Despite the well-known thermodynamic traits of ecosystem functioning, their description by means ... more Despite the well-known thermodynamic traits of ecosystem functioning, their description by means of conventional physics should be regarded as incomplete, even if we take into account the most recent advancements in this field. The analytical difficulties in this field have been especially complex to get a reliable modeling of species diversity per plot (H p ) by endowing this indicator with a fully clear theoretical meaning. This article contributes to resolve such difficulties starting from (a) the previous proposal of an ecological state equation, and (b) the preceding empirical finding of an ecological equivalent of Planck's constant at the evolutionary scale. So, in the first instance, this article proposes an equation for density distributions of H p values (ED H ) based on a simple transformation of the Maxwell-Boltzmann distribution for molecular velocity values (M-BD v ). Our results indicate that the above-mentioned equation allows an appropriate fit between expected and observed distributions. Besides, the transformation from M-BD v to ED H establishes connections between species diversity and other indicators that are consistent with well-known ecological principles. This article, in the second instance, uses ED H s from a wide spectrum of surveys as an analytical framework to explore the nature and meaning of stationary trophic information waves (STIWs) whose stationary nature depends on the biomass-dispersal trade-off in function of H p values (B-D TO-H ) that characterizes the most of the explored surveys. B-D TO-H makes these surveys behave as ecological cavity resonators (ECR) by trapping functional oscillations that bounce back and forth between the two opposite edges of the ECR: from r-strategy (at low biomass and diversity, and high dispersal) to K-strategy, and vice versa. STIWs were obtained by using the spline-adjusted values from the arithmetical difference between standardized values of species richness (S) and evenness (J ) in function of H p values (i.e., a 2D scalar space H p , S-J ). Twice the distance on the abscissas (2 H p ) between successive extreme values on the ordinates (whatever a maximum or a minimum) along the abovementioned spline adjustment was taken as the value of ecological wavelength ( e ). e was assessed in order to obtain the value of the ecological equivalent of Planck's constant (h e ec ) at the intra-survey scale that was calculated as: h e ec = e × m e × I e ; where m e : individual biomass, and I e : an ad-hoc indicator of dispersal activity. Our main result is that the observed value of h e ec 's mantissa is statistically equivalent to the mantissa of the physical Planck's constant (h = 6.62606957E − 34 J s) in all of the discontinuous (i.e., with interspersed categories in which n = 0) statistical density distributions of H p values per survey. R.A. Rodríguez et al. / Ecological Modelling 313 (2015) 162-180 163 This means that h e ec = 6.62606957Eϕ J e nat/individual, where ϕ = −x i , . . ., −3, −2, −1, 0,+1, +2, +3, . . .,+x i depending on the type of taxocenosis explored. That is to say, h e ec indicates the minimum amount of energy exchange allowed between two individuals. The exploration of the analytical meaning of this result in the final sections of the article explains why quantum mechanics (QM) is a useful tool in order to explain several key questions in evolutionary biology and ecology, as for example: the physical limit of adaptive radiation; the balance between competitive exclusion and functional redundancy to promote species coexistence by avoiding the negative effects of competitive exclusion; the apparent holes in the fossil record; the progression of body size along a wide spectrum of taxa as a general evolutionary trend; the non-continuous nature of net energy flow at the ecosystem level; the way in which the energy level is stabilized under stationary ecological conditions; the reasons of the higher sensitivity of high diversity ecosystems under environmental impact despite their higher stability under natural conditions; the tangible expression of complex concept as ecological inertia and elasticity; as well as the increased risk from pushing the biosphere until a rupture limit because of the potential discrete behavior of ecological resilience in the large scale due to the quantum nature of ecosystem functioning.
We analyzed a post-clearcut chronosequence (0.5 to 60 years after harvesting) in the laurel fores... more We analyzed a post-clearcut chronosequence (0.5 to 60 years after harvesting) in the laurel forest of La Palma island (Canarian Archipelago) to determine the recovery of the stands with respect to species composition, richness, life strategies and structural parameters of the canopy. Multivariate analysis showed that exotic species, as well as annual ruderal species were confined to early-successional stages, while native perennials, typical of laurel forests, dominated the late-successional stages. Total species richness decreased significantly with time after clear-cutting. The relative fast recovery of understory native species may be due to low forest floor disturbance during harvesting. Shade-intolerant pioneer, pioneer-remnant and shade-tolerant late-successional species were the main life strategies of native tree species. Most structural parameters showed a continuous and monotonic increase (basal area, biomass) or decrease (density, percentage of photosynthetic biomass) during succession. Once clear-cutting, here performed with an interval of 8 years, is abandoned, the recovery of the laurel forest seems possible due to careful logging that protects the soil and a rapid asexual regeneration of native tree species, revealing this to be a sustainable management practice.
The importance of introduced rats as damaging factors on island biotas is globally recognized. Th... more The importance of introduced rats as damaging factors on island biotas is globally recognized. The predation of artificial avian nests by Ship rats (Rattus rattus) in fragmented laurel forests in Tenerife (Canary Islands) was explored. The influence of road edge, patch type, and position (ground versus tree) on nest survival in two forest remnants differing in conservation degree, were assessed using failure-time analysis. Overall, nest predation was greater in the preserved than in the disturbed remnant. Nest predation also differed among and within patches, variation being greater within the disturbed remnant. The probability of nest failure was higher at the interior than along the road edge in both remnants, but the road edge effect on nest predation was more intense in the disturbed remnant. Predation pressure was higher in patches of mature, closed canopy or dense understorey with stump sprouting. Ground nests were predated at higher rates than tree nests at any location. These results contrast with other nest predation studies in fragmented landscapes where forest edges rather than the interior are more frequently used by predators. Predatory activity by rats seems negatively affected by forest disturbance and road edge effect. Overall, artificial nest predation patterns by rats confirm a potential predation risk for the avifauna of the Canarian laurel forest. This should be considered in implementing conservation management programmes.
El uso de estructuras de drenaje viario y otros pasos inferiores potenciales para reptiles se enc... more El uso de estructuras de drenaje viario y otros pasos inferiores potenciales para reptiles se encuentra escasamente estudiado. En esta nota presentamos una evidencia fotográfica de lagartos ocelados (Timon lepidus) usando un conducto estrecho lineal de drenaje bajo una carretera de tráfico intenso en Andalucía occidental (Sevilla). Nuestros datos sugieren que los lagartos podrían estar usando esta alternativa de desplazamiento contribuyendo a movimientos entre hábitats de esta especie amenazada, disminuyendo el riesgo de atropellos y mitigando los efectos de la fragmentación del hábitat.
Studies dealing with interactions between vertebrate frugivores and fleshy-fruited plants have fo... more Studies dealing with interactions between vertebrate frugivores and fleshy-fruited plants have focused on the selective role of vertebrates upon fruit or plant traits (le, dispersal syndromes), assuming that these systems are coevolved (Howe & Estabrook. 1977. ...
Response to comments on " Uncertainty principle in niche assessment: A solution to the d... more Response to comments on " Uncertainty principle in niche assessment: A solution to the dilemma redundancy vs. competitive exclusion, and some analytical consequences " a b s t r a c t The influence of quantum ecological uncertainty (QEU: a discrete statistical trade-off between the standard deviations of species diversity and energy, two indicators that are essential to define the ecological niche of every species), has been proposed as a plausible explanation to the debate between the competitive exclusion principle (CEP) and the hypothesis of functional redundancy (HFR). The debate CEP ↔ HFR is a manifestation of the wide spectrum of issues connected with a very important problem in ecology: the so-called " biodiversity paradox " (i.e.: How is it possible that so many species can coexist despite the underlying influence of interspecific competition?). Any testable theoretical alternative to explain species coexistence depends on an accurate assessment of the ecological niche in practice. However, under QEU, the assessment of ecological niche cannot be as accurate as we want due to an objective limitation of nature: the above-mentioned trade-off. Consequently, it is nonsense following the debate about this topic in the conventional way; it is necessary to change our traditional point of view about this issue in order to develop a non-conventional interpretation of ecosystem functioning. However, QEU has been strongly criticized in a recently published article. This article is devoted to clarify certain misunderstandings whose nature is evident by reading the above-mentioned criticism and its precursory publications in comparison with the spectrum of articles that supports QEU. The general fulfillment of QEU has also been questioned by the above-mentioned criticism, so it is additionally supported in this article by a noticeably abbreviated inclusion of results from field data, surveyed under different circumstances in comparison with previous data, from two inland water taxocenes (zooplankton rotifers and crustaceans, Acton Lake, Ohio, U.S.A.) to which this model has not been applied so far. Our general conclusion is that the criticism to QEU has been groundlessly proposed due to epistemological inaccuracies; fragmentary understanding about the principles connected with QEU; as well as an incomplete literature review.
Spatial and temporal variations in fruit fall are critical in the structuring of plant population... more Spatial and temporal variations in fruit fall are critical in the structuring of plant populations and are important determinants of canopy composition. We analyzed fruit fall in two laurel forests, near Tenerife, Canary Islands, during one year to quantify temporal variation in fruit abundance and its relationship with canopy composition. There was some temporal synchrony among fruiting tree species in fruit fall phenology at the two study forests. Although the canopy composition of both sites differed significantly, the fruit fall composition did not show significant differences. In spite of that, some species showed differences in abundance between sites, with a greater biomass of Laurus azorica, Ilex perado and Myrica faya at Aguirre than at El Moquinal site. The temporal variation on fruit fall composition was low and it was not possible to infer seasonality in these laurel forests on the basis of fruit fall composition. The analysis revealed significant differences among sites, but not between species.
The introduction of non-native gastropods on islands has repetitively been related to a decline o... more The introduction of non-native gastropods on islands has repetitively been related to a decline of the endemic fauna. So far, no quantitative information is available even for the native gastropod fauna from the laurel forests (the so-called Laurisilva) of the Canary Islands. Much of the original laurel forest has been logged in recent centuries. Based on vegetation studies, we hypothesized that densities and the number of introduced species decline with the age of the regrowth forests. We sampled 27 sites from which we collected thirty native and seven introduced species. Two introduced species, Milax nigricans and Oxychilus alliarius, were previously not reported from the Canary Islands. Assemblage composition was mainly structured by disturbance history and altitude. Overall species richness was correlated with slope inclination, prevalence of rocky outcrops, amounts of woody debris and leaf litter depth. Densities were correlated with the depth of the litter layer and the extent of herb layer cover and laurel canopy cover. Introduced species occurred in 22 sites but were neither related to native species richness nor to the time that elapsed since forest regrowth. One introduced slug, Lehmannia valentiana, is already wide-spread, with densities strongly related to herb cover. Overall species richness seemed to be the outcome of invasibility, thus factors enhancing species richness likely also enhance invasibility. Although at present introduced species contribute to diversity, the potential competition between introduced slugs and the rich native semi-slug fauna, and the effects of introduced predatory snails ( Oxychilus spp. and Testacella maugei) warrant further monitoring.
Some snails disguise the shell with a covering of soil or other material. Among species in the Ca... more Some snails disguise the shell with a covering of soil or other material. Among species in the Canarian enid genus Napaeus, some rock-dwelling species cover the shell with lichens; in one of these, N. barquini, the process is known to be active. In some ground-dwelling species the muddy covering may be acquired passively, as for example in N. variatus. Napaeus badiosus is a snail with an almost smooth shell which is not disguised in the field. It normally rests out of sight of predators. Four specimens of N. badiosus were transferred to a glass terrarium with a layer of loose, humid soil without stones and vegetation. The snails acquired a soil layer with prominent protuberances that covered the whole shell, reducing the risk of attack by visual predators. The appearance of the disguised N. badiosus shell is compared with those of N. barquini and of N. variatus. The disguise of N. badiosus is similar to that of N. barquini. This active disguise thus appears to be facultative, adopted when hiding places are not available. Mechanisms of disguise are briefly discussed; the behaviour of other disguised species should be investigated.
Distribución, riqueza y composición florística de los últimos relictos de la sabina canaria (Juni... more Distribución, riqueza y composición florística de los últimos relictos de la sabina canaria (Juniperus turbinata ssp. canariensis) en Tenerife
Delgado et al.: Logging and topography effects on artificial nest predation by rats in laurel for... more Delgado et al.: Logging and topography effects on artificial nest predation by rats in laurel forests -53 -APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 11(1): 53-65.
Despite the well-known thermodynamic traits of ecosystem functioning, their description by means ... more Despite the well-known thermodynamic traits of ecosystem functioning, their description by means of conventional physics should be regarded as incomplete, even if we take into account the most recent advancements in this field. The analytical difficulties in this field have been especially complex to get a reliable modeling of species diversity per plot (H p ) by endowing this indicator with a fully clear theoretical meaning. This article contributes to resolve such difficulties starting from (a) the previous proposal of an ecological state equation, and (b) the preceding empirical finding of an ecological equivalent of Planck's constant at the evolutionary scale. So, in the first instance, this article proposes an equation for density distributions of H p values (ED H ) based on a simple transformation of the Maxwell-Boltzmann distribution for molecular velocity values (M-BD v ). Our results indicate that the above-mentioned equation allows an appropriate fit between expected and observed distributions. Besides, the transformation from M-BD v to ED H establishes connections between species diversity and other indicators that are consistent with well-known ecological principles. This article, in the second instance, uses ED H s from a wide spectrum of surveys as an analytical framework to explore the nature and meaning of stationary trophic information waves (STIWs) whose stationary nature depends on the biomass-dispersal trade-off in function of H p values (B-D TO-H ) that characterizes the most of the explored surveys. B-D TO-H makes these surveys behave as ecological cavity resonators (ECR) by trapping functional oscillations that bounce back and forth between the two opposite edges of the ECR: from r-strategy (at low biomass and diversity, and high dispersal) to K-strategy, and vice versa. STIWs were obtained by using the spline-adjusted values from the arithmetical difference between standardized values of species richness (S) and evenness (J ) in function of H p values (i.e., a 2D scalar space H p , S-J ). Twice the distance on the abscissas (2 H p ) between successive extreme values on the ordinates (whatever a maximum or a minimum) along the abovementioned spline adjustment was taken as the value of ecological wavelength ( e ). e was assessed in order to obtain the value of the ecological equivalent of Planck's constant (h e ec ) at the intra-survey scale that was calculated as: h e ec = e × m e × I e ; where m e : individual biomass, and I e : an ad-hoc indicator of dispersal activity. Our main result is that the observed value of h e ec 's mantissa is statistically equivalent to the mantissa of the physical Planck's constant (h = 6.62606957E − 34 J s) in all of the discontinuous (i.e., with interspersed categories in which n = 0) statistical density distributions of H p values per survey. R.A. Rodríguez et al. / Ecological Modelling 313 (2015) 162-180 163 This means that h e ec = 6.62606957Eϕ J e nat/individual, where ϕ = −x i , . . ., −3, −2, −1, 0,+1, +2, +3, . . .,+x i depending on the type of taxocenosis explored. That is to say, h e ec indicates the minimum amount of energy exchange allowed between two individuals. The exploration of the analytical meaning of this result in the final sections of the article explains why quantum mechanics (QM) is a useful tool in order to explain several key questions in evolutionary biology and ecology, as for example: the physical limit of adaptive radiation; the balance between competitive exclusion and functional redundancy to promote species coexistence by avoiding the negative effects of competitive exclusion; the apparent holes in the fossil record; the progression of body size along a wide spectrum of taxa as a general evolutionary trend; the non-continuous nature of net energy flow at the ecosystem level; the way in which the energy level is stabilized under stationary ecological conditions; the reasons of the higher sensitivity of high diversity ecosystems under environmental impact despite their higher stability under natural conditions; the tangible expression of complex concept as ecological inertia and elasticity; as well as the increased risk from pushing the biosphere until a rupture limit because of the potential discrete behavior of ecological resilience in the large scale due to the quantum nature of ecosystem functioning.
We analyzed a post-clearcut chronosequence (0.5 to 60 years after harvesting) in the laurel fores... more We analyzed a post-clearcut chronosequence (0.5 to 60 years after harvesting) in the laurel forest of La Palma island (Canarian Archipelago) to determine the recovery of the stands with respect to species composition, richness, life strategies and structural parameters of the canopy. Multivariate analysis showed that exotic species, as well as annual ruderal species were confined to early-successional stages, while native perennials, typical of laurel forests, dominated the late-successional stages. Total species richness decreased significantly with time after clear-cutting. The relative fast recovery of understory native species may be due to low forest floor disturbance during harvesting. Shade-intolerant pioneer, pioneer-remnant and shade-tolerant late-successional species were the main life strategies of native tree species. Most structural parameters showed a continuous and monotonic increase (basal area, biomass) or decrease (density, percentage of photosynthetic biomass) during succession. Once clear-cutting, here performed with an interval of 8 years, is abandoned, the recovery of the laurel forest seems possible due to careful logging that protects the soil and a rapid asexual regeneration of native tree species, revealing this to be a sustainable management practice.
The importance of introduced rats as damaging factors on island biotas is globally recognized. Th... more The importance of introduced rats as damaging factors on island biotas is globally recognized. The predation of artificial avian nests by Ship rats (Rattus rattus) in fragmented laurel forests in Tenerife (Canary Islands) was explored. The influence of road edge, patch type, and position (ground versus tree) on nest survival in two forest remnants differing in conservation degree, were assessed using failure-time analysis. Overall, nest predation was greater in the preserved than in the disturbed remnant. Nest predation also differed among and within patches, variation being greater within the disturbed remnant. The probability of nest failure was higher at the interior than along the road edge in both remnants, but the road edge effect on nest predation was more intense in the disturbed remnant. Predation pressure was higher in patches of mature, closed canopy or dense understorey with stump sprouting. Ground nests were predated at higher rates than tree nests at any location. These results contrast with other nest predation studies in fragmented landscapes where forest edges rather than the interior are more frequently used by predators. Predatory activity by rats seems negatively affected by forest disturbance and road edge effect. Overall, artificial nest predation patterns by rats confirm a potential predation risk for the avifauna of the Canarian laurel forest. This should be considered in implementing conservation management programmes.
El uso de estructuras de drenaje viario y otros pasos inferiores potenciales para reptiles se enc... more El uso de estructuras de drenaje viario y otros pasos inferiores potenciales para reptiles se encuentra escasamente estudiado. En esta nota presentamos una evidencia fotográfica de lagartos ocelados (Timon lepidus) usando un conducto estrecho lineal de drenaje bajo una carretera de tráfico intenso en Andalucía occidental (Sevilla). Nuestros datos sugieren que los lagartos podrían estar usando esta alternativa de desplazamiento contribuyendo a movimientos entre hábitats de esta especie amenazada, disminuyendo el riesgo de atropellos y mitigando los efectos de la fragmentación del hábitat.
Studies dealing with interactions between vertebrate frugivores and fleshy-fruited plants have fo... more Studies dealing with interactions between vertebrate frugivores and fleshy-fruited plants have focused on the selective role of vertebrates upon fruit or plant traits (le, dispersal syndromes), assuming that these systems are coevolved (Howe & Estabrook. 1977. ...
Response to comments on " Uncertainty principle in niche assessment: A solution to the d... more Response to comments on " Uncertainty principle in niche assessment: A solution to the dilemma redundancy vs. competitive exclusion, and some analytical consequences " a b s t r a c t The influence of quantum ecological uncertainty (QEU: a discrete statistical trade-off between the standard deviations of species diversity and energy, two indicators that are essential to define the ecological niche of every species), has been proposed as a plausible explanation to the debate between the competitive exclusion principle (CEP) and the hypothesis of functional redundancy (HFR). The debate CEP ↔ HFR is a manifestation of the wide spectrum of issues connected with a very important problem in ecology: the so-called " biodiversity paradox " (i.e.: How is it possible that so many species can coexist despite the underlying influence of interspecific competition?). Any testable theoretical alternative to explain species coexistence depends on an accurate assessment of the ecological niche in practice. However, under QEU, the assessment of ecological niche cannot be as accurate as we want due to an objective limitation of nature: the above-mentioned trade-off. Consequently, it is nonsense following the debate about this topic in the conventional way; it is necessary to change our traditional point of view about this issue in order to develop a non-conventional interpretation of ecosystem functioning. However, QEU has been strongly criticized in a recently published article. This article is devoted to clarify certain misunderstandings whose nature is evident by reading the above-mentioned criticism and its precursory publications in comparison with the spectrum of articles that supports QEU. The general fulfillment of QEU has also been questioned by the above-mentioned criticism, so it is additionally supported in this article by a noticeably abbreviated inclusion of results from field data, surveyed under different circumstances in comparison with previous data, from two inland water taxocenes (zooplankton rotifers and crustaceans, Acton Lake, Ohio, U.S.A.) to which this model has not been applied so far. Our general conclusion is that the criticism to QEU has been groundlessly proposed due to epistemological inaccuracies; fragmentary understanding about the principles connected with QEU; as well as an incomplete literature review.
Spatial and temporal variations in fruit fall are critical in the structuring of plant population... more Spatial and temporal variations in fruit fall are critical in the structuring of plant populations and are important determinants of canopy composition. We analyzed fruit fall in two laurel forests, near Tenerife, Canary Islands, during one year to quantify temporal variation in fruit abundance and its relationship with canopy composition. There was some temporal synchrony among fruiting tree species in fruit fall phenology at the two study forests. Although the canopy composition of both sites differed significantly, the fruit fall composition did not show significant differences. In spite of that, some species showed differences in abundance between sites, with a greater biomass of Laurus azorica, Ilex perado and Myrica faya at Aguirre than at El Moquinal site. The temporal variation on fruit fall composition was low and it was not possible to infer seasonality in these laurel forests on the basis of fruit fall composition. The analysis revealed significant differences among sites, but not between species.
The introduction of non-native gastropods on islands has repetitively been related to a decline o... more The introduction of non-native gastropods on islands has repetitively been related to a decline of the endemic fauna. So far, no quantitative information is available even for the native gastropod fauna from the laurel forests (the so-called Laurisilva) of the Canary Islands. Much of the original laurel forest has been logged in recent centuries. Based on vegetation studies, we hypothesized that densities and the number of introduced species decline with the age of the regrowth forests. We sampled 27 sites from which we collected thirty native and seven introduced species. Two introduced species, Milax nigricans and Oxychilus alliarius, were previously not reported from the Canary Islands. Assemblage composition was mainly structured by disturbance history and altitude. Overall species richness was correlated with slope inclination, prevalence of rocky outcrops, amounts of woody debris and leaf litter depth. Densities were correlated with the depth of the litter layer and the extent of herb layer cover and laurel canopy cover. Introduced species occurred in 22 sites but were neither related to native species richness nor to the time that elapsed since forest regrowth. One introduced slug, Lehmannia valentiana, is already wide-spread, with densities strongly related to herb cover. Overall species richness seemed to be the outcome of invasibility, thus factors enhancing species richness likely also enhance invasibility. Although at present introduced species contribute to diversity, the potential competition between introduced slugs and the rich native semi-slug fauna, and the effects of introduced predatory snails ( Oxychilus spp. and Testacella maugei) warrant further monitoring.
Some snails disguise the shell with a covering of soil or other material. Among species in the Ca... more Some snails disguise the shell with a covering of soil or other material. Among species in the Canarian enid genus Napaeus, some rock-dwelling species cover the shell with lichens; in one of these, N. barquini, the process is known to be active. In some ground-dwelling species the muddy covering may be acquired passively, as for example in N. variatus. Napaeus badiosus is a snail with an almost smooth shell which is not disguised in the field. It normally rests out of sight of predators. Four specimens of N. badiosus were transferred to a glass terrarium with a layer of loose, humid soil without stones and vegetation. The snails acquired a soil layer with prominent protuberances that covered the whole shell, reducing the risk of attack by visual predators. The appearance of the disguised N. badiosus shell is compared with those of N. barquini and of N. variatus. The disguise of N. badiosus is similar to that of N. barquini. This active disguise thus appears to be facultative, adopted when hiding places are not available. Mechanisms of disguise are briefly discussed; the behaviour of other disguised species should be investigated.
Distribución, riqueza y composición florística de los últimos relictos de la sabina canaria (Juni... more Distribución, riqueza y composición florística de los últimos relictos de la sabina canaria (Juniperus turbinata ssp. canariensis) en Tenerife
Delgado et al.: Logging and topography effects on artificial nest predation by rats in laurel for... more Delgado et al.: Logging and topography effects on artificial nest predation by rats in laurel forests -53 -APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 11(1): 53-65.
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