Satellite Images Combined with Field Data Reveal Negative Changes in the Distribution of Babassu Palms after Clearing off Amazonian Forests

Abstract

When the Amazonian rain forest is cut to create pasture, some of the original vegetal species survive clearing, even expressing their ability to invade agro-systems. It is true of the babassu palm, which can be considered, paradoxically, a natural resource by the "Interstate Movement of Babassu Fruit Breaker Women" or as native weed by land owners-farmers. To manage potential conflict of land uses, we study here the current density of this palm tree in different habitats, based on a combination of field data and remote sensing data. Firstly, we checked that the field survey methodology (i.e., counting free-trunk palm trees over 20 cm in circumference) provides density values compatible with those stemming from satellite images interpretation. We can see then that, a PA-Benfica Brazilian territory revealed an average density of the babassu lower in pastures (2.86 ind/ha) than in the dense forest (4.72 ind/ha) from which they originate and than in fallow land (4.31 ind/ha). We analyze in detail density data repartition in three habitats and we discuss results from the literature on the density of this palm tree versus its resilience at different developmental stages after forest clearing, depending on anthropogenic-or not-factors, including solar radiation, fire, weeding, clear cutting, burying fruit, and competition with forage grass. All these results can be exploited for the design of future management plans for the babassu palm and we think that the linked methodology and interdisciplinary approach can be extended to others palms and trees species in similar problematic issues.

Deforestation effects on Attalea palms and their resident Rhodnius, vectors of Chagas disease, in eastern Amazonia

“…Stage I: Clearcut. Our findings indicate that deforestation for cattle ranching has a negative impact on adult Attalea populations; the intuition (or perception) that palms are more abundant in CP than in preserved landscapes [17,27,33,52] seems to be driven by the fact that palms are just easier to see in open land than in denser forest (Table 3, Fig 3). Our results suggest that as many as~70-80% of adult Attalea palms may be felled as OGF is converted to CP.…”

“…In consultation with municipal and state health officials, we selected two rural localities (which we will call simply "L1" and "L2" hereafter) located~30 km apart (~50 km by road) and with similar settlement and land-use patterns-small house clusters plus scattered farms (yielding < 2.0 residents per km 2 ) on land originally covered by moist broadleaf forest but now including three landscape classes clearly differing in their degree of anthropogenic disturbance [27]: i. Old-growth forest ("OGF" hereafter), i.e., relatively large patches (> 500 ha) of mature, well-preserved forest-either apparently uncut or in late-stage recovery;…”

“…Stage II: Recovery. Attalea palms are among the pioneers of secondary-forest regrowth when Amazonian land converted to CP is abandoned [27]. Our data reflect this as an increase of palm density estimates in YSF relative to CP; the much higher YSF palm density in L2 (~62 adult Attalea per ha) than in L1 (~16 per ha) is likely due to a longer period of forest regrowth in our L2 transect-as also suggested by the faster rate of decline of palm detections (Fig 3) and by the taller stems of YSF palms in L2 (mean 4.7 m, SD 1.5) than in L1 (3.9 m, SD 0.9) (see S2 Dataset).…”

“…Chagas disease transmission risk is therefore thought to be higher in disturbed landscapes where Attalea palms are abundant near houses [17,18,21,22]. For example, Attalea palms dominate many rural landscapes of eastern Amazonia-the region from which the vast majority of acute Chagas disease outbreaks has been reported in the last decades [21][22][23][24] and one in which destruction of native rainforests has been particularly extensive over the same time-period [25][26][27]. However, and in spite of the public-health implications of a possible link between deforestation and Chagas disease risk, the responses of Amazonian Attalea palms and their resident Rhodnius populations to anthropogenic landscape disturbance remain largely uncharted (but see [14,17,18,27]).…”

Attalea speciosa, die Babassupalme

“…Im trockenen Cerrado und auf weidewirtschaftlich genutzten Flächen taucht sie bevorzugt in kleinen Gruppen oder in Form einzelner Individuen auf (Anderson & Balick 1988). Die Verbreitung der Art verdeutlicht, dass A. speciosa nicht nur in feuchten und trockenen tropischen Gebieten gedeiht, sondern auch relativ resistent gegenüber Störung durch den Menschen ist (Mitja et al 2018). Heutzutage ist der Artenkomplex im Amazonasgebiet und im Cerrado weit verbreitet, jedoch wird sein Entstehungsort eher im tropischen Regenwald vermutet, mit späterer Besiedlung trockenerer Lebensräume (Mitja & Ferraz 2001).…”