Temporal and spatial variation of litter production in Sonoran Desert communities
Temporal and spatial variation of litter production in Sonoran Desert communities
复制标题
索诺兰沙漠群落凋落物产生的时空变化
作者：
A. Martínez;Silvia Núñez;Haydeé Miranda;A. Búrquez
对索诺兰沙漠南部边界附近三个相邻沙漠群落的凋落物产生的季节性模式进行了分析。年凋落物产量存在较大的空间差异，主要是由于植被组成和结构的差异造成的。在生产力最高的地点（阿罗约斯），年凋落物量为 357 g m-2yr-1，这个数字高于一些热带落叶林。在平原（平原）的开阔沙漠中，凋落物产量仅为 60 克 m-2yr-1，在山坡（山坡）的荆棘丛中，凋落物产量为 157 克 m-2yr-1。地形和水文特征影响植被的组成、结构和功能，改变沙漠生态系统降雨量和生产力之间的一般关系。凋落物产生的时间模式表现出明显的季节性，有两个主要的凋落物大量减少时期：一个是在9月至11月的夏季降雨之后（秋季凋落物产生），另一个是在3月至5月的冬季降雨之后（春季凋落物产生）。在开阔的沙漠地区，春季凋落物产量明显高于秋季产量，而在斜坡地区，秋季产量最为重要。阿罗约斯遗址在两个旱季期间产生了类似的垃圾量。物种组成决定了最大落叶的季节。在平原，短暂性和多年生植物的旺盛冬季生长构成了凋落物产量的大部分，而在山坡上，大多数多年生植物在整个冬春季节保持休眠状态，仅在夏季生长之后才出现了凋落物的显着高峰。在阿罗约地区，季节之间的生长差异不太明显。繁殖和木质凋落物最大产量的时间也因地点而异。
The seasonal pattern of litter production was analyzed in three contiguous desert communities near the southern boundaries of the Sonoran Desert. There was a large spatial variation in annual litter production mainly caused by differences in the composition and structure of vegetation. In the most productive site (Arroyos) annual litterfall was 357 g m-2yr-1, a figure higher than some tropical deciduous forests. Litter production was only 60g m-2yr-1in the open desert in the plains (Plains) and 157 g m-2yr-1 in the thornscrub on the slopes (Hillsides). Topographic and hydrologic features influence the composition, structure and function of the vegetation, modifying the general relationship between rainfall and productivity described for desert ecosystems. The temporal pattern of litter production showed marked seasonality with two main periods of heavy litterfall: one after the summer rains from September to November (autumn litter production) and another after the winter rains from March to May (spring litter production). In the open desert areas, spring litter production was significantly higher than the autumn pulse, while in the slopes, the autumn production was the most important. The Arroyos site produced similar litterfall amounts during the two dry seasons. The species composition defined the season of maximum leaf-fall. In the Plains, the vigorous winter growth of ephemeral and perennial plants made up most of the litter production, while in the Hillsides, most perennials remained dormant throughout the winter-spring period and a significant peak of litterfall occurred only after the summer growth. This difference in growth between seasons was less pronounced in the Arroyos. The timing of maximum production of reproductive and woody litter also differed from site to site.