This week, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) issued an alarming report. Hundreds of thousands of different species of animals and plants are facing extinction because of human activity. Nature is declining globally at rates unprecedented in human history — and the rate of species extinctions is accelerating, with grave impacts on people around the world now likely.

The appreciation of the importance of biodiversity can be seen as we look carefully into the underlying idea behind a verse in this week’s parsha. There are a series of laws which deal with the intermingling of species:

Do not mate your animal into another species, do not plant your field with mixed seed; and a garment that is a mixture of combined fibres (wool and linen) shall not come upon you. (Vayikra 19:19.)

The Torah describes these prohibitions as a chok, a non-rational law. Nevertheless, the Spanish commentator, Rabbenu Bachya (1255-1340) sees in these laws a sensitivity to biodiversity. He writes that by mingling these different kinds, we are upsetting a cosmic order. We need to respect the created diversity of all parts of our world. By inappropriate mixing or grafting we are causing an imbalance in a pre-established pattern in creation.

Many of the problems that we are now experiencing in loss of species around the world come from excess deforestation. The independent Committee on Climate Change (CCC) advised the government last week that for Britain to cut greenhouse gasses to zero by 2050, we will need to plant almost three billion trees!

Our parsha refers to the planting of trees in the land of Israel:

When you come to the land and plant any fruit tree (Vayikra 19:23.)

The Midrash Tanhuma on this passage sees here, an ongoing requirement to plant trees:

When you come into the land and plant.” The Holy One, blessed be He, said to Israel, Even though you find it (i.e., the land) full of all bounty, you shall not say, ‘Let us settle down and not plant.’ Rather, be careful in planting, as stated, “and plant any tree for food.” Just as you came in and found plantings which others had planted, so you shall plant for your children, in case someone says, ‘Since I am old and tomorrow I shall die, why should I toil for others?’

Our current generation has been born into a world that has enjoyed the blessings of amazing biodiversity. It is our responsibility not to spoil this for the next generation.