The Experts below are selected from a list of 8709 Experts worldwide ranked by ideXlab platform
Johannes M H Knops - One of the best experts on this subject based on the ideXlab platform.
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effect of loss of plant functional group and simulated nitrogen deposition on subalpine ecosystem properties on the tibetan plateau
Science of The Total Environment, 2018Co-Authors: Rulan Zhang, Shuangshuang Liu, Huakun Zhou, Johannes M H KnopsAbstract:Biodiversity loss impacts on ecosystem functioning can vary greatly among ecosystems types and different ecosystem processes can respond differently. Here we conducted a plant functional group removal experiment with and without nitrogen (N) addition (5gNm-2year-1) to examine the effects of plant functional group types presence, nitrogen deposition and their interaction effects on plant diversity, aboveground biomass, soil nutrients, soil microbial biomass and soil enzyme activity. After 4years, the removal of dominant grass did increase subordinates, Forb richness, and decreased total aboveground biomass significantly. However, the removal of Forb resulted in a rapid decline in species richness, which did not change strongly the aboveground biomass, regardless of N addition. This pattern suggests that the dominant grass can compensate for the loss of Forb removal with respect to production, but cannot compensate with respect to species loss. Forb cannot compensate for grass removal with respect to production, but can compensate with respect to species loss. Nitrogen addition only has a small effect on species richness, and also not enhances aboveground biomass. In addition, the majority of soil properties did not respond to either plant functional group removal, or N addition. Only soil CO2 efflux and soil NO3--N content significantly changed with plant functional group removal. Soil respiration rate was positively correlated with both plant species richness (R2=0.97) and aboveground biomass (R2=0.64). Our results show that the short-term losses of plant functional group have significant effects on plant diversity and productivity, and only minor impact on soil properties.
Mark D Bertness - One of the best experts on this subject based on the ideXlab platform.
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facilitative and competitive interaction components among new england salt marsh plants
PeerJ, 2017Co-Authors: John F Bruno, Nancy C Emery, Tatyana A Rand, Mark D BertnessAbstract:: Intra- and interspecific interactions can be broken down into facilitative and competitive components. The net interaction between two organisms is simply the sum of these counteracting elements. Disentangling the positive and negative components of species interactions is a critical step in advancing our understanding of how the interaction between organisms shift along physical and biotic gradients. We performed a manipulative field experiment to quantify the positive and negative components of the interactions between a perennial Forb, Aster tenuifolius, and three dominant, matrix-forming grasses and rushes in a New England salt marsh. Specifically, we asked whether positive and negative interaction components: (1) are unique or redundant across three matrix-forming species (two grasses; Distichlis spicata and Spartina patens, and one rush; Juncus gerardi), and (2) change across Aster life stages (seedling, juvenile, and adult). For adult Aster the strength of the facilitative component of the matrix-Forb interaction was stronger than the competitive component for two of the three matrix species, leading to net positive interactions. There was no statistically significant variation among matrix species in their net or component effects. We found little difference in the effects of J. gerardi on Aster at later life-history stages; interaction component strengths did not differ between juveniles and adults. However, mortality of seedlings in neighbor removal plots was 100%, indicating a particularly strong and critical facilitative effect of matrix species on this Forb during the earliest life stages. Overall, our results indicate that matrix forming grasses and rushes have important, yet largely redundant, positive net effects on Aster performance across its life cycle. Studies that untangle various components of interactions and their contingencies are critical to both expanding our basic understanding of community organization, and predicting how natural communities and their component parts will respond to environmental change.
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structure and organization of a northern new england salt marsh plant community
Journal of Ecology, 2004Co-Authors: Patrick J Ewanchuk, Mark D BertnessAbstract:Summary 1 Northern New England marshes are characterized by mid-elevation areas of sparse vegetation, but high species diversity, which are not found in the well-studied marshes further south. These Forb pannes occur in habitats that are more waterlogged and anoxic than adjacent clonal turf-dominated areas. 2 When the clonal turfs were transplanted into Forb pannes, they showed reduced growth with and without neighbours present, suggesting that they are physically limited from invading the Forb pannes. Conversely, when Forb panne species were transplanted into surrounding turf areas, they flourished when neighbours were removed, but were suppressed when neighbours were present, suggesting that interspecific plant competition restricts the Forbs to panne habitats. 3 Recovery of disturbance-generated bare patches was extremely slow, taking twice as long as in southern New England marshes. Secondary succession in northern New England marshes was driven by competitive interactions rather than by facilitative processes typical in southern New England marshes. 4 Differences in the structure and dynamics between northern and southern New England marsh systems may be due to differences in climate and human impacts. Waterlogged pannes are probably more common in northern marshes because they are generally larger and less ditched and drained. Reduced solar radiation and summer heating in northern New England reduces the potential for high soil salinities seen in southern marshes. This lack of the need for amelioration by neighbours probably explains the absence of facilitation.
Hung-wen Liu - One of the best experts on this subject based on the ideXlab platform.
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Identification and Characterization of Enzymes Catalyzing Pyrazolopyrimidine Formation in the Biosynthesis of Formycin A.
Organic letters, 2017Co-Authors: Shao-an Wang, Yasushi Ogasawara, Mark W. Ruszczycky, Hung-wen LiuAbstract:Genome scanning of Streptomyces kaniharaensis, the producer of formycin A, reveals two sets of purA, purB, purC, and purH genes. The Pur enzymes catalyze pyrimidine assembly of purine nucleobases. To test whether enzymes encoded by the second set of pur genes catalyze analogous transformations in formycin biosynthesis, formycin B 5′-phosphate was synthesized and shown to be converted by ForA and Forb to formycin A 5′-phosphate. These results support that For enzymes are responsible for formycin formation.
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Identification and Characterization of Enzymes Catalyzing Pyrazolopyrimidine Formation in the Biosynthesis of Formycin A
2017Co-Authors: Shao-an Wang, Yasushi Ogasawara, Mark W. Ruszczycky, Hung-wen LiuAbstract:Genome scanning of Streptomyces kaniharaensis, the producer of formycin A, reveals two sets of purA, purB, purC, and purH genes. The Pur enzymes catalyze pyrimidine assembly of purine nucleobases. To test whether enzymes encoded by the second set of pur genes catalyze analogous transformations in formycin biosynthesis, formycin B 5′-phosphate was synthesized and shown to be converted by ForA and Forb to formycin A 5′-phosphate. These results support that For enzymes are responsible for formycin formation
Rulan Zhang - One of the best experts on this subject based on the ideXlab platform.
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effect of loss of plant functional group and simulated nitrogen deposition on subalpine ecosystem properties on the tibetan plateau
Science of The Total Environment, 2018Co-Authors: Rulan Zhang, Shuangshuang Liu, Huakun Zhou, Johannes M H KnopsAbstract:Biodiversity loss impacts on ecosystem functioning can vary greatly among ecosystems types and different ecosystem processes can respond differently. Here we conducted a plant functional group removal experiment with and without nitrogen (N) addition (5gNm-2year-1) to examine the effects of plant functional group types presence, nitrogen deposition and their interaction effects on plant diversity, aboveground biomass, soil nutrients, soil microbial biomass and soil enzyme activity. After 4years, the removal of dominant grass did increase subordinates, Forb richness, and decreased total aboveground biomass significantly. However, the removal of Forb resulted in a rapid decline in species richness, which did not change strongly the aboveground biomass, regardless of N addition. This pattern suggests that the dominant grass can compensate for the loss of Forb removal with respect to production, but cannot compensate with respect to species loss. Forb cannot compensate for grass removal with respect to production, but can compensate with respect to species loss. Nitrogen addition only has a small effect on species richness, and also not enhances aboveground biomass. In addition, the majority of soil properties did not respond to either plant functional group removal, or N addition. Only soil CO2 efflux and soil NO3--N content significantly changed with plant functional group removal. Soil respiration rate was positively correlated with both plant species richness (R2=0.97) and aboveground biomass (R2=0.64). Our results show that the short-term losses of plant functional group have significant effects on plant diversity and productivity, and only minor impact on soil properties.
Johannes Kollmann - One of the best experts on this subject based on the ideXlab platform.
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mixed evidence for the cultivar vigour hypothesis the case of calcareous grassland Forbs in a matrix of festuca rubra
Ecological Engineering, 2014Co-Authors: Emer A Walker, Harald Meimberg, Johannes KollmannAbstract:According to the cultivar vigour hypothesis, cultivars are frequently selected for traits such as increased biomass and resource capture, which may hinder the establishment of non-cultivars. Despite this concern, cultivar seed material is still used in grassland restoration. An alternative is wild plant material, which is commercially produced and used in the respective region (‘regional seed’). We established a greenhouse experiment to examine the performance of cultivar and regional Forb species with and without competition from cultivar and regional dominant grass species. This was conducted in order to understand the potential effects of sowing cultivar seed in grassland restoration projects. Three calcareous grassland Forb species (Buphthalmum salicifolium, Dianthus carthusianorum and Linum perenne) and one dominant grass species (Festuca rubra ssp. commutata) were selected. One Forb species was sown in the centre of each pot and either zero, two or four F. rubra ssp. commutata individuals were planted around it. Above-ground biomass, plant height, leaf length, leaf width, number of leaves and stems were measured. When grown without competitors, each Forb species performed differently with only L. perenne exhibiting cultivar vigour. Cultivar Forbs were less negatively affected by competition with F. rubra ssp. commutata than their regional counterparts, thus supporting the cultivar vigour hypothesis. Overall, regional F. rubra ssp. commutata suppressed the above-ground biomass of the Forbs species more than the cultivar F. rubra ssp. commutata, thus highlighting the potential competitiveness of regional seed. Ultimately, the goals of the restoration project will determine the source of seed material to be used in the project. Due to the complex nature of the issues involved in restoration, it should be considered that the reliance on simple guidelines in relation to the source of seed material used in grassland restoration has its limitations.