Tree species can influence biogeochemistry through variation in the quantity and chemistry of their litter, and associated impacts on the soil heterotrophic community. However, the role that different plant traits play in these processes is not well understood, nor is it clear whether species effects on soils largely reflect a gymnosperm vs. angiosperm contrast. Using a replicated, long-term monoculture plot experiment, we examined variation in soils among 14 gymnosperm and angiosperm tree species 30 years after plot establishment, and assessed the role of litter chemistry vis-à-vis such variation. Differences in litter calcium concentrations among tree species resulted in profound changes in soil acidity and fertility that were similar within and among tree groups. Tree species rich in calcium were associated with increased native earthworm abundance and diversity, as well as increased soil pH, exchangeable calcium, per cent base saturation and forest floor turnover rate.

Summary1. There are conflicting reports concerning the adaptive features of tree populations originating from cold, high-altitude environments. We hypothesize that such trees will possess adaptive features that will be demonstrated in a common environment, such as elevated rates of net CO 2 exchange, elevated needle nitrogen concentration and high proportional biomass allocation to roots. To test this hypothesis we measured tree and seed properties of 54 populations of Norway spruce [Picea abies (L.) Karst.] located along eight altitudinal transects (from c. 600 to 1500 m) in southern Poland. We also measured growth, biomass partitioning, net photosynthetic capacity (A max ), needle dark respiration (RS) and carbohydrate, nitrogen (N) and chlorophyll concentration of seedlings originating from these populations grown for 2 to 7 years in a common garden at 150 m elevation. Measured in situ along the elevational transects, there were linear declines in seed mass, average d.b.h. and height growth increment of seed trees with increased altitude or lower mean annual temperature. 2. In the common garden, the Norway spruce populations from colder, high-altitude habitats had higher N concentration in needles than those from low altitudes. Both A max and needle RS increased with altitude of seed origin and were significantly related to needle N concentration. High-altitude populations also had higher concentrations of chlorophyll and carotene than those from low elevations. Despite higher photosynthetic rates in high-altitude populations, seedling height and dry mass in the common garden declined with altitude of seed origin. Proportional dry mass partitioning to roots nearly doubled with increasing altitude of origin, while the length of the shoot-growth period was reduced. The high respiration rates, high allocation to roots and reduced shoot-growth period are probably responsible for the low growth rate potential of high-altitude populations, more than offsetting their higher photosynthetic rates. 3. The results of this study showed that Norway spruce populations from cold mountain environments are characterized by several potentially adaptive features. Because these were similar to conifer population responses along a latitudinal gradient of origin, they are probably driven by climate. These climate-driven differences were common to all transects: for a given altitude or mean annual temperature, plant traits were independent of mountain range of origin. However, populations originating from cold high-elevation sites often differed per unit change in altitude or mean annual temperature more than did low elevation populations. The scaling of nitrogen, CO 2 exchange and biomass and allocation patterns may be useful in modelling Norway spruce response on montane forest ecosystems under changing environments.

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Ring-width chronologies of Picea abies (L.)

Summary• A wide variety of transparent materials are currently used for minirhizotron tubes. We tested the null hypothesis that minirhizotron composition does not influence root morphology and dynamics.• Minirhizotron data were compared for glass, acrylic and butyrate tubes in apple ( Malus domestica ) and acrylic and butyrate tubes in a study with six forest tree species.• Root phenology and morphology were generally similar among tubes. Apple root production was greatest against glass; these roots became pigmented later and lived longer than roots near acrylic or butyrate. Roots generally became pigmented faster next to butyrate than next to acrylic. Root survivorship was shorter near butyrate tubes in three of the four hardwood species; however, survivorship was shorter near acrylic tubes for the three conifer species. Comparison of minirhizotron standing crop data with root standing crop from cores showed that the acrylic data matched more closely than the butyrate data.• This study reveals that the transparent material used often has little effect on root production but can substantially influence root survivorship in some plants.