ProPopulus Team
Combining tree farming with agriculture is far from a new idea, but recent research sheds light on just how effective poplars can be in wide alley agroforestry systems. A study published in Agriculture, Ecosystems & Environment (Piotto et al., 2024) offers valuable insights into how these systems influence the growth of poplars and the productivity of intercrops such as wheat and soybeans during the first four years of tree establishment.
The research, carried out by Simone Piotto, Anna Panozzo, Gaia Pasqualotto, Vinicio Carraro, Giuseppe Barion, Giustino Mezzalira, Lorenzo Furlan, Selina Sterup Moore and Teofilo Vamerali, focused on the poplar clone Moncalvo.
The team compared two planting systems in Northern Italy: a traditional intensive plantation with 277 trees per hectare, and a silvoarable system with much wider spacing, equivalent to just 35 trees per hectare and 40 meters between tree rows.
Over a four-year period, the scientists monitored phenology and radial growth of poplars while also recording how annual crops planted in the alleys—mainly wheat and soybeans—responded to the presence of trees.
Bigger trees, slower springs
Results revealed some fascinating dynamics. In the silvoarable system, poplars showed larger diameters at breast height (DBH), averaging 23.8 cm compared to 20.5 cm in the intensive plantation. In other words, trees grew thicker when they had more space and less competition for water and nutrients.
On the other hand, tree height was slightly reduced, with silvoarable poplars reaching 14.3 m against 15.5 m in the dense control plots. Phenology also changed: budburst in spring occurred around two weeks later in the agroforestry system, a delay linked to colder night temperatures and lower soil moisture at the beginning of the growing season.
Winners and losers among crops
The effects on intercrops were equally revealing. Wheat, a winter crop, often benefited from the tree rows. Yields increased by up to 28% at 12 meters from the poplar rows compared to full-sun conditions. This suggests that moderate shading and microclimatic effects can in fact support cereal production.
Soybeans told a different story. Being a summer crop with higher light requirements, yields decreased in proximity to the trees. At just 6 meters from the rows, the reduction reached 38% compared to open-field controls.
These findings highlight that the timing of crop cycles relative to tree development plays a key role in agroforestry performance.
Towards climate-resilient agroecosystems
According to Piotto and colleagues, the results underline the potential of wide alley agroforestry systems to balance tree growth with crop production. By reducing intraspecific competition, poplars achieved greater radial growth, which is especially relevant for timber production. At the same time, farmers could still harvest significant yields from intercrops, especially winter cereals.
From a climate adaptation perspective, such systems may offer multiple advantages. Poplars act as carbon sinks, improve soil structure, and increase biodiversity. Crops, on the other hand, provide short-term income and food security. Together, they create diversified and more resilient landscapes.
Looking ahead
The study published in Agriculture, Ecosystems & Environment provides strong evidence that alley agroforestry with poplars can be a win–win solution, but crop choice matters. Wheat appears to integrate well into these systems, while soybeans face greater challenges.
As the authors note, more research is needed to explore the performance of different clones and crop combinations, as well as longer-term impact. Nevertheless, this work marks an important step forward in understanding how poplars can be at the heart of innovative agroforestry designs that combine timber production, sustainable agriculture, and climate resilience.