Environmental changes in biodiversity hotspot ecosystems of
South Ecuador: RESPonse and feedback effECTs (FOR2730)

Abstract:

Human influence and its impacts are perceptible in all ecosystems resulting in land transformation, changes in global biogeochemistry, climate change, and loss of biological diversity. Mapping the spatial and temporal patterns of human influence is essential to address land use management and conservation programs. In this study, we tailored the Human Footprint index (HF) developed at global level to evaluate the spatial and temporal patterns of human pressure in South Ecuador for 1982, 1990 and 2008. Landscape and ecosystem levels were analyzed to identify the contribution of different human proxies to the HF.We also used the HF to evaluate the effectiveness of protected areas to reduce human pressure in the surrounding landscape. We found that levels of human pressure increased and the wildest areas decreased since 1982. We identified important “hotspots of changes” in the seasonally dry forests in the western part and the premontane evergreen forest in the eastern part of the study area. Our results show that each human proxy contributes in a different way to the observed values of HF in the studied ecosystems. Finally, we found that Podocarpus NP, the most important protected area in our study region, seems to be partially effective in reducing human pressure inside and in the buffer zones where only a low increase in HF was detected. However, the HF values observed in the surrounding landscape were higher than those observed in the buffer zone and inside the protected area. We demonstrated that HF could be a useful regional evaluation tool to facilitate conservation planning.

Abstract:

The forests of South Ecuador have high conservation value because they are highly threatened, but also possess high diversity and endemism levels. However, as the process of conservation is inherently spatial, the little available information about the factors that promote vulnerability of these forests as well as the spatial distribution of the conservation targets have produced some conservation pitfalls. The main objective of this dissertation was to generate spatial information about the threats and biological values occurring in this region to prioritize areas for conservation. The second chapter analyzes the deforestation and fragmentation patterns in the region since the 1970s using aerial photographs and satellite images to identify areas with remaining forest, fronts of deforestation, annual deforestation rates and the dynamics in the composition and configuration of the landscape of South Ecuador. We recorded annual deforestation rates of 0.75% (1976 – 1989) and 2.86% (1989 – 2008) for two consecutive survey periods. Also, we found that South Ecuador is experiencing an ongoing fragmentation process due to an increase in the number of patches, a decrease in mean patch size and an increase in the isolation of forest fragments. This study also contributes to a better understanding of forest change dynamics in the tropics. We found that substantial portions of natural forests are being degraded or converted into pastures and that main fronts of deforestation are located in the lowest areas in the premontane evergreen forest. The third chapter describes the temporal and spatial patterns of human pressure, as it is one of the main factors that influence the effectiveness of conservation strategies. At local scale, we adapted at local scale the Human Footprint Index (HF) developed by Sanderson et al. (2002), to evaluate spatial changes in HF during a 26 year period at both landscape and ecosystem levels. This information allowed us to identify “hotspots of change” and the wildest areas remaining in order to evaluate how different human proxies contribute to HF and to demonstrate how effective the most important protected areas have been in reducing human pressure inside and outside their boundaries. The findings show a noticeable 4 increase in human pressure levels in South Ecuador and a progressive reduction in the wildest areas. We also identified that the important “hotspots of changes” are located in the western region and the Rio Zamora river basin. The most impacted vegetation types were seasonally dry forest and shrubland. Here, population density is the human proxy with the highest contribution to the observed patterns. Finally, we found that Podocarpus National Park has been partially effective in reducing human pressure inside and outside its borders. HF levels have increased inside and outside the boundaries of the protected area, but the human pressure was always lower than that observed in the surrounding landscape. The fourth chapter analyzes the patterns of alpha and beta diversity of endemic plant species to evaluate the congruence of both patterns and to identify areas with the highest diversity of endemic plants in order to prioritize areas for conservation. We found that hotspots of alpha diversity are concentrated along the Andes, but this diversity was only slightly congruent with beta diversity patterns of endemic plants mostly concentrated in the western and eastern escarpments of the Andes, and in the Coastal and Amazon cordilleras. We also found that approximately 40% of the areas with the highest alpha and beta diversities have already disappeared due to deforestation and that only 30% is under protection in Ecuador. Thus, we propose 12 potential areas with a high priority of conservation mostly located in South Ecuador to improve the representativeness and complementarity of the current reserve network. Finally, the fifth chapter synthesizes the principal findings of this thesis highlighting the implications for conservation and suggesting potential areas to be preserved based on human pressure levels, remaining forest and alpha and beta diversity patterns of endemic plants.

Abstract:

To reconstruct the environmental history including vegetation, fire and climate dynamics, from the Cajanuma valley area (3285 m elevation) in the Podocarpus National Park, southern Ecuador, we address the following major research question: (1) How did the mountain vegetation developed during the late Glacial and Holocene? (2) Did fire played an important control on the vegetation change and was it natural or of anthropogenic origin?. Palaeoenvironmental changes were investigated using multiple proxies such as pollen, spores, charcoal analyses and radiocarbon dating. Pollen data indicated that during the late Glacial and transition to the early Holocene (ca. 16 000–10 500 cal yr BP) herb páramo was the main vegetation type around the study area, while subpáramo and mountain rainforest were scarcely represented. The early and mid-Holocene (ca. 10 500 to 5600 cal yr BP) is marked by high abundance of páramo during the early Holocene followed by a slight expansion of mountain forest during the mid-Holocene. During the mid- to late Holocene (ca. 5600–1200 cal yr BP) there is a significant presence of páramo and subpáramo while Lower Mountain Forest decreased substantially, although, Upper Mountain Forest remained relatively stable during this period. The late Holocene, from ca. 1200 cal yr BP to present, was characterized by páramo; however, mountain forest and subpáramo presented significantly abundance compared to the previous periods. Fires became frequent since the late Holocene. The marked increased local and regional fire intensity during the wetter late Holocene strongly suggests that were of anthropogenic origin. During the late Glacial and early Holocene, the upper forest line was located at low elevations; but shifted slightly upslope to higher elevations during the mid-Holocene.

Abstract:

Late Holocene human impact and environmental changes were reconstructed from a sediment core of the Laguna Daniel Alvarez (2200 m asl) located on the outskirts of the city of Loja, southeastern Ecuador. Palaeoenvironmental changes were investigated by pollen, spore, algae and charcoal analysis in com- bination with X-Ray Fluorescence (XRF) scanning and element analysis of d13C, Total Organic Carbon (TOC), Total Nitrogen (TN) and radiocarbon dating. This multi-proxy study provides in detail the set- tlement history in the inner-Andean dry valley in southern Ecuador over the last ca. 1400 years. Between 630 and 1470 AD, Zea mays was intensively cultivated around the studied lake by the native Palta culture in the Loja region. After ca. 1470 AD, Z. mays cultivation collapsed, accompanied by an increase in fallow vegetation, such as Mimosa and Poaceae, probably as a result of the Inca invasion and occupation from 1463 to 1531 AD in southern Ecuador. After ca. 1570 AD, Amaranthaceae/Chenopo- diaceae markedly increased, re?ecting the beginning of the Spanish Conquest. In 1531 AD, Loja became Spanish and, during the ?rst ca. 100 years of the Spanish regime, Loja developed into the forti?ed capital of the province. In the 17th century, crop growing strongly declined due to the diminished indigenous population that probably suffered from new diseases introduced by the Spanish invaders. Pinus and Eucalyptus as well as Plantago lanceolata were introduced in the Loja region about 220 years ago.

Abstract:

Forest fragmentation can negatively affect tropical epiphyte diversity, but the processes leading to such impoverishment are insufficiently understood. Due to a lack of experimental studies, the relative influence of dispersal constraints vs. growth conditions remains particularly controversial. This paper addresses the fate of late juvenile and adult vascular epiphytes in response to severe forest disturbance in montane southern Ecuador. Plant growth and survival on trunks and lower branches of isolated remnant trees was studied for the first three years following clear-cutting. Overall epiphyte mortality was substantially increased on remnant trees (72% over 3 years) relative to undisturbed forest (11%). Mortality on remnant trees was higher during the first year (52%) than during the second (20%) and third year (26%). Pteridophytes and dicots suffered higher losses than monocots. Plants surviving on remnant trees generally showed a marked negative growth regarding maximum leaf length, whereas the annual increment in leaf number varied more strongly among taxa (families). The present study provides the first field-experimental evidence for the adverse effects of forest disturbance on the performance of later, well-established life stages of vascular epiphytes. The results suggest that growth conditions may often be a more important predictor of epiphyte diversity in disturbed habitats than dispersal constraints. Similar plant responses can be expected to occur along forest edges. Therefore, the retention of scattered green trees, narrow strips or small fragments of forest are unlikely to be sufficient management tools for the conservation of epiphyte diversity in tropical landscapes.

Abstract:

Although vascular epiphytes contribute substantially to the biodiversity of tropical montane forests, it is unclear how their diversity and community composition is affected by forest alteration. We studied the response of vascular epiphyte assemblages to different intensities of land-use in a montane wet forest of northeastern Ecuador: (1) unmanaged mature forest; (2) mature forest with mid- and understorey opened for cattle grazing; and (3) isolated remnant trees in cattle pastures. The numbers of individuals and species of epiphytes per host tree did not differ significantly between land-use types, neither did total epiphyte species richness (n = 30 trees). However, total species richness of pteridophytes was significantly lower on isolated remnant trees compared to unmanaged forest, whereas several taxa rich in xerotolerant species (Bromeliaceae, Orchidaceae, Piperaceae) exhibited the opposite trend. An analysis of floristic composition using ordination (NMS) and randomisation techniques (MRPP) showed that epiphyte assemblages on isolated remnant trees were significantly distinct from unmanaged forest while managed forest was intermediate between those two vegetation types. Ordination analysis further indicated reduced floristic heterogeneity in disturbed habitats. These results suggest considerable, rapid species turnover since land-use change 6 years prior to study, with pteridophytes being replaced by more xerotolerant taxa. We attribute this floristic turnover primarily to changes in microclimate towards higher levels of light and desiccation stress associated with forest disturbance. Our results support the notion that community composition offers a more sensitive indicator of human disturbance than species richness.