Soil–Plant Characterization in Agrosilvopastoral System Established in a Fe-Mn Abandoned Mine After Long-Term Closure

Academic Edi o s: Fe enc Fodo and Mau izio Badiani Recei ed: 20 Sep embe 2024 Re ised: 15 Decembe 2024 Accep ed: 26 Decembe 2024 Published: 27 Decembe 2024 Ci a ion: San os, E.S.; Ab eu, M.M.; Rossini-Oli a, S. Soil–Plan Cha ac e iza ion in Ag osil opas o al Sys em Es ablished in a Fe-Mn Abandoned Mine A e Long-Te m Closu e. Plan s 2025,14, 60. h ps:// doi.o g/10.3390/plan s14010060 Copy igh : © 2024 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion (CC BY) license (h ps://c ea i ecommons.o g/ licenses/by/4.0/). A icle Soil–Plan Cha ac e iza ion in Ag osil opas o al Sys em Es ablished in a Fe-Mn Abandoned Mine A e Long-Te m Closu e E ika S. San os 1,* , Ma ia Manuela Ab eu 1and Sabina Rossini-Oli a 2 1LEAF—Linking Landscape, En i onmen , Ag icul u e and Food Resea ch Cen e , Associa e Labo a o y TERRA, Ins i u o Supe io de Ag onomia, Uni e sidade de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Po ugal; [email p o ec ed] 2Depa men o Plan Biology and Ecology, Uni e sidad de Se illa, A da. Reina Me cedes S/N, 41080 Se ille, Spain; [email p o ec ed] *Co espondence: [email p o ec ed]; Tel.: +351-213653446 Abs ac : Small abandoned mining a eas o Fe and Mn oxides loca ed in he Po uguese sec o o he Ibe ian Py i e Bel (SW o Eu ope) ha e been con e ed in o ag osil opas o al sys ems wi h e y ew en i onmen al managemen measu es a e hei closu e. Al hough a he landscape scale, no isible di e ences we e obse ed be ween he o me mining in e en ion a eas and adjacen a eas, i is essen ial o assess he s a e and en i onmen al isk o he soil–plan sys em, especially in he he baceous pas u es g azed by domes ic animals. This was ca ied ou in he Fe agudo mining a ea, whe e an ag osil opas o al sys em, composed o holm oak and d yland pas u e, had been es ablished a e he closu e o he mine a ≈ 45 yea s. The soils p esen ed neu al pH and a iable e ili y deg ee. The pseudo- o al soil concen a ions o Cu, Mo, and Zn exceeded he Po uguese limi alues es ablished o ag icul u e use (>180 mg Cu/kg; >8.2 mg Mo/kg; 349 mg Zn/kg), bu hei soil a ailable ac ions we e small (<8.4% o he pseudo- o al concen a ions). T ees and he baceous plan s showed good de elopmen , and he concen a ions o he elemen s (excep Mn) we e conside ed no mal o su icien . Fo Mn, mos o he plan samples exceeded phy o oxic Mn alues, bu no isual signs o phy o oxici y we e obse ed. Only he concen a ions o Fe and K in he shoo s o some he baceous samples exceeded he maximum ole able le els o ca le and sheep, so he isk o animals can be conside ed small since o he sou ces a e p esen in animal eed. In gene al, his ag osil opas o al sys em did no pose a signi ican en i onmen al isk. Keywo ds: d yland pas u e; he baceous co e ; holm oak; biogeochemical cha ac e iza ion; en i onmen al isk 1. In oduc ion Mining ac i i ies a ec app oxima ely 4 × 10 5 km 2 o land wo ldwide [ 1 ] and can lea e a deg aded a ea i en i onmen al managemen issues a e no conside ed du ing and a e closu e. Ancien mining ac i i y in he Po uguese sec o o he Ibe ian Py i e Bel (PIPB, SW o Eu ope) has led o se e al en i onmen al p oblems due o he exis ence o e y ew (i any) measu es o manage and minimize en i onmen al o human heal h isks [ 2 , 3 ]. In Po ugal, un il he XX h cen u y, he e was no legal obliga ion o ehabili a e land a e he closu e o mines. Thus, in some small/medium abandoned mines, he i s pos -closu e ac i i ies we e ocused on he dispe sion o mine was es wi h/wi hou mixing wi h na u al soils. Some o hese a eas we e econ e ed o ag icul u e, pas o alism, Plan s 2025,14, 60 h ps://doi.o g/10.3390/plan s14010060 Plan s 2025,14, 60 2 o 13 o es y, o a combina ion o hese (ag osil opas o al sys ems) by he local popula ion and he na ional en i y esponsible o en i onmen al ehabili a ion (Exmin), as well as le o na u al plan coloniza ion. Independen ly o he high o al concen a ions o po en ially haza dous elemen s in soils om PIPB mining a eas, he a ailable ac ion is usually low, allowing he de elopmen o some plan species [ 2 , 4 ]. In ac , some abandoned mining a eas (e.g., mining a eas o Mn and Fe oxides) ha e been classi ied as ha ing low/medium en i onmen al isk [ 3 , 5 ], and no ob ious landscape-scale di e ences ha e been obse ed be ween he o me mining in e en ion a ea and adjacen a eas. Al hough he en i onmen al eco e y p ocesses associa ed wi h plan de elopmen (na u al a enua ion and phy os abiliza ion) a e slow, especially in con amina ed a eas, hese can con ibu e o imp o ing soil quali y [ 6 , 7 ] and minimizing land deg ada ion. The imp o emen o soil quali y by plan s depends, o example, on he species, he s a a ype (he baceous, sh ubs, and ees), he ype o oo sys em, and i s de elopmen . In addi ion, ege a ion de elopmen can imp o e soil s uc u e and e ili y, p omo e biological ac i i y, and inc ease wa e e en ion capaci y [8]. The ag osil opas o al sys em is a ype o land use ha combines pas u e o odde p oduc ion wi h a woody componen o sh ubs and ees, wi h di e en li es ock com- plemen ing each o he in he same a ea [ 9 , 10 ]. This in eg a ed sys em can con ibu e o se e al en i onmen al bene i s and ecosys em se ices, such as educing soil deg ada ion o e en imp o ing some soil p ope ies and inc easing C s ocks, hus ensu ing odde a ail- abili y a leas du ing he ainy season [ 9 – 11 ]. Al hough he e ec o seasonali y is mo e p onounced in d yland sys ems, he combina ion o legume and g ass species, pe ennial and annual he baceous species, sh ubs, and ees p omo es complemen a i y, sus ainabili y, and esilience o he sys em. Acco ding o di e en cha ac e is ics o soils and in insic plan s, plan s g owing in con amina ed soils may up ake and accumula e di e en le els o po en ially haza dous elemen s in edible pa s [ 12 , 13 ]. This can lead o a po en ial isk o human and animal heal h when he plan s a e consumed; he e o e, an assessmen o he elemen al composi ion o he plan s is needed be o e making a decision on land use. In his sense, he bioaccumula ion o elemen s in he soil–plan –animal sys em has been s udied by some au ho s [ 14 – 18 ]. The aim o his s udy was o e alua e he gene al s a us and po en ial en i onmen al isk o he soils and plan s (he baceous shoo s o he d yland pas u e and holm oak lea es) in an ag osil opas o al sys em es ablished in a Fe-Mn mine om Po ugal a e long- e m closu e (≈45 yea s ago). 2. Resul s and Discussion This s udy p esen s a gene al e alua ion o he quali y o soils and plan s g owing in an ag osil opas o al sys em es ablished ≈ 45 yea s a e he closu e o he Fe agudo mine (Figu e 1A,B). Soils om he holm oak a ea a e unde he in luence o he baceous and ee hizosphe e sys ems and canopy, while soils om he pas u e a ea ha e only he baceous oo s. Independen ly o he a ea sampled (designa ed as holm oak o he baceous pas u e) and dep h, he soils had neu al pH alues and a sligh ly acid eac ion, indica ed by he pH in KCl, wi h low elec ical conduc i i y (Table 1) being conside ed non-saline soils. These pa ame e alues coincide wi h e y low o al acidi y (Table 1), co esponding o he concen a ion o Al and H + in he exchangeable complex o he colloidal ac ion. The concen a ions o o ganic C and nu ien s (Table 1) showed some a iabili y. Thus, he concen a ions o o ganic C and ex ac able P a ied om e y small (4.4 g C o g /kg and <10 mg P/kg) o e y high (>60 g C o g /kg and >90 mg P/kg), while ex ac able K was Plan s 2025,14, 60 3 o 13 mainly conside ed as high o e y high [ 19 , 20 ]. Ca ion exchange capaci y was conside ed be ween medium o high (10–40 cmol c /kg [ 15 ]) and was co ela ed o o ganic C amoun s ( ≈0.8 ,p< 0.05). The exchangeable complex was domina ed by Ca. In soils collec ed unde holm oak ees, he concen a ions o o ganic C, N o al, and ex ac able K and P dec eased signi ican ly wi h dep h (Table 1) because mos o he oo s a e loca ed be ween 10 and 20 cm dep h, and mos o he elemen up ake occu s. Plan s 2025, 14, 60 3 o 13 <10 mg P/kg) o e y high (>60 g Co g/kg and >90 mg P/kg), while ex ac able K was mainly conside ed as high o e y high [19,20]. Ca ion exchange capaci y was conside ed be ween medium o high (10–40 cmolc/kg [15]) and was co ela ed o o ganic C amoun s ( ≈ 0.8, p < 0.05). The exchangeable complex was domina ed by Ca. In soils collec ed unde holm oak ees, he concen a ions o o ganic C, N o al, and ex ac able K and P dec eased significan ly wi h dep h (Table 1) because mos o he oo s a e loca ed be- ween 10 and 20 cm dep h, and mos o he elemen up ake occu s. Figu e 1. Ag osil opas o al sys em es ablished in Fe agudo mine a ea (A,B) and collec ion o soil samples (C,D). The s udied soils p esen ed highe e ili y, e alua ed by he concen a ions o o - ganic C and NPK, han he Spolic Technosols collec ed in a simila mining a ea (Rosalga ) and he uncon amina ed soils o he egion, bo h na u ally colonized by au och honous ege a ion [4,21]. This may indica e a di ec posi i e effec o soil managemen , possibly wi h some e ilize applica ion o he whole su ace and/o he ag osil opas o al sys em i sel . The imp o emen o soil e ili y in he ag osil opas o al sys ems due o he in- c ease in nu ien s and o ganic ma e inpu s has been epo ed [22]. The soils unde he holm oak canopy did no show a simila ichness in o ganic ma e and nu ien s as hose ou side he canopy (Table 1), which is no usually obse ed [10,23]. In semi-na u al sys- ems wi h holm oak (dehesa), he ee co e leads o an inc ease in soil e ili y due o he A B C D Figu e 1. Ag osil opas o al sys em es ablished in Fe agudo mine a ea (A,B) and collec ion o soil samples (C,D). The s udied soils p esen ed highe e ili y, e alua ed by he concen a ions o o ganic C and NPK, han he Spolic Technosols collec ed in a simila mining a ea (Rosalga ) and he uncon amina ed soils o he egion, bo h na u ally colonized by au och honous ege a ion [ 4 , 21 ]. This may indica e a di ec posi i e e ec o soil managemen , possibly wi h some e ilize applica ion o he whole su ace and/o he ag osil opas o al sys em i sel . The imp o emen o soil e ili y in he ag osil opas o al sys ems due o he inc ease in nu ien s and o ganic ma e inpu s has been epo ed [ 22 ]. The soils unde he holm oak canopy did no show a simila ichness in o ganic ma e and nu ien s as hose ou side he canopy (Table 1), which is no usually obse ed [ 10 , 23 ]. In semi-na u al sys ems wi h holm oak (dehesa), he ee co e leads o an inc ease in soil e ili y due o he accumula ion o some allen lea es and he educed decomposi ion o o ganic ma e in he shaded a ea unde he ee c owns [10,11,23]. Plan s 2025,14, 60 4 o 13 In gene al, he e was no g ea he e ogenei y in he chemical cha ac e is ics o he soils om holm oak and he baceous pas u e co e (Table 1), al hough alues ou side he main ange we e ob ained o some samples (e.g., ex ac able K in a sample om he baceous co e ; ex ac able P in a supe icial sample om holm oak; o al N in a sample om holm oak a he second dep h). Al hough a a ia ion in soil pa icle size dis ibu ion associa ed wi h he i egula disposal o mine was es (e.g., slags) was isually obse ed (Figu e 1C,D), no he e ogenei y in soil chemical cha ac e is ics was ob ained. This small a ia ion in he chemical cha ac e is ics can be ela ed o he con inuous soil managemen since he mine closu e, which allowed he mixing o di e en mine ma e ials (e.g., slags and o he mine was es, hos ocks) wi h na u al soil and he es ablishmen o a chemical equilib ium o e ime. Table 1. Physicochemical cha ac e is ics o he soils, collec ed unde he holm oaks canopy and he baceous pas u es wi hou ee co e in he ag osil opas o al sys em es ablished in he Fe agudo mining a ea a e closu e (minimum–maximum; mean ± SD; n = 8). Fo each pa ame e , alues om holm oak samples wi h an as e isk indica e signi ican di e ences be ween dep hs. Holm Oak 0–10 cm Holm Oak 10–20 cm He baceous Pas u e 0–20 cm pHH2O 6.4–7.2 6.8 ±0.3 6.2–6.9 6.6 ±0.3 5.7–6.8 6.4 ±0.4 pHKCl 5.3–6.8 5.9 ±0.5 * 4.5–5.7 5.1 ±0.5 * 4.7–6.0 5.5 ±0.4 EC 1(µS/cm) 109–360 211 ±76 * 40.1–174 83.8 ±45 * 114–221 152 ±38 O ganic C (g/kg) 28.2–89.1 45.1 ±20.1 * 4.4–28.2 12.9 ±7.5 * 20.4–87.9 42.4 ±23.0 To al N (g/kg) 2.2–4.8 3.0 ±0.9 * 0.3–2.7 1.2 ±0.7 * 1.4–5.0 2.9 ±1.2 Ex ac able K (mg/kg) 120–523 354 ±122 * 41.5–147 101 ±38 * 4.2–498 297 ±195 Ex ac able P (mg/kg) 8.3–69.9 34.3 ±17.4 1.2–91.7 37.0 ±29.9 13.2–101 50.9 ±42.6 CEC2and exchangeable ca ions (cmolc/kg) CEC 217.5–49.0 29.2 ±9.4 8.9–25.4 18.3 ±6.2 14.6–30.2 24.0 ±5.7 Ca 10.9–44.1 21.2 ±10.5 * 3.2–15.6 10.3 ±5.1 * 12.8–20.4 17.2 ±3.2 Mg 3.7–8.6 6.8 ±1.8 4.2–9.1 7.1 ±1.9 0.3–9.5 5.7 ±3.1 Na 0.4–0.7 0.5 ±0.1 0.3–0.8 0.6 ±0.2 0.2–0.7 0.4 ±0.2 K0.3–0.9 0.6 ±0.2 * 0.1–0.3 0.2 ±0.1 * 0.3–0.9 0.6 ±0.2 To al acidi y 0.1–0.2 0.1 ±0.1 0.1–0.2 0.1 ±0.1 0.1–0.3 0.2 ±0.1 1Elec ical conduc i i y; 2ca ion exchange capaci y. Soils om bo h plan sys ems had concen a ions o Cu, Mo, and Zn in he pseudo- o al ac ion (Table 2) ha exceeded he e e ence alues p oposed by Po uguese legisla ion o shallow soils and ag icul u al use (180 mg Cu/kg; 6.9 mg Mo/kg; 340 mg Zn/kg [ 24 ]). Special a en ion should be paid o Mo, whose concen a ions we e 10 imes highe han he e e ence alue. Fo B, only e y ew soil samples exceeded he e e ence alue indica ed in he same legisla ion (120 mg/kg [ 24 ]). Mo eo e , he pseudo- o al concen a ions o Ca, Cu, P, Mg, and Mn in he Fe agudo soils we e clea ly highe han hose ound in soils Plan s 2025,14, 60 5 o 13 collec ed om a simila mining a ea in he Ce cal-Odemi a egion (Rosalga mine), whe e he o ebody also comp ised ein s uc u es o Fe and Mn oxides, bu he a ea is domina ed by na u al and au och honous ege a ion [ 4 ]. Concen a ions o Cu, Mn, and Zn we e also highe han hose ound in uncon amina ed soils o he egion [ 21 ]. Concen a ions o Na in he sampled soils we e somewha high. Table 2. Pseudo- o al concen a ions o chemical elemen s in soils, collec ed unde holm oaks canopy and he baceous pas u es wi hou ee co e in he ag osil opas o al sys em es ablished in he Fe agudo mining a ea a e closu e (minimum–maximum; mean ± SD; n = 8). Fo each elemen , alues om holm oak samples wi h an as e isk indica e signi ican di e ences be ween dep hs. Elemen s Holm Oak 0–10 cm Holm Oak 10–20 cm He baceous Pas u e 0–20 cm g/kg Ca 4.2–14.3 7.1 ±3.2 * 0.8–5.9 3.9 ±1.8 * 3.2–7.1 5.7 ±1.4 K2.0–3.8 3.0 ±0.6 * 1.1–2.6 2.1 ±0.5 * 1.9–3.8 3.0 ±0.7 Mg 4.1–6.1 5.1 ±0.8 3.8–7.2 5.3 ±1.4 3.5–9.2 5.2 ±1.9 P0.5–1.2 0.7 ±0.2 0.3–1.2 0.6 ±0.3 0.5–1.3 0.8 ±0.3 S0.6–0.8 0.7 ±0.1 * 0.1–0.6 0.4 ±0.2 * 0.6–0.8 0.7 ±0.1 Fe 35.0–82.9 48.5 ±16.5 35.0–93.2 56.9 ±20.1 34.5–80.1 47.6 ±16.9 Mn 27.9–115 88.4 ±28.4 15.2–110 68.8 ±31.3 36.7–124 86.1 ±29.2 mg/kg B66.4–149 91.6 ±28.9 59.1–157 101 ±32.6 59.5–141 88.7 ±29.4 Cu 121–462 302 ±106 124–572 315 ±179 106–446 246 ±116 Mo 35.7–126 92.9 ±27.3 8.2–127 73.3 ±40.9 21.9–177 87.4 ±47.7 Na 364–1730 1207 ±443 294–1421 861 ±374 372–2093 1132 ±576 Zn 162–734 433 ±168 189–941 497 ±276 157–982 409 ±266 Al hough he high concen a ions o some o hese elemen s in he pseudo- o al ac ion can be associa ed wi h he mine was es inco po a ed in na u al soils (e.g., Mn and Cu), amoun s o nu ien s such as Ca, P, and Mg (Table 2) can sugges he applica ion o amendmen s o p omo e pas u e de elopmen . In ac , hese concen a ions, as well as he con en s o exchangeable Ca and Mg, o al N, and ex ac able P de e mined in he s udied soils (Table 1), we e much highe compa ed o hose in uncon amina ed soils om he egion and no used o ag icul u al pu poses [21]. E en i he pseudo- o al concen a ions o he elemen s in he Fe agudo soils we e high (Table 2), he soil a ailable ac ions o he same elemen s, co esponding o he elemen s in soil solu ion and e ained in he exchangeable complex o colloidal ac ions, we e gene ally low (<8.4% o he pseudo- o al concen a ions; Table 3). Excep ions we e ob ained o Ca in all soils and Na in some soil samples unde oak ees (Ca 11–35% and Na 9.7–22% o pseudo- o al concen a ions; Table 3). The a ailable ac ion o hese elemen s, as well as Mg, was co ela ed wi h hei pseudo- o al concen a ions ( > 0.80, p < 0.05). The a ailabili y o Ca in holm oak soils also seems o be ela ed o he o ganic C con en ( ≈ 0.86, p< 0.05). Fo he o he elemen s, no co ela ions we e ound be ween Plan s 2025,14, 60 6 o 13 he concen a ions in he soil a ailable ac ion and pH, o ganic C concen a ions, and pseudo- o al concen a ions. Table 3. Concen a ions o chemical elemen s in he a ailable ac ion o soils, collec ed unde holm oaks canopy and he baceous pas u es wi hou ee co e , in he ag osil opas o al sys em es ablished in he Fe agudo mining a ea a e closu e (minimum–maximum; mean ± SD; n = 8). Fo each elemen , alues om holm oak samples wi h an as e isk indica e signi ican di e ences be ween dep hs. Elemen s mg/kg Holm Oak 0–10 cm Holm Oak 10–20 cm He baceous Pas u e 0–20 cm Ca 455–2025 1031 ±445 * 266–903 602 ±256 * 730–960 840 ±83.1 K15.8–54.9 34.0 ±12.8 * 8.9–46.9 18.4 ±13.09 * 8.4–73.2 44.0 ±22.7 Mg 268–430 370 ±65.5 266–431 352 ±66.5 204–478 326 ±86.8 P3.5–8.1 5.6 ±1.5 2.2–14.1 5.3 ±4.4 1.0–18.8 7.5 ±7.2 S12.1–19.3 16.1 ±2.4 * 6.3–15.0 10.1 ±3.0 * 10.1–16.7 12.4 ±2.1 Fe 6.7–37.2 17.2 ±11.4 7.5–136 41.6 ±44.2 3.6–57.2 18.0 ±18.8 Mn 25.9–554 398 ±169 * 493–791 619 ±103 * 297–573 442 ±93.5 B0.5–1.4 1.1 ±0.3 * 0.2–1.1 0.6 ±0.3 * 0.2–0.5 0.4 ±0.1 Cu 0.1–0.7 0.4 ±0.2 * 0.1–3.6 1.3 ±1.2 * 0.1–0.6 0.3 ±0.2 Na 64.4–142 92.6 ±23.6 43.1–140 101 ±34.6 30.5–150 66.8 ±40.5 Zn 0.2–3.6 1.9 ±1.0 0.8–5.1 3.0 ±1.4 0.9–4.4 2.0 ±1.3 In soils unde holm oak ees, he a ailable ac ion o K, S, and B dec eased signi i- can ly wi h dep h (Table 3), simila o elemen s shown in Table 2, jus i ying he dec ease in he EC in he same pa e n. Howe e , he concen a ions o Cu and Mn in he same ac ion inc eased wi h dep h. Dehyd ogenase ac i i y is an impo an indica o o he unc ionali y o he o e all soil mic obial communi y, as i is an in acellula enzyme p esen in all li ing o ganisms and o ganic ma e decomposi ion [ 25 ]. The s udy soils showed g ea he e ogenei y in he dehyd ogenase ac i i y, independen ly o plan sys em and dep h (Table 4). In soils unde holm oak ees, he enzyma ic ac i i y dec eased signi ican ly wi h he dep h. The lowes dehyd ogenase ac i i y (0.2 µ g TPF. g .16 h −1 ) was ob ained in a soil sample collec ed be ween 10 and 20 cm dep h unde holm oak plan s, which also p esen ed he lowes N concen a ion (0.3 g/kg). Al hough soil dep h may con ibu e o a dec ease in dehyd ogenase ac i i y due o a possible dec ease in ae a ion, o he soil physicochemical cha ac e is ics may in luence dehyd ogenase ac i i y [ 26 ]. In ac , he enzyma ic ac i i y in soils unde holm oaks was ela ed o wo impo an nu ien s in he soil sys em, o al N ( ≈0.85 ,p< 0.01) and a ailable S ( ≈ 0.93, p< 0.01), as well as o ganic C con en ( ≈ 0.79 p< 0.01). Plan s 2025,14, 60 7 o 13 Table 4. Ac i i y o dehyd ogenase in soils collec ed unde holm oaks ees canopy and he baceous pas u es wi hou ee co e in he ag osil opas o al sys em es ablished in he Fe agudo mining a ea a e closu e (minimum–maximum; mean ± SD; n = 8). Values om holm oak samples wi h an as e isk indica e signi ican di e ences be ween dep hs. µg TPF. g .16 h−1 Holm Oak 0–10 cm Holm Oak 10–20 cm He baceous Pas u e 0–20 cm 29.2–172 93.8 ±51.0 * 0.2–85.6 22.6 ±28.7 * 36.1–216 90.4 ±71.5 Dehyd ogenase ac i i ies in soils om he baceous oo sys ems (Table 4) we e in he same ange as hose in he su ace laye o holm oak soils and also co ela ed wi h o al N concen a ion in he soils ( = 0.89, p< 0.01). The ag osil opas o al sys em included a low densi y o holm oak (Que cus ilex L.), wi h good de elopmen and a con inuous he baceous co e o signi ican densi y. This he baceous co e was mainly composed o species o he gene a T i olium,Silene,Plan ago, An hemis,O ni hopus, and di e en species o he amily Poaceae. No isual di e ences we e obse ed in he composi ion o he baceous di e si y and plan co e depending on soil cha ac e is ics. A he landscape scale, he e we e some small a eas, andomly sca e ed, wi h au och honous sh ub species belonging mainly o he genus Cis us. In gene al, no signi ican changes we e obse ed in he landscape o he mine a ea, which is simila o he adjacen a eas and o he ag osil opas o al sys ems in he egion. Al hough he a ailabili y o elemen s in soil a ec s hei concen a ions in plan s, o he p ocesses can occu in he soil-plan sys em (e.g., an agonism o syne gism be ween elemen s, limi a ion o oo up ake, wa e a ailabili y, and plan species [ 12 , 13 ]). Mo eo e , in mode n pas u e sys ems, he elemen al composi ion o plan s, especially mac onu ien s, can be mo e ela ed o e ilize applica ion [27] han o hei a ailabili y in he soil. In he s udy a ea, independen ly o he concen a ion o he elemen s in he a ailable ac ion o he soil, di e en accumula ion pa e ns we e ob ained acco ding o he elemen and he plan sys em (Table 5). The shoo s om he he baceous pas u e showed he highes concen a ions o elemen s, excep Mn, compa ed o he lea es o he holm oak. In ac , he accumula ion o elemen s in shoo s/lea es depends on he species, being a combined esponse o he up ake and ansloca ion capaci y o he plan s and he concen a ion o elemen s in he a ailable ac ion o he soil [ 12 ]. Mo eo e , o Mn, in e ac ions be ween elemen s a he oo le el and an agonis ic eac ions wi h Cu, Zn, and/o Fe can occu [ 13 ]. Concen a ions o Cu, Fe, and Zn in bo h plan sys ems we e conside ed no mal o su icien o plan s in gene al, while mos o he plan samples exceeded phy o oxic le els (400 mg Mn/kg [ 13 ]) o Mn. Howe e , no isual signs o Mn phy o oxici y we e obse ed (e.g., chlo osis and nec o ic pa s in old lea es, blackish-b own o ed nec o ic pa s, and c ying lea ips [ 13 ]). In gene al, ees o he genus Que cus a e epo ed o be accumula o s o Mn in lea es [ 28 ], al hough he speci ic concen a ion depends on he species and eda oclima ic condi ions. In s udies ca ied ou on holm oaks g owing in na u al a eas and u ban pa ks in he egions o Campania and Flo ence (I aly), Mn concen a ions in he lea es we e lowe han hose ob ained in he p esen s udy [ 29 , 30 ]. The highe ole ance o plan s o Mn in Fe agudo, since no isual phy o oxic signs we e obse ed, can be ela ed o his plan popula ion. In ac , popula ions o se e al plan species (e.g., Cis us and La andula genus) g owing in mining a eas o he Ibe ian Py i e Bel show highe concen a ions o elemen s in plan issues compa ed o hose om uncon amina ed a eas, wi hou any phy o oxic e ec , due o e icien ole ance and an ioxidan mechanisms [21,31–33]. Plan s 2025,14, 60 8 o 13 Table 5. Concen a ions o chemical elemen s in oak lea es and shoo s o he baceous pas u e collec ed in he ag osil opas o al sys em es ablished in he Fe agudo mining a ea a e closu e (minimum– maximum; mean ± SD; n = 8). Values o he same elemen wi h an as e isk indica e signi ican di e ences be ween plan s. Elemen s Holm Oak Lea es He baceous Pas u e g/kg Ca 3.9–5.9 4.7 ±0.6 * 3.8–9.8 6.7 ±1.9 * K4.2–6.8 5.3 ±0.9 * 13.5–24.0 20.0 ±0.4 * Mg 1.4–1.9 1.6 ±0.2 * 2.4–4.0 3.3 ±0.5 * N14.9–19.6 17.1 ±1.7 * 19.9–28.4 23.4 ±2.7 * P1.0–1.5 1.3 ±0.2 * 2.5–4.0 3.4 ±0.6 * mg/kg Fe 149–251 183 ±33 * 154–767 384 ±222 * Mn 197–2273 1429 ±677 * 197–755 469 ±197 * Cu 8.2–20.5 11.7 ±4.4 7.6–14.0 10.6 ±2.2 Na 78.9–272 189 ±67.6 * 1611–7732 3892 ±1939 * Zn 24.6–33.4 28.0 ±2.8 * 35.6–55.8 43.1 ±7.6 * Al hough no s ong co ela ion be ween Mn concen a ion in he a ailable soil ac ion (o pseudo- o al ac ion) and plan s was ob ained, i is e iden ha he a ailabili y o his elemen in soil is high (Table 3) and should ha e some ela ionship wi h Mn plan amoun s. Concen a ions o o he elemen s (N, P, K, Mg, Cu, Fe, and Zn) in holm oak lea es we e in he same ange as hose collec ed in di e en loca ions, land uses, and soils ([ 29 , 30 , 34 ] and e e ences he ein). Acco ding o he same au ho s, he N:P a io in lea es, conside ed a use ul nu i ional indica o o plan s, is e y a iable. The alues calcula ed in he p esen s udy a ied be ween 10 and 16, which a e in he same ange as hose epo ed by he p e ious au ho s o he same species. Howe e , hese a ios may indica e N o P nu ien limi a ion depending on he sample (in gene al, N:P < 14 indica es N limi a ion, and N:P a io > 16 indica es P limi a ion [35]). The s udied a ea is an ag osil opas o al sys em whe e he soils had inco po a ed mine was es, so i is impo an o assess he isk o consump ion o he baceous ege a ion by domes ic animals. Acco ding o Mine al Tole ances o Animals [ 36 ], he shoo s o he he baceous pas u e g owing in some o he sampled a eas had concen a ions o Fe (660.5 and 767.3 mg/kg) and K (21.1–24.0 g/kg) ha exceeded he maximum ole able le els (MTL) based on indices o animal heal h o ca le and sheep (500 mg Fe/kg and 20 g K/kg ). Al hough he absolu e alues o hese samples may indica e some cau ion, he mean alues o all he baceous pas u es sampled we e below (384 mg Fe/kg) o a he limi (20 g K/kg) o he MTL. Fu he mo e, Fe and K a e elemen s ha a e conside ed o cause mode a e ad e se e ec s in animals when o e ed o long pe iods o ime [ 37 ]. Thus, i was conside ed ha he heal h conce n may also be low due o he exis ence o dilu ion ac o wi h shoo s consumed in adjacen a eas and o he ood sou ces p o ided o he animals. In ac , he die o ca le is no limi ed o he baceous ma e ial om he s udy a ea. Being a d yland pas u e, he amoun o pas u e p oduced is no su icien a any ime o he yea , and a me s need o buy pas u e o silage om o he o igins. Plan s 2025,14, 60 9 o 13 Mo eo e , i is epo ed by [ 36 ] ha K and Fe concen a ions in some o ages can each highe alues (>50 g K/kg and 700–800 mg Fe/kg). Simila o he o he ypes o plan s, elemen concen a ions in o ages can a y wi h species and a ie y, g ow h s age, c op managemen p ac ices, and seasons [ 12 , 27 , 38 , 39 ]. The e o e, he isk o consump ion by domes ic animals can be conside ed low. Simila esul s ha e been ob ained in pas u es g own on eco e ed mining was es om high moun ain a eas [40]. 3. Ma e ials and Me hods 3.1. Si e Desc ip ion Fe agudo is an abandoned mine ( ≈ 38 ha) loca ed in he Beja dis ic (37 ◦ 38 ′ 9 ′′ no h, 8 ◦ 3 ′ 58 ′′ wes ), which is pa o he Po uguese sec o o he Ibe ian Py i e Bel [ 3 ]. The o ebody, which o ms s a i o m and ein s uc u es (small o medium dimension), consis s o Fe and Mn oxides (py olusi e) and Mn ca bona es ( hodoch osi e and hodoni e) and was in ensi ely exploi ed in he o ies and i ies o he wen ie h-cen u y, bo h in wells and galle ies up o 40 m dep h and in open pi . The exploi a ion o he o ebody began in 1875 and ended in 1970, mainly due o he closu e o he o e p ocessing company. The Mn-oxides and ca bona es p oduced concen a es wi h 50 and 38–48% Mn, espec i ely [41,42]. The en i onmen al haza d impac o he Fe agudo mining a ea was conside ed in e media e (le el h ee, whe e le el i e is conside ed wi h ex eme impac ) due o he small olume o mine was es wi h ela i ely low o al concen a ions o po en ially oxic elemen s, excep o Mn [ 3 ]. A e he closu e, he in e en ions in he a ea esul ing om he mining ac i i y led o he sp ead o mine was es o e he opog aphic su ace, which con ibu ed o he al e a ion o pedogenesis p ocesses in soils de eloped on di e en ma e ials, depending on he a ea (e.g., mine was es o a mix u e o mine was es, hos ocks, and na u al o me soils), and sowing o he baceous plan s. The land use o he a ea included g azing and o es y [3]. In ecen decades, Fe agudo mining a ea has been an ag osil opas o al sys em ex en- si ely managed, which includes holm oak (Que cus ilex L.), wi h low densi y, spaced by a homogeneous and dense co e age o a biodi e se pas u e composed mainly o species om amilies Poaceae and As e aceae (Figu e 1A,B). Al hough some spon aneous species can ex- is in he pas u e land, mos o hem we e sown. In e y limi ed a eas, especially wi h high s oniness, he e a e pa ches o au och honous sh ubs wi h Cis us and La andula species. Soils om some a eas wi hin he s udy a ea a e classi ied as Spolic Technosols [ 43 ]. The na u al soils in he a ea adjacen o he mine a e classi ied as Lep osols ([ 43 ], co esponding o “Li ossolos” in he Po uguese soil classi ica ion [44]). Acco ding o he Köppen classi ica ion, he egion has a Medi e anean clima e (Csa), wi h ho (a e age 23 ◦ C) and d y summe s ( he d ies mon h wi h an a e age o 3 mm ain all) and mode a ely cold (a e age 10.8 ◦ C) and we win e s. The annual ain all (a e age 572 mm) occu s mos ly in win e wi h an i egula pa e n (Clima ogical no mal 1971–2000, Beja s a ion [45]). 3.2. Sample Collec ion and Analysis Due o he unclea de ini ion o he bounda ies o he old mining a ea, he p esen s udy selec ed wo zones a ound he all open-pi whe e he con amina ion le el may be highe . The zones we e pas u e a ound holm oaks whe e he e was a s ong in luence o ee canopy and oo s (he ea e e e ed o as holm oak a ea) and he baceous pas u e wi hou ee co e whe e he e was no in luence o holm oaks (he ea e e e ed o as pas u e a ea). Eigh plo s we e selec ed in each zone (n = 16 plo s in he o al s udy a ea). In he sp ing, composi e soil samples (composed o i e subsamples; Figu e 1C,D) and he co esponding plan samples we e collec ed in each plo .