SMES vegetation quadrat data

The purpose of this study is to determine whether or not
the activities of small mammals regulate plant community
structure, plant species diversity, and spatial vegetation
patterns in Chihuahuan Desert shrublands and grasslands. What
role if any do indigenous small mammal consumers have in
maintaining desertified landscapes in the Chihuahuan Desert?
Additionally, how do the effects of small mammals interact with
changing climate to affect vegetation patterns over time? This
study will provide long-term experimental tests of the roles of
consumers on ecosystem pattern and process across a latitudinal
climate gradient. The following questions or hypotheses will be
addressed.

1) Do small mammals influence patterns of plant species
composition and diversity, vegetation structure, and
spatial patterns of vegetation canopy cover and biomass
in Chihuahuan Desert shrublands and grasslands? Are small
mammals keystone species that determine plant species
composition and physiognomy of Chihuahuan Desert
communities as Brown and Heske (1990a) and Gibbens et al.
(1993) suggest? Do small mammals have a significant role
in maintaining the existence of shrub islands and spatial
heterogeneity of creosotebush shrub communities?

2) Do small mammals affect the taxonomic composition and
spatial pattern of vegetation similarly or differently in
grassland communities as compared to shrub communities?
How do patterns compare between grassland and shrubland
sites, and how do these relatively small scale patterns
relate to overall landscape vegetation patterns?

3) Do small mammals interact with short-term (annual) and long-term (decades) climate change to affect temporal
changes in vegetation spatial patterns and species
composition?

本研究旨在探究小型哺乳动物的活动是否会调控奇瓦瓦荒漠灌丛与草原中的植物群落结构、植物物种多样性以及植被空间格局。本土小型哺乳动物消费者在维持奇瓦瓦荒漠荒漠化景观中发挥着何种作用（若存在的话）？此外，小型哺乳动物的影响如何与气候变化相互作用，进而随时间推移影响植被格局？本研究将针对跨纬度气候梯度下消费者对生态系统格局与过程的作用开展长期实验验证。本次研究将解答以下问题与假说：

1) 小型哺乳动物是否会影响奇瓦瓦荒漠灌丛与草原中的植物物种组成与多样性格局、植被结构，以及植被盖度与生物量的空间分布格局？正如Brown与Heske（1990a）以及Gibbens等人（1993）所提出的，小型哺乳动物是否为决定奇瓦瓦荒漠植物群落物种组成与外貌的关键种（keystone species）？小型哺乳动物在维持灌丛岛（shrub islands）的存续以及三齿拉雷亚灌木（creosotebush）群落的空间异质性方面是否发挥着显著作用？

2) 相较于灌丛群落，小型哺乳动物对草原群落的植被分类组成与空间格局的影响是相似还是存在差异？草原与灌丛样地的植被格局存在何种差异？这些相对微观尺度的格局又与整体景观植被格局存在何种关联？

3) 小型哺乳动物是否会与短期（年度）及长期（数十年）的气候变化相互作用，进而影响植被空间格局与物种组成的时间动态变化？