Forum 664 Commentary Commentary Towards a rhizo-centric view of plant-microbial feedbacks under elevated atmospheric CO 2 The stimulatory effects of elevated CO 2 on plant productivity have been reported for many ecosystems (Ainsworth & Long, 2005), but whether such effects will persist in the face of increasing nutrient limitation is unclear. In nitrogen (N)-limited ecosystems, elevated CO 2 h...

re-vegetation of bare soil is believed to increase, or at least maintain the organic matter levels of soil. the aim of this study was to investigate the soil characteristics changes, nutrient pool sizes and their availability under mid canopy, and canopy gap positions of saltbush in an area re-vegetated with atriplex lentiformis. some of the physical and chemical soil characteristics (the parti...

Microbial activity is known to continue during the winter months in cold alpine and Arctic soils often resulting in high microbial biomass. Complex soil nutrient dynamics characterize the transition when soil temperatures approach and exceed 0 1C in spring. At the time of this transition in alphine soils microbial biomass declines dramatically together with soil pools of available nutrients. Th...

Nutrient availability often limits primary production, yet the processes governing the dynamics of nutrient limitation are poorly understood. In particular, plant-available (e.g., nitrate) versus plant-unavailable (e.g., dissolved organic nitrogen) nutrient losses may have qualitatively different impacts on nutrient limitation. We examine processes controlling equilibrium and transient nutrient...

Ecological theory and evidence suggest that plant community biomass and composition may often be jointly controlled by climatic water availability and soil nutrient supply. To the extent that such colimitation operates, alterations in water availability caused by climatic change may have relatively little effect on plant communities on nutrient-poor soils. We tested this prediction with a 5-y r...

Nutrient resorption from senescing leaves is a key mechanism of nutrient conservation for plants. The nutrient resorption efficiency is highly dependent on leaf nutrient status, species identity and soil nutrient availability. Nitrogen is a limiting nutrient in most ecosystems, it is widely reported that nitrogen resorption efficiency (NRE) was highly dependent on the soil nitrogen availability...

This paper reviews nutrient deficiencies in agricultural crops of PNG using the literature of agronomic trials and field observations made throughout the country. Nutrient deficiencies have been investigated systematically since the mid-1950s, but research has mainly focused on export tree crops and relatively little information is available on food crops. Literature analysis and field observat...

In mechanized timber harvesting, it is common practice to build brush mats from logging residues on skid trails. Protective effects of brush mats against soil compaction are documented by several studies. On the other hand, a large quantity of nutrients is concentrated on the skid trail. Fully mechanized harvesting has been criticized frequently for this reallocation of nutrients. Is there real...