Prevalence of interspecific competition in a mixed poplar/black locust plantation under adverse climate conditions

Abstract

& Key message In a mixed poplar/black locust plantation in central France, adverse conditions have led to a prevalence of interspecific competition, resulting in a poorer performance than monocultures. & Context In mixed tree plantations, the presence of woody N 2 -fixing species is thought to reduce N needs by fertilization. However, benefits associated to soil nitrogen enrichment have to outweigh the negative effects of interspecific competition. To do so, co-occurring tree species have to be chosen carefully to promote niche sharing between species and reduce competition. Black locust and poplar mixtures therefore seem promising since both species are fast growing and have potentially complementary crown shapes. & Aims Our objective was to evaluate the impact of the poplar/black locust mixture on the growth, above-and belowground biomass production, and nitrogen allocation of the two species, as compared to their respective monocultures. & Methods An experimental plantation mixing poplar and black locust was set up in central France. For five growing seasons, growth, nitrogen allocation, and carbon allocation were monitored for the two species growing either in mixture or in monoculture. & Results After a couple of promising growing seasons, black locust growth and survival slowly declined, mainly in the mixture. At the stand level, biomass production in the mixed plots was nearly 50% below the most productive monoculture (poplar) by age 5 years. & Conclusion Under adverse conditions, interspecific competition in the mixture was the preponderant interaction, resulting in higher mortality and lower biomass production than the two monocultures.

Poplar Short Rotation Coppice Plantations under Mediterranean Conditions: The Case of Spain

“…with Robinia spp. [154][155][156]. The mixture of Populus alba L.-Robinia pseudoacacia in SRC under Mediterranean conditions showed encouraging results in the first rotation [76], but they were not as promising in the second [157].…”

“…The mixture of Populus alba L.-Robinia pseudoacacia in SRC under Mediterranean conditions showed encouraging results in the first rotation [76], but they were not as promising in the second [157]. A similar design mixing R. pseudoacacia with the euramerican genotype 'Dorskamp' in central France demonstrated interspecific competition in the mixture as the preponderant interaction, resulting in higher mortality and lower biomass production than the two monocultures [155]. However, this mixture would appear to be advantageous given the different strategies shown by the two species in terms of the amount of litter and the dynamics of the main nutrients [158].…”

“…However, the excessive use of nitrogen fertilizers as part of conventional practice is increasingly being questioned because of environmental risks [181][182][183] and the high economic costs. Therefore, the use of alternatives to improve the nutritional status, such as designs with mixed plantations that include nitrogen fixing species [155] or alternative fertilization through the use of sewage sludge or waste water, have gained prominence in recent years [184][185][186]. Besides not having to use traditional fertilizers, these materials are purified and/or reused and the plantations thus act as phytoremediators [187].…”

Hybrid and Environmental Effects on Gene Expression in Poplar Clones in Pure and Mixed with Black Locust Stands

“…Importance of genotype by environment interactions for establishment of plantations has been recognized and demonstrated much earlier [4]. Studies conducted with poplar, eucalyptus and black locust species or hybrids [9,11,[26][27][28][29] clearly showed an effect of local conditions on performance and productivity of the genotypes. Many transcriptome studies of plants growing under field conditions were performed for Arabidopsis, rice and maize (see [30] for review), but less for poplar [31][32][33][34].…”

Nutrient Contribution of Litterfall in a Short Rotation Plantation of Pure or Mixed Plots of Populus alba L. and Robinia pseudoacacia L.

“…Most SRC plantations are established as monocultures with a single species, although the possibility of mixed stands has also been explored [10][11][12]. Mixed plantations, in addition to increasing genetic variability and favoring tolerance to certain stresses, can also provide productive benefits based on complementary or facilitation strategies [13].…”