Rufford Small Grant (for Nature Conservation)

In association with the Whitley Laing Foundation GRASSES MATTER! RESTORING NATURAL GRASSLANDS AFFECTED BY INVASIVE WOODY PLANTS AND INCREASING PUBLIC SUPPORT FOR THEIR CONSERVATION CONTINUATION GRANT / FINAL REPORT

Name of Recipient and Organisation: SERGIO MARTÍN ZALBA GEKKO Grupo de Estudios en Conservación y Manejo Departamento de Biología, Bioquímica y Farmacia Universidad Nacional del Sur San Juan 670 (8000) Bahía Blanca - Argentina Tel: 54-291-4595100 Ext 2420 Fax: 54-291-4595130 Email: [email protected]

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INTRODUCTION The activities and results obtained between 2004 and 2005 in the project Grasses Matter! Restoring Natural Grasslands Affected by Invasive Woody Plants and Increasing Public Support for their Conservation funded by the Continuation Grant are presented in this report. During this period the strategy for controlling Aleppo pine (Pinus halepensis), the main invasive species in the study area, was optimised. Five homogenous management zones were established in the Ernesto Tornquist Provincial Park (ETPP) and the most appropriate method of control was determined for each one. The resources required for completing the control and recommended frequencies of complementary control actions were estimated. This information was used to adjust the control actions for this species, which allowed work to be carried out in areas of high conservation value in the reserve. To compliment this data, an evaluation of the importance of feral horse manure as an invasion window for the advance of pines and other invasive plants was carried out. At the same time, trials of the efficiency of four control methods (cutting, cutting and herbicide treatment of stems, herbicide spray, and fire) for the management of another highly invasive species, Spanish broom (Spartium junceum), were undertaken. Significant progress was made concerning the cultivation requirements of native plants of ornamental interest. In particular alternative techniques for stimulating germination and propagation of cuttings of two species of great ornamental value, Pavonia cymbalaria and Grindelia ventanensis, were tried out. The latter species is endemic to the study area. During the study period an intensive educational campaign was carried out to promote the value of natural grassland habitats, in which schools in the region of the reserve were targeted. Students and teachers from the neighbouring area of the ETPP took part in workshops based on a strategy of awareness, supported by games and artistic activities. The botanical garden was opened to the public twice a week as a result of support received from this project. This report is divided into five sections: Control of Alien Woody Plants; Cultivation Requirements of Native Plants; Education and Public Awareness; and Dissemination of the Project. Papers published during this project are cited throughout the report.

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1. CONTROL OF ALIEN WOODY PLANTS 1.1. Optimising the strategy for the control of Pinus halepensis Data concerning the extension and distribution of the pine invasion in the reserve was updated in order to optimise the strategy for the control of Pinus halepensis. Areas of different density were defined by means of an aerial photography survey, and were then verified on the ground. It was found that high density woods (more than 600 pines/ha.) occupy 1% of the reserve, those of medium density (200-600 pines/ha.) represented 2%, low density areas (10-200 pines/ha.) 16% of the total area, and those of very low density (less than 10 pines/ha.) occupied the largest percentage of the area: 73% of the reserve. Different management alternatives were analysed: biological control, grazing, felling, fire and application of herbicides, and their effectiveness, cost, environmental and social impact were considered, as well as any possible effect on public opinion. Control methods that had seldom been used, or were without confirmed results in the country or similar areas, or which lead to an impact that was not compatible with the objectives of the area, were rejected at this point. Each alternative method for control was evaluated to test its effectiveness in controlling the invasion, considering whether it was necessary to repeat control actions in the same area. The ecological impact of control actions carried out on the whole ecosystem, or more specifically on the problem species, was analysed. Literature reviews and field evaluations were carried out for both aspects. The variable cost and effort of the alternative methods of control were evaluated using field trials or by extrapolating information from previous work on other species. The social impact referred to the effects that the control actions might have on the neighbouring community of the reserve, including effects on public health, economic goods and activities. Public opinion might have opposed the use of some control methods whether or not they caused an impact. Therefore a search was made in the local media for the period 1943-2005 for issues relating to the management of the ETPP in order to analyse these aspects. Representatives of different sectors of the community were also consulted and the visual impact caused by the presence of fallen trees was monitored (1). The use of biological control was rejected since the method has not often been used and successful results on a large scale are unknown in other regions of the world. Sheep are the main control agents of conifers but grazing pressure only has an affect on young pines of less than two years. This method was not evaluated as an alternative as it would be impossible to eradicate the invasion of 1

CUEVAS, YA, ZALBA SM & RM BOÓ. 2005. Controlling invasive pines in a grassland nature reserve: Proposal of optimization. Annual Meeting of The Ecological Society of America, Mérida, México, 8 al 12/01/2006.

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pines already established in the Tornquist Park with this method. On the other hand, exotic herbivores actually encourage the establishment of pine seedlings (2), accelerate the establishment of scrub vegetation (3), and favour the propagation of other exotic species (4), according to results obtained from other studies in this project. The other alternatives evaluated for pine control: felling, controlled burning and herbicide application, were found to be the most appropriate methods and the most commonly used on a world scale, so they were selected as the best alternatives for the area. Mechanical or manual cutting are the most commonly used methods for controlling invasive plants. In the case of pines no regeneration was observed from underground shoots or stumps, if the trees were cut near to the base, and so this is highly effective when all foliage is eliminated. Mechanical and manual felling proved to be very specific methods that minimized damage to untargeted species. This technique was very effective during this project (5), although the recovery of native vegetation underneath the remains of the felled pines was slow, possibly due to the impact of accumulated pine needles under the felled trees. This effect was at a maximum at the time of felling but decreased over time (6) and the cleared areas showed good recovery with increased vegetation cover and species diversity (7). Moreover, felling is not associated with any impact on the inhabitants of the surrounding area (nil social impact). However when negative public opinion was considered, it was thought that as this alternative would result in notable visual impact it might lead to great opposition. This rejection would be due to elimination of the trees rather than the visual impact of felled trees, but according to our results this impact was overcome in approximately one year (6). Controlled burning is a method that affects the whole ecosystem, reducing the cover and density of the problem species, which can be applied to standing invasive plants or after cutting or application of herbicides. In the case of pines, in which fire stimulates seed release and creates appropriate conditions for establishment, the use of controlled burning of standing trees (not previously cut) might

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DE VILLALOBOS AE & ZALBA SM. 2003. Efecto del pastoreo sobre el establecimiento de plántulas de Pinus halepensis, una especie invasora de pastizales naturales. En Libro de Resúmenes XXIX Jornadas Argentinas de Botánica, San Luis, p. 73. 3

DE VILLALOBOS AE & ZALBA SM. 2004. Sobrepastoreo y modificación de la vegetación en una reserva de pastizal pampeano. En Libro de Resúmenes II Reunión Binacional de Ecología, Mendoza, p. 254. 4

LOYDI A & ZALBA SM. 2004. Impacto de los bosteaderos de caballos cimarrones sobre la flora de una reserva de pastizal pampeano. En Libro de Resúmenes II Reunión Binacional de Ecología, Mendoza, p. 207. 5

ZALBA SM, BARRIONUEVO LB, C UEVAS YA & DE VILLALOBOS AE. 2003. Restauración de ambientes naturales afectados por especies exóticas en el Parque Provincial Ernesto Tornquist. En Anales de las II Jornadas Interdisciplinarias del Sudoeste Bonaerense. Editorial de la Universidad Nacional del Sur. Bahía Blanca. 6

DISPIGNO L & ZALBA SM. 2003. Cambios en las comunidades vegetales luego del control de ejemplares aislados de Pinus halepensis. En Libro de Resúmenes XXIX Jornadas Argentinas de Botánica, San Luis, p. 68. 7

BARRIONUEVO LB, C UEVAS Y & ZALBA SM. 2001. Control de pinos en una reserva natural de pastizal pampeano. Libro de Resúmenes 1 er Encuentro Binacional de Ecología, Bariloche, p. 55

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promote the dispersal of the invasive species (8). However, fire is recommended as a complementary action to mechanical felling: felling the trees and leaving the felled trees on the ground allows seed release and then after one year controlled burning of the cleared area affects the established seedlings. However, considering the characteristics of the area (strong winds of variable direction) there is a high risk of fire spreading to adjoining properties and therefore controlled burning is considered as an alternative with high potential social impact. Herbicides have not often been used for controlling pines. The impact on untargeted species and on the environment as a whole (proximity to water sources, depth of the water table, etc.) requires careful consideration, especially when herbicides are used in natural areas. Moreover, its use implies risk of contamination, e.g. by affecting water courses or by accidental spills, with high potential social impact. These disadvantages can be reduced if the appropriate herbicides are selected, as well as the application method, area and timing. For the case in study the eventual use of herbicide is recommended in the form of a foliar application to young plants or the injection of trunks of mature standing pines. Various aspects of the reproductive biology of P. halepensis were studied, including the release of seed from cones of felled trees, variations in the germination percentage of these seeds according to the time of year in which the trees were felled and the survival of seeds in the ground, in order to evaluate the effective frequency of application of different control options, i.e. the time period before which it is necessary to control the species in previously cleared areas. The results showed that there was a massive opening of mature cones from felled trees that remained on the site. The percentage of cones that open was very high, varying between 72 and 90%. Most of the cones from felled pines cut at different times of the year open en masse during the summer following felling. Trees felled in November and January immediately released a large amount of seed. Pines felled in March showed two peaks of seed release: one immediately after felling, which ceased during the winter months and another the following summer ( nine months after felling). The cones of pines felled in May, July and September opened the following summer, so the cones remained closed for seven, five and three months respectively (Figure 1).

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ZUCCHINO EE & ZALBA SM. 2003. Efecto de un incendio sobre el establecimiento y la supervivencia de plántulas de Pinus halepensis en el Parque Provincial E. Tornquist. En Libro de Resúmenes XXIX Jornadas Argentinas de Botánica. San Luis, p. 74.

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Jan '02 Mar '03

3000

May '02 Jul '03

Sep '02 Nov '03

2500 2000 1500 1000

Jan-03

0

Jan-04

500 Jan-02

No. of released seeds

3500

Month and year Figure 1. Chronology of seed release from cones of pines felled in different seasons of the year (the arrows show the times of felling, and lines of the same colour represent seed release from cones of pines cut at that time).

The germination tests showed that seed released from pines felled in January, March, September and November (which were retained for a relatively short time in their cones) had significantly higher germination percentages (F=6,061; p