protection of associated non-timber-quality stands during forest management planning could increase understory conservation at landscape level, and these could be better reserves of understory diversity than retentions of timber-quality stands.

Differential forage use between large native and domestic herbivores in Southern Patagonian Nothofagus forests

Plant—animal interactions at the landscape level become particularly relevant when land use is diversified. Nothofagus forests in southern Patagonia have been used for timber and cattle grazing purposes during the last century, causing livestock to increase (Bos taurus and Ovis aries) and large native herbivores, such as guanaco (Lama guanicoe), either maintained or decreased their populations. Within this scenario, feeding interactions between guanaco and domestic herbivores were analysed in a mosaic of open habitats and different Nothofagus forest types and management histories, whereby a total of six habitat types were identified through satellite image analysis. A total of 205 floristic surveys were conducted to characterize the plant species composition at the landscape level. Diet composition of herbivores was assessed once each season during a year, using microhistological analysis of feces. Results showed higher plant richness in open lands and lower in closed, unmanaged forests. Overall, 43 plant taxa were detected in herbivore feces, which represent 56% of plant richness detected in the field. Both guanacos and domestic herbivores included mainly grasses in their diet, which were found predominantly in open lands. Tree seedlings and saplings were consumed by all herbivores, as well, except during winter. Differential forage use between guanaco and domestic herbivores in southern Patagonian Nothofagus forests did exist. However, competition for available resources among theses herbivores resulted in an alternation of feeding sites, which varied throughout the year. Management plans in southern Southern Patagonia (livestock, silvopastoral plans and timber harvesting) do not consider the direct or indirect consequences on guanaco populations. The challenge, therefore, is to generate management decisions to avoid either guanacos or domestic herbivores from becoming detrimental to the sustainability of managed forested ecosystems.

Using assembly rules to measure the resilience of riparian plant communities to beaver invasion in subantarctic forests

The present study measures the resilience of riparian herbaceous communities to beaver invasion in subantarctic forests of southern Chile and Argentina. Divergence in community composition and spatial structure was measured comparing beaver-disturbed and undisturbed vegetation assemblages along a sequence of beaver meadow ages; the former by performing a Principal Component Analysis and the later by estimating a co-occurrence index (C-score). Community composition and spatial structure of vegetation showed an increasingly divergent trend from undisturbed sites to older beaver meadows. These results indicated that understory vegetation in deciduous subantarctic forests was not resilient to beaver invasion. Using “assembly rules” as a conceptual framework, we propose a resilience index of host communities to disturbances caused by herbivore invaders that also can be used for subsequent restoration programs to monitor the effectiveness of intervention and mitigation efforts.

Herramientas disponibles para la construcción de un modelo de producción para la lenga (Nothofagus pumilio) bajo manejo en un gradiente de calidades de sitio

Los bosques de lenga representan el principal recurso forestal del sur de Argentina y Chile. Esta es la especie nativa mejor estudiada, habiendose desarrollado la suficiente informacion ecologica, biometrica y silvicola, como para definir sistemas de prediccion y manejo que ayuden a la planificacion y la ordenacion forestal. En un proyecto forestal a largo plazo, primero debe definirse la planificacion territorial (uso del suelo) y diagramar las diferentes alternativas de produccion. En las tierras destinadas a la produccion forestal se debe realizar un Plan General de Ordenacion, de modo de lograr un suministro continuo y sustentable de madera rolliza para las empresas involucradas. Para ello se debe contar con modelos fehacientes que brinden simulaciones adecuadas para generar la informacion base de dicha planificacion. Por lo que el objetivo de este trabajo fue construir un modelo de produccion para un gradiente de sitios basado en las metodologias y modelos de la bibliografia. Se definieron cinco supuestos de trabajo (sistema silvicola, objetivos del manejo forestal, crecimientos, rendimientos y presencia de ganado), y se seleccionaron las metodologias y modelos biometricos a utilizar (crecimiento en altura y clasificaciones de sitio, modelos de crecimiento en diametro, indice de densidad de rodales y diagramas de raleos, calculo del turno, del volumen total y rendimientos del bosque, definidos a lo largo de un rango de clases de sitio). A partir de los modelos se definio un manejo silvicola y se analizaron sus alcances. El mismo quedo conformado por cinco intervenciones intermedias (tres raleos de productos secundarios y dos con productos aserrables) y una corta final. Por otra parte, se analizo la evolucion de un rodal sin intervencion silvicola, discutiendose la significancia biologica y el alcance de los modelos utilizados. Finalmente, se presentan los resultados del modelo de produccion de acuerdo a las diferentes clases de sitio, con los rendimientos e intervenciones silvicolas a lo largo del tiempo (desde 435 m3/ha de trozas aserrables para un turno de 150 anos en una clase de sitio I, hasta 81 m3/ha para un turno de 213 anos en una clase de sitio V).

Thinning schedules to reduce risk of windthrow in Nothofagus pumilio forests of Patagonia, Argentina

En este trabajo se propone y analiza un metodo de raleo para reducir el riesgo de volteos por viento en bosques jovenes de lenga (Nothofagus pumilio) en un sitio de alta calidad (IS60= 23,2 m). Los raleos se llevaron a cabo en un bosque puro y coetaneo de 67 anos (edad al DAP), efectuandose las primeras intervenciones en 1996. Este metodo propone raleos sucesivos por lo bajo para mantener la estabilidad del rodal, a traves de reducciones sucesivas de la densidad de copas y el crecimiento paulatino de los arboles remanentes seleccionados (arboles meta). El sistema se lleva a cabo en cinco etapas sucesivas (anillado del 50% de los arboles no seleccionados al ano cero; extraccion de los arboles anillados y anillado del restante 50% al ano 3; extraccion de los arboles anillados y anillado de los arboles padres remanentes al ano 6; y extraccion de los arboles padres al ano 10). En el ensayo se definieron dos niveles de raleo a lo largo de dos hectareas: un raleo suave con 872 ind/ha y un raleo fuerte con 489 ind/ha. A lo largo de las mismas se establecieron 6 parcelas permanentes, mientras que en sectores no raleados se establecieron 4 parcelas testigo. Anualmente se registraron los crecimientos en diametro, area basal y volumen total, asi como la mortalidad y la dinamica de copas en los tratamientos testigo. Por otra parte, los rendimientos de los productos de la primera intervencion (ano 3) fueron medidos y discriminados segun tipo de productos. Los resultados de los primeros seis anos de intervencion de esta propuesta de raleo presentan altos crecimientos y rendimientos, evitando la apertura brusca del dosel que puede poner en peligro al rodal frente a un volteo de viento.

Foliar anatomical and morphological variation in Nothofagus pumilio seedlings under controlled irradiance and soil moisture levels

Foliar anatomy and morphology are strongly related to physiological performance; therefore, phenotypic plasticity in leaves to variations in environmental conditions, such as irradiance and soil moisture availability, can be related to growth rate and survivorship, mainly during critical growth phases, such as establishment. The aim of this work was to analyze changes in the foliar internal anatomy (tissue proportions and cell dimensions) and external morphology (leaf length, width and area) of Nothofagus pumilio (Poepp. et Endl.) Krasser seedlings growing in a greenhouse under controlled irradiance (three levels) and soil moisture (two levels) during one growing season (measured three times), and to relate them to physiological traits. Three irradiance levels (4, 26 and 64% of the natural incident light) and two soil moisture levels (40 and 80% soil capacity) were evaluated during November, January and March. Internal foliar anatomy of seedlings was analyzed using digital photographs of histological cuttings, while leaf gross morphology was measured using digital calipers and image analysis software. Most internal anatomical variables presented significant differences under different irradiance levels during the growing season, but differences were not detected between soil moisture levels. Palisade parenchyma was the tissue most sensitive to irradiance levels, and high irradiance levels (64% natural incident light) produced greater values in most of the internal anatomical variables than lower irradiance levels (4-24% natural incident light). Complementarily, larger leaves were observed in medium and low irradiance levels, as well as under low soil moisture levels (40% soil capacity). The relationship of main results with some eco-physiological traits was discussed. Foliar internal anatomical and external morphological plasticity allows quick acclimation of seedlings to environmental changes (e.g., during harvesting). These results can be used to propose new forest practices that consider soil moisture and light availability changes to maintain high physiological performance of seedlings.

Determining Abiotic and Biotic Factors that Limit Transplanted Nothofagus pumilio Seedling Success in Abandoned Beaver Meadows in Tierra del Fuego

As ecosystem engineers, North American beavers (Castor canadensis) change many environmental conditions in water-sheds, felling trees, damming streams, and flooding riparian zones. In Tierra del Fuego, where beavers were introduced in 1946, these alterations have produced meadows that appear to be long-term alternate stable states, lacking signs of resilience and natural forest regeneration. The aim of this work was to determine the abiotic and biotic factors that affect native tree seedling success in abandoned beaver meadows in Nothofagus pumilio forests. Environmental conditions including light, soil moisture, herbaceous plant community composition, and reinvasion potential were measured in areas impacted by beavers and in unimpacted old-growth forests. Additionally, we monitored the survival and success of N. pumilio seedlings transplanted in plots where meadow vegetation was cleared. Tree seedlings showed little growth, and survival varied by type of beaver impact. While survival was high and similar to unimpacted sites in zones cut but not flooded by beavers, it was significantly lower in meadow zones that were previously flooded and cut, compared to old-growth forests. We found that the reinvasion of herbaceous plants into transplantation study plots was negatively related to tree seedling survival, and herbaceous (monocot) plant cover itself was related to beaver-created gradients in soil moisture and light availability. Overall, these abiotic changes modified the meadow’s plant community and enhanced herbaceous vegetation cover, particularly monocots and exotics, thus hindering transplanted seedling survival.

Survival and growth of Nothofagus pumilio seedlings under several microenvironments after variable retention harvesting in southern Patagonian forests

ContextVariable retention prescriptions for Nothofagus pumilio forests provide for biodiversity conservation and natural regeneration by controlled opening of the canopy. Harvesting generates different microenvironments which present dissimilar conditions for seedling establishment, due to positive or negative influences over biotic and abiotic factors.AimsThis study evaluated seedling survival and performance in different microenvironments within the harvested stands. Tested hypotheses stated that seedling stress and performance were influenced by harvesting due to changes in forest structure, microclimate, soil properties, and nutrient availability.MethodsIn the stands harvested by variable retention, five contrasting microenvironments were selected as treatments for the experiments and sampling. Environmental variables were related to ecophysiological, seedling survival, and performance.ResultsThe modification of forest structure (crown cover and tree density) and the presence of coarse woody debris greatly affect the effective rainfall and global radiation reaching understorey level, influencing seedling stress and consequently survival and performance. Harvesting also modifies soil properties (e.g., soil bulk density) and coarse woody debris accumulation which in turn influences soil moisture and/or solar radiation levels. Analyses showed that seedlings received benefits of microenvironment variation after harvesting. Areas covered with middle or fine woody debris presented regeneration with better ecophysiological response and seedling performance, although dispersed retention areas (far away from remnant trees) and roads could also present suitable conditions for seedling survival and performance.ConclusionsThe proportion of different microenvironments in the harvested forests will determine the amount of natural recruitment of regeneration and consequently the success of proposed silvicultural management. Forest practices must be manipulated to increase the proportion of favorable microenvironments (e.g., woody debris), allowing greater natural regeneration success during the first years after harvesting.