Carbon Storage in Cold Temperate Ecosystems in Southern Patagonia, Argentina

Recently there has been an increasing interest of research related to improve the understanding of carbon (C) sequestration mainly under Article 3.4 of the Kyoto Protocol of the United Nations Framework Convention on Climate Change where countries can count this sequestration as a contribution to reduce greenhouse gas emission (IPCC, 2001). Data on C storage in forests, grasslands and shrublands are essential for understanding the importance of rapidly increasing level of CO2 in the atmosphere and its potential effect on global climate change. In South America, mean annual temperature is predicted to increase by 3-4 °C in both summer and winter between 30° and 55° SL (Manabe & Wetherald, 1987). Such an increase would have significant effects on Patagonian ecosystems. In this context, secondary indigenous forests are considered efficient C sink ecosystems. Nothofagus antarctica (ñire), one of the main deciduous native species in the Patagonian region (Argentina), covers 751.643 hectares over a wide latitudinal (from 36° 25' to 54° 53' SL) and altitudinal (near sea level to 2000 m.a.s.l.) distribution. These forests occur naturally in different habitats such as poorly drained sites at low elevations, exposed windy areas with shallow soils, depressions under cold air influence, or in drier eastern sites near the Patagonian steppe (Veblen et al., 1996). These forests provide a range of wood products including poles, firewood and timber for rural construction purposes. Site quality for N. antarctica ranges from tall trees up to 15 m in dominant height on the best sites to shrubby trees of 2 m tall on rocky, xeric and exposed sites, and also in poorly drained sites. Previous research has highlighted the importance of stand age on the magnitude of C pools in both forest biomass and forest floor pools (Silvester & Orchard, 1999; Davis et al., 2003). Largescale canopy disturbance in N. antarctica forests may occur as a result of blowdown, snow avalanches or fire. This results in abundant regeneration (100,000 seedlings ha-1 less than 1m tall, up to 20 years of age) followed by self thinning due mainly to light competition resulting in a final stand density of 200-350 trees ha-1 at mature stages (more than 180 years of age). It is important to emphasize that many researchers have only focused on aboveground carbon sequestration (Davis et al., 2003). However, roots in forest ecosystems can contribute up to two times more biomass than above-ground components in young growth phases (Peri et al., 2006, 2008). There are few studies of above- and below-ground pools of C storage in Patagonian Nothofagus forests that provide an understanding about ecosystem functionality (Peri et al., 2004, 2005) and the consequences of different disturbance and management regimes. In this context, forest ecosystem pools and fluxes of C are strongly affected by forest management (Finér et al., 2003). Peri et al. (2010) showed that C storage in tree components (leaves, stems, branches, roots) and forest floor change as a result of different forest structure determined by the proportion of crown classes, development stages (age) and the site quality where trees grow. The steppe ecosystem, mainly characterised by the presence of tussock, short grasses and shrubs, covers 85% of the total area. Grazing has modified the structure of Patagonian ecosystems by reducing vegetation cover, increasing bare areas, and changing floristic composition. Erosion and degradation processes have occurred in several areas of Patagonia due to an overestimation of the carrying capacity of these rangelands, inadequate distribution of animals in very large and heterogeneous paddocks, and year-long continuous grazing (Golluscio et al., 1998). In Patagonia, most of the actual knowledge about the environmental factors that affect net primary production of grasslands at regional level derives from the importance of mean annual precipitation, radiation and temperature (Jobbágy & Sala, 2000). However, data on C accumulation in both above- and belowground components of plant functional types are essential for evaluating the impacts of grazing on C cycle and long -term effects on the C balance of grasslands. Global estimates of the relative amounts of C in different vegetation types suggest that grasslands approximately contribute more than 10% of the total biosphere store (Nosberger et al., 2000). Also, it has been demonstrated that most temperate grasslands under existing management conditions are considered to be C sink and sequester more C than arable crops (Connan et al., 2001). Therefore, the aim of this manuscript was to describe the amount of C in both above- and below-ground components for the main cold temperate ecosystems in Southern Patagonia (Argentina). In particular, the aim was to quantify the C storage in an age sequence and among crown classes for individual trees grown at different site qualities of deciduous N. antarctica forests in Southern Patagonia and under silvopastoral use, and to quantify the amount of C for main grassland steppe ecosystems including the effect of grazing.EEA Santa CruzFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Effects of management practices on water yield in small headwater catchments at Cordillera de los Andes in southern Chile

In several parts of the world, drinking water is obtained from springs in natural and managed mountainous forests. Since forests regulate quality as well as quantity of water, the effects of forest-management activities on water yield are an important subject of study. The objective of this study was to evaluate the effects of forest management on water yield in managed and unmanaged temperate native rainforests in the Andean range of southern Chile. The study area is located in San Pablo, a forest reserve of 2,184 ha located at the Andean range of southern Chile (39º 35’ S, 72º 07’ W, 600-925 m a.s.l.). From April 2003 to October 2008, seven experimental small catchments were monitored for rainfall, throughfall, stemflow, soil water infiltration, soil water percolation and runoff. In 2002, one catchment with a secondary deciduous forest was managed, through thinning, causing a reduction in basal area by 35% whereas the other one remained unthinned as control. Both watersheds are adjacent and are located at 600 – 720 m of elevation on deep loam textured volcanic soils (100 - 120 cm). In November 2006, a watershed covered with evergreen old-growth forests was thinned extracting 40% of the total basal area whereas another adjacent catchment remained unthinned as control. Both watersheds are located at 725 – 910 m a.s.l. and have the same aspects. The effects of management of deciduous secondary forests showed that for the period April 2003-March 2007, the mean value of the increase in total annual streamflow was 12.7%, ranging from 10.9% to 14.6%. Thinning of the evergreen old-growth forest increased the streamflow for the period November 2006-October 2008 with 6.1%, ranging from 4.4% to 7.8%, with greater differences during summertime (15.7 to 206%)

Aboveground nutrient cycling in temperate forest ecosystems of southern Chile

Forest ecosystems have important ecological, economic, and social values, but are subject to varying ecosystem pressures, including enhanced atmospheric nitrogen deposition. This paper quantifies nutrient fluxes in varying forest types in southern Chile in order to evaluate external and internal nutrient cycling within ecosystems, with a focus on the aboveground compartment. The objectives were to establish baseline data for pristine forest ecosystems and to study differences between forest types. Measurements were performed in four stands in the lower Andean mountain range (San Pablo de Tregua), two stands in the Central Depression (Paillaco) and six catchments in the Coastal mountain range (40°S). External nutrient inputs and losses were assessed by analyzing precipitation, throughfall, stemflow, soil percolation, and streamflow. Internal aboveground nutrient cycling was quantified by means of a canopy budget model, litterfall collection, and a litterbag decomposition experiment. Although temperate forests in southern Chile still represent a unique opportunity to study pristine ecosystems, measurements of water and ion fluxes indicate that forests in the central depression are exposed to enhanced external nitrogen inputs

Litterfall and leaf decomposition in Nothofagus pumilio forests along an altitudinal gradient in Tierra del Fuego, Argentina

To achieve a fuller understanding of forest ecosystem functioning, it is necessary to know decomposition dynamics. The objective of this study was to quantify litter production, decomposition and mineralization in Nothofagus pumilio forests, in Tierra del Fuego, Argentina, along an altitudinal gradient during a two-year period and relate them to microclimate conditions and soil properties. We did the research along an altitudinal sequence at 210, 330, 460 and 590 m a.s.l., where climate, soil properties and forest structure were characterized. Litterfall decreased with altitude, and it was highly related with leaf and reproductive organ production. Decomposition decreased with altitude, being associated with microclimate and soil properties rather than with other measured variables, such as leaf chemistry. Values of decomposition constant (k) were influenced by altitude and varied between seasons and years within a given altitude. Nitrogen content increased with altitude in the two-year period, while P content decreased. Decomposition rates allowed us to separate the forest stands according to altitudinal gradients, and their intrinsic abiotic characteristics, which could increase the understanding of the nutrient flux and dynamics in these austral forest ecosystems.Fil: Moretto, Alicia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Distribution of sea-air CO 2 fluxes in the Patagonian Sea: Seasonal, biological and thermal effects

Sea-air CO2 fluxes (FCO2) in the Patagonian Sea (PS) were studied using observations collected in 2000-2006. Based on the PS frontal structures and the thermal and biological contributions to FCO2 we present a regional subdivision between distinct regimes that provide new insights on the processes that control these fluxes. The coastal regime (CR) is a net source of atmospheric CO2 (4.9 x 10-3mol.m-2.d-1) while the open shelf regime (SHR) is a net CO2 sink (-6.0 x 10-3mol.m-2.d-1). The interface between these two regions closely follows the location of along-shore fronts. In addition, based on the nature of the processes that drive the FCO2, the PS is subdivided between northern (NR) and southern (SR) regions. Both, NR and SR are CO2 sinks, but the CO2 uptake is significantly higher in NR (-6.4 x 10-3mol.m-2.d-1) than in SR (-0.5 x 10-3mol.m-2.d-1). The data reveal a strong seasonality in FCO2. The mean CO2 capture throughout the PS in austral spring is -5.8 x 10-3mol.m-2.d-1, reaching values lower than -50 x 10-3mol.m-2.d-1 in NR, while in winter FCO2 is close to equilibrium in SR. The analysis of the biological and thermal effects (BE and TE, respectively) on seasonal pCO2 variability indicates that regions of CO2 emission are dominated by the TE while regions of CO2 uptake are dominated by the BE. Our results indicate that the biological pump is the dominant process determining the sea-air CO2 flux in the PS.Fil: Kahl, Lucía Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Bianchi, Alejandro A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Osiroff, Ana Paula. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Pino, Diana Ruiz. Universite Pierre et Marie Curie; FranciaFil: Piola, Alberto Ricardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Overview of Mollisols in the world: Distribution, land use and management

Mollisols a.k.a., Black Soils or Prairie Soils make up about 916 million ha, which is 7% of the world’s ice-free land surface. Their distribution strongly correlates with native prairie ecosystems, but is not limited to them. They are most prevalent in the mid-latitudes of North America, Eurasia, and South America. In North America, they cover 200 million ha of the United States, more than 40 million ha of Canada and 50 million ha of Mexico. Across Eurasia they cover around 450 million ha, extending from the western 148 million ha in southern Russia and 34 million ha in Ukraine to the eastern 35 million ha in northeast China. They are common to South America’s Argentina and Uruguay, covering about 89 million and 13 million ha, respectively. Mollisols are often recognized as inherently productive and fertile soils. They are extensively and intensively farmed, and increasingly dedicated to cereals production, which needs significant inputs of fertilizers and tillage. Mollisols are also important soils in pasture, range and forage systems. Thus, it is not surprising that these soils are prone to soil erosion, dehumification (loss of stable aggregates and organic matter) and are suffering from anthropogenic soil acidity. Therefore, soil scientists from all of the world’s Mollisols regions are concerned about the sustainability of some of current trends in land use and agricultural practices. These same scientists recommend increasing the acreage under minimum or restricted tillage, returning plant residues and adding organic amendments such as animal manure to maintain or increase soil organic matter content, and more systematic use of chemical amendments such as agricultural limestone to replenish soil calcium reserves

Global patterns of insect herbivory in gap and understorey environments, and their implications for woody plant carbon storage

Insect herbivory is thought to favour carbon allocation to storage in juveniles of shade-tolerant trees. This argument assumes that insect herbivory in the understorey is sufficiently intense as to select for storage; however, understoreys might be less attractive to insect herbivores than canopy gaps, because of low resource availability and - at temperate latitudes - low temperatures. Although empirical studies show that shade-tolerant species in tropical forests do allocate more photosynthate to storage than their light-demanding associates, the same pattern has not been consistently observed in temperate forests. Does this reflect a latitudinal trend in the relative activity of insect herbivory in gap versus understorey environments? To date there has been no global review of the effect of light environment on insect herbivory in forests. We postulated that if temperature is the primary factor limiting insect herbivory, the effect of gaps on rates of insect herbivory should be more evident in temperate than in tropical forests; due to low growing season temperatures in the oceanic temperate forests of the Southern Hemisphere, the effect of gaps on insect herbivory rates should in turn be stronger there than in the more continental temperate climates of the Northern Hemisphere. We examined global patterns of insect herbivory in gaps versus understories through meta-analysis of 87 conspecific comparisons of leaf damage in contrasting light environments. Overall, insect herbivory in gaps was significantly higher than in the understorey; insect herbivory was 50% higher in gaps than in understoreys of tropical forests but did not differ significantly between gaps and understories in temperate forests of either hemisphere. Results are consistent with the idea that low resource availability - and not temperature - limits insect herbivore activity in forest understoreys, especially in the tropics, and suggest the selective influence of insect herbivory on late-successional tree species may have been over-estimated

Carbon density and sequestration in the temperate forests of northern Patagonia, Argentina

Introduction: Forests are a crucial part of the global carbon cycle and theirproper management is of high relevance for mitigating climate change. Thereis an urgent need to compile for each region reference data on the carbon(C) stock density and C sequestration rate of its principal forest types tosupport evidence-based conservation and management decisions in terms ofclimate change mitigation and adaptation. In the Andean Mountains of northernPatagonia, extensive areas of temperate forest have developed after massiveanthropogenic fires since the beginning of the last century.Methods: We used a plot design along belt transects to determine referencevalues of carbon storage and annual C sequestration in total live (above- andbelowground biomass) and deadwood mass, as well as in the soil organiclayer and mineral soil (to 20 cm depth) in different forest types dominated byNothofagus spp. and Austrocedrus chilensis.Results: Average total carbon stock densities and C sequestration rates rangefrom a minimum of 187 Mg.ha1 and 0.7 Mg.ha1.year1 in pure and mixed N.antarctica shrublands through pure and mixed A. chilensis forests taller than7 m and pure N. pumilio forests to a maximum in pure N. dombeyi forestswith 339 Mg.ha1 and 2.2 Mg.ha1.year1, respectively. Deadwood C representsbetween 20 and 33% of total wood mass C and is related to the amount oflive biomass, especially for the coarse woody debris component. The topsoilcontains between 33 and 57% of the total estimated ecosystem carbon in thetall forests and more than 65% in the shrublands, equaling C stocks of around100–130 Mg.ha1 in the different forest types.Conclusion: We conclude that the northern Patagonian temperate forestsactually store fairly high carbon stocks, which must be interpreted in relationto their natural post-fire development and relatively low management intensity.However, the current high stand densities of these forests may well affect their future carbon storage capacity in a warming climate, and they represent agrowing threat of high-intensity fires with the risk of a further extension ofburned areas in the future.Fil: Loguercio, Gabriel Angel. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Simon, Alois. Hawk University Of Applied Sciences And Arts; AlemaniaFil: Neri Winter, Ariel Fernando. Universität Göttingen; AlemaniaFil: Ivancich, Horacio Simón. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Reiter, Ernesto J.. Universität Göttingen; AlemaniaFil: Caselli, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Heinzle, Facundo Gabriel. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Leuschner, Christoph. Universität Göttingen; AlemaniaFil: Walentowski, Helge. No especifíca