Rain events decrease boreal peatland net CO2uptake through reduced light availability

2015 ◽  
Vol 21 (6) ◽  
pp. 2309-2320 ◽  
Author(s):  
Jelmer J. Nijp ◽  
Juul Limpens ◽  
Klaas Metselaar ◽  
Matthias Peichl ◽  
Mats B. Nilsson ◽  
...  
Keyword(s):  
Light Availability ◽  
Rain Events ◽  
Reduced Light

scholarly journals Physiological and ecological consequences of the water optical properties degradation on reef corals

Coral Reefs ◽  
2021 ◽  
Author(s):  
Tomás López-Londoño ◽  
Claudia T. Galindo-Martínez ◽  
Kelly Gómez-Campo ◽  
Luis A. González-Guerrero ◽  
Sofia Roitman ◽  
...  
Keyword(s):  
Optical Properties ◽  
Population Decline ◽  
Light Availability ◽  
Potential Effect ◽  
Optical Quality ◽  
Light Penetration ◽  
Reef Corals ◽  
Orbicella Faveolata ◽  
Light Quantity ◽  
Reduced Light

AbstractDegradation of water optical properties due to anthropogenic disturbances is a common phenomenon in coastal waters globally. Although this condition is associated with multiple drivers that affect corals health in multiple ways, its effect on light availability and photosynthetic energy acquisition has been largely neglected. Here, we describe how declining the water optical quality in a coastal reef exposed to a turbid plume of water originating from a man-made channel compromises the functionality of the keystone coral species Orbicella faveolata. We found highly variable water optical conditions with significant effects on the light quantity and quality available for corals. Low-light phenotypes close to theoretical limits of photoacclimation were found at shallow depths as a result of reduced light penetration. The estimated photosynthetically fixed energy depletion with increasing depth was associated with patterns of colony mortality and vertical habitat compression. A numerical model illustrates the potential effect of the progressive water quality degradation on coral mortality and population decline along the depth gradient. Collectively, our findings suggest that preserving the water properties seeking to maximize light penetration through the water column is essential for maintaining the coral reef structure and associated ecosystem services.

scholarly journals Mesophotic.org: a repository for scientific information on mesophotic ecosystems

Database ◽  
2019 ◽  
Vol 2019 ◽  
Author(s):  
Pim Bongaerts ◽  
Gonzalo Perez-Rosales ◽  
Veronica Z Radice ◽  
Gal Eyal ◽  
Andrea Gori ◽  
...  
Keyword(s):  
Large Scale ◽  
Scientific Information ◽  
Temporal Trends ◽  
Light Availability ◽  
Research Community ◽  
Future Research ◽  
Photosynthetic Organisms ◽  
Future Research Directions ◽  
Available Information ◽  
Reduced Light

Abstract Mesophotic coral ecosystems (MCEs) and temperate mesophotic ecosystems (TMEs) occur at depths of roughly 30–150 m depth and are characterized by the presence of photosynthetic organisms despite reduced light availability. Exploration of these ecosystems dates back several decades, but our knowledge remained extremely limited until about a decade ago, when a renewed interest resulted in the establishment of a rapidly growing research community. Here, we present the ‘mesophotic.org’ database, a comprehensive and curated repository of scientific literature on mesophotic ecosystems. Through both manually curated and automatically extracted metadata, the repository facilitates rapid retrieval of available information about particular topics (e.g. taxa or geographic regions), exploration of spatial/temporal trends in research and identification of knowledge gaps. The repository can be queried to comprehensively obtain available data to address large-scale questions and guide future research directions. Overall, the ‘mesophotic.org’ repository provides an independent and open-source platform for the ever-growing research community working on MCEs and TMEs to collate and expedite our understanding of the occurrence, composition and functioning of these ecosystems. Database URL: http://mesophotic.org/

The influence of fire on Spartina pectinata wetland communities in a northeastern Kansas tallgrass prairie

1995 ◽  
Vol 73 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Stephen R. Johnson ◽  
Alan K. Knapp
Keyword(s):  
Tallgrass Prairie ◽  
Light Availability ◽  
Fire Frequency ◽  
Plant Species Composition ◽  
Prairie Wetlands ◽  
Asclepias Syriaca ◽  
Spartina Pectinata ◽  
Galium Aparine ◽  
Reduced Light ◽  
Diverse Plant

Wetlands dominated by the C4 grass Spartina pectinata were investigated to quantify differences in plant species composition and diversity in response to fire frequency. The study site was a tallgrass prairie in northeastern Kansas that included Spartina wetlands subjected to spring fires at 1-, 2-, 4-, 10-, and 20-year intervals. Because C3 forbs in these wetlands responded strongly to different fire frequencies, the light environment and gas exchange responses of the ubiquitous forb Asclepias syriaca were also assessed. In general, species diversity was lower in annually burned wetlands because of lower forb diversity. Maximum H′ in annually burned sites was 1.64 versus 2.77 in 10- and 20-year burned sites. However, individual forb responses varied. Asclepias increased and Solidago canadensis and Galium aparine decreased in importance with increasing fire frequency. Canopy sunlight interception was greater in annually burned wetlands than in wetlands with lower burn frequencies. Despite reduced light availability, midseason photosynthetic rates of Asclepias were higher in annually burned sites. The results suggest that frequent fire in tallgrass prairie wetlands results in less diverse plant communities, similar to responses of upland prairie, and that the timing of fire, relative to life history and phenology of the subordinate species, strongly influences responses of individual forbs. Key words: wetlands, tallgrass prairie, Spartina pectinata communities, fire.

Influence of corn (Zea mays) population and row spacing on corn and velvetleaf (Abutilon theophrasti) yield

Weed Science ◽  
1998 ◽  
Vol 46 (4) ◽  
pp. 447-453 ◽  
Author(s):  
John R. Teasdale
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Management Strategies ◽  
Light Availability ◽  
Integrated Weed Management ◽  
Row Spacing ◽  
Corn Yield ◽  
Corn Production ◽  
One Year ◽  
Reduced Light

Research was conducted to determine the optimum population and row spacing for corn production and for suppressing velvetleaf growth and seed production. Corn was grown in a factorial arrangement of three populations targeted at 64,000 (1 ×), 96,000 (1.5 ×), or 128,000 (2 ×) plants ha−1and two row spacings of 38 or 76 cm. Influences on corn were determined in weed-free plots, and influences on velvetleaf were determined for target plants established at 1.5–m intervals along the center of corn interrows. Four velvetleaf plantings were made at weekly intervals beginning at corn planting. Corn row spacing had little influence on corn or velvetleaf. Corn yield exhibited a parabolic response to population with a maximum of approximately 90,000 plants ha−1in one year, no response to population in another year, and a linear decline with increasing population in a dry year. Velvetleaf seed production was reduced 69 to 94% by the 1.5 × population and 99% by the 2 × population compared to the standard 1 × population when velvetleaf emerged with corn. Velvetleaf seed production was eliminated when velvetleaf emerged at or later than corn leaf stages 3, 5, and 6 for corn populations of 2 ×, 1.5 ×, and 1 ×, respectively. Reduced velvetleaf seed production was correlated with lower positioning of plants in the corn canopy and reduced light availability. Results suggest that higher corn populations could aid integrated weed management strategies by reducing seed production and limiting the build-up of weed populations.

Effects of shading on seagrass morphology and thermal optimal of productivity

2020 ◽  
Vol 71 (8) ◽  
pp. 913 ◽  
Author(s):  
Eunice Kong ◽  
Yan Xiang Ow ◽  
Samantha Lai ◽  
Siti Maryam Yaakub ◽  
Peter Todd
Keyword(s):  
Synergistic Effects ◽  
Light Availability ◽  
Temperature Response ◽  
Leaf Size ◽  
Net Photosynthesis ◽  
Shoot Density ◽  
Net Productivity ◽  
Halophila Ovalis ◽  
Light Levels ◽  
Reduced Light

Light and temperature are important factors affecting seagrass primary productivity. Acclimatisation to reduced light availability may affect the optimal temperature at which seagrasses photosynthesise, potentially causing synergistic effects between increasing water temperatures and decreasing light levels on coastal productivity. This study investigated the effects of reduced light availability on the morphology (leaf size, shoot density) and thermal optimal of net productivity in Halophila ovalis (R.Br.) Hook. A 12-week in situ shading experiment was conducted at Chek Jawa Wetlands, Singapore, testing high (68% shading), low (49%) and control (0%) shadings. Every 4 weeks, photosynthetic and respiration rates of H. ovalis leaves and the root–rhizome complex were measured in closed incubation chambers at temperatures from 22 to 42°C (at 4°C intervals). A fitted temperature-response model of net photosynthesis was used to estimate the thermal optimal for each shading treatment. High shading reduced shoot density (mean±s.e.) 87.06±7.86% and leaf surface area 31.72±24.74%. Net productivity (6mg O2 g–1 DW h–1) and its thermal optimal (28–30°C) were not significantly different among shading treatments throughout the experiment. Light levels appeared to have minimal influence on the thermal dependency of H. ovalis net productivity.

Climbing strategies determine light availability for both vines and associated structural hosts

2008 ◽  
Vol 56 (6) ◽  
pp. 527 ◽  
Author(s):  
Anna-Maria Llorens ◽  
Michelle R. Leishman
Keyword(s):  
Host Species ◽  
Light Availability ◽  
Canopy Openness ◽  
Shoot Height ◽  
Leaf Mass ◽  
Open Forest ◽  
Root Climber ◽  
Shading Effects ◽  
Reduced Light ◽  
Leaf Mass Fraction

This study investigated biomass allocation traits and shading impact of vines (ground-rooted climbing plants) on their hosts in a tall open forest understorey community (Blue Gum High Forest) in Sydney, Australia. Eighty-six vine individuals from 11 species (7 natives and 4 exotics) were recorded and sampled on 26 individuals from 5 host species. All host species sampled were <3 m in height. Each recorded climber was assigned to one of the five established climbing strategies: tendril climber, petiole climber, stem twiner, scrambler or root climber. No root climbers were recorded. Each species was also recorded as native or exotic. We measured shading effects of the different climbing strategies by removing vines from their hosts and measuring the change in canopy openness (diffuse non-interceptance, DIFN) above the host. Vines had significantly greater specific leaf area than their hosts. The most abundant climbing strategy was stem twining, followed by scrambling, petiole twining and tendril climbing. Leaf mass fraction (leaf mass per total aboveground biomass) did not differ among climbing strategies or between natives and exotics. Vines reached taller heights on taller hosts and the percentage of host’s shoot height reached differed significantly among climbing strategies: petiole twiners and scramblers reached the largest percentage host shoot height (97% and 92%, respectively) whereas stem twiners and tendril climbers reached 68% and 61%, respectively. Total relative shading of the host increased significantly with increasing vine biomass. There were significant differences between climbing strategies in the shading imposed on hosts. In the context of average canopy openness above the understorey for this site (24%), scramblers reduced light availability to their hosts by nearly 25%, compared with petiole-tendril twiners (14%) and stem twiners (8%). Thus, climbing strategies differentially shape the light environment available to their structural hosts.

Sign in / Sign up

Export Citation Format

Share Document