The Mediterranean dry herbaceous systems support a wide range of native species, such as plants, invertebrates, and birds, so they have a high conservation value of nature. In this context, harvesting practices (dates and frequency, type of hay, machinery used or application of fertilizers) can directly or indirectly affect the spatial variability of plant diversity or productivity, and therefore the overall levels of biodiversity.
Since in recent years hay mowing has increased significantly in the Iberian Southwest, especially due to the increase in cattle, a group of ecologists conducted a study that covered an area of 20 x 25 kilometers in the South of Portugal.
To determine if the frequency and type of hay mowing influence the diversity and quality of herbaceous systems, researchers conducted inventories of the flora species for three years. In addition, they collected vegetation samples in various agricultural fields to determine their productivity and forage quality in the laboratory.
Fields exposed to frequent hay mowing present less biodiversity
The nutritive quality of the vegetation depended more on the use of the soil than on the frequency of mowing, being higher in the pastures than in the hay crops or in the fields.
However, the effects of the mowing on the nutritional quality of the vegetation were very dependent on the meteorological characteristics of each year, observing a positive effect on the nutritional quality in the dry years, but not in the wet ones, according to the researchers.
Finally, the researchers observed that the intensification of hay mowing has a moderate effect, compared to the use of soil, and that it seems to be insufficient to differentiate common vegetation from agricultural fields, possibly due to the high rotation of land use types to which the agricultural parcels in that geographical area are subjected.
The results, published in the journal Agriculture, Ecosystems, And Environment, revealed that agricultural fields cultivated with forage species and with more frequent hay mowing present less biodiversity.