Clasificación de las actividades recreativas

Internal Final EROI assesses the portion of Land Produce reinvested in the agroecosystem as Biomass Reused in order to get a unit of consumable Final Produce. The relative amount of these internal flows exposes a clear-cut distinction between historic solar-based agricultural systems compared with fossil fuelled industrial ones at present, as organic farm systems nearly always bear greater internal flows per unit of output (Figure 9):

= =

Figure 9: Internal Final EROI in the four municipalities of the Valles County (Catalonia, Iberia) c.1860 and in 1999. Source: Part II of this working paper by Marco et al.

Internal Final EROI1860 =

,

, = 1.13 Internal Final EROI1999 = ,

, = 2.20

In our Catalan example Internal Final EROI increased from 1.13 c.1860 to 2.20 in 1999. In this case the opposite directionality of change is the result of a greater investment in keeping up the agroecosystem’s funds in the former case compared with the latter one— which means bearing a higher sustainability cost that has been currently given up (Guzmán & Gonzalez de Molina 2009, Guzmán et al. 2011). This makes apparent that energy efficiency ratios, as measured by Final EROI from a farm-operator viewpoint, can be enhanced either by increasing the Final Produce per unit of TIC or by reducing the inputs spent per unit of output (that is maximizing the numerator or minimizing the denominator). Given that up to a point BR and EI can be substituted for one another, three possible strategies to increase agricultural energy yields appear: 1) attain greater output per unit of inputs consumed, whether internal or external, which means increasing the joint energy efficiency—by increasing complexity and organized information in the agroeocosystem; 2) reduce inputs consumed per unit of output by relying on internal inputs and saving external inputs; and 3) reduce inputs consumed per unit of output by relying on external inputs and saving internal inputs. It becomes apparent that there has been a historical substitution trend from internal towards external inputs throughout the socioecological transition from traditional organic agroecosystems to industrialized ones. According to the above interpretation of the different role played by BR and EI, we deem that reusing a relevant share of Land Produce can be related to a high diversity of land covers in the cultural landscape, which in turn increases the number of ecotones and habitats in the agroforestry mosaics of these types of heterogeneous land matrix, as Marull et al. (2010, 2008) pointed out for this same Catalan case and periods, or as been

stated by other authors in different contexts (Murcia 1995, Benton et al. 2003, Tscharntke et al. 2005, Harper et al. 2005, Bianchi et al. 2006, Gustavsson et al. 2007, Fischer et al. 2008b). We presume that this would be true as long as BR constitutes a smooth and repeated intermediate disturbance (as opposite to climax community) that helps to maintain ecological functionality into moderate levels of human ecological disturbance, as suggested by Margalef (2006). This assumption fits with the so-called Intermediate Disturbance Hypothesis (IDH), one of the disputed explanations of the maintenance of biodiversity in ecosystems most debated in ecology (Connell 1978; Van der Maarel, 1993; Wilson, 1994; Padisak 1993; Tilman 1994; Reynolds 1995; Chesson and Huntly 1997; Dial and Roughgarden 1998). Several authors have claimed to apply the IDH to the anthropogenic disturbances exerted by agriculture, forestry and pastoral land-uses as well, either from an ecological (Pickett and White 1985; Fahrig and Jonsen 1998), agroecological (Gliessman 1998) or biological conservation (Pierce 2014) viewpoint. Our set of EROIs aims at helping this line of research, by using energy throughputs as a variable to study how different levels of human disturbance affect the associated biodiversity kept in agroecosystems (Altieri 1999).

According to the above hypothesis, an adequate level of internal biomass reusing like the one usually maintained in many traditional organic farm systems, was able to keep up an intermediate level of landscape complexity that maximized biodiversity maintenance (Tscharntke et al. 2005 and 2012b), and enhanced the agroecosystem resilience as defined by Holling (1973). On the contrary, relying on EI and getting rid of BR have led to monocultures with more homogeneous land covers, thus reducing landscape complexity and lessening the number of habitats and species richness. Hence, our EROI analysis assumes that an increasing dependence on external inputs goes hand in hand with biodiversity loss—as has been tested by other observers (Ruiz-Pérez 1990, Matson et al. 1997, Myers et al. 2000, Sala et al. 2000, Alodos et al. 2004, Stefanescu et al. 2005, Santos et al. 2008, Gerard et al. 2010, Parcerisas et al., 2012, Basnou et al. 2013). This is only a working hypothesis that has to be tested or rejected by the forthcoming research, and our EROI analysis intends to make it possible.

As a preliminary empirical evidence of these underlying assumptions, Table 4 disaggregates the flow of Biomass Reused c.1860 into their main components. It reveals that 58% was vegetal organic matter returned to the soil either fresh or burnt, 2% were seeds and 40% was biomass reused in barnyards as feed, fodder, grass and crop by- products eaten by livestock or straw used in stall bedding. The former was used to keep soil biodiversity and fertility, whereas the latter also contributed to soil fertility through manure and led to high cropland and farmland diversity. The production of fodder and feed involved 14% of cropland area, while at the same time livestock was feed in pastures (7% of farmland area) or in the grass layers below open forests and other uncultivated land, thus helping to maintain agroforestry landscapes mosaics. Besides these direct contributions to belowground associated biodiversity and aboveground diversity of vegetal covers there were others indirect, such as crop rotations, stubble grazing or fallow weed

grazing, which required keeping vegetal hedgerows that in turn enhanced the mosaic pattern in arable land, and so on (Table 4).13

Table 4: Disaggregation of BR (biomass reused) flow in the Catalan case study c.1860. Numbers are in GJ, percentages into parentheses are weight over total BR flow. Source: Part II of this working paper by Marco et al.

Biomass Reused (BR): 237,165 GJ (100%) Farmland Biomass Reused (FBR): 142,154 GJ (60%) Seeds: 3,898 GJ (2%)

Buried biomass from cropland: 95,689 (40%)

Hormigueros: 42,567 GJ (18%) Livestock-Barnyard Biomass Reused (LBBR): 95,011 GJ (40%) Feed: 8,449 GJ (4%) Fodder: 12,418 GJ (5%)

Crop byproducts eaten by livestock: 47,904 GJ (20%) Rough grazing in natural pastures: 13,676 GJ (6%) Straw used in stall bedding: 8,209 GJ (3%) Other from woodland & scrub: 4,355 GJ (2%)

This hypothesis on the significance of BR and the related EROI indicators is a key point of our proposal that requires further research by combining energy analysis with landscape ecology methods (Marull et al, forthcoming a, b and c). As an additional important tool to support this line of research on the funds and functioning that keep up biodiversity in agroecosystems, we propose a further indicator, the NPP EROI, in the next section.