1,727,477 research outputs found
Topical gradients in plant ecology
No full textPlant ecology spans multiple levels of biological organization and spatio-temporal scales, and over four dozen plant ecology textbooks have been published since Warming's (1895) 'Oecology of Plants.' With increasing emphasis on specialization, students and teachers can feel paralyzed by the vast literature, and as such may lack an adequate appreciation of the history of the field. The objective of this study was to derive a comprehensive set of topics that are covered in plant ecology textbooks, and to ask (1) what are the most important topical gradients among textbooks, and (2) has the emphasis of topics changed over time? The NMS ordination determined that the first gradient represented a clear contrast in emphasis on physiological ecology versus community ecology. The second gradient represented a contrast in emphasis on abiotic environmental factors versus biotic factors. Negative interactions, growth, demography, gas exchange, mineral nutrition, stress, diversity, disturbance, herbivory, paleoecology, ecosystem ecology, pollution, and global change have increased in emphasis over time. The increasing reliance on data and the number of authors per textbook illustrates how the discipline has matured into a rigorous quantitative science that requires a diversity of specializations. These results can be used to inform the development of curricula within a single course or across several years of study, and to assist the development of new and revised textbooks. Plant ecologists need to be familiar with this core set of topics in addition to becoming an expert in a few of them
Temperature and substrate availability regulate soil respiration in the tropical mountain rainforests, Hainan Island, China
No full textTropical forest plays a key role in global C cycle; however, there are few studies on the C budget in the tropical rainforests in Asia. This study aims to (i) reveal the seasonal patterns of total soil respiration (R-T), litter respiration (R-L) and soil respiration without surface organic litter (R-NL) in the primary and secondary Asian tropical mountain rainforests and (ii) quantify the effects of soil temperature, soil moisture and substrate availability on soil respiration. The seasonal dynamics of soil CO2 efflux was measured by an automatic chamber system (Li-8100), within the primary and secondary tropical mountain rainforests located at the Jianfengling National Reserve in Hainan Island, China. The litter removal treatment was used to assess the contribution of litter to belowground CO2 production. The annual R-T was higher in the primary forest (16.730.87 Mg C ha(1)) than in the secondary forest (15.100.26 Mg C ha(1)). The rates of R-T, R-NL and R-L were all significantly higher in the hot and wet season (MayOctober) than those in the cool and dry season (NovemberApril). Soil temperature at 5cm depth could explain 5561% of the seasonal variation in R-T, and the temperature sensitivity index (Q(10)) ranked by R-L (Q(10) 3.39) > R-T (2.17) > R-NL (1.76) in the primary forest and by R-L (4.31) > R-T (1.86) > R-NL (1.58) in the secondary forest. The contribution of R-L to R-T was 2223%, while litter input and R-T had 1 month time lag. In addition, the seasonal variation of R-T was mainly determined by soil temperature and substrate availability. Our findings suggested that global warming and increased substrate availability are likely to cause considerable losses of soil C in the tropical forests.Plant SciencesEcologySCI(E)3ARTICLE5325-334
Variations of root and heterotrophic respiration along environmental gradients in Chinas forests
No full textRoot and heterotrophic respiration may respond differently to environmental variability, but little evidence is available from large-scale observations. Here we aimed to examine variations of root and heterotrophic respiration across broad geographic, climatic, soil and biotic gradients. We conducted a synthesis of 59 field measurements on root and heterotrophic respiration across Chinas forests. Root and heterotrophic respiration varied differently with forest types, of which evergreen broadleaf forest was significantly different from those in other forest types on heterotrophic respiration but without statistically significant differences on root respiration. The results also indicated that root and heterotrophic respiration exhibited similar trends along gradients of precipitation, soil organic carbon and satellite-indicated vegetation growth. However, they exhibited different relationships with temperature: root respiration exhibited bimodal patterns along the temperature gradient, while heterotrophic respiration increased monotonically with temperature. Moreover, they showed different relationships with MOD17 GPP, with increasing trend observed for root respiration whereas insignificant change for heterotrophic respiration. In addition, root and heterotrophic respiration exhibited different changes along the age sequence, with insignificant change for root respiration and decreasing trend for heterotrophic respiration. Overall, these results suggest that root and heterotrophic respiration may respond differently to environmental variability. Our findings could advance our understanding on the different environmental controls of root and heterotrophic respiration and also improve our ability to predict soil CO2 flux under a changing environment.Plant SciencesEcologySCI(E)6ARTICLE5358-367
Tuber size variation and organ preformation constrain growth responses of a spring geophyte
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33119.pdf (Publisher’s version ) (Open Access
Herstel van schrale hellinggraslanden in Zuid-Limburg
No full textSchrale hellinggraslanden in Zuid-Limburg zijn van oudsher soortenrijk, maar zijn in de loop van de twintigste eeuw in kwaliteit,omvangen aantal sterk afgenomen. Herstelbeheer heeft voor de kal kgraslandflora weliswaar tot verbetering geleid, maar herstel van de hele gradiënt (van plateau tot dal) is niet bereikt. Ook zijn enkele kenmerkende faunagroepen sterk achteru itgegaa n, terwijl de huidige status van veel anderefaunagroepen in de hellingschraallanden onbekend is. Om te komen tot verder herstel van de hellingschraallanden in ons land is in 2004 nieuw onderzoek gestart naar de oorzaken van de achteruitgang en de mogelijkheden voor herstel van bodem, vegetatie en fauna. In deze bijdrage wordt nader ingegaan op de specifieke onderzoeksvragen en de geïntegreerde aanpak die wordt gehanteerd
Forest regeneration and restoration in Vietnam
No full textIt is generally thought that asymmetric competition for light and asymmetric growth, determines the course of succession in a regenerating secondary tropical forest, but it is hardly ever quantified. In this study a shrub and three woody tree species were monitored in time during the first five years of succession. Light competition and light-use were related to the success of species. It appeared that in a slow growing vegetation the importance of asymmetric competition for light and growth can be much less than often assumed. The species composition that was present from the very early beginning of succession remained for at least the first five years. Nitrogen-use efficiency may partly determine a plant’s success during forest regeneration. Whole canopy nitrogen-use efficiency and its underlying traits were compared among pioneer species over the first five years of succession. Nitrogen-use efficiency was largely determined by leaf life span and resorption and differed twofold among species. It was however not related to growth rates and only partly to species height. Nitrogen-use efficiency was slightly different within a species between successional stands that differed in height, leaf area index and resource availability, but an increase in competitive pressure did not result in major changes in the use of nitrogen. Forest regeneration is often slow or stagnates due to the excessive growth of non-woody plants and shrubs. One often used method to accelerate succession, called liberation, is opening up the vegetation canopy around young target trees which increases their growth. A 3D-model is used which enables us to examine how stature, crown structure and physiological traits of target trees and characteristics of the surrounding vegetation together determine the growth of trees. The model was applied to a liberation experiment that was conducted on pioneer species in a young secondary forest. Species responded differently to the treatment depending on their height, crown structure and their light demands. The responses were also dependent on the height and density of the vegetation and the gap radius from which it was removed. Another method to enhance regeneration is by planting tree species in the existing vegetation. Lines are cut and overstory thinning is applied to increase light levels. The line width and the degree of overstory thinning affect growth of target species differently depending on the characteristics of the surrounding vegetation and the light demands of the target trees themselves. The same model approach was used to test for the effects of line width, the degree of overstory thinning, planting trees in different successional stands of the same forest and planting trees in a forest stand with different light levels than the stand in which they were originally grown. It was shown that the optimal stand for each species, the optimal line width in a stand and the optimal degree of overstory thinning, can be predicted. With the model approach presented here it is possible to simulate different management activities aimed at improving forest regeneration and it has therefore a large potential in forest restoration ecology
Plant ecology
No full text"Plant Ecology provides a unique and up-to-date treatment of all aspects of the field, making it ideally suitable as a textbook and reference work for students, researchers and practitioners." "More than 500 high-quality images and drawings, mostly in colour, aid the reader in visualizing and understanding numerous key topics. Its clear structure and straightforward style make it user friendly and particularly accessible for students. The integrity and authoritativeness of the information is guaranteed by an experienced author team." "Whilst Plant Ecology is primarily aimed at graduate students of biology, post-graduate students and researchers in botany, geosciences and landscape ecology will also find this text invaluable as a reference work. In fact, everybody whose study or work touches on agriculture, forestry, land use, and landscape management will find this text a rich learning experience."--BOOK JACKET
Plastic responses in the competition for light among genotypes of a stoloniferous species
No full textThe ability to adjust the phenotype (e.g. plasticity) is thought to be beneficial for the performance of a plant, because it prevents overinvestment in support structures when plant density is low, and allows a plant to position its leaves high in the canopy when density is high. However, as the plastic responses differ within species, exclusion of less responsive genotypes from dense vegetation is likely to occur. A 5 year old competition experiment between 10 genotypes of the stoloniferous plant Potentilla reptans was used to study the consequences of the genotypic differences in plasticity, and the interplay between these genotypes, in order to gain more insights in the mechanisms behind the competition for light Within the competition experiment, leaves that were positioned higher in the canopy had higher light interception and higher photosynthetic rates per unit invested biomass than lower places leaves. Placing laminas at the top of the canopy is thus of great importance to the performance of a genotype. Using artificially created light gradients, it was also shown that the speed of height increase determines which genotypes can place their leaves at the top. Height increase of the canopy differed between mono-genotypic stands, and thus depends on the genotypes that form the canopy. A canopy model of the competition experiment showed that the dominant genotype had rather shade tolerant photosynthetic characteristics, which allowed it to have positive carbon gain at the bottom of the vegetation. Therefore, low leaf turnover may have contributed to the abundance of this genotype. Coexistence could than occur because other genotypes have a higher carbon gain in the top layers of the canopy. A game theoretical analysis of the canopy model showed that for all genotypes the total lamina area that would maximize the photosynthetic rate of the genotype itself was higher than total the lamina area that would maximize the photosynthetic rate of the vegetation as whole. Selection would thus favor the former strategy, leading to lower biomass production of the whole canopy. Finally, the analyses indicate that a decrease of the total lamina area of the dominant genotypes would increase its own photosynthetic rate, but that it would increase the performance of other genotypes more. Yet although a mutation in the lamina area of the dominant genotype would not increase its performance, the vegetation is not evolutionarily stable, as a mutant in the lamina area of the other genotypes would lead to better performance of these mutants. Overall the results suggest that the performance of an individual is not only determined by its own characteristics, but also by that of its competitors. In addition to the ability to reach the top of canopy, relatively shade tolerant characteristics may be selected for if plant density is high. The findings also demonstrate that is important to know at what level of organization selection operates. The understanding of competitive exclusion would greatly benefit if plastic response were studied in relation to photosynthetic traits, and to temporal changes that occur during the growing season
Concepts in Alpine Plant Ecology
No full textThe alpine life zone is perhaps the only biome that occurs globally where mountains are high enough. At latitudinally varying elevation, the alpine belt hosts small stature plants that vary greatly in morphology, anatomy and physiology. In this contribution, I summarize a number of principles that govern life in what is often considered a cold and hostile environment. The 12 conceptual frameworks depicted include the key role of aerodynamic decoupling from free atmospheric climatic conditions, the problematic concepts of limitation and stress in an evolutionary context, and the role of developmental flexibility and functional diversity. With its topography driven habitat diversity, alpine plant diversity is buffered against environmental change, and the multitude of microclimatic gradients offers ‘experiments by nature’, the power of which awaits multidisciplinary exploration
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