Browsing by Subject "PLANT LITTER DECOMPOSITION"

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  • Bais, A. F.; Lucas, R. M.; Bornman, J. F.; Williamson, C. E.; Sulzberger, B.; Austin, A. T.; Wilson, S. R.; Andrady, A. L.; Bernhard, G.; McKenzie, R. L.; Aucamp, P. J.; Madronich, S.; Neale, R. E.; Yazar, S.; Young, A. R.; de Gruijl, F. R.; Norval, M.; Takizawa, Y.; Barnes, P. W.; Robson, T. M.; Robinson, S. A.; Ballare, C. L.; Flint, S. D.; Neale, P. J.; Hylander, S.; Rose, K. C.; Wangberg, S. -A.; Haeder, D. -P.; Worrest, R. C.; Zepp, R. G.; Paul, N. D.; Cory, R. M.; Solomon, K. R.; Longstreth, J.; Pandey, K. K.; Redhwi, H. H.; Torikaiaj, A.; Heikkila, A. M. (2018)
  • Bornman, Janet F.; Barnes, Paul W.; Robson, T. Matthew; Robinson, Sharon A.; Jansen, Marcel A. K.; Ballare, Carlos L.; Flint, Stephan D. (2019)
    Exposure of plants and animals to ultraviolet-B radiation (UV-B; 280-315 nm) is modified by stratospheric ozone dynamics and climate change. Even though stabilisation and projected recovery of stratospheric ozone is expected to curtail future increases in UV-B radiation at the Earth’s surface, on-going changes in climate are increasingly exposing plants and animals to novel combinations of UV-B radiation and other climate change factors (e.g., ultraviolet-A and visible radiation, water availability, temperature and elevated carbon dioxide). Climate change is also shifting vegetation cover, geographic ranges of species, and seasonal timing of development, which further modifies exposure to UV-B radiation. Since our last assessment, there is increased understanding of the underlying mechanisms by which plants perceive UV-B radiation, eliciting changes in growth, development and tolerances of abiotic and biotic factors. However, major questions remain on how UV-B radiation is interacting with other climate change factors to modify the production and quality of crops, as well as important ecosystem processes such as plant and animal competition, pest-pathogen interactions, and the decomposition of dead plant matter (litter). In addition, stratospheric ozone depletion is directly contributing to climate change in the southern hemisphere, such that terrestrial ecosystems in this region are being exposed to altered patterns of precipitation, temperature and fire regimes as well as UV-B radiation. These ozone-driven changes in climate have been implicated in both increases and reductions in the growth, survival and reproduction of plants and animals in Antarctica, South America and New Zealand. In this assessment, we summarise advances in our knowledge of these and other linkages and effects, and identify uncertainties and knowledge gaps that limit our ability to fully evaluate the ecological consequences of these environmental changes on terrestrial ecosystems.
  • Harju, A. Vilhelmiina; Narhi, Ilkka; Mattsson, Marja; Kerminen, Kaisa; Kontro, Merja H. (2021)
    Views on the entry of organic pollutants into the organic matter (OM) decaying process are divergent, and in part poorly understood. To clarify these interactions, pesticide dissipation was monitored in organic and mineral soils not adapted to contaminants for 241 days; in groundwater sediment slurries adapted to pesticides for 399 days; and in their sterilized counterparts with and without peat (5%) or compost-peat-sand (CPS, 15%) mixture addition. The results showed that simazine, atrazine and terbuthylazine (not sediment slurries) were chemically dissipated in the organic soil, and peat or CPS-amended soils and sediment slurries, but not in the mineral soil or sediment slurries. Hexazinone was chemically dissipated best in the peat amended mineral soil and sediment slurries. In contrast, dichlobenil chemically dissipated in the mineral soil and sediment slurries. The dissipation product 2,6-dichlorobenzamide (BAM) concentrations were lowest in the mineral soil, while dissipation was generally poor regardless of plant-derived OM, only algal agar enhanced its chemical dissipation. Based on sterilized counterparts, only terbutryn appeared to be microbially degraded in the organic soil, i.e., chemical dissipation of pesticides would appear to be utmost important, and could be the first response in the natural cleansing capacity of the environment, during which microbial degradation evolves. Consistent with compound-specific dissipation in the mineral or organic environments, long-term concentrations of pentachloroaniline and hexachlorobenzene were lowest in the mineral-rich soils, while concentrations of dichlorodiphenyltrichloroethane (DTT) and metabolites were lowest in the organic soils of old market gardens. OM amendments changed pesticide dissipation in the mineral soil towards that observed in the organic soil; that is OM accelerated, slowed down or stopped dissipation.