19552768 Aripo Savannas Case Study PDF

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THE CROPPER FOUNDATION

As Aripo savanna In this case study:

The Aripo Savannas The Aripo Savannas are a natural savanna ecosystem situated between the Northern and Central Ranges in Trinidad. In August 2007, the Aripo Savannas and some of the surrounding forest ecosystems were given the designation of Environmentally Sensitive Area (ESA) under the ESA Rules 2001. The Aripo Savannas Environmentally Sensitive Area (ASESA) includes - in addition to the savanna ecosystems - marsh forest and palm marsh. This case study will focus on the ASESA.

Section 1

Table 1: A recent history of activity in the ASESA

History & Background 2

Many of the descriptions of the Aripo Savannas provided in this and other sections are drawn from a study that was undertaken by the Caribbean Natural Resources Institute (CANARI) to prepare a literature review on the Aripo Savannas Environmentally Sensitive Area. 1 A recent history of the Aripo Savannas is provided in this table:

1

EMA, “Aripo Savannas Environmentally Sensitive Area Literature Review to Facilitate the Preparation of Management Plans,” (Prepared by CANARI, 2007a).

2

The Long Stretch Forest Reserve was established in January, 1934 under the Forest Ordinance Chapter 141 of 1916. The Long Stretch Forest Reserve is part of the Cumuto/ Arena Range under the management of the North West Conservancy.

3

SPNPPA has three main objectives: preservation of species, conservation of species, and protection of wildlife. The plan included 61 protected areas in six categories. SPNPPA was approved in principle by the Cabinet of Trinidad and Tobago. However, the legislation failed largely because of bureaucratic bickering and resource  managementconflict.

Figure 1: Old Army Bunker

Location & Topography In 1962, W.D. Richardson undertook vegetation and ecological studies of the Aripo Savannas. His studies yieldedveryimportantinformationabouttheflora,faunaandecosystemsthatexistinAripoSavannas.Many subsequent studies have been based on these fundamental studies undertaken by Richardson, and information for his studies is still used quite extensively. Many of the descriptions provided in the sections on Climate, Soils, Vegetation and Flora are based on Richardson’s work. 4 The ASESA is located at latitude 100 35’ 30’’ N and longitude 610 12’ 0’’, and is bordered to the north by the Valencia River, to the east by the Eastern Main Road between Valencia and Sangre Grande, to the West by the Aripo River and to the south by the Trinidad Government Railway Reserve (now abandoned) - (see Figure 2). The area of the ASESA is 1788 hectares. The open savannas cover a total area of 267 hectares, and comprise three large savannas between 60.7 hectares and 80.9 hectares, one a little under 40.5 hectares, and a number of smallsavannasalllessthan10.1hectares.Thesavannasaregenerallyflatandrisegentlytothenorth. The microtopography, however, is undulating or broken up into hummocks in some places. The savannas are situated on old alluvial terraces elevated 30 to 45m above sea level. These terraces fan out from the foothills of the Northern Range and consist of layers of gravel, sands and clays representing depositional environments believed to be of Pleistocene age.

4

W. D. Richardson, “Observations of the Vegetation and Ecology of the Aripo Savannas Trinidad,” The Journal of Ecology, 51 no.2 (1962), 295-313.

The ASESA is delineated by the redlineinthefigureopposite. The savannas are numbered 1 to 10. Savannas 9 and 10 are not showninthisfigure.Savanna 1 is generally used for public visits to the savannas.

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Figure 2: Map of Aripo Savannas

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Source: EMA (2008 b)

Climate Rainfall Average annual rainfall ranges from 2400 to 2600mm, with two distinctseasonalfluctuations;thedry(JanuarytoMay)andwet (June to December) seasons.5 The seasonal variation of the rain is determined mainly by the annual north-south migration of the Inter Tropical Convergence Zone. Temperature and Sunlight Monthly temperatures in Trinidad range from minimum of 22.7oC to a maximum of 31.3oC. 6 The average number of hours of sunshine for Trinidad is 7.2 hours.

Humidity and Winds During the night and pre-dawn, relative humidity (RH) may be at 100%. In the dry season RH may be 60% in the afternoon and in the wet season 75%. The prevailing wind direction changes from dry season to wet season. During the dry season prevailing winds are from the north-east, whilst during the wet season prevailing winds are from the south-east. Wind speeds seldom exceed 40 kph and are higher during the dry season - particularly in the afternoon.

Soils In 1953, W. P. Panton produced a study on the soils of the Aripo Savanna district.7 Panton’s work provides the majority of the information used in this section. 7 Most of the soil in the savannas has some clay component and can be divided into four slightly differentsoilprofiles.(See Table 2.) These differences are attributed principally to slight textural variations in the parent material. Weathering and groundwater movements have modifiedalluvialmaterialandcreatedahardpan layer (claypan) of cemented clays that is impervious to water movement. The claypan underlies the ASESA at varying depths, and in places where the claypan is close to the surface floodingoccurs.Theclaypanisthemajordriver contributingtofloodingofthesavannas. Someofthesavannasbecomefloodedonlyafter a rainfall event, for example savanna 1, while Figure 3: Flooded Section of Savanna 1 there are others that remain inundated for the entire wet season, for example savanna 9. The waterlogged conditions during the wet season inhibit root growth and function due to a lack of oxygen - a condition called “physiological drought”. Alternatively, in the dry season, the sandy soils dry out rapidly and give rise to physical drought. Also, as the claypan and fragipan dry out, they become extremely hard so that roots can no longer penetrate to the lower horizons, nor can water move upwards through the soil. Plants, however, have adapted to the conditions of low nutrient availability and the floodingordroughtinthesavannasandspecialisedformsofplantscontinuetothriveinthearea.Someofthe adaptations of plants to the conditions in the ASESA will be described in the section on vegetation. 5

EMA, “State of the Environment Report”, 1998.

6

CSO, “First Compendium of Environmental Statistics Trinidad and Tobago”, (Ministry of Planning and Development of Trinidad and Tobago, 2007).

7

W. P. Panton, “Field and Laboratory Studies of the Soils of the Aripo Savanna District”, (Dip. diss. Imperial College of Tropical Agriculture Trinidad, 1953).

Table 2

Soil types of Aripo Savannas 8

Vegetation The uniqueness of the ecosystems (high density of rare, threatened and endemic species) of the ASESA has promptedmanagementoftheAripoSavannassince1980.AnumberofstudiesonthefloraofASESAhavebeen undertaken by J.S. Beard in 1946, W.D. Richardson in 1962, S.I. Schwab in 1985 and others, and recorded a total of 457 plant species of which 39 are restricted to the Aripo Savannas, 16 to 20 are rare or threatened, and two are endemic. 9 Three main ecosystem types comprise the ASESA: open savannas, palm marsh and marsh forest. Open Savannas The soils of the open savannas are generally thin, low in nutrients and are underlaid by a claypan layer. Theshallownessoftheclaypanpreventslargestandsoftreesfrombeingestablished;individualtreesspaced far-apart from each other are more common. 10 Sedges, grasses and herbs dominate the savanna landscape. Some examples of these include Lagenocarpus tremulus (herbaceous sedge), Lagenocarpus guianensis (herbaceous sedge), Chrysobalanus icaco var. pellocarpa (shrub), Miconia ciliate (shrub), Paspalum pulchellum (herb), and Rhynchospora barbata (herb). Ground orchids like Otostylis brachystalix, Pogonia tenuis, and Epistephium parviflorum are also found in the savannas. Anumberofspeciesarerareorconfinedtothesesavannas;theyinclude clubmoss and several species of bladderwort. 11 The sundew is an insectivorous (consumes insects) plant growing in the savannas. Insectivorous plants, like the sundew, are typical of environments where nitrogen and other nutrients are limited. The plants consume insects for nitrogen. In this way, the sundew Figure 4: Sundew compensates for the low soil nutrition of the savanna soils. 8

Panton 1953

9

EMA 2007a

10

EMA,“AdministrativeRecordfortheEnvironmentallySensitiveArea:AripoSavannasScientificReserve”,(PortofSpainTrinidad,2007b). Forestry Division Ministry of Agriculture, Lands, and Fisheries, “Technical Document Forestry Division/ OAS Project on the Establishment of a system of National Parks and Protected Areas”, (Port of Spain Trinidad, 1980).

11

Marsh Forest The marsh forest covers most of the land area of the ASESA. This forest surrounds the other two plant communities and in places it joins the palm marsh community. The marsh forestisfloodedforseveralmonthsofthe year (during the wet season), and the plants in the marsh forest have adapted to these alternatingfloodinganddryconditions. Flooding is a result of the claypan which underlies the marsh forest (see explanation in section on soil). The claypan under the marsh forest is thinner and deeper than in the open savannas. The root systems of some plants, such as palms, penetrate deep into the claypan where other roots cannot. This feature allows the palms to access water during drought periods and to protect the roots from physiological drought. Another example of a plant which has Figure 5: Marsh Forest adapted to the conditions is the moriche palm whichhasaerialrootsthatallowforapartoftheroottobeoutofthewaterinfloodedconditions. The difference in plant communities between the open savannas and the marsh forest is stark and the ecotone therefore is very narrow and sharp. The plant community in the marsh forest can be separated into strata: the upper stratum trees consist of wild kaimit, yellow mangue, bois bande and cajuca and the lower stratum consists of biscuit-wood and agalie. 12 There are a few species of plants that are restricted to the marsh forest, for example, the lady slipper orchid. Palm Marsh The palm marsh community is found fringing the savannas in a belt usually 20m wide, and in clumps in the open savannas. 13 The palm marsh usually comprises a moriche palm - fat pork association. Inecology,an“association”isdefined as a group of organisms that live together in a geographical region and constitute a community with a few dominant species. The moriche palms form evenly spaced stands with a thick understory of shrubs or tall sedges or grasses.14

12 13 14

Figure 6: Palm Island

Forestry Division 1980 J. S. Beard, “The Natural Vegetation of Trinidad”, (Oxford Forest Mem. 20, 1946). EMA 2007b

Fauna The Aripo savannas support a diverse group of organisms many of which are rare or threatened. These include the red brocket deer, armadillo, agouti, lappe, opossum and porcupine. Earthworms also inhabit the open savannas. Inthewetseason,earthwormactivitybecomesvisibleonthesavannaseveninlow-floodedconditions;the worm casts build up mounds of dirt that rise above the water surface. 15 Worm casts are biologically active mounds containing thousands of bacteria, enzymes and remnants of plant materials that were not digested by the earthworm. 16 Termites are also found on the savanna landscape and their ground nests can be found scatteredovertheopensavanna.Inflatareasthenestsareoftenfoundassociatedwithsmallclumpsof vegetation. The plant communities in ASESA provide a diverse array of habitats for birds. Rare species of birds include the scarlet-shouldered parrotlet, the white-tailed golden-throat hummingbird, the savanna hawk, thesulphuryflycatcherandred-belliedmacawwhichfeedsontheseedsofthemorichepalms. 17 Duringthefloodedconditionsthesavannassupportseveralspeciesoffishes,frogsandreptiles.Waterboasand caimans are common in the savannas occupying the palm marsh and marsh forest communities. 18

15

Richardson 1962

16

MaryAppelhof,“WormsEatMyGarbage”,(MichiganUSA:FlowerfieldEnterprises,2006),68.

17

EMA, “Managing Together: a summary of the management plans for the Aripo Savannas, and environmentally sensitive area”, (prepared by CANARI, 2008a).

18

Forestry Division 1980

Section 2 This section focuses on one of the options that exist for addressing some of the drivers that impact on the Aripo Savannas and surrounding ecosystems. Teachers and students are encouraged to identify other possible driving forces acting on the Aripo Savannas, and some responses to these challenges. See the Administrative Record fortheEnvironmentallySensitiveArea:AripoSavannasScientificReserveorAripoSavannasEnvironmentally Sensitive Area Resource Management Plan: A Framework for Participatory Management for more information on drivers.

Figure 7: Some of the driving forces that impact on Aripo Savanna Environmentally Sensitive Area

Information for section 2 is drawn from two main sources. These are “Aripo Savannas Area Literature Review to Facilitate the Preparation of Management Plans” 19 and “Managing together: a summary of the management plans for the Aripo Savannas, an environmentally sensitive area” 20: both of these documents were prepared by CANARI.

Quarrying Areas within the ASESA – mainly along the Aripo River - have been mined for gravel, sand and clay for use in thelocalconstructionindustrysincethe1960s.KPQuarrieswasthefirstquarryingcompanytominetheAripo Savannas. In 1979, KP began operations on 16 hectares of the northern part of the Aripo Savannas on a one year lease. Mining operations continued until 1996 when KP Quarries pulled out of the ASESA. During the seventeen-year period, the company mined approximately 60 hectares of the area. However, KP Quarries was not the only mining operator during this time. In 1982, six companies were known to be operating on 162 hectares of the savannas and royalties were being accepted by the government on a gravel load basis. Mining operations physically damaged the savannas, and in some areas intense excavation and wash plant activities irremediably destroyed the ecology. Comparison of aerial photos of the Aripo Savannas taken in 1969 and 1994 showed that the area in the south-western part of the savannas to the north of Savanna 1 and immediately to the east of the Aripo River was destroyed by quarrying. The EMA has noted that quarrying has disturbed 2 to 5% of the marsh forest and palm marsh communities. Although quarry operations have been stopped in the ASESA, the effects are still felt (Box 1). The high demand for aggregates for the local construction industry puts the ASESA at risk for quarrying in the future. This demand from the local construction industry is an example of an indirect driver. 19

EMA 2007a

20

EMA 2007b

Mining operations physically damaged the savannas, and in some areas intense excavation and wash plant activities irremediably destroyed the ecology. Comparison of aerial photos of the Aripo Savannas taken in 1969 and 1994 showed that the area in the south-western part of the savannas to the north of Savanna 1 and immediately to the east of the Aripo River was destroyed by quarrying. The EMA has noted that quarrying has disturbed 2 to 5% of the marsh forest and palm marsh communities. Although quarry operations have been stopped in the ASESA, the effects are still felt (Box 1). The high demand for aggregates for the local construction industry puts the ASESA at risk for quarrying in the future. This demand from the local construction industry is an example of an indirect driver.

Figure 8: Black River

Discussion: Can the problems due to quarrying be reversed? If yes, how can it be done? See the Administrative Record for the Environmentally Sensitive Area: Aripo Savannas ScientificReserveorAripoSavannasEnvironmentally Sensitive Area Resource Management Plan: A Framework for Participatory Management for more information. These two documents are available on EMA’s website.

21

Edmund Charles, Interview, September 2008.

One of the forest marsh communities situated to the northwestern edge of Savanna 1 is an example of the effects of quarrying on the savannas. KP Quarries - while in operation - constructed a road through the savannas for ease of access to the quarrying site. The road acted as a dam to the Black River and causedfloodinginoneoftheadjacentforestmarshcommunities. The damming of the Black River causes water to inundate that forest marsh community for almost the entire year, and has a detrimental effect on the growth of palms. The palms in that forest marsh community are now experiencing crown thinning disease. Crown thinning disease is usually a result of chronic stress;inthiscasethestressisthecontinuouspresenceofwater to which the palms are unaccustomed. 21

Fire FireisamajorproblemforthebiodiversitywithintheASESA.Thedirectimpactoffireisinjuryormortality offloraandfauna.Theindirectimpactincludesthepossiblelossorchangeinbiodiversity.Whenfiresburn trees, understory plants or ground vegetation, the microclimate of the area can be radically altered, and this can subsequently affect recovery of the forest. For example, the removal of trees can result in a decrease in humidity of an area, which can cause leaf litter to dry out, and increase the susceptibility to burning. Thechangeinmicroclimatealsoreducestheabilityoftheforesttorecoverfromdisturbance.Largefiresoccurredin1987and2003,anditissuggestedthattheseweretheresultofhumancarelessness.Thesefiressignificantlydamagedlargeareasofpalmswampandmarshforest.Itissuggestedthatfiresareactuallysetbyhunterstolureanimalsoutoftheforestedareas.IllegalfarmersmayalsosetfirestoclearareasoftheASESAfor agriculture.

Hunting Hunting for animals in the Aripo Savannas occurred on a regular basis during pre-Colombian and historic Amerindian times. Trapping and removal of birds – particularly for the brilliantly-coloured feathers of the red-bellied macaw – was common in the savannas. Indigenous peoples kept birds as pets and also used the feathers for decorative purposes. Legal restrictions linked to the protected area status of Aripo Savannas prohibit unlawful entry into the area for hunting. The lack of adequate surveillance over the savannas, coupled with the lucrative price of wild meat (that is, the meat of animals not reared for human consumption) encourages illegal hunting of small gameincludingdeerandlappe.Illegalcollectionoffloraandfaunaforprivatecollectionsandforsaleisalso a common occurrence.

Disturbance Residential and agricultural squatting is highlighted as a major problem in the management of the Aripo Savannas. In 2003, it was estimated that approximately 375 hectares of land within the savannas was squatted upon. Clearingthelandforagriculture,aswellasextensivefiresandquarryinghavegreatlyimpactedontheecology of some areas in the savannas. Forester Edmund Charles notes that squatting takes place on the borders of the savannas. From comparisons of aerial photos of the Aripo Savannas taken in 1969 and 1994, ecologist Michael Oatham concluded that the status of the savanna ecosyst...