《Ecological Engineering》刊登“干旱对科罗拉多三角洲鸟类与河岸植被的影响”

作者：Osvel Hinojosa-Huerta，Pamela L. Nagler, Yamilett K. Carrillo-Guererro, Edward P. Glenn

刊物：《Ecological Engineering》，2013年，51卷，275-321页

关键词：干旱；河岸栖息地；河岸专属鸟类；洪水；怪柳；胡杨；柳树；牧豆

摘要：位于墨西哥的科罗拉多三角洲河岸走廊是全球重要的鸟类栖息地。来自美国和墨西哥的河流孕育了这里包括深根吸水植物在内的各种植物。本文研究了2002年至2007年间区域干旱对研究区海岸植被以及鸟类富裕度与多样性的影响。与1995年至2002年相比，研究区2002年至2007年的地表径流量显著减少，这导致当地树木（主要是某种柳树和杨树）覆盖面积大量减少，而灌木（主要是怪柳，这是一种引进的盐生植物灌木）覆盖面积却在逐渐增加。尽管如此，总体植被覆盖率还是维持在70%左右，总体鸟类种群密度和多样性也基本未变。此外，海岸专属物种在不断减少，而普通物种在不断增加。虽然流量减少削弱了栖息地价值，对海岸专属鸟类也造成了负面影响，但是海岸区域依然保持着自我修复性。尽管地表径流能够减少土壤盐碱化的发生，孕育新生树木，但维持当地生态系统的主要水源却是发源于美国和墨西哥灌区的地下水。在气候变化背景下，河川径流量将会减少，而人类对下垫面的改造会减少地下水的补给量，从而使土壤盐碱化加重，这都会令科罗拉多三角洲海岸栖息地的未来变得愈发不确定。如果当地政府希望永远保持这一块珍贵的栖息地，那么就需要实施更多积极的修复计划。

Effects of drought on birds and riparian vegetation in the Colorado River Delta, Mexico

Authors: Osvel Hinojosa-Huerta，Pamela L. Nagler, Yamilett K. Carrillo-Guererro, Edward P. Glenn

Journal: Ecological Engineering, Volume51, 2013, pages 275-321

Key words: Drought; Riparian habitats; Riparian-obligate birds; Floods; Climate change; Tamarix; Populus; Salix; Prosopis

Summary:

The riparian corridor in the delta of the Colorado River in Mexico supports internationally important bird habitat. The vegetation is maintained by surface flows from the U.S. and Mexico and by a high, non-saline aquifer into which the dominant phreatophytic shrubs and trees are rooted. We studied the effects of a regional drought on riparian vegetation and avian abundance and diversity from 2002 to 2007, during which time surface flows were markedly reduced compared to the period from 1995 to 2002. Reduced surface flows led to a reduction in native tree cover but an increase in shrub cover, mostly due to an increase in Tamarix spp., an introduced halophytic shrub, and a reduction in Populus fremontii and Salix gooddingii trees. However, overall vegetation cover was unchanged at about 70%. Overall bird density and diversity were also unchanged, but riparian-obligate species tended to decrease in abundance, and generalist species increased. Although reduction in surface flows reduced habitat value and negatively impacted riparian-obligate bird species, portions of the riparian zone exhibited resilience. Surface flows are required to reduce soil salt levels and germinate new cohorts of native trees, but the main source of water supporting this ecosystem is the aquifer, derived from underflows from irrigated fields in the U.S. and Mexico. The long-term prospects for delta riparian habitats are uncertain due to expected reduced flows of river water from climate change, and land use practices that will reduce underflows to the riparian aquifer and increase salinity levels. Active restoration programs would be needed if these habitats are to be preserved for the future.

原文链接: http://www.sciencedirect.com/science/article/pii/S0925857412004375