Chilean Matorral Research Articles

Effects of soil heating changes on soil hydraulic properties in Central Chile

Wildfires are natural phenomena for most ecosystems on Earth. Many soil properties are impacted by fire, including soil hydraulic properties. We used a laboratory experiment to replicate the temperatures reached by a natural wildfire and documented the effects on soil hydraulic properties. This study hypothesizes that the impact of heating on soil hydrological properties can be explained by the interaction of a number of variables especially organic matter content (OM), cation exchange capacity (CEC), texture, pH, and electrical conductivity (EC). The main objective of this study is to explore the interconnections between soil hydraulic, chemical, and physical properties, focusing on understanding how these relationships change across different ecoregions and temperatures. Sixteen soils were collected across 16 sites susceptible to forest fires in the Central Zone of Chile and heated to 100 °C and 300 °C for two hours. These sites were representative of two distinct ecoregions: the Chilean Matorral (CM) and the Valdivian Temperate Forests (VTF). Chemical, physical, and hydraulic soil properties were measured before and after heating. At 100 °C, there were no significant changes in chemical, physical, or hydraulic soil properties. At 300 °C, significant changes were observed in most soil properties in soils from both ecoregions. The OM content and CEC decreased, whereas pH and electrical conductivity increased. In addition, clay content and water aggregate stability (WSA) decreased, while all hydraulic properties increased their values. The aforementioned results demonstrate that infiltration increased after the soil was heated. This can be attributed primarily to decreases in clay content. At the same time, the water repellency (R) index decreased, allowing water to more easily wet the soil particles. Correlations revealed that CEC and clay are the main factors ruling soil hydraulic properties at all temperatures. Clay mineralogy also contributes to the soil hydraulic behavior observed. Nonlinear models were developed to estimate hydraulic properties at 100 °C and 300 °C, using the main soil properties. The models illustrated that the soils of the CM ecoregion, which are characterized by lower OM and influence of clay/CEC ratio, would be less affected by fire compared to the soils of VTF. The water holding capacity would decrease in both ecoregions. However, due to the greater changes in OM and clay in VTF, the impact would be greater than in CM.11Ca2+ = Calcium cations (meq/ 100g); CEC = Cation exchange capacity (meq/ 100g); CM = Chilean Matorral; EC = Electrical conductivity (μS/cm); I = Cumulative infiltration (cm); K = Unsaturated hydraulic conductivity (mm/h); K+ = Potassium cations (meq/ 100g); Ks = Saturated hydraulic conductivity (mm/h); Mg2+ = Magnesium cations (meq/100g); Na+ = Sodium cations (meq/100g); OM = Organic matter (g/100g); R index = Water repellency index; Se = Ethanol sorptivity (cm/s05); Sw = Water sorptivity (cm/s05); VTF = Valdivian Temperate Forest; WSA = Water-stable aggregates (%).

Morphological and molecular data on the bat flies, Basilia silvae (Brèthes, 1913) and Trichobius parasiticus Gervais, 1844 parasitizing Chilean bats.

Among mammals, bats harbour the greatest taxonomic diversity of ectoparasitic arthropods. This is mainly due to their high mobility, wide distribution range and gregarious social behaviour. In Chile, 17 species of bats have been reported; however, their ectoparasitic arthropofauna has been little studied. There are currently 12 taxa recorded, belonging to two classes and associated with only four species of bats. This study aimed to investigate the diversity of parasitic flies associated with bats in three ecoregions: Atacama Desert, Chilean Matorral and Valdivian temperate forest. During 2021, using mist nets, bats were captured in Anzota caves (Atacama Desert ecoregion), Huelquén and Alto Jahuel (Chilean Matorral ecoregion), Cherquenco and San Patricio (Valdivian temperate forest). Each bat was carefully checked during a 15-min interval for the collection of ectoparasites. The arthropods were deposited in vials with 96% ethanol. A total of 26 bats corresponding to three species (Vespertilionidae: Histiotus magellanicus Philippi, 1866, Myotis arescens (Osgood, 1943); Phyllostomidae: Desmodus rotundus (Geoffroy, 1810)) were captured from which a total of 142 ectoparasitic arthropods were collected. Bat flies were separated/identified under a stereomicroscope. Additionally, from the fieldwork, we report the presence of other ectoparasites associated with Chilean bats. In our study, we report new host-parasite associations between Trichobius parasiticus Gervais, 1844 (Diptera: Streblidae) on D. rotundus, and Basilia silvae (Brèthes, 1913) (Diptera: Nycteribiidae) in M. arescens in Chile. Our study extended the latitudinal range of distribution for B. silvae to Araucanía region, and we report for first time T. parasiticus in the country. Additionally, partial sequences of the cytochrome c oxidase I gene were obtained from these specimens. Although there is slight morphological variation in the specimens of T. parasiticus, phylogenetic analyses suggest that they correspond to the same species. The sequences generated for B. silvae represent the first for the species. Authors recommend the use of an integrative approach in the identification of ectoparasites in poorly studied ecoregions and hosts. The integration of different markers is necessary to determine more precisely the phylogenetic relationships between South American populations and species of the genera Basilia and Trichobius.

Chilean Darwin Wasps (Ichneumonidae): Biogeographic Relationships and Distribution Patterns.

Ichneumonidae, or Chilean Darwin wasps, are an important component of South American hymenopteran diversity, but the taxonomic and distributional knowledge on this insect is still deficient. Taking advantage of recently updated taxonomic knowledge, we assessed biogeographic relationships at the genus level and biodiversity spatial patterns along the latitudinal gradient. The results show the presence of 264 species in Chile, arranged in 102 genera and 22 subfamilies. Biogeographic relationships are based on six elements (cosmopolitan (n = 50; 36%), endemic (n = 29; 21%), Neotropical (n = 22; 16%), Holarctic-Oriental (n = 19; 14%), south-temperate (n = 16; 11%) and Australasian) and composed of just three genera: Anacis, Labena, and Meringops. Species and genera show a bimodal distribution along the latitudinal gradient: around 34° and 38° S. From an ecoregional perspective, richness is concentrated in the Valdivian temperate forests, but when assessed at a 0.5 × 0.5 cell scale, several outstanding cells are in the contact zone between the temperate forests and the Chilean Matorral. On the other hand, the Atacama Desert shows little or no presence of Darwin wasps. The results agree with Charles Porter, who identified a northern province composed of Neotropical and cosmopolitan genera with their own representatives in the far north (11 genera), a distributional gap in the core of the Atacama Desert, and around 128 genera in Porter's Neantarctic realm, covering all of Chile from 25° S to Cape Horn, including the Juan Fernandez islands. These results reinforce knowledge gaps and the need for more sampling and studies of available collections. Due to sampling gaps at this stage, identifying a continued increase or decrease in richness towards higher latitudes is not possible. More taxonomic and distributional information is also needed to assess potential threats to endemic genera and species.

Leopardus guigna(Carnivora: Felidae)

AbstractLeopardus guigna (Molina, 1782) is a felid commonly called the kodkod. It is the smallest cat in the Americas—about the size of a small house cat—and is 1 of 13 species in the genus Leopardus. Leopardus guigna has the smallest distribution of any New World felid, restricted to southern Chile and Argentina where it is strongly associated with the Chilean Matorral and Valdivian Temperate Rainforest ecoregions. Leopardus guigna is listed on Appendix II of the Convention for the International Trade of Endangered Species and as “Vulnerable” (VU) by the International Union for the Conservation of Nature due to habitat loss and fragmentation, human persecution, and its declining population.

Assessing the Importance of Native Mycorrhizal Fungi to Improve Tree Establishment after Wildfires.

The Chilean matorral is a heavily threatened Mediterranean-type ecosystem due to human-related activities such as anthropogenic fires. Mycorrhizal fungi may be the key microorganisms to help plants cope with environmental stress and improve the restoration of degraded ecosystems. However, the application of mycorrhizal fungi in the restoration of the Chilean matorral is limited because of insufficient local information. Consequently, we assessed the effect of mycorrhizal inoculation on the survival and photosynthesis at set intervals for two years after a fire event in four native woody plant species, namely: Peumus boldus, Quillaja saponaria, Cryptocarya alba, and Kageneckia oblonga, all dominant species of the matorral. Additionally, we assessed the enzymatic activity of three enzymes and macronutrient in the soil in mycorrhizal and non-mycorrhizal plants. The results showed that mycorrhizal inoculation increased survival in all studied species after a fire and increased photosynthesis in all, but not in P. boldus. Additionally, the soil associated with mycorrhizal plants had higher enzymatic activity and macronutrient levels in all species except in Q. saponaria, in which there was no significant mycorrhization effect. The results suggest that mycorrhizal fungi could increase the fitness of plants used in restoration initiatives after severe disturbances such as fires and, consequently, should be considered for restoration programs of native species in threatened Mediterranean ecosystems.

Correction: Compound and simple leaf woody species of the Chilean matorral are equally affected by extreme drought

Correction: Compound and simple leaf woody species of the Chilean matorral are equally affected by extreme drought

Compound and simple leaf woody species of the Chilean matorral are equally affected by extreme drought

Two main leaf types are recognized among vascular plant species: compound and simple. Compound leaves are believed to be photosynthetically more productive than simple ones, by diluting mass tissue in more projected area. Conversely, simple leaves are believed to be more stress-tolerant by packing mass tissue in less projected area during stress like drought. Nevertheless, convective cooling is more efficient in compound than simple leaves, a process that could alleviate water loss in drought periods. In Central Chile, woody species with simple and compound leaves coexist. This zone is facing a mega-drought event, causing browning and tree mortality. However, how severe droughts affect photosynthetic traits on both leaf-type species have not been addressed so far. We measured photosynthetic traits in well-watered and drought conditions in three compound and three simple leaf species, and drought response ratios were obtained. We hypothesized that with no water limitation compound leaf species will show higher net photosynthesis (AN) than simple leaf species associated with a higher mesophyll conductance (gm). Opposite results are expected for simple leaf species due to their stress-tolerant physiology, showing fewer changes in their photosynthetic traits. We found that gm and AN were larger in compound leaf species in well-watered conditions. With drought, both leaf-type species were negatively affected despite foliar temperature in compound leaf species was 4 °C lower. Our result suggests that regardless of leaf shape the matorral species in Central Chile will be seriously affected in their AN due to the megadrought currently affecting this zone.

Generalised seed mortality driven by heat shock in woody plants from Mediterranean Chile

Background Wildfires have shaped plant traits and ecosystems worldwide. Most research on the relevance of fire on plant evolution comes from Mediterranean-type ecosystems (MTEs), where a great proportion of the studied species have fire-stimulated germination. However, seed fire ecology is widely unknown for the woody flora of the Chilean matorral, the only MTE where natural fires are infrequent owing to the scarcity of non-anthropogenic ignition sources. Aim The study aimed to evaluate whether seed sensitivity to heat is generalised among the woody species of the matorral. Methods We performed heat shock experiments on the seeds of 21 woody plant species not previously assessed. These species and those from previous studies were classified according to their response as stimulated, tolerant and inhibited. The preponderance of any of these categories was statistically evaluated. Key results Exposure to 100°C for 5 min significantly decreased seed survival in all studied species. Conclusions Seed persistence to fire is less common than previously reported among woody plants from the Chilean MTE. Implications Increased wildfire events in the future may erode the genetic diversity of the Chilean flora. Germplasm banks may become crucial in post-fire restoration programs in this ecoregion, where the landscape has become increasingly flammable.

Host range dynamics at different scales: host use by a hemiparasite across its geographic distribution.

The complexity of natural communities is the result of interactions among species that coexist within them. Parasitic interactions are among the most common species interaction types, and analysis of parasite-host ranges can advance understanding of how host-parasite pairs structure community interactions across their geographic distributions. Using network analysis and host preference relative index, we analysed host use by the South American mistletoe, Tristerix corymbosus (Loranthaceae), in 22 localities among two biomes: Chilean matorral and temperate forest. The total number of host species recorded was 27, and 40% of these species were non-native. The non-native Populus sp. was shared between biomes. There was a positive relationship between host range and potential host species richness at the studied localities. On average, the mistletoe parasitized each host species relative to its abundance. However, some host species in some localities are more parasitized than expected. Network structure showed a differences in host use between the two biomes: Aristotelia chilensis was central in the temperate forest, with Populus sp. in the Chilean matorral. Host use intensity in the Chilean matorral was higher for non-native species. Tristerix corymbosus has a wide host range and could be considered a generalist parasite across its full geographic distribution, but at local scales, host preferences differed among localities and are related to host coverage. Alterations in community composition, due to natural events or human activities, can modify the availability of possible hosts. Hence, the mistletoe with the described characteristics may be able to change its infection preference while maintaining the interaction functionality.

Updating records of a threatened felid species of the Argentinian Patagonia: the Guigna Leopardus guigna (Molina, 1782) (Mammalia: Carnivora: Felidae) in Los Alerces National Park

The Guigna Leopardus guigna is an endemic felid of the Valdivian Temperate Forests in Argentina and Chile, and of the Chilean Matorral ecoregion. It is a small-sized felid (1.6–2.5 kg), one of the least known wild felids, and categorized as Vulnerable to extinction. Here, we present two new reliable records in Los Alerces National Park, Chubut Province, Argentina, the southernmost protected area, in which the species is present. The first record is an individual found dead on 6 June 2019 on the bank of Frey River near Amutui Quimei Lake. The second record was an individual casually captured in an American Mink Neovison vison cage on 7 December 2019 near Menéndez Lake. Both records were in forested Nothofagus sites very nearby to watercourses. In order to maintain viable long-term Guigna populations, corridors between protected areas should be established, particularly in habitat dominated by human presence and activities. We strongly recommend further fieldwork in protected areas and between them to increase the knowledge about the distribution, habitat use, and ecology of the Guigna.

Modelling the critical transition from Chilean evergreen forest to savanna: Early warning signals and livestock management

Semi-desert areas are sensitive to changes in rainfall and agricultural pressure, prone to abrupt changes and to the collapse of ecological functions. The sclerophyllous evergreen forest of central Chile, known as matorral, has been extensively overgrazed by domestic livestock. As a consequence, the native and endemic species of this forest community have been replaced by a savanna-type environment dominated by the species Acacia caven, known as espinales. It has been hypothesized that the collapse of matorral forest can be abrupt, and the two ecosystems represent two alternative stable states. To understand the ecological dynamics that occur during this transition, their signature in space, and the consequences of livestock management, a cellular automata model that considers the local interaction among forest vegetation, Acacia, and livestock management was developed. By simulating and analyzing the process of fragmentation in space and time, in a gradient of livestock pressure and aridity, the results show that the system exhibits properties of "robust criticality", with a shift of patch-size distributions from models matching power-laws to models matching truncated power-laws as livestock pressure increases nearby the point of collapse. Simulation results in scenarios with rotation of livestock at the tipping point reveal the interaction between resting frequency and forest conservation. These results provide information to design better management strategies in human-modified landscapes in the remaining Chilean matorral.

Postfire responses of the woody flora of Central Chile: Insights from a germination experiment.

Fire is a selective agent shaping plant traits and community assembly in fire-prone ecosystems. However, in ecosystems with no fire history, it can be a cause of land degradation when it is suddenly introduced by humans, as plant species may not be able to respond to such novel disturbance. Unlike other Mediterranean-type ecosystems (MTE) of the world, natural fires have not been frequent during the Quaternary in the matorral of Central Chile, and thus, plant adaptive responses are expected to be uncommon. We evaluated the effect of heat shock on seed survival and germination of 21 native woody plants of the Chilean matorral and compiled information on smoke-stimulation and resprouting, to evaluate the importance of fire-adaptive responses in the context of the other MTE. We found that in the Chilean woody flora negative seed responses to fire cues were more frequent than positive responses. Although resprouting is a relatively widespread trait, fire-stimulated germination is not as common in the Chilean matorral as in other MTE. The seeds of seven endemic species were strongly damaged by fire cues and this should be considered in post-fire restoration planning. However, our results also showed that many species were resistant to elevated doses of heat shock and in some, germination was even stimulated. Thus, future research should focus on the evolutionary causes of these responses. These findings could help to develop strategies for fire management in the Chilean matorral. In addition, they will improve our understanding of the evolutionary forces that shaped this plant community and to better frame this region among the other MTE worldwide.

Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene.

Climatic niche evolution in the Andean genus Menonvillea (Cremolobeae: Brassicaceae)

Fil: Salariato, Diego Leonel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Botanica Darwinion. Academia Nacional de Ciencias Exactas, Fisicas y Naturales. Instituto de Botanica Darwinion; Argentina

Diversification patterns in the CES clade (Brassicaceae tribes Cremolobeae, Eudemeae, Schizopetaleae) in Andean South America

Fil: Salariato, Diego Leonel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Botanica Darwinion. Academia Nacional de Ciencias Exactas, Fisicas y Naturales. Instituto de Botanica Darwinion; Argentina

Deforestation changes land–atmosphere interactions across South American biomes

South American biomes are increasingly affected by land use/land cover change. However, the climatic impacts of this phenomenon are still not well understood. In this paper, we model vegetation–climate interactions with a focus on four main biomes distributed in four key regions: The Atlantic Forest, the Cerrado, the Dry Chaco, and the Chilean Matorral ecosystems. We applied a three member ensemble climate model simulation for the period 1981–2010 (30years) at 25km resolution over the focus regions to quantify the changes in the regional climate resulting from historical deforestation. The results of computed modelling experiments show significant changes in surface fluxes, temperature and moisture in all regions. For instance, simulated temperature changes were stronger in the Cerrado and the Chilean Matorral with an increase of between 0.7 and 1.4°C. Changes in the hydrological cycle revealed high regional variability. The results showed consistent significant decreases in relative humidity and soil moisture, and increases in potential evapotranspiration across biomes, yet without conclusive changes in precipitation. These impacts were more significant during the dry season, which resulted to be drier and warmer after deforestation.

Assessing the distribution of a Vulnerable felid species: threats from human land use and climate change to the kodkodLeopardus guigna

AbstractClimate change and habitat fragmentation are considered key pressures on biodiversity, and mammalian carnivores with a limited geographical distribution are particularly vulnerable. The kodkodLeopardus guigna, a small felid endemic to the temperate forests of southern Chile and Argentina, has the smallest geographical range of any New World felid. Although the species occurs in protected areas in both countries, it is not known how well these areas protect the kodkod either currently or under climate change scenarios. We used species distribution models and spatial analyses to assess the distribution of the kodkod, examining the effects of changes in human land use and future climate change. We also assessed the species’ present representation in protected areas and in light of climate change scenarios. We found that the kodkod has already lost 5.5% of its range as a result of human land use, particularly in central areas of its distribution with intermediate habitat suitability. Climate change, together with human land use, will affect 40% of the kodkod's present potential distribution by the year 2050. Currently, 12.5% of the species’ potential distribution lies in protected areas and this will increase to 14% in the future. This increase does not, however, mean an increase in protected habitat but rather a reduction of the species' total potential range; a relatively larger percentage will be protected in Argentina than in Chile but the species is more susceptible to extinction in Argentina and the Chilean Matorral.

Genetic diversity and population structure of the mistletoe Tristerix corymbosus (Loranthaceae)

The genetic structure of a plant species is influenced by life-history traits, geographical range and ecological interactions that shape gene flow. We examined the genetic structure of the South American mistletoe Tristerix corymbosus using random amplification of polymorphic DNA. This species is found mainly in Chile and inhabits two biomes, the Chilean matorral and the temperate forest. The main pollinator agent, a hummingbird, is the same across the whole range, but the disperser assemblage varies between biomes. We selected 22 populations, eight of which were located in the Chilean matorral, where fruits are yellow and birds act as seed dispersers, and 14 populations in the temperate forest, where fruits are green and a marsupial disperses the mistletoe seeds. A total of ten primers were used to generate amplification products for 121 individuals (ca. six individuals per population) and 91 bands were scored. Results show that this mistletoe species is highly variable with 81 % of the bands polymorphic and a Shannon’s diversity index among populations of 0.634. The temperate forest shows slightly higher diversity indices than the Chilean matorral. The central region of the mistletoe geographic range was more variable than the north and the south regions, suggesting that it is a genetically mixed zone. It is likely that gene flow occurs mainly via hummingbirds moving pollen between biomes and birds moving seeds from north to south during spring migrations.

Land-atmosphere coupling during the Last Glacial Maximum: An Australian perspective

South American biomes are increasingly affected by land use/land cover change. However, the climatic impacts of this phenomenon are still not well understood. In this paper, we model vegetation–climate interactions with a focus on four main biomes distributed in four key regions: The Atlantic Forest, the Cerrado, the Dry Chaco, and the Chilean Matorral ecosystems. We applied a three member ensemble climate model simulation for the period 1981–2010 (30 years) at 25 km resolution over the focus regions to quantify the changes in the regional climate resulting from historical deforestation. The results of computed modelling experiments show significant changes in surface fluxes, temperature and moisture in all regions. For instance, simulated temperature changes were stronger in the Cerrado and the Chilean Matorral with an increase of between 0.7 and 1.4 °C. Changes in the hydrological cycle revealed high regional variability. The results showed consistent significant decreases in relative humidity and soil moisture, and increases in potential evapotranspiration across biomes, yet without conclusive changes in precipitation. These impacts were more significant during the dry season, which resulted to be drier and warmer after deforestation.

Diversity and Activity of Denitrifiers of Chilean Arid Soil Ecosystems

The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility, and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS) genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of denitrifiers in particular.