ABSTRACT In this note we examine the population structure of Teline monspessulana, an exotic plan... more ABSTRACT In this note we examine the population structure of Teline monspessulana, an exotic plant that is invading fragments of the Maulino Forest. We evaluate density T. monspessulana, sizes, proportion of reproductive individuals and his relation with the size of the patches in 8 forest fragments. Our results indicate a high proportion of individuals growing inside fragments. Moreover, the fragment size is not correlated with T. monspessulana density.
Shrubs can have a net positive effect on the recruitment of other species, especially relict spec... more Shrubs can have a net positive effect on the recruitment of other species, especially relict species in dry-stressful conditions. We tested the effects of nurse shrubs and herbivory defoliation on performance (survival and growth) of nursery-grown seedlings of the largest living palm, the relict wine palm Jubaea chilensis. During an 18-month period, a total of more than 300 seedlings were exposed to of four possible scenarios produced by independently weakening the effects of nurse shrubs and browsers. The experiment followed a two-way fully factorial design. We found consistent differences in survival between protected and unprotected seedlings (27.5% and 0.7%, respectively), and herbivory had a dramatic and overwhelmingly negative effect on seedling survival. The invasive rabbit (Oryctolagus cuniculus) is clearly creating a critical bottleneck in the regeneration process and might, therefore, partially explain the general lack of natural regeneration of wine palms under natural conditions. Apparently biotic filters mediated by ecological interactions are more relevant in the early stages of recruitment than abiotic, at least in invaded sites of central Chile. Our data reveal that plant-plant facilitation relationship may be modulated by plant-animal interactions, specifically by herbivory, a common and widespread ecological interaction in arid and semi-arid environments whose role has been frequently neglected. Treatments that protect young wine palm seedlings are mandatory to enable the seedlings to attain a height at which shoots are no longer vulnerable to browsing. Such protection is an essential first step toward the conservation and reintroduction of this emblematic and threatened species.
Many studies have attempted to assess the relative effects of different vectors of a disease on a... more Many studies have attempted to assess the relative effects of different vectors of a disease on animal populations. To this end, three measures have been proposed: Vectorial efficiency, Vectorial capacity and recently Vectorial effectiveness (or Vectorial impact). In this study we relate these measures to derive some of their properties emphasising in the vectorial impact for its importance in both, population performance of parasites and the proportion of the prevalence of one parasite due to a given vector. We applied the quantitative expressions advanced in this study to a simple Chilean example with one parasite (Trypanosoma cruzi), two vectors (Triatoma infestans and Mepraia spinolai) and one animal population (humans: Chagas's disease).
La fragmentación y pérdida de habitat son las causas más importantes de pérdida de biodiversidad ... more La fragmentación y pérdida de habitat son las causas más importantes de pérdida de biodiversidad en el mundo. Este libro recoge los avances teóricos, metodológicos y empíricos de los estudios realizados en Chile, en relación a estos fenómenos de creciente desarrollo, dado el ...
... Javier A. Simonetti 1 , Audrey A. Grez 2 & Ramiro O. Bustamante 1 ... run a laboratory ex... more ... Javier A. Simonetti 1 , Audrey A. Grez 2 & Ramiro O. Bustamante 1 ... run a laboratory experiment, offering seeds of three common species from the Mau-lino forest: Aetoxicum ... Efecto de la fragmentación del bosque maulino sobre la granivoría de semillas que difieren en tamaño. ...
Aim Taxonomic comparisons of alien floras across climatically similar regions have been proposed ... more Aim Taxonomic comparisons of alien floras across climatically similar regions have been proposed as a powerful approach for increasing our understanding of plant invasions across scales. However, detailed comparisons between the alien biotas of climatically similar regions are scarce. This study aims to compare the taxonomic patterns of alien species richness in mediterranean- type climate areas of central Chile and
... MARCELA TORRES-GÓMEZ 1 *, LUISA E. DELGADO 1 , VICTOR H. MARÍN 1 & RAMIRO O. BUSTAMAN... more ... MARCELA TORRES-GÓMEZ 1 *, LUISA E. DELGADO 1 , VICTOR H. MARÍN 1 & RAMIRO O. BUSTAMANTE 2. ... [ Links ]. LOCKABY B, D ZHANG, J MCDANIEL, H TIAN & S PAN (2005) Interdisciplinary research at the urban-rural interface: the WestGa project. ...
ABSTRACT Plant regeneration is strongly determined by light and soil moisture differences between... more ABSTRACT Plant regeneration is strongly determined by light and soil moisture differences between habitats; both variables are modified by large-scale forest fragmentation. Several studies have indicated this alteration as the mechanism involved in tropical forest community change. The effects of fragmentation may be much more severe in Mediterranean and deciduous forests, because plant species in these forests show a stress tolerance tradeoff between shade and drought. Our study was performed in the deciduous fragmented Coastal Maulino Forest: Reserva Nacional Los Queules (RNLQ) and surrounding small fragments. We hypothesised that Aristotelia chilensis (shade intolerant but drought tolerant) should increase its regeneration in small patches as a consequence of the change in habitat suitability (i.e. luminous and drier), while Cryptocarya alba (shade tolerant but drought intolerant) should have less regeneration in small fragments. We also expected that Nothofagus glauca and N. obliqua, which have shade and drought tolerances intermediate between A. chilensis and C. alba, should respond less to forest fragmentation. We used two estimations of plant regeneration: (i) seedling and sapling densities via field observations and (ii) seed germination and seedling establishment via a field-based experiment. Natural regeneration patterns of C. alba indicated a depressed regeneration within small forest fragments compared to RNLQ, although experimental germination, establishment and recruitment proportions did not vary between habitats. In contrast, A. chilensis regeneration was favored by forest fragmentation, with increased seedling and sapling densities and germination in small forest fragments. Both N. glauca and N. obliqua were less affected by forest fragmentation in their natural and experimental regeneration. This study highlights the relevance of studying changes in abiotic factors as a consequence of human activities, and considering safe sites (defined by regeneration niche attributes) for implementing conservation actions and ecological restoration.
Background: Arid and semi-arid environments impose limitations on plant regeneration. This is esp... more Background: Arid and semi-arid environments impose limitations on plant regeneration. This is especially important during biotic dispersal in plants with recalcitrant seeds, in relation to when and where birds disperse these seeds.Aims: We examined the effect of the onset of seasonal precipitation on the regeneration of Cryptocarya alba (Lauraceae), comparing seedling recruitment during early and late onset of precipitations.Methods: We
... (Anelida, Histriobdellidae) to organic enrichment: experimental assessment Rodrigo Pardo ÆIrm... more ... (Anelida, Histriobdellidae) to organic enrichment: experimental assessment Rodrigo Pardo ÆIrma Vila Æ Ramiro Bustamante ... Investigaciones Zoológicas Chilenas 7: 1958. Bahamonde, N., A. Carvacho, C. Jara, M. López, F. Ponce, M. A. Retamal & E. Rudolph, 1998. ...
SUMMARY 1. A key aspect of the ecology and evolution of adaptive prey responses to predator risk ... more SUMMARY 1. A key aspect of the ecology and evolution of adaptive prey responses to predator risk is the timing by which the former develop a defensive trait in response to inducing signals released by the latter. This property, called reactivity, has been shown to affect population stability and persistence. 2. Theoretically, the minimal predator density required by prey to exhibit induced defences is expected to increase with the effectiveness of the defence and decrease with its cost. Likewise, the time required for the prey population to exhibit an induced defence is expected to increase together with cost. 3. The freshwater rotifers Brachionus calyciflorus and B. havanaensis and their predator Asplanchna brightwelli were used to test the hypothesis that prey species exhibiting defences that offer a larger fitness benefit and lower fitness cost are more reactive to predator signals, in terms of requiring shorter exposure time and lower signal concentration to trigger a morphological defence reaction. 4. Our results showed that both prey species exhibited costly and effective defences after induction by predator infochemicals. Faster reactions were observed at higher levels of predator cues. Nevertheless, the observed relationship between reactivity and benefit ⁄ cost of defences did not agree with our expectations. 5. To our knowledge, this is the first study in which the timing of induction of morphological defences is experimentally assessed over a gradient of risk signals. We propose new research directions to disentangle the mechanisms and project the consequences of prey decisions at the morphological level.
The ecological processes and interactions that involve plants at the seed level may be altered in... more The ecological processes and interactions that involve plants at the seed level may be altered in a fragmented forest, with consequences on plant recruitment and forest structure. We studied seed production, pre-dispersal seed predation and germination of non-damaged and damaged seeds of the endemic and vulnerable Nothofagus glauca tree, in small fragments and in a continuous area of the Maulino
ABSTRACT In this note we examine the population structure of Teline monspessulana, an exotic plan... more ABSTRACT In this note we examine the population structure of Teline monspessulana, an exotic plant that is invading fragments of the Maulino Forest. We evaluate density T. monspessulana, sizes, proportion of reproductive individuals and his relation with the size of the patches in 8 forest fragments. Our results indicate a high proportion of individuals growing inside fragments. Moreover, the fragment size is not correlated with T. monspessulana density.
Shrubs can have a net positive effect on the recruitment of other species, especially relict spec... more Shrubs can have a net positive effect on the recruitment of other species, especially relict species in dry-stressful conditions. We tested the effects of nurse shrubs and herbivory defoliation on performance (survival and growth) of nursery-grown seedlings of the largest living palm, the relict wine palm Jubaea chilensis. During an 18-month period, a total of more than 300 seedlings were exposed to of four possible scenarios produced by independently weakening the effects of nurse shrubs and browsers. The experiment followed a two-way fully factorial design. We found consistent differences in survival between protected and unprotected seedlings (27.5% and 0.7%, respectively), and herbivory had a dramatic and overwhelmingly negative effect on seedling survival. The invasive rabbit (Oryctolagus cuniculus) is clearly creating a critical bottleneck in the regeneration process and might, therefore, partially explain the general lack of natural regeneration of wine palms under natural conditions. Apparently biotic filters mediated by ecological interactions are more relevant in the early stages of recruitment than abiotic, at least in invaded sites of central Chile. Our data reveal that plant-plant facilitation relationship may be modulated by plant-animal interactions, specifically by herbivory, a common and widespread ecological interaction in arid and semi-arid environments whose role has been frequently neglected. Treatments that protect young wine palm seedlings are mandatory to enable the seedlings to attain a height at which shoots are no longer vulnerable to browsing. Such protection is an essential first step toward the conservation and reintroduction of this emblematic and threatened species.
Many studies have attempted to assess the relative effects of different vectors of a disease on a... more Many studies have attempted to assess the relative effects of different vectors of a disease on animal populations. To this end, three measures have been proposed: Vectorial efficiency, Vectorial capacity and recently Vectorial effectiveness (or Vectorial impact). In this study we relate these measures to derive some of their properties emphasising in the vectorial impact for its importance in both, population performance of parasites and the proportion of the prevalence of one parasite due to a given vector. We applied the quantitative expressions advanced in this study to a simple Chilean example with one parasite (Trypanosoma cruzi), two vectors (Triatoma infestans and Mepraia spinolai) and one animal population (humans: Chagas's disease).
La fragmentación y pérdida de habitat son las causas más importantes de pérdida de biodiversidad ... more La fragmentación y pérdida de habitat son las causas más importantes de pérdida de biodiversidad en el mundo. Este libro recoge los avances teóricos, metodológicos y empíricos de los estudios realizados en Chile, en relación a estos fenómenos de creciente desarrollo, dado el ...
... Javier A. Simonetti 1 , Audrey A. Grez 2 & Ramiro O. Bustamante 1 ... run a laboratory ex... more ... Javier A. Simonetti 1 , Audrey A. Grez 2 & Ramiro O. Bustamante 1 ... run a laboratory experiment, offering seeds of three common species from the Mau-lino forest: Aetoxicum ... Efecto de la fragmentación del bosque maulino sobre la granivoría de semillas que difieren en tamaño. ...
Aim Taxonomic comparisons of alien floras across climatically similar regions have been proposed ... more Aim Taxonomic comparisons of alien floras across climatically similar regions have been proposed as a powerful approach for increasing our understanding of plant invasions across scales. However, detailed comparisons between the alien biotas of climatically similar regions are scarce. This study aims to compare the taxonomic patterns of alien species richness in mediterranean- type climate areas of central Chile and
... MARCELA TORRES-GÓMEZ 1 *, LUISA E. DELGADO 1 , VICTOR H. MARÍN 1 & RAMIRO O. BUSTAMAN... more ... MARCELA TORRES-GÓMEZ 1 *, LUISA E. DELGADO 1 , VICTOR H. MARÍN 1 & RAMIRO O. BUSTAMANTE 2. ... [ Links ]. LOCKABY B, D ZHANG, J MCDANIEL, H TIAN & S PAN (2005) Interdisciplinary research at the urban-rural interface: the WestGa project. ...
ABSTRACT Plant regeneration is strongly determined by light and soil moisture differences between... more ABSTRACT Plant regeneration is strongly determined by light and soil moisture differences between habitats; both variables are modified by large-scale forest fragmentation. Several studies have indicated this alteration as the mechanism involved in tropical forest community change. The effects of fragmentation may be much more severe in Mediterranean and deciduous forests, because plant species in these forests show a stress tolerance tradeoff between shade and drought. Our study was performed in the deciduous fragmented Coastal Maulino Forest: Reserva Nacional Los Queules (RNLQ) and surrounding small fragments. We hypothesised that Aristotelia chilensis (shade intolerant but drought tolerant) should increase its regeneration in small patches as a consequence of the change in habitat suitability (i.e. luminous and drier), while Cryptocarya alba (shade tolerant but drought intolerant) should have less regeneration in small fragments. We also expected that Nothofagus glauca and N. obliqua, which have shade and drought tolerances intermediate between A. chilensis and C. alba, should respond less to forest fragmentation. We used two estimations of plant regeneration: (i) seedling and sapling densities via field observations and (ii) seed germination and seedling establishment via a field-based experiment. Natural regeneration patterns of C. alba indicated a depressed regeneration within small forest fragments compared to RNLQ, although experimental germination, establishment and recruitment proportions did not vary between habitats. In contrast, A. chilensis regeneration was favored by forest fragmentation, with increased seedling and sapling densities and germination in small forest fragments. Both N. glauca and N. obliqua were less affected by forest fragmentation in their natural and experimental regeneration. This study highlights the relevance of studying changes in abiotic factors as a consequence of human activities, and considering safe sites (defined by regeneration niche attributes) for implementing conservation actions and ecological restoration.
Background: Arid and semi-arid environments impose limitations on plant regeneration. This is esp... more Background: Arid and semi-arid environments impose limitations on plant regeneration. This is especially important during biotic dispersal in plants with recalcitrant seeds, in relation to when and where birds disperse these seeds.Aims: We examined the effect of the onset of seasonal precipitation on the regeneration of Cryptocarya alba (Lauraceae), comparing seedling recruitment during early and late onset of precipitations.Methods: We
... (Anelida, Histriobdellidae) to organic enrichment: experimental assessment Rodrigo Pardo ÆIrm... more ... (Anelida, Histriobdellidae) to organic enrichment: experimental assessment Rodrigo Pardo ÆIrma Vila Æ Ramiro Bustamante ... Investigaciones Zoológicas Chilenas 7: 1958. Bahamonde, N., A. Carvacho, C. Jara, M. López, F. Ponce, M. A. Retamal & E. Rudolph, 1998. ...
SUMMARY 1. A key aspect of the ecology and evolution of adaptive prey responses to predator risk ... more SUMMARY 1. A key aspect of the ecology and evolution of adaptive prey responses to predator risk is the timing by which the former develop a defensive trait in response to inducing signals released by the latter. This property, called reactivity, has been shown to affect population stability and persistence. 2. Theoretically, the minimal predator density required by prey to exhibit induced defences is expected to increase with the effectiveness of the defence and decrease with its cost. Likewise, the time required for the prey population to exhibit an induced defence is expected to increase together with cost. 3. The freshwater rotifers Brachionus calyciflorus and B. havanaensis and their predator Asplanchna brightwelli were used to test the hypothesis that prey species exhibiting defences that offer a larger fitness benefit and lower fitness cost are more reactive to predator signals, in terms of requiring shorter exposure time and lower signal concentration to trigger a morphological defence reaction. 4. Our results showed that both prey species exhibited costly and effective defences after induction by predator infochemicals. Faster reactions were observed at higher levels of predator cues. Nevertheless, the observed relationship between reactivity and benefit ⁄ cost of defences did not agree with our expectations. 5. To our knowledge, this is the first study in which the timing of induction of morphological defences is experimentally assessed over a gradient of risk signals. We propose new research directions to disentangle the mechanisms and project the consequences of prey decisions at the morphological level.
The ecological processes and interactions that involve plants at the seed level may be altered in... more The ecological processes and interactions that involve plants at the seed level may be altered in a fragmented forest, with consequences on plant recruitment and forest structure. We studied seed production, pre-dispersal seed predation and germination of non-damaged and damaged seeds of the endemic and vulnerable Nothofagus glauca tree, in small fragments and in a continuous area of the Maulino
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