Restoration of Degraded Mediterranean Rangelands

Transcription

1 7 th SER European Conference on Ecological Restoration August, Avignon, France Restoration of Degraded Mediterranean Rangelands Vasilios P. Papanastasis Aristotle University of Thessaloniki, Greece

2 Structure of the presentation 1. Introduction 2. Degradation causes 3. Ecological considerations 4. Restoration potential 5. Restoration measures 6. Case studies 7. Grazing planning 8. Conclusions

3 Introduction Rangelands: marginal lands that are mainly used by domestic and wild animals Mediterranean rangelands: grazing lands that are found in the Mediterranean isoclimatic zone of the Mediterranean basin countries Mediterranean isoclimatic zone: seasonal climate (cool and rainy winters vs hot and dry summers) Degraded rangelands: rangelands that provide forage of limited quantity and quality Restoration: repair rangelands with respect to their health, integrity & self-sustainability (SER 2002)

4 Introduction Total Mediterranean area: 9,1 million km 2 Mediterranean zone (15%): 1,4 million km 2 Rangelands of the Mediterranean zone (49%): km 2 Pastures (38%): km 2 Forests and shrublands (62%): km 2 (FAOSTAT 2008 & Le Houerou 1981)

5 Introduction Livestock Kind of animals: Sheep, goats, cattle and camels Sheep equivalents (in 2008): Whole Mediterranean: 496 millions Mediterranean zone : 121 millions Stocking rate in the Mediterranean zone (sheep equivalents/ha): Global: 1.8 North Mediterranean: 1.1 < grazing capacity South Mediterranean: 3.7 > grazing capacity Conclusion: irrationally grazed rangelands - degraded (FAOSTAT 2008 & Le Houerou 1992)

6 Degradation causes North Mediterranean Rural exodus Urbanization Extensification / abandonment of mountainous rangelands Intensification of animal production in lowlands (indoor feeding) Increased grazing presence on lowlands, especially in animal concentration points Devastated wildfires in rangelands and forests

7 Degradation causes Dense shrubland Wild fires Animal sheds Watering points

8 Degradation causes South Mediterranean Increased rural populations Increased livestock numbers Conversion part of rangelands to croplands Increased grazing presence on the remaining rangelands Rangeland desertification

9 Degradation causes Coastal zone Dry zone

10 Ecological considerations - History of grazing Wild animals of tropical origin Crete: pygmy elephants, hippos, deer (10,000 BC) Cyprus, Sardinia: same animals (6,000 5,000 BC) Disappeared for unknown reasons Killed by people? Competition with domestic animals? Replaced by: Wild animals of temperate origin (e.g. deer, wild goats, wild sheep) Domestic animals Orpheus with wild animals (3 rd century AD)

11 Ecological considerations - History of grazing Livestock in the Mediterranean Eastern Mediterranean: Holocene (10,000 6,000 BC) Crete: Neolithic period (6,000 5,000 BC) Western Mediterranean: Bronze age (3,000 BC) Goats (Kyathos), 5 th Century BC Cattle (mosaic), 3rd century AD Sheep (Kylix), 5th Century BC

12 Ecological considerations - History of grazing Evolution of livestock economy Open and free grazing Sedentary grazing Impact on ecosystems Direct grazing by livestock Opening up of forests to create grazing land Goats the main animal species

13 Ecological considerations - Adaptations of vegetation Spininess Chemical repulsion Acer creticum Thymus capitatus

14 Ecological considerations - Adaptations of vegetation Reproduction Dactylis glomerata Architecture Olea oleander

15 Ecological considerations - Adaptations of vegetation Deep root system Subterranean buds & seeds Paliurus spina-christi Trifolium subterraneum

16 Ecological considerations - Role of goats Browsers Predilection for woody species Make better use of low-protein high-fiber roughage They are also grazers

17 Ecological considerations Fire risk reduction Fires normally start from the ground and spread up to the crown of forests and shrublands Grazing results in reduction of ground fuel and fire risk

18 Ecological considerations - Conservation Grazing results in: keeping up forests open favoring light-liking species Grazing helps maintaining open landscapes

19 Ecological considerations - Grazing management Proper grazing Proper numbers Proper arrangement Proper animal species

20 Ecological considerations - Grazing management Improper grazing Undergrazing Improper animal species Overgrazing

21 Restoration potential Mediterranean rangelands: modified plant communities Two views about their origin: 1. Forestry oriented view Derived from high forests after their destruction by human activities Restoration target They need to be converted to high forests Livestock grazing should be totally banned Rangelands should be wiped out

22 Restoration potential 2. Management oriented view They evolved with humans over the millennia Most rangelands can not return to high forests by natural processes but to some kind of woodlands Woodlands have limited or no grazing capacity Restoration target Livestock grazing should be maintained under controlled management Rangelands should be maintained in order to preserve the heterogeneity of the mediterranean landscape

23 Restoration potential Potential ecosystem Disturbance Desired rangeland Prolonged disturbance Degraded rangeland Irreversible disturbance Desertified rangeland (Aronson et al. 1993, SRM 1995)

24 Restoration potential Desired rangeland or desired plant community Of the several plant communities that may occupy a site, the one that has been identified through a management plan to best meet the plan s objectives for the site (SRM 1995) It can be a state of the state and transition model developed for the particular area It can be described in species life forms or functional groups

25 Restoration potential (Heady & Child 1994)

26 Restoration potential Grazing affects structure function Grazing effects can be Positive Negative Grazing management can be appropriate inappropriate

27 Restoration potential - Positive effects of grazing Grazing assists thinning through sprout control Animal manure improves soil fertility

28 Restoration potential - Negative effects of grazing Chewing up young sprouts or seedlings Soil trampling

29 Restoration potential Two main types of threshold should be crossed in degraded rangelands (Hobbs & Harris 2001) 1. Biotic interactions (e.g. species composition) 2. Abiotic limitations (e.g. soil erosion) Grazing process Can adjust biotic relationships Cannot repair damaged abiotic factors

30 Restoration measures Soft measures Appropriate grazing management Adjusting livestock numbers Selecting the right kind of animals Adopting the proper grazing system

31 Restoration measures Hard measures Technical works for soil erosion Soil fertility restoration Plant species restoration Combined measures

32 Case studies Central Tunisia Arid Mediterranean climate (<350mm rainfall) Rangelands : highly degraded due to overgrazing Restoration target : shrub plantations Restoration project : Stop the erosion Produce forage for livestock Technical works with stones Shrub introduction (alien or indigenous) Community controlled grazing with sheep & goats Restoration measures : hard & soft End results : increased forage production up to 5 t DM / ha (Sarniguet et al. 1995)

33 Central Tunisia Stone wall dam Alien shrubs Stone lines Indigenous shrubs

34 Case studies - South Portugal Semi-arid Mediterranean climate (<600mm rainfall) Degraded agrosilvopastoral systems (montado) with Quercus suber and Q. ilex Traditional land use : rotation of bare fallow wheat oats followed by 6 years grazing Restoration target : sustainable silvopastoral system Restoration project seeding with a mixture of legumes and grasses fertilization appropriate grazing with cattle and sheep Restoration measures : hard & soft End result : increase of stocking rate more than 8 times (Crespo et al. 2002)

35 South Portugal Weed invasion Shrub encroachment Seeded mixture of legumes and grasses

36 Case studies - Northern Greece Sub humid Mediterranean climate (>600mm rainfall) Degraded kermes oak shrublands (too dense & tall) Traditional land use: combining wildfires and overgrazing Restoration target: conversion to open shrublands Restoration project : prescribed burning seeding with a mixture of grasses & legumes appropriate grazing with goats Restoration measures : hard & soft End results : Increase of animal production by more than 4 times (Liacos et al. 1980, Papanastasis & Liacos 1991)

37 North Greece Prescribed burning Dense shrubland Seeding Experimental plan Open shrubland

38 Grazing planning Grazing part of the restoration plan Grazing management should be appropriate Livestock to provide with alternative feed resources during the restoration period Emphasis on communally grazed rangelands Farmers must be involved in the restoration plan Avoid social unrest

39 Conclusions Mediterranean rangelands have a historical trajectory of evolution with the presence of large herbivores Most of the degraded Mediterranean rangelands can be restored to sustainable ecosystems Degraded grazing lands that resulted from inappropriate grazing activities can be restored by grazing management when these activities have not irreversibly damaged their physical environment If the physical environment is damaged then more decisive measures, than simply adjusting grazing management are needed Grazing management should be part of any plan that is implemented to restore degraded rangelands

40 Thank you