Silvicultural Practices in the Management of Diospyros melanoxylon (Tendu) Leaf Production: Options and Trade-offs.

Non-timber forest products (NTFPs) are known to provide livelihoods for forest-based communities across the world. While ensuring the sustainability of NTFP harvests is a key challenge, optimizing the production of NTFPs through appropriate silvicultural practices is also critical for forest-based economies. In Central India, the suitability of fire or pruning practices for enhancing the production of leaves of the tendu tree (Diospyros melanoxylon) has been much debated. While villagers commonly adopt annual litter fires, the state Forest Department urges leaf collectors to adopt the more labor-intensive practice of pruning. On the other hand, conservationists recommend completely hands-off management (no fire or pruning). In this study, we compared leaf production from the competing practices of litter fire, pruning, pruning-with-fire, and hands-off management, that are experimented with in community-managed forests. We checked for confounding factors such as tree canopy cover, presence of tendu trees, and inherent differences in forest type. We conducted the study during the pre-harvest season from March to May 2020 in villages in the northern Gadchiroli district of Maharashtra, India. We found that pruning and pruning-with-fire lead to higher root sprout production and, in turn, higher leaf production per unit area when compared to litter fire and the control (no pruning or fire). Fire alone led to a negative impact on leaf production. Implementing pruning instead of litter fire, however, comes with labor costs. Its adoption is therefore linked with the institutional arrangements for tendu management and marketing that shape community perception of costs. गौण वन उत्पादने जगभरातील वन-आधारित समुदायांसाठी उपजीविका म्हणून महत्त्वाची आहेत. त्यांच्या शाश्वत उपलब्धतेसाठी तसेच त्यांच्यावर अवलंबून आजीविकांच्या दृष्टीने वन उपजाच्या नियोजन पद्धतींचा वनवृक्षशास्त्राच्या दृष्टीने अभ्यास होणे गरजेचे आहे. मध्य भारतातील वन-आधारित समुदाय अनेक वर्ष तेंदू वृक्षाच्या पानांना (म्हणजे बिडी-पत्त्याला) निरनिराळ्या पद्धतीने संकलित करीत आहेत व त्याकरिता निरनिराळ्या पद्धतीने नियोजन करीत आहेत. झाडाची झुडपी वाढ करून, पाने हाता जवळ वाढवणे हा त्यातील मुख्य उद्देश आहे. यामध्ये झाडाच्या रोपांची मुळाशी छाटणी करणे (खुट/बेल कटाई) किंवा, जंगलातील पाचोळा पेटवणे, किंवा या दोन्ही पद्धती एकत्रित वापरणे ('छाटणी-व-आग') अशा पद्धतींचा समावेश आहे. अलीकडे काही लोक तेंदू संवर्धनासाठी झाडाची विना-नियोजन वाढ होऊ देतात (म्हणजे विना आग आणि विना खुट कटाईने). यातील कोणत्या पद्धतीने प्रती हेक्टरी सर्वात जास्त तेंदू पाने तयार होतात याचा अभ्यास आम्ही केला. यासाठी आम्ही उत्तर गडचिरोली, महाराष्ट्र येथील काही गावांच्या सामुहिक वन क्षेत्रात मार्च ते मे २०२० मध्ये वेगवेगळ्या नियोजन पद्धतीमध्ये होणाऱ्या तेंदूपत्ता उत्पन्नाचा पद्धतशीर अभ्यास केला. एकूण आम्हाला असे दिसले की, आग वापरण्यापेक्षा तेंदूच्या रोपांची मुळाशी केलेली छाटणी व 'छाटणी-व-आग' या पद्धती अधिक पानांचे उत्पन्न देतात. आम्ही पाहिले की स्थानिक जंगल प्रकार, त्याची दाटी, व तेंदू वृक्षाची निकटता या निकषांमुळे पानांच्या उत्पन्नात नियोजन पद्धतीपेक्षा जास्त परिणाम होत नाही. परंतु यातील कोणतीही पद्धत वापरताना व वन-आधारित उपजीविका सांभाळत, तसेच सामुहिक वन नियोजन करताना काही व्यावहारिक अडचणी आहेत. त्यांचावरही आम्ही या अभ्यासात विचार केला आहे.

Agro-Physiological Traits of Kaffir Lime in Response to Pruning and Nitrogen Fertilizer under Mild Shading.

Mild shading has been reported to increase leaf production in kaffir lime (Citrus hystrix) through the improvement of agro-physiological variables, such as growth, photosynthesis, and water-use efficiency; however, there is still a knowledge gap concerning its growth and yield after experiencing severe pruning in harvest season. Additionally, a specific nitrogen (N) recommendation for leaf-oriented kaffir lime is still unavailable due to its lesser popularity compared to fruit-oriented citrus. The present study determined the best pruning level and N dose based on agronomy and the physiology of kaffir lime under mild shading. Nine-month-old kaffir lime seedlings grafted to rangpur lime (C. limonia) were arranged in a split-plot design, i.e., N dose as a main plot and pruning as a subplot. Comparative analysis resulted in 20% higher growth and a 22% higher yield in the high-pruned plants by leaving 30 cm of main stem above the ground rather than short ones with a 10 cm main stem. Both correlation and regression analysis strongly highlighted the importance of N for leaf numbers. Plants treated with 0 and 10 g N plant-1 experienced severe leaf chlorosis due to N deficiency, while those treated with 20 and 40 g N plant-1 showed N sufficiency; thus, the efficient recommendation for kaffir lime leaf production is 20 g N plant-1.

Reconstructed life history metrics of the iconic seagrass Posidonia oceanica (L.) detect localized anthropogenic disturbance signatures.

Substantial losses of the seagrass Posidonia oceanica have initiated investigations into localized resilience declines related to anthropogenic disturbances. In this study, we determined reconstructed shoot age and interannual growth metrics can detect anthropogenic impact effects on P. oceanica production. Interannual rhizome vertical growth, leaf production, and demographics of shoots collected from sewage and trawling impacted areas were examined using mixed effects modeling. Detected impact effects were specific to the type of impact, manifesting as an older-skewed age distribution of sewage outfall shoots and reduced vertical growth and reduced leaf production of trawling site shoots. A stress event period was also detected for all shoots >5 years old, with trawling impacted shoots indicating little recovery. Reconstructed age and growth metrics are simple to measure, incorporate multiple years of in situ shoot development, and are advantageous for identification of declining P. oceanica resilience prior to catastrophic losses.

Herbivory and leaf expansion of Cyathea phalerata Mart (Cyatheaceae) in subtropical Atlantic Forest, southern Brazil / Herbivoria e expansão foliar de Cyathea phalerata Mart. (Cyatheaceae) em Floresta Atlântica subtropical no sul do Brasil

Herbivory is an interaction with great impact on plant communities since relationships between herbivores and plants are fundamental to the distribution and abundance of species over time and space. The aim of this study was to monitor the rate of leaf expansion in the tree fern Cyathea phalerata and evaluate the damage caused by herbivores to leaves of different ages and whether such damage is related to temperature and precipitation. The study was performed in a subtropical Atlantic Forest fragment located in the municipality of Caraá, in the northeast hillside of Rio Grande do Sul state, in southern Brazil. We monitored 24 mature individuals of C. phalerata with croziers in a population of approximately 50 plants. Leaf expansion rate, percentage of damaged leaves and leaf blade consumption rate by herbivory were calculated. Monthly means for temperature and accumulated rainfall were calculated from daily data. Croziers of C. phalerata were found to expand rapidly during the first and second months after emergence (3.98 cm day-¹; 2.91 cm day-¹, respectively). Damage caused by herbivory was observed in all of the monitored leaves, but none of the plants experienced complete defoliation. The highest percentage (57%) of damaged leaves was recorded at 60 days of monitoring, and also the highest monthly consumption rate of the blade (6.04%) occurred with young, newly-expanded leaves, while this rate remained between 1.50 and 2.21% for mature leaves. Rates of monthly leaf consumption and damaged leaves showed positive and strong relationship with each other and with temperature. The rapid leaf expansion observed for C. phalerata can be considered a phenological strategy to reduce damage to young leaves by shortening the developmental period and accelerating the increase of defenses in mature leaves.

A herbivoria é uma interação de grande impacto sobre as comunidades de plantas, uma vez que as relações entre herbívoros e plantas são fundamentais para a distribuição e abundância das espécies ao longo do tempo e do espaço. O objetivo deste estudo foi monitorar a taxa de expansão foliar da samambaia arborescente Cyathea phalerata e avaliar o dano causado por herbívoros a folhas de diferentes idades, assim como verificar se este dano está relacionado à temperatura e à precipitação. O estudo foi realizado em um fragmento de Floresta Atlântica subtropical localizado no município de Caraá, na encosta nordeste do estado do Rio Grande do Sul, no sul do Brasil. Nós monitoramos 24 indivíduos maduros de C. phalerata com báculos em uma população de aproximadamente 50 plantas. A taxa de expansão foliar, a porcentagem de folhas danificadas e a taxa de consumo da lâmina foliar por herbivoria foram calculados. Médias mensais de temperatura e precipitação acumulada foram calculadas a partir de dados diários. Báculos de C. phalerata expandiram rapidamente durante o primeiro e o segundo mês após emergência (3,98 cm dia-¹; 2,91 cm dia-¹, respectivamente). O dano causado por herbivoria foi observado em todas as folhas monitoradas, mas nenhuma das plantas sofreu desfolhação completa. A maior porcentagem (57%) de folhas danificadas foi registrada aos 60 dias de monitoramento, e também a maior taxa de consumo mensal (6,04%) ocorreu em folhas jovens, recém expandidas, enquanto esta taxa permaneceu entre 1,50 e 2,21% em folhas maduras. As taxas mensais de consumo da lâmina foliar e de folhas danificadas mostraram relação positiva e forte entre si e com a temperatura. A rápida expansão foliar observada em C. phalerata pode ser considerada uma estratégia fenológica para reduzir o dano a folhas jovens, abreviando o período de desenvolvimento e acelerando o aumento das defesas em folhas maduras.

Herbivory and leaf expansion of Cyathea phalerata Mart. (Cyatheaceae) in subtropical Atlantic Forest, southern Brazil

Abstract Herbivory is an interaction with great impact on plant communities since relationships between herbivores and plants are fundamental to the distribution and abundance of species over time and space. The aim of this study was to monitor the rate of leaf expansion in the tree fern Cyathea phalerata and evaluate the damage caused by herbivores to leaves of different ages and whether such damage is related to temperature and precipitation. The study was performed in a subtropical Atlantic Forest fragment located in the municipality of Caraá, in the northeast hillside of Rio Grande do Sul state, in southern Brazil. We monitored 24 mature individuals of C. phalerata with croziers in a population of approximately 50 plants. Leaf expansion rate, percentage of damaged leaves and leaf blade consumption rate by herbivory were calculated. Monthly means for temperature and accumulated rainfall were calculated from daily data. Croziers of C. phalerata were found to expand rapidly during the first and second months after emergence (3.98 cm day-1; 2.91 cm day-1, respectively). Damage caused by herbivory was observed in all of the monitored leaves, but none of the plants experienced complete defoliation. The highest percentage (57%) of damaged leaves was recorded at 60 days of monitoring, and also the highest monthly consumption rate of the blade (6.04%) occurred with young, newly-expanded leaves, while this rate remained between 1.50 and 2.21% for mature leaves. Rates of monthly leaf consumption and damaged leaves showed positive and strong relationship with each other and with temperature. The rapid leaf expansion observed for C. phalerata can be considered a phenological strategy to reduce damage to young leaves by shortening the developmental period and accelerating the increase of defenses in mature leaves.

Resumo A herbivoria é uma interação de grande impacto sobre as comunidades de plantas, uma vez que as relações entre herbívoros e plantas são fundamentais para a distribuição e abundância das espécies ao longo do tempo e do espaço. O objetivo deste estudo foi monitorar a taxa de expansão foliar da samambaia arborescente Cyathea phalerata e avaliar o dano causado por herbívoros a folhas de diferentes idades, assim como verificar se este dano está relacionado à temperatura e à precipitação. O estudo foi realizado em um fragmento de Floresta Atlântica subtropical localizado no município de Caraá, na encosta nordeste do estado do Rio Grande do Sul, no sul do Brasil. Nós monitoramos 24 indivíduos maduros de C. phalerata com báculos em uma população de aproximadamente 50 plantas. A taxa de expansão foliar, a porcentagem de folhas danificadas e a taxa de consumo da lâmina foliar por herbivoria foram calculados. Médias mensais de temperatura e precipitação acumulada foram calculadas a partir de dados diários. Báculos de C. phalerata expandiram rapidamente durante o primeiro e o segundo mês após emergência (3,98 cm dia-1; 2,91 cm dia-1, respectivamente). O dano causado por herbivoria foi observado em todas as folhas monitoradas, mas nenhuma das plantas sofreu desfolhação completa. A maior porcentagem (57%) de folhas danificadas foi registrada aos 60 dias de monitoramento, e também a maior taxa de consumo mensal (6,04%) ocorreu em folhas jovens, recém expandidas, enquanto esta taxa permaneceu entre 1,50 e 2,21% em folhas maduras. As taxas mensais de consumo da lâmina foliar e de folhas danificadas mostraram relação positiva e forte entre si e com a temperatura. A rápida expansão foliar observada em C. phalerata pode ser considerada uma estratégia fenológica para reduzir o dano a folhas jovens, abreviando o período de desenvolvimento e acelerando o aumento das defesas em folhas maduras.

Herbivory and leaf expansion of Cyathea phalerata Mart. (Cyatheaceae) in subtropical Atlantic Forest, southern Brazil / Herbivoria e expansão foliar de Cyathea phalerata Mart. (Cyatheaceae) em Floresta Atlântica subtropical no sul do Brasil

Abstract Herbivory is an interaction with great impact on plant communities since relationships between herbivores and plants are fundamental to the distribution and abundance of species over time and space. The aim of this study was to monitor the rate of leaf expansion in the tree fern Cyathea phalerata and evaluate the damage caused by herbivores to leaves of different ages and whether such damage is related to temperature and precipitation. The study was performed in a subtropical Atlantic Forest fragment located in the municipality of Caraá, in the northeast hillside of Rio Grande do Sul state, in southern Brazil. We monitored 24 mature individuals of C. phalerata with croziers in a population of approximately 50 plants. Leaf expansion rate, percentage of damaged leaves and leaf blade consumption rate by herbivory were calculated. Monthly means for temperature and accumulated rainfall were calculated from daily data. Croziers of C. phalerata were found to expand rapidly during the first and second months after emergence (3.98 cm day-1; 2.91 cm day-1, respectively). Damage caused by herbivory was observed in all of the monitored leaves, but none of the plants experienced complete defoliation. The highest percentage (57%) of damaged leaves was recorded at 60 days of monitoring, and also the highest monthly consumption rate of the blade (6.04%) occurred with young, newly-expanded leaves, while this rate remained between 1.50 and 2.21% for mature leaves. Rates of monthly leaf consumption and damaged leaves showed positive and strong relationship with each other and with temperature. The rapid leaf expansion observed for C. phalerata can be considered a phenological strategy to reduce damage to young leaves by shortening the developmental period and accelerating the increase of defenses in mature leaves.

Resumo A herbivoria é uma interação de grande impacto sobre as comunidades de plantas, uma vez que as relações entre herbívoros e plantas são fundamentais para a distribuição e abundância das espécies ao longo do tempo e do espaço. O objetivo deste estudo foi monitorar a taxa de expansão foliar da samambaia arborescente Cyathea phalerata e avaliar o dano causado por herbívoros a folhas de diferentes idades, assim como verificar se este dano está relacionado à temperatura e à precipitação. O estudo foi realizado em um fragmento de Floresta Atlântica subtropical localizado no município de Caraá, na encosta nordeste do estado do Rio Grande do Sul, no sul do Brasil. Nós monitoramos 24 indivíduos maduros de C. phalerata com báculos em uma população de aproximadamente 50 plantas. A taxa de expansão foliar, a porcentagem de folhas danificadas e a taxa de consumo da lâmina foliar por herbivoria foram calculados. Médias mensais de temperatura e precipitação acumulada foram calculadas a partir de dados diários. Báculos de C. phalerata expandiram rapidamente durante o primeiro e o segundo mês após emergência (3,98 cm dia-1; 2,91 cm dia-1, respectivamente). O dano causado por herbivoria foi observado em todas as folhas monitoradas, mas nenhuma das plantas sofreu desfolhação completa. A maior porcentagem (57%) de folhas danificadas foi registrada aos 60 dias de monitoramento, e também a maior taxa de consumo mensal (6,04%) ocorreu em folhas jovens, recém expandidas, enquanto esta taxa permaneceu entre 1,50 e 2,21% em folhas maduras. As taxas mensais de consumo da lâmina foliar e de folhas danificadas mostraram relação positiva e forte entre si e com a temperatura. A rápida expansão foliar observada em C. phalerata pode ser considerada uma estratégia fenológica para reduzir o dano a folhas jovens, abreviando o período de desenvolvimento e acelerando o aumento das defesas em folhas maduras.

Daily Temperature Effect on Seedling Growth Dynamic of Three Invasive Alien Species.

A greater relative growth rate (RGR) is positively correlated with a species' ability to deploy a larger leaf area either due to a greater total number of leaves (LN) in the canopy or due to an average size of individual leaves (LA). This study aimed to analyze and compare, (1) the temporal (i.e., daily) RGR, leaf production rate (LPR), and leaf area production rate (LAPR) changes during the early growth stages of three among the most invasive species in the world, namely, Ailanthus altissima, Phytolacca americana, and Robinia pseudoacacia. (2) the interspecific differences in the relationship between RGR, LPR, LAPR, and mean daily air temperature. Our results show that growth dynamics as a function of temperature differ between invasive alien species (IAS). While these differences are partly explained by differences due to the growth form of the investigated species, the three IAS have a different behavior to adjust RGR, LPR, and LAPR with air temperature changes even within the same growth form, and in agreement with species habitat requirements in their native range. In conclusion, the results help disentangle the relative role of RGR, LPR, and LAPR in defining non-native species growth responses to mean daily air temperature also in relation to a species' growth form.

Phenology of the endangered palm Ceroxylon quindiuense (Arecaceae) along an altitudinal gradient in Colombia / Fenología de la palma en peligro Ceroxylon quindiuense (Arecaceae) a lo largo de un gradiente altitudinal en Colombia

Abstract Introduction: Understanding the phenology of plant populations is vital for their conservation and management. We studied the vegetative and reproductive phenology of the endangered palm Ceroxylon quindiuense along an altitudinal gradient in the Central Cordillera of Colombia. Objective: We describe the leaf production rate, and flowering and fruiting cycles, and calculate food offer for the fauna, as a tool for the proper management of the palm. Methods: At each sampling site (2 400, 2 600, 2 800, 3 000 m.a.s.l.), we marked 40 adult individuals (20 pistillate, 20 staminate), which we followed bimonthly for 24 months. We studied leaf production by counting fallen leaves. We followed flower and fruit production through observations with binoculars and photographs. Results: Each adult individual produced, on average, one leaf every 69 days. Although isolated individuals flowered throughout the year, most palms flowered synchronously at each elevation in October 2016-August 2017 and in August 2018-February 2019 and had ripe fruits 7-13 months later. Flowering started at 2 600 m, followed by 2 800 and 3 000 m. Palms at 2 400 m, the lower limit of the palm stands in the area, showed a singular behavior, with scarce flower and fruit production, some individuals that changed sex, and a higher proportion of pistillate palms. Each palm produced 1-11 (x̄ = 5.3, SD = 2.2) inflorescences and 1-10 (x̄ = 5.3, SD = 2.2) infructescences. The average number of fruits per infructescence was 4 465 (SD = 1 488). With an estimated population of adult palms between 256 000 and 600 000 and an overall ratio of pistillate: staminate individuals 1:1 or 1:2, total fruit production in the area during each fruiting period is estimated as 2.0-7.1 billion fruits. Conclusions: The huge number of flowers and fruits and their gradual availability along the altitudinal gradient have a major impact on the spatial and temporal distribution of food offer for fauna associated with the palm.

Resumen Introducción: Comprender la fenología de las poblaciones de plantas es vital para su conservación y manejo. Estudiamos la fenología vegetativa y reproductiva de la palma amenazada Ceroxylon quindiuense a lo largo de un gradiente altitudinal en la Cordillera Central de Colombia. Objetivo: Describimos la tasa de producción de hojas, los ciclos de floración y fructificación, y calculamos la oferta alimentaria para la fauna, como una herramienta para el adecuado manejo de la palma. Métodos: En cada sitio de muestreo (2 400, 2 600, 2 800, 3 000 m.s.n.m.), marcamos 40 individuos adultos (20 pistilados, 20 estaminados), que seguimos bimestralmente durante 24 meses. Estudiamos la producción de hojas contando las caídas al suelo. Seguimos la producción de flores y frutos a través de observaciones con binoculares y fotografías. Resultados: Cada individuo adulto produjo, en promedio, una hoja cada 69 días. Aunque los individuos aislados florecieron durante todo el año, la mayoría de las palmas florecieron sincrónicamente en cada elevación entre octubre 2016 y agosto 2017 y de agosto 2018 a febrero 2019 y tuvieron frutos maduros entre 7-13 meses después. La floración comenzó a los 2 600 m, seguida de los 2 800 y los 3 000 m. Las palmas a 2 400 m, límite inferior de los palmares de la zona, mostraron un comportamiento singular, con escasa producción de flores y frutos, varios individuos que cambiaron de sexo y una mayor proporción de palmas pistiladas. Cada palma produjo 1-11 (x̄ = 5.3, SD = 2.2) inflorescencias y 1-10 (x̄ = 5.3, SD = 2.2) infrutescencias. El número promedio de frutos por infrutescencia fue de 4 465. Con una población estimada de palmas adultas entre 256 000 y 600 000 y una proporción total de individuos pistilados: estaminados 1:1 o 1:2, la producción total de frutos en el área durante cada período de fructificación se estima en 2.0-7.1 mil millones de frutos. Conclusiones: La gran cantidad de flores y frutos y su progresiva disponibilidad a lo largo del gradiente tienen un impacto importante en la distribución espacial y temporal de la oferta de alimento para la fauna asociada a la palma.

Shading Affects Yield, Elemental Composition and Antioxidants of Perennial Wall Rocket Crops Grown from Spring to Summer in Southern Italy.

Shading nets have been increasingly drawing research interest, as they allow us to improve the environmental conditions for greenhouse-grown crops. The effects of two shading nets (50% and 79% shading degree), plus an unshaded control, on yield, mineral composition and antioxidants of perennial wall rocket (Diplotaxis tenuifolia L.-D.C.) grown under tunnels in southern Italy were determined. The shading application resulted in a yield decrease, compared to the unshaded control, except for the highest production under 50% shading in July. The highest yield was recorded in the April-May and May-June and the lowest in July. Similar trends were recorded for plant dry weight, leaf number per rosette and mean weight, but the latter showed the highest value under 79% light extinction in July. The rocket leaves were brighter in the summer cycles than in the spring ones. Leaf nitrate was highest in spring and under 79% shading. Potassium, phosphorus, calcium and magnesium showed the highest values in spring and in the unshaded control. The lipophilic antioxidant activity showed the highest values under the 79% shading net in the spring cropping seasons, whereas in July it did not significantly differ from 50% light extinction. The hydrophilic antioxidant activity always attained the highest values in the unshaded control. The unshaded leaves had the highest total phenol accumulation when grown in April-May and the lowest in July. The total ascorbic acid content was always highest in the unshaded control leaves compared to the shading treatments. Fifty percent crop shading is, therefore, an effective sustainable tool for increasing the yield of perennial wall rocket leaves in July, when the light intensity under the plastic tunnel exceeds the plant requirements, also resulting in a mineral composition that is not significantly different from that of the unshaded crops.

Leaf Production and Expansion: A Generalized Response to Drought Stresses from Cells to Whole Leaf Biomass-A Case Study in the Tomato Compound Leaf.

It is clearly established that there is not a unique response to soil water deficit but that there are as many responses as soil water deficit characteristics: Drought intensity, drought duration, and drought position during plant cycle. For a same soil water deficit, responses can also differ on plant genotype within a same species. In spite of this variability, at least for leaf production and expansion processes, robust tendencies can be extracted from the literature when similar watering regimes are compared. Here, we present response curves and multi-scale dynamics analyses established on tomato plants exposed to different soil water deficit treatments. Results reinforce the trends already observed for other species: Reduction in plant leaf biomass under water stress was due to reduction in individual leaf biomass and areas whereas leaf production and specific leaf area were not affected. The dynamics of leaf expansion was modified both at the leaf and cell scales. Cell division and expansion were reduced by drought treatments as well as the endoreduplication process. Combining response curves analyses together with dynamic analyses of tomato compound leaf growth at different scales not only corroborate results on simple leaf responses to drought but also increases our knowledge on the cellular mechanisms behind leaf growth plasticity.

Pervasive interactions between foliar microbes and soil nutrients mediate leaf production and herbivore damage in a tropical forest.

Producing and retaining leaves underlie the performance and survivorship of seedlings in deeply shaded tropical forests. These habitats are characterized by conditions ideal for foliar bacteria, which can be potent plant pathogens. Leaf production, retention and susceptibility to enemies may ultimately depend upon interactions among soil nutrients and foliar microbes, yet this has never been tested. We experimentally evaluated the degree that foliar bacteria and soil resource supply mediate leaf dynamics for five common tree species (five different families) in a Panamanian forest. We reduced foliar bacteria with antibiotics for 29 months and measured leaf production, retention and damage for seedlings nested within a replicated 15-yr factorial nutrient enrichment experiment (nitrogen, N; phosphorus, P; potassium, K). Our results demonstrate that when we applied antibiotics, soil nutrients - particularly N - always regulated seedling leaf production (and to a lesser extent herbivore damage) for all five tree species. In addition, it was common for two macronutrients together to negate or completely reverse the impact of applying either one alone. Our findings of frequent plant-microbe-nutrient interactions are novel and suggest that these interactions may reinforce plant species-environment associations, thereby creating a fairly cryptic and fine-scale dimension of niche differentiation for coexisting tree species.

The stands of Copernicia tectorum (Arecaceae) in the Caribbean lowlands of Colombia: a managed pioneer palm facing river dynamics / Poblaciones de Copernicia tectorum (Arecaceae) en las tierras bajas del Caribe de Colombia: una palma pionera expuesta a la dinámica de un río

Copernicia tectorum is a palm that grows in large populations on seasonally flooded savannas in the Caribbean region of Colombia, where its stems and expanded leaves are used in construction, and its unexpanded leaves are used to make handicrafts. We studied abundance and population structure in 34 plots of 20×10m (0.68 ha) of three localities (Plato, Córdoba and Magangué) at the Mompox Depression, an inner delta formed by the confluence of four large rivers. We recorded growth and mortality of 164 palms of different size classes over 13 months, and additionally we estimated seedling and juvenile mortality in two 10x10m plots within the same sites. Data analysis using Kolgomorov-Smirnov (KS), Kruskal-Wallis and Mann-Whitney tests were made on Statgraphics Plus and SPSS. We related the structure and dynamics of the palm stands to flood intensity. Copernicia tectorum has the fastest leaf production rate recorded for any palm (19-23 leaves/year in subadults and adults), and a short life span of ca. 46 years. The abundance, density and high leaf production rate of this palm offer a great potential for the sustainable use of its unexpanded leaves (especially at Plato, where there are ca. 480ha of palm stands with 300-1 000 individuals/ha), as leaf harvest from subadult and adult individuals does not appear to affect population structure. The palm is a pioneer of the flood plain, and the palm stands at particular sites appear to wax and wane following sedimentation dynamics, in which the species plays in important role. Current population structure and the scarce recruitment of juveniles at the study site suggest that the population is waning in that site. Management actions should be taken to reestablish natural river dynamics at the lagoon complex where the palm grows. Appropriate management of palm stands may contribute to minimize any negative effects of river dynamics.

La palma Copernicia tectorum forma grandes poblaciones en sabanas estacionalmente inundables de la región Caribe de Colombia, donde sus tallos y hojas se utilizan en construcción y sus cogollos para la elaboración de artesanías. Estudiamos la abundancia y la estructura poblacional en 34 parcelas de 20×10m (0.68 ha), en tres localidades (Plato, Córdoba y Magangué) en la Depresión Momposina, un delta interior formado por la confluencia de cuatro grandes ríos. Registramos el crecimiento y la mortalidad de 164 palmas de diferentes clases de tamaño durante 13 meses y estimamos además la mortalidad en plántulas y juveniles en dos parcelas de 10x10m en los mismos sitios. Los análisis se realizaron con las pruebas de Kolgomorov-Smirnov (KS), Kruskal-Wallis y Mann-Whitney en Statgraphics Plus and SPSS. Relacionamos la estructura y dinámica de los palmares con la intensidad de la inundación. Copernicia tectorum tiene la tasa de producción de hojas más rápida registrada hasta ahora para cualquier palma (19-23 hojas por año en subadultos y adultos) y una vida corta de ca. 46 años. La abundancia, densidad y alta tasa de producción de hojas de la palma ofrecen un gran potencial para el uso sostenible de sus cogollos (especialmente en Plato, donde hay unas 480 ha de palmares con 300-1 000 individuos/ha), ya que la cosecha de hojas de palmas adultas y subadultas, parece no afectar la estructura de la población. La palma es una pionera de las llanuras inundables, y los palmares en un sitio particular crecen y se reducen siguiendo la dinámica de sedimentación, en la cual la especie juega un papel importante. La estructura actual de las poblaciones y el escaso reclutamiento en las clases juveniles en el sitio de estudio sugieren que allí la población se está reduciendo. Se deben emprender acciones de manejo que apunten a restablecer la dinámica fluvial natural en los complejos cenagosos en los que crece la palma. A su vez, el manejo apropiado de los palmares ...

Dinámica del daño foliar en plántulas de Drimys granadensis (Winteraceae) y Clusia multiflora (Clusiaceae) en el bosque altoandino de la Cordillera Oriental colombiana

Leaf damage dynamics of Drimys granadensis (Winteraceae) and Clusia multiflora (Clusiaceae) seedlings in the High-Andean Forest. Because of their slow growth, shade-tolerant species remain exposed to foliar damage long before reproductive age. Foliar damage can be controlled through synchronous leaf production and specialized phytochemical strategies. in this study, the dynamics of foliar damage in different cohorts of seedlings were evaluated to determine if the High-Andean species, Clusia multiflora (Clusiaceae) and Drimys granadensis (Winteraceae) appeal to the synchronous leaf production for controlling the herbivory and pathogenical damage, and to establish the possible relations between the healthy state, growth and mortality of seedlings. Since a recently-emerged seedling could not supply the physiological costs of specialized strategies, we expected the highest synchronous leaf production in the youngest individuals, and differences between cohorts in foliar damage. Four variables were measured to evaluate the health state along time, in three cohorts of seedlings: Proportion of predated leaves (Pp), proportion of healthy leaves (Ps), proportion of leaves with symptoms of disease or punctual damage (Pe) and growing (% increment of height). Both species showed significant differences between periods in the proportion of healthy leaves, but there was not an effect of time-cohort interaction, therefore synchronic production of leaves was not a strategy more used for any particular cohort. Foliar damage oscillated along time, fact that can be explained by the pulses of leaf production. However, this strategy had little efficiency to control the pathogen attack. in general, the unified behavior of all variables was affected by cohort, time, species an all the different interactions. Association between growing and foliar damage were conditioned by climate. The highest mortality ocurred during the dry season, and one fourth of the D. granadensis deaths were caused by the joint action of herbivory and drought. Results suggest that in spite of the synchronous leaf production in all cohorts, this strategy quickly loses the efficiency for controlling foliar damage, because the means of Ps were below of 0.25 at the end of the monitoring period. The differences between species in the dynamics of health state should explain partially their coexistence in the High-Andean forest. Rev. Biol. Trop. 56 (3): 1087-1100. Epub 2008 September 30.

Además de las estrategias fitoquímicas especializadas, las plantas pueden usar la producción sincrónica de hojas como un método de saciado de patógenos y herbívoros. Con el fin de determinar si las especies del bosque altoandino colombiano Clusia multiflora (Clusiaceae) y Drimys granadensis (Winteraceae) recurren a la producción sincrónica de hojas para controlar los efectos de la herbivoría y el ataque microbiano, y establecer que relación existe entre el estado de salud, el crecimiento y la mortalidad de plántulas, se evaluó la dinámica del daño foliar sobre diferentes cohortes. Dado que una plántula tolerante a la sombra recientemente emergida no puede suplir los costos fisiológicos de una estrategia especializada, se esperaba una alta sincronía en la producción de hojas en las plántulas más jóvenes, y diferencias en el daño foliar entre cohortes. Se midieron cuatro variables que evaluaban el estado de salud a lo largo del tiempo, en tres cohortes de plántulas: Proporción de hojas predadas, proporción de hojas sanas, proporción de hojas enfermas o con daño puntual y crecimiento. Ambas especies mostraron diferencias significativas entre épocas, en la proporción de hojas sanas; pero no hubo un efecto de la interacción tiempo-cohorte, por lo tanto la producción sincrónica de hojas no fue una estrategia más usada por alguna cohorte en particular. El daño foliar osciló a través del tiempo, lo cual puede ser explicado por los pulsos en la producción de hojas. Sin embargo, ésta estrategia tuvo poca eficiencia para controlar el ataque por patógenos. En general, el comportamiento unificado de todas las variables fue afectado por la cohorte, el tiempo, la especie y todas las diferentes interacciones. La relación entre crecimiento y daño foliar fue condicionado por el clima. La mayor mortalidad se dio durante la estación seca, y un cuarto de las muertes en D. granadensis fueron causadas por la acción conjunta de herbivoría y sequía. Los resultados sugieren que a pesar de la producción sincrónica de hojas en todas las cohortes, fue poca la eficiencia para controlar el daño foliar, ya que las medias de Ps estuvieron por debajo de 0.25 al final del seguimiento. Las diferencias en la dinámica del estado de salud entre especies podrían explicar parcialmente la coexistencia en el bosque altoandino.

Severity of Curvularia Stem Blight Disease of Cassava in West Africa.

In diagnostic surveys, Curvularia stem blight affected 9, 13, and 38% of cassava fields, respectively, in Benin, Ghana, and Nigeria. Disease incidence (number of plants with visible symptoms per total sampled) ranged between 0 and 80%, and severity (number of lesions) between 2 and 25 lesions per stem. In greenhouse studies, the fungus inhibited shoot growth depending on the degree of bud colonization, such that when buds were completely colonized, they failed to sprout. Partially colonized buds sprouted, but depending on genotype, overall growth was reduced 20 to 50% compared with healthy stems. Shoot growth for all artificially inoculated cultivars was consistently lower than for the respective noninoculated plants, and they suffered up to 50% leaf abscission. In two field localities, shoot sprouting for cultivars TMS 30572 and Odongbo was reduced 4 to 18% and 26 to 58% compared with noninoculated stems.