An overview of biodiversity conservation in

F. B. Vincent FLORENS

Department of Biosciences University of Mauritius Outline Introducing Mauritius: Basic facts about terrestrial biodiversity

Conservation challenges in Mauritius ± laboratory of / ?

Conservation successes in Mauritius ± laboratory of conservation - ?

Selected case studies of conservation and ecological restoration

Remaining challenges, lessons and conclusions Mauritius

‡ ~ 7.6 MY old ‡ Volcanic island ‡ ~900 km East of ‡ Maximum altitude 828m ‡ 1865 Km2

‡ Discovered by the Portuguese in early 16th Century ‡ Colonised: 1638 Dutch - 1722 French - 1810 British Mauritius (Masacrenes islands)

Myers et al., 2000, Nature 403: 853-585 Mauritius Biodiversity overview

Florens 2013. In Sodhi et al. (eds) Conservation Biology: Voices from the tropics. Biodiversity ± Angiosperms

691 species (39.5 % endemism) Biodiversity - 42 species (33% endemism) Biodiversity- Reptiles 20 species (80% endemism) Biodiversity ± Ecosystems A wealth of different ecosystems from dry coastal vegetation to wet tropical and mossy forests, marshes etc : Symbol of human-caused extinction 6WLOOFORVHWRRXUKHDUWV« 0DQ\H[WLQFWLRQVORVWRIIXQFWLRQV IUXJLYRUHVEURZVHUV« 

1 Roussette 1864 1840 Gibbus Pigeon Hollandais Tropidophora 1914 1826 carinata 1881 Grey Parrot P Schouten 1759 Burrowing boa 1974 Dodo 1700

Ren hen 1693

Raven Parrot 1674

Other paintings J Hume 0 1600 1620 1640 1660 1680 1700 1720 1740 1760 1780 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 Approximate year of extinction rates

100

90

80

70

60

50 of extinction of 40

30

20

Pourcentage d'extinction Pourcentage 10

Percentage 0 PlantesPlants ReptilesReptiles BirdsOiseaux EscargotsSnails From bad to worst.... Habitat destruction (Major cause of extinctions) Minimum viable populations? Habitat fragmentation µ*KRVWRISDVWGHIRUHVWDWLRQ¶

Ahead of the world in terms of habitat destruction and fragmentation

(6RXUFH9DXJKDQDQG:LHKH3DJHDQG'¶$UJHQW 6RXUFH9DXJKDQDQG:LHKH3DJHDQG'¶$UJHQW Predictions rather grim

Ecosystem degradation has been and is predicted to continue to be most rapid in developing or relatively low income countries (Laurance 2001 TREE) Overexploitation: Edible palms

As early as 1638 some native species started to become rare in some areas, like the palmiste blanc in Port Louis

$EDQRQKDUYHVWLQJRI³SDOPHWWRV´ZDVGHFODUHGE\+XJR in 1670 EXWQRWHQIRUFHG« Alien species* (23 serious Animals invader species)

Psidium cattleianum

Feral pig Macaque«.

Lantana camara

* Worst threat on most oceanic islands (Caujape-Castells et al 2010 PPEES) Rate of invasion by alien plants of native forests Extreme invasion by alien plants Understorey heavily dominated by alien plants

11000 Native 10000 Natives Aliens Alien 9000 SORWVRIPðIURPVLWHVZLWKµEHVWSUHVHUYHG¶IRUHVWV) 8000

7000

6000

5000

4000

3000

Number of individuals

2000

1000

0 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5 19.5 >20 Diameter size class (cm) Alien plant invasion progress over 20 years

> 2.5 cm Sites Lorence & This study dbh Sussman ¶V % alien Brise Fer 20.8 27.5 Ï plants Bel Ombre 34.8 60.7 Ï

Native Brise Fer 49 42 “ 7.4 n.s. species Bel Ombre 56 55 “ 7.7 n.s. richness Native Brise Fer 76.2 58 “ 9.1 Ð density Bel Ombre 71.5 63 “ 11.2 Ð (1000 m2) Acute conservation FKDOOHQJHV« Many species on the brink, including CWR

Pandanus pseudomontanus

Hyophorbe amaricaulis Rarest screwpine in the world Rarest species worldwide

Dombeya mauritiana 1 survivor in the wild Conservation Management Areas

All invasive alien plants weeded

Fenced to exclude alien pigs (Sus scrofa) and Java deer (Rusa timorensis) Effect of weeding on woody plants Results: Individual and population level ( grandiflorum ± Tambalacoque) Reproductive output (S. grandiflorum ± µ'RGRWUHH¶

Invasion strongly reduces reproductive output

Flowering is more abundant in areas without alien plants*

(U122,78 = 3520.5; P = 0.002) Fruting is in average 37 times higher in managed areas*

(U140,135 = 6662.5; P< 0.001)

* Baider & Florens (2006) In Laurance & Peres Emerging threats to tropical forests. Chicago Univ Press Growth and mortality of

Higher growth rate in managed (weeded) sites

Mean growth rate/year Site N (cm ± 95%CI)

Non-weeded 125 0.046 ± 0.046

Weeded 155 0.112 ± 0.042

Higher mortality rate on invaded forests

Site N ‚ Mean mortality/year

Non-weeded 140 13 2.7%

Weeded 160 1 0.16% Mean growth rate of all woody native species

Non weeded Weeded

Average Average Number (dbh, mm) -95% 95% Number (dbh, mm) -95% 95%

Brise Fer 795 0.10 0.08 0.12 686 0.58 0.45 0.72

Mare Longue 1353 0.08 0.06 0.11 995 0.44 0.35 0.53 Community changes over 4 years Weeded Not weeded

500 500 2003 450 450 400 400 2007 350 350 300 300 250 250 200 200 150 150

100 100 Brise Brise Fer 50 50 0 0 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10 to 15 to > 20 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10 to 15 to > 20 15 20 15 20

500 500 450 450 400 400 350 350 300 300 250 250 200 200 Number Number of individuals 150 150 100 100 50 50 0 0 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10 to 15 to > 20 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10 to 15 to > 20 MareLongue 15 20 15 20 DBH class (cm) Invasion effect on native Cyathea spp. (tree ferns) Comparison between 1 ha invaded and 1 ha weeded

(Thormann, Baider & Florens unpubl data)

350 Adult 318 Juvenile 300

250

200

150

Individuals/ha 100

50 3 0 0 0 Managed Invaded Large epiphyticInvasion ferns effect on native Cyathea spp. (tree ferns) Comparison between 1 ha invaded and 1 ha weeded

(Thormann, Baider & Florens unpubl data)

350 Adult 318 Juvenile 300

250

200

150

Individuals/ha 100

50 3 0 0 0 (Bindewald, Baider &Managed Florens unpubl) Invaded Population recovery within 24 years

180 Kruskal-Wallis test: H = 154.49; p < 0.001 {0.1ha plots} b 160

140

per ha per 120 Asplenium nidus 100

Asplenium nidus Asplenium 80

60

40

Density adult of 20 a a

0 250 Kruskal-WallisNon-weeded test: Weeded 1996 Weeded 1986 H = 122.73; p < 0.001 {0.1ha plots} b

per ha per 200 Microsorum

150

100

Microsorum punctatum Microsorum a

50 a

Density adult of

0 Non-weeded Weeded 1996 Weeded 1986

Butterflies: Species richness

12.5 Alien-invaded forest 11.5 ) Non-invaded forest 10.5 Tau - 9.5 Mao

( 8.5

7.5

6.5

5.5

4.5

3.5

2.5

1.5

0.5 Estimated species species richness Estimated -0.5 1 5 9 13 17 21 25 29 33 37 41 Cumulative number of transects

Florens et al 2010. Biodiversity and Conservation Butterfly: Abundance Average density of butterfly per transect

Sites Weeded Non-weeded forest forest Bel Ombre (Bellouguet) 6.75 0 Bel Ombre (Fixon) 4.5 0.17 %ULVH)HU µ2OG3ORW¶ 6 0.17 %ULVH)HU µ5DOHLJK3ORW¶ 2.83 0.33 Brise Fer 1 (Low canopy) 6 0.40 Brise Fer 2 (High canopy ) 7.67 0.50 Macchabé 8.75 0.50 Mare Longue 5 0.40 Total 5.94 0.31

Florens et al 2010. Biodiversity and Conservation Abundance of birds Method: Fixed radius point counts, with a radius of 20 m (Hostetler & Main, 2008)

Namah, Baider & Florens unpubl Exclusion fencing as conservation measure

Fenced to exclude alien pigs (Sus scrofa) and Java deer (Rusa timorensis) )HQFLQJDVVXPHGWRZRUN«%XWGLGQRW Influence of pig and deer exclosures 250 Mare Longue Weeded + Fenced 200 Exclosure + alien plants weeding

150

Alien guava fruiting Not weeded + Not fenced 100 season No exclosure, no weeding.

Number of 'live' artificial seedling artificial 'live' of Number 50 Exclosures are ineffective in 0 controlling trampling / 10/1/04 10/2/04 10/3/04 10/4/04 10/5/04 10/6/04 10/7/04 10/8/04 10/9/04 10/1/05 10/2/05 10/3/05 10/11/0310/12/03 10/10/0410/11/0410/12/04 250 Brise Fer uprooting damage by large alien mammals 200

NotNo weeded exclosure, + Not no fenced weeding Seedling numberSeedling 150 Alien guava fruiting 100 season NotExclosure weeded + only Fenced

Number of 'live' artificial seedling artificial 'live' of Number 50

0

18/1/04 18/2/04 18/3/04 18/4/04 18/5/04 18/6/04 18/7/04 18/8/04 18/9/04 18/1/05 18/2/05 18/12/03 Date 18/10/04 18/11/04 18/12/04 Alien rats Rattus rattus and R. norvegicus

Seed predation

Canarium - Burseraceae Mimusops - Predator control

Trap (Macaque) Traps (rat, mongooseFDW«

Poison stations (rat) Predator control: e.g. Hare and rat

$OLHQPDPPDOHUDGLFDWLRQIURPDQRIIVKRUHLVOHW *XQQHU¶V4XRLQ µVSHFWDFXODU¶UHFRYHU\

1500 1982 1350 1993 1200 Hare and rat eradication 2004 1050

900

750

600 Pandanus vandermeeschii Pandanus 450

300

150 Frequency of of Frequency 0 Seedlings and non- Reproductive trees Dead adult trees Screwpine (Pandanus reprodutive trees vandermeeschii) Re-introduction/augmentation programs Mauritius is well known for some conservation successes« < 30 birds 4 birds 18 birds

Now 600 Now 440 Now 450

Captive breeding

Re-introduction

Artificial nests (nest boxes)

Supplementary feeding

Predator control Land analogue species

2008 2002

2010 Restoration sites

Most of the restoration activities and research are however carried out on offshore islets

Native habitats on mainland Mauritius harbor more endemic and threatened species (1-2 orders of magnitude more compared to the islets), deserving far greater conservation attention

Initial alien weed control (Mainly Psidium cattleianum)

Herbicide use:

Cheaper

Less collateral damage

Quickly adopted by private sector Regular maintenance weeding to control re-infestation Harungana madagascariensis (Hypericicaceae)

µ9LHWQDP¶ (1995)

µ9LHWQDP¶ (+ 15 years) 30 U14,14 = 7.5; p < 0.0001 25

20 Min-Max saplings per plot per saplings 25%-75% a 15 n a Median value g n u 10 r a

H 5 0

Number of Before After

14 12 10 8 6 4 2 0

a a s s a a a a a s a s a a a i i a i a a a i n i e t e e i a e r r e e p o l d x g e e f l n o i c m o i s f r l l u p e h a o k a a s s f u e e L y n e n r s o y i e h r L n i n c d g a N t i n p x a p i V t l u e C n d O r s d o i r n n C n H A e o m o u r t u r o n A i i r e a T n c M a a o d A e G M D i d H S W S r u o b a

Mean growth rate in trunk girth (mm/yr) L

Recent policies

Government policy: restrictions of ecological research to `office hours` (08.00- « Plan to cull Endangered species Conclusions

Grim situation attracted considerable conservation efforts (summarized in Jones 2008)

As a result, Mauritius now contributes to the advancement of restoration and conservation science through serving as a laboratory to test various approaches

1. Control of invasive alien plants

2. Control and eradication of invasive alien animals

3. Population reintroduction/augmentation or analogue introduction Conclusions

Many species, including threatened ones, can recover dramatically as a consequence of the sole removal of invasive alien plants.

It does not suffice to set protected areas. Conservation management within these areas is important. Invasions are worsening worldwide, and Mauritius provides a window into the future of other countries.

Our findings also indicate that imminent plant extinctions can be averted by little more than timely control of the invading plants.

Use of evidence-based approach to restoration and conservation is much easier said than done Acknowledgments

The organisers of the workshop for inviting me to present today in particular Ehsan Dulloo, Prof.Jaufeerally-Fakim, Shelagh Kell and Nigel Maxted

Thank you for your attention