Differences In Distribution Of Biomass Research Articles

Leaf mass per area, not total leaf area, drives differences in above-ground biomass distribution among woody plant functional types.

Here, we aim to understand differences in biomass distribution between major woody plant functional types (PFTs) (deciduous vs evergreen and gymnosperm vs angiosperm) in terms of underlying traits, in particular the leaf mass per area (LMA) and leaf area per unit stem basal area. We used a large compilation of plant biomass and size observations, including observations of 21084 individuals on 656 species. We used a combination of semiparametric methods and variance partitioning to test the influence of PFT, plant height, LMA, total leaf area, stem basal area and climate on above-ground biomass distribution. The ratio of leaf mass to above-ground woody mass (MF /MS ) varied strongly among PFTs. We found that MF /MS at a given plant height was proportional to LMA across PFTs. As a result, the PFTs did not differ in the amount of leaf area supported per unit above-ground biomass or per unit stem basal area. Climate consistently explained very little additional variation in biomass distribution at a given plant size. Combined, these results demonstrate consistent patterns in above-ground biomass distribution and leaf area relationships among major woody PFTs, which can be used to further constrain global vegetation models.

Pasture characteristics in three different ecotypes at Khovd Aimag, Western Mongolia.

The transition of nomadic pastoralism to more sessile forms of rangeland utilization and increased stocking rates can result in the degradation of pasture. After political changes in the 1990s in Mongolia, population growth and missing alternative livelihoods intensified the grazing pressure on pastures, and further decreased the condition of the fragile arid ecosystems. To learn more about the productivity and quality of pasture land in Khovd Aimag in the western region of Mongolia, standing biomass was measured in the alpine region, mountain steppe and semi-desert. Plant samples were analyzed for nitrogen and fiber contents by wet chemistry and Near Infrared Spectroscopy (NIRS). Results show clear differences in distribution of biomass with reduced biomass in the vicinity of temporary settlements. From July to early September plant nitrogen contents decreased in the alpine region, remained unchanged in the mountain steppe and increased in the semi-desert. Nitrogen concentrations were elevated in vegetation close to temporary settlements. For fiber contents (ADF) no clear patterns were found. Neither biomass/m2 nor vegetation cover were appropriate indicators for food quality.

Biocidal action of ozone against planktonic and sessile Pseudomonas fluorescens

The efficacy of ozone biocidal action against planktonic and sessile Pseudomonas fluorescens was studied using different contact times and biocide concentrations. Bacterial biofilms were formed on different metallic substrata frequently used as structural materials in industrial installations. The results showed that the biocidal action of ozone against planktonic cells can be represented by a dose‐response relationship in which the contact time factor was more significant than the concentration. The efficacy of ozone against sessile bacteria was lower than that found for planktonic cells. Turbulent flow significantly improved the inactivation rate, suggesting that a diffusional impediment was involved in the mass transfer process. However, diffusional resistance alone cannot explain the observed decrease in biocidal efficacy. Ozone penetration into the biofilm appeared to be a function of simultaneous diffusion and a reaction of the biocide in the biofilm matrix; the latter may be the result of microscale differences in biomass distribution as well as hydrodynamic conditions. In addition, oxidation by‐products may contribute an additional resistance to ozone diffusion, which may be even higher than that of the biofilm itself.

Growth and development of silver birch, pedunculate oak and beech as affected by deer browsing

Comparison of species abundance in fenced and non-fenced plots indicated a lower browsing-induced mortality for beech than for pedunculate oak and silver birch. Comparison of saplings classified as browsed or unbrowsed, showed that browsing reduced sapling size and changed above-ground biomass distribution (more branch biomass and less leaf biomass). Generally, the effects of browsing did not differ between saplings regenerated under a forest canopy and saplings regenerated in large gaps or in heathland and clearings. Differences in height and above-ground biomass between browsed and unbrowsed saplings were large for beech compared with silver birch and pedunculate oak. Differences in biomass distribution between browsed and unbrowsed saplings were small for pedunculate oak compared with the other two species.