## 2 The Montado Ecosystem
### The Components of the Montado
#### 2.2.3 Pastures, Characteristics, and Management  
Pastures are communities mainly composed of herbaceous plants and sometimes associated with shrubs consumed by grazing animals (mainly ruminants) in the production site itself. They are systems of high heterogeneity due to variations in the number of species present and differences in the length of phenological cycles of the constituent plants, as well as continuous changes caused by different environmental and grazing factors [7; 56; 57]. The floristic composition of the pasture is a good indicator of pasture quality [1]. It depends on each region's soil and climate conditions and the grazing system adopted. According to [PERSON] and [PERSON] [58], in a pasture sown with _Poa pratensis_ L. and _Trifolium repens_ L. (50/50), the percentage of _Trifolium repens_ L. can vary from 1 to 80% after a few years, depending on the interval between each grazing period: weekly grazing provides 80% _Trifolium repens_ L.; grazing every 4 weeks provides only 50%; if grazing is only every 12 weeks, the percentage of _Trifolium repens_ L. will be only 1%. However, pasture rest periods are fundamental for plant development and seed production [1]. According to [PERSON] and [PERSON] [58], we can conclude that: (i) a sown pasture is quickly transformed into a poor-quality pasture, with an undesirable floristic composition, as a result of an inadequate grazing system; (ii) an adequate grazing system can transform an old and degraded pasture into a pasture of excellent quality. The floristic composition of the pasture is affected by grazing selectivity, stocking rate density, and grazing season [59]. In addition to this, [PERSON] & [PERSON] [58] identified three causes for the degradation of pasture floristic composition: (i) poor soil drainage; (ii) poor soil fertilization/corrections; (iii) poor grazing management, abusing continuous grazing. However, according to [PERSON] et al. [60], in a study conducted in China, grazing with cattle, sheep, and goats does not affect the species richness of pasture plants, although it significantly reduces plant biomass and increases heterogeneity in plant heights. [PERSON] et al. [1] carried out a study in Montado pastures to evaluate the effects of the type of grazing (continuous vs. deferred) and the application of dolomitic limestone on the floristic composition of the pasture. The authors identified 103 different species belonging to 25 botanical families. This work infers that deferred grazing may contribute to the increase in the number of legume species in the pasture and improve the floristic composition of the pasture. From this same study, the authors also conclude that grazing with high biotic loads eliminates undesirable plants with low nutritional value, such as _Diplotaxis catholica_ L.  
The pasture structure directly influences intake by grazing animals ([PERSON] and [PERSON], 2006) cited by [61]. Consequently, the pasture height is a significant factor influencing the intake and production of grazing animals [62]. Animal production is affected by the feed value of the pasture, which is a function of voluntary feed intake (quantity) and nutritive value [7]. The nutritive value of pasture, or the quality, is described in terms of crude CP, acid detergent fiber (ADF), neutral detergent fiber (NDF), ash, lignin (ADL), lipids, metabolizable energy (ME), and digestible OM ([PERSON] et al., 2007) cited by [7]. The nutritive value of the pasture thus determines the productive response per unit of pasture consumed [7]. The constituent plants of the pasture generally have a high proportion of water, varying between 10 and 50% DM, and pastures with high nutritive value usually have low DM values [63]. According to [PERSON] et al. [64], the inter-annual precipitation variability can explain the differences in the quantity and chemical composition of the various pasture species. Biomass production and its nutritive value increase with the annual increase in rainfall if it occurs in favorable periods for pasture growth (autumn and spring).