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Climate risks

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Despite the general increase in temperature due to climate change, the risk of late frost is not expected to decrease; in fact, recent SIMC studies show a higher probability resulting from the combination of two climatic trends with increased risk: 

  1. systematic temperature rises in winter and the early months of spring accelerate the phenological development of crops, with phenological phases that are far more sensitive to cold spells occurring in early spring
  2. increased variability in meteorological trends in the late March/early April, which sees stable or increasing episodes of sub-zero temperatures

Very high temperatures can lead to various problems for plants. Above a certain thermal threshold, which varies according to the plant, photosynthesis begins to decline and respiration increases causing lower net assimilation. In addition, heat waves can provoke defensive plant reactions such as the production of waxy layers to inhibit water loss, which also limits photosynthetic processes by partially closing the stomata. These effects persist even once the heat wave has passed. The greatest damage from extreme heat occurs in summer, however above-average temperatures at other times of the year can cause harmful physiological changes or alter the phenological stages, compromising yields.

Drought is the “decrease of the water available in a particular period for a particular area” (Wilhite, 1993); according to this definition it therefore appears to be a sporadic phenomenon that can also affect non-arid areas. In fact, drought is a normal and recurrent part of the hydrological cycle, which can occur in both dry and wet regions. Drought originates from the lack of precipitation over an extended period of time, usually a season or more, and is evaluated in relation to the local balance between precipitation and evapotranspiration (evaporation + transpiration). It is also linked to the time interval in which it occurs (season), the delay in the start of the rainfall period and the effectiveness of the precipitation, i.e. the intensity and frequency of rainfall. Other factors such as temperature, wind and soil moisture are often associated with drought and can contribute to aggravating its severity.

Erosion is a natural process that consists of the physical separation and subsequent removal of fragments, called “clasts”, and solutes generated by meteoric degradation from soils and outcropping rocks. The term is not only applied to the physical-chemical process, but also to the effects that erosion produces on the land. Erosion can be accelerated by anthropic intervention that upsets the environmental balance, leading to a net loss of soil with harmful consequences both for the environment and agricultural production. Agriculture is mainly affected by the following types of erosion: 

  1. due to intense precipitation (washout)
  2. wind erosion
  3. unsuitable land arrangements, especially in mountainous or hilly environments, causing landslides and mudslides

Excess water occurs when the water content of the soil is higher than the field capacity across the profile or only in some respects, resulting in free water on the surface. The negative effects of excess water manifest on the soil and the crop. On the soil this results in insufficient aeration, favouring the anaerobic activity of microorganisms, and in the anomalous evolution of the organic substance that causes insufficient structural aggregation of the soil, making it difficult for water and air to move even in periods when stagnation is absent. The effects of stagnation on crops are partially attributable to the phenomena mentioned above. The first negative effect of scarce oxygen availability consists in the reduction of root respiratory activity, which entails a slowdown or stasis in development; the absorption of nutritional elements is reduced and the concentration of nutrients in the plant also decreases, while the growth of the root system is limited. Another important aspect concerns plant diseases: plants in asphyxiated soils are less resistant to parasitic attacks and these soil conditions also favour fungal attacks.

Temporary flooding of usually dried areas. Flooding may be caused by rivers, creeks, channels, lakes and, for coastal areas, seas.

Frozen water in the atmosphere that precipitates to the ground in the form of ice grains of varying sizes.

Root asphyxia, erosion.

The combination of abiotic (pedoclimatic) and biotic (living animal and plant organisms) factors and their mutual interactions favourable for agricultural production with certain quantitative and qualitative characteristics, without the excessive use of technical resources.

Loss of commercial value of agricultural production caused by harmful organisms such as pathogens (fungi, bacteria, viruses, viroids and phytoplasmas) or parasites (insects, mites, nematodes and molluscs).

The inland intrusion of salt water from the sea through the subsoil; this phenomenon, which can occur in river deltas, is mainly due to reduced river flows caused by limited mountain water releases, uncontrolled withdrawals and careless water management. From an agronomic standpoint, this phenomenon causes an increase in the osmotic pressure of the circulating solution, nutritional imbalance and toxicity of the individual ions among crops, depending on the specific salt tolerance, with stunted vegetative development that leads to yield losses, which worsens in periods of drought when salt dilution is limited.

Wind is a non-negligible climatic factor, especially in areas affected by frequent and intense winds. The origin of prevailing winds is extremely important: in fact, if coming from the sea, they make rain and cloud cover more frequent and reduce temperature variations; if coming from cold or hot areas, they substantially modify the characteristic climate of a certain area located at specific latitudes and altitudes. Wind has a number of direct and indirect effects on vegetation, of a physical and biological nature, including:

  1. the transport of hot or cold air masses, interfering with the energy balance of plants and, consequently, the evapotranspiration process
  2. the acceleration of ripening (e.g. cereal development) and drying processes
  3. lodging
  4. breaking of branches and whole plants, falling fruit, damage to tunnels and greenhouses
  5. wind erosion