Leaf dynamics, nutrient (N, P, K, Ca, and Na) changes, and retranslocation from the leaves of 13 species were investigated in four representative forest communities of the Central Himalaya, India. In evergreens of the temperate regions, with leaf longevities of several years, there is negligible movement of substances from leaves during the first year. For evergreens of the Central Himalaya, by contrast, loss of leaf mass beings in autumn and often continues until summer, when new leaves are formed. The decrease in leaf dry mass during this period was 12.3-34.1% of the maximum leaf mass. The concentration of N, P, and K decreased from the initial peak, stabilized as leaves matured, and declined markedly during senescence, while Ca and Na concentrations increased throughout the life-span of leaves. Leaf mass loss was positively related to most of the nutrient retranslocation percentages. There were significant correlations between retranslocation levels of many nutrients. The dominant canopy species (chir pine), which is adapted to infertile sites, showed conspicuously greater levels of nutrient retranslocation than species adapted to fertile sites (oaks). However, species of different growth forms occupying the same sites differed markedly in the extent of nutrient retranslocation.

The phenology of tree components of natural forests occurring between 350 and 2150 m in Kumaun Himalaya is described. All forests had more evergreen than deciduous taxa. The degree of evergreenness increased with increasing elevation and decreasing summer dryness. For most species (including all dominants) concentrated leafdrop and simultaneous leafing occurred during the warm-dry period of the year. About half of the species showed multiple leafing.All species had a sharp flowering peak in April. Wet-season flowering was rare. Most of the species flowered synchronously. In the sal-(Shorea robusta) and pine (Pinus roxburghii) forests a single peak of fruit maturation occurred in summer, while in other forests there also was a secondary peak in autumn.

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In an agrisilvicultural system having poplar (Populus deltoides, clone G-3) as a tree component and wheat crop as an intercrop, wheat yield was studied under five age classes of poplar and compared to wheat yield under pure cropping. A substantial reduction in wheat yield (23.3%) under three-year-old poplar plantation was observed. Maximum MAI (GBH, 20 cm) was recorded in a three-year-old poplar planting. Pruning after the third year permitted some recovery in yield. The reduction in wheat yield was significantly correlated with MAI (GBH) of poplar and occurred even under one-and-two-year-old poplar plantings.