Project description:On-farm tree plantation is a form of land use where trees are planted at the edge or interspersed with crops. It has been practiced in different parts of Ethiopia due to its contribution to the household economy and soil fertility. This study was carried out to evaluate the variation in tree/shrub plantations along altitudinal gradients and plantation niches, and farmers' on-farm tree plantation practices at Kobo and Guba Lafto districts, North-eastern Ethiopia. Transect walks and semi-structured questionnaire were administered to appraise farmers' tree/shrub plantation practices and compositions between August and December 2020. A total of 135 plots along altitudinal gradients (Forty-five sample plots per altitude) and 135 retrieved questionnaires (45 per altitude) were analyzed. At each plot, tree/shrub richness, diversity, stem density, and important value index (IVI) were computed. Multivariate analysis, descriptive statistics, and preference rankings were used to evaluate vegetation data and farmers' perceptions on tree/shrub plantations. The results showed that most farmers (78.5 %) integrate trees with their crops for household use and soil fertility maintenance. The multivariate analysis revealed a significant reduction in the number of taxa, stem density, richness, and diversity with increasing elevation, from homestead to the boundary and on-farm plantation niches. Ziziphus spina-christi and Cordia africana were the most preferred tree species; Fabaceae was the dominant family representing 18.9 % of the species. The results emphasized considerable variations in relative density, relative dominance, and important value index (IVI) across altitudinal gradients and plantation niches. Acacia seyal and Z. spina-christi contributed the highest IVI at lower and middle elevations, whereas Eucalyptus globulus had high IVI at a higher elevation. In the study districts, the distribution of multifunctional indigenous tree plantations gradually decreases with the entire altitudinal gradients compared to exotic trees/shrubs. This calls for substantial efforts on the propagation and conservation of native tree and shrub genetic resources.

Project description:To delineate the biogeographic structure of Lebanon based on native tree and shrub species distribution using ecological niche modeling and dissimilarity indices. Lebanon, Middle East, and Mediterranean basin (34° N-35° W). We compiled a species list of Lebanon phanerophytes and used ecological niche models (ENM) to obtain surface distributions for each species. Then we defined groups of species with overlapping whole distributional ranges (global chorotypes) and significantly similar distributions within Lebanon (regional chorotype). To evaluate spatially grouped sets of species, we mapped the predicted distribution of species belonging to each chorotype. We measured the biogeographic distinctness amongst them using turnover and nestedness indices. Finally, we identified biogeographic transition zones based on the geographical mixture of chorotypes within Lebanon. We grouped the 60 species into nine global and five regional chorotypes. The chorotypes encompassing more than half of all species were rather nested and occurred on the western side of the country at low to middle elevations of Mount Lebanon (Mediterranean and Euro-Siberian chorotypes). The most dissimilar chorotypes occurred in the northeastern part of the country on the Anti-Lebanon mountains (Irano-Turanian) and the southern lowland (Saharo-Arabian). We found a hotspot of species richness at intermediate elevation on the northwestern slopes of the Lebanon range and a biogeographic transition zone at high elevation and the eastern slopes of Mount Lebanon, as well as the southern Anti-Lebanon mountains. Species distribution models allowed us to overcome gaps in occurrence data when studying biogeographical delineation. The first biogeographical structure of Lebanon was generated. The western part of Lebanon belongs to the (East) Mediterranean region, and the northeastern part to the Irano-Turanian region. The remaining areas are part of biogeographical transitional zones. The few endemic trees are characteristics of these transition zones.

Project description:Boreal forests are experiencing dramatic climate change, having warmed 1.0°-1.9°C over the last century. Yet forest regeneration practices are often still dictated by a fixed seed zone framework, in which seeds are both harvested from and planted into predefined areas. Our goal was to determine whether seedlings sourced from southern seed zones in Minnesota USA are already better adapted to northerly seed zones because of climate change. Bur oak (Quercus macrocarpa) and northern red oak (Quercus rubra) seedlings from two seed zones (i.e., tree ecotypes) were planted into 16 sites in two northern seed zones and measured for 3 yr. Our hypotheses were threefold: (1) tree species with more southern geographic distributions would thrive in northern forests where climate has already warmed substantially, (2) southern ecotypes of these species would have higher survival and growth than the northern ecotype in northern environments, and (3) natural selection would favor seedlings that expressed phenotypic and phenological traits characteristic of trees sourced from the more southern seed zone. For both species, survival was high (>93%), and southern ecotypes expressed traits consistent with our climate adaptation hypotheses. Ecotypic differences were especially evident for red oak; the southern ecotype had had higher survival, lower specific leaf area (SLA), faster height and diameter growth, and extended leaf phenology relative to the northern ecotype. Bur oak results were weaker, but the southern ecotype also had earlier budburst and lower SLA than the northern ecotype. Models based on the fixed seed zones failed to explain seedling performance as well as those with continuous predictors (e.g., climate and geographical position), suggesting that plant adaptations within current seed zone delineations do align with changing climate conditions. Adding support for this conclusion, natural selection favored traits expressed by the more southern tree ecotypes. Collectively, these results suggest that state seed sourcing guidelines should be reexamined to permit plantings across seed zones, a form of assisted migration. More extensive experiments (i.e., provenance trails) are necessary to make species-specific seed transfer guidelines that account for climate trends while also considering the precise geographic origin of seed sources.

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Ten North-American tree and shrub species

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