To select the genetic source of Pinus patula Shiede and Deppe seed best adapted to different native zones for reforestation, seedlings of 12 provenances native to a selected altitudinal gradient in Oaxaca, southern Mexico, were planted on two sites at contrasting altitudes (high 3000 m above sea level (masl) and low, 2500 masl) within the species natural distribution, and tested for growth in height at age 18, 24 and 36 months. Differences among provenances and between sites showed significance (p<0.05). Seedling growth showed a climatic and altitudinal pattern, in which seedlings from populations originating in low-middle altitudes had higher growth than populations originating in high altitudes, and from the extreme low altitude limit. Results were used to delineate climatic and altitudinal seed zones for contemporary and future climate zones in the decade centered in year 2030, using the average results of six climate-emissions scenarios. The results indicate that splitting the region into four seed zones is appropriate under contemporary climate scenarios with the following altitude limits: Zone 1, from 2300 to 2500 masl; Zone 2, 2500 to 2700 masl; Zone 3, 2700 to 2900 masl and Zone 4 from 2900 to 3100 masl. The equivalence on climatic intervals was also defined for mean annual temperature, precipitation and an annual aridity index (AAI). Values of contemporary AAI occurring at a given altitude by year 2030 were determined, with results suggesting that populations should be shifted 200 to 250 m attitudinally upward, through a program of assisted migration, to realign them to the future climate for which they are adapted.

The effects of temperature and light were examined on the germination of 14 seedlots of 10 Eucalyptus species, which are important for revegetation of native communities in north-western New South Wales. The species tested were E. albens, E. blakelyi, E. chloroclada, E. dealbata, E. camaldulensis, E. melanophloia, E. melliodora, E. pilligaensis, E. populnea and E. sideroxylon. Species were subjected to three alternating day/night temperatures (15/5, 25/15 and 35/25°C), representing winter, spring/autumn and summer conditions, respectively, and two light treatments (light/dark or dark), in growth cabinets. Limited quantities of seed of most seedlots prevented full factorial combinations of most treatments. Overall germination was high but varied significantly between species and seedlots within species. Differences were small, but light combined with winter or spring/autumn temperatures resulted in higher average germination (96%) than darkness and summer temperatures (93%). Seedlots of E. chloroclada, E. blakelyi, E. camaldulensis, E. sideroxylon, E. melliodora and E. melanophloia germinated consistently well under all treatment conditions, whereas germination in seedlots of E. albens, E. dealbata, E. melliodora, E. pilligaensis and E. populnea varied with treatments. Germination of small seeds was higher in the presence of light whereas larger seeds germinated better in continuous darkness. The time to first germination was three times faster under summer and spring/autumn temperatures than winter temperatures. In conclusion, temperature and light can significantly impact germination percentage and rate, depending on the species and provenances, and therefore should be considered in planning restoration projects in both nursery and field.

Aiming to determine if there is genetic differentiation among Pinus patula Schiede et Chamizo populations along an altitudinal gradient and for quantifying the genotype x environment interaction, 13 Pinus patula populations were sampled from forests of the Native Indian Community of Ixtlán de Juárez, Oaxaca, state of México, along an altitudinal gradient (2400 m to 3000 m), cones being collected on groups of trees on every 50 m of altitudinal step). Seedlings were grown in tree pots in two different environments: a shadehouse located at Ixtlán de Juárez, and in a greenhouse and then in a shadehouse situated at Quebec, Canada. Total seedling height was measured at 6-months of age in both locations. Results indicated that populations differed significantly (P = 0.025), but there was no significant genotype x environment interaction (P = 0.426; B type genetic correlation = 0.93). Population from 2650 m (middle altitude) exhibited the best height. Although not definitive, our study suggests the presence of a weak altitudinal pattern of variation in seedling height, where populations originating of mid-altitudes exhibit the highest growth potential while populations from the upper and lower altitudinal extremes exhibit the lowest growth potential.